ENT Notes - Clerkship 2019 PDF

ENT NOTES 1  OTOLOGY The Physiology Of Hearing Sound is a waveform of mechanical energy, which exerts pressure throughout the medium in which it is transmitted. Hearing (the perception of sound) is essential fo...

ENT NOTES 1  OTOLOGY The Physiology Of Hearing Sound is a waveform of mechanical energy, which exerts pressure throughout the medium in which it is transmitted. Hearing (the perception of sound) is essential for speech and language development, and is thus a prime prerequisite for communication. The pinna functions as a funnel that collects sound and transmits it to the external auditory canal. We can tell the direction of sound by the fact that sound will tend to be louder in the ipsilateral ear and will also arrive earlier at that ear. The external auditory canal amplifies sound in the frequency range 3-4 kHz. This is due to the resonating properties of the external auditory canal. For hearing to occur, sound needs to pass from air in the external canal into the fluid medium of the cochlea, wherein lie the pressure sensors – the hair cells. If sound should pass directly into the cochlea, over 99% of sound energy would be reflected at the interface. To match the impedance (resistance to sound transmission) of air to that of the cochlear fluid, we need an intervening mechanism for sound transmission. The tympanic membrane and the ossicular chain (malleus, incus and stapes) are responsible for "impedance matching”. A much greater pressure is required to transmit sound through liquid as compared to transmission by air. Pressure equals force divided by area. By the Hydraulic Principle, the same force that is exerted on the tympanic membrane, when exerted on the footplate of the stapes, will exert a pressure at the footplate that is 13 times greater than that at the tympanic membrane. This occurs because the ratio of the functional area of the tympanic membrane to that of the footplate of the stapes is 13 to 1. The pressure at the footplate of the stapes is further increased by the mechanical advantage gained by the lever system of the malleus and the incus. The relative lengths of the handle of the malleus to that of the long process of the incus is 1.3 to 1.0. The tympanic membrane and ossicular chain therefore increase the pressure at the footplate of the stapes 18 fold (1.3 times 14). A requirement for maximum sensitivity of the tympanic membrane to sound pressure is equality of pressure in the external auditory canal to that in the tympanic cavity. The Eustachian tube is responsible for maintaining the middle ear pressure close to atmospheric pressure. This ensures that energy is not wasted in overcoming any pressure differential across the tympanic membrane. The middle ear is a balanced system i.e. it moves about a fulcrum and the moments about that fulcrum are equal. The ossicles are suspended in the tympanic cavity by very tenuous ligaments. These provide minimal frictional force and resistance to movement. Sound pressure that reaches the inner ear produces travelling waves in the liquid of the cochlear duct and eventual movement of the basilar membrane. The sensitive receptor hair cells lie in the organ of Corti on the basilar membrane. We can identify the frequency of sound heard by the place on the basilar membrane that best responds (resonates) to that sound (Place Theory). High frequencies mainly stimulate the basal turn of the cochlea. The intensity of sound is predominantly detected by the rate of production of action potentials in the auditory nerve. Hearing loss Hearing loss can be broadly classified into conductive and sensorineural hearing loss. Conductive hearing loss occurs when conditions of the external ear or middle ear prevent efficient transfer of sound pressure to the inner ear. Conditions affecting the inner ear or the auditory nerve will lead to sensorineural hearing loss. 2  Common causes of conductive hearing Common causes of sensorineural loss hearing loss a) Otitis media with effusion--- a) Presbycusis---usually secondary to commonest cause in children ischaemia of the Organ of Corti b) Noise induced hearing loss b) Wax impaction--- common in all age groups c) Acute and chronic otitis media c) Ototoxicity (aminoglycosides, loop diuretics, cytotoxic agents e.g. Cisplatin, quinolones) d) Meningitis d) Ossicular chain discontinuity (post trauma or secondary to infection) e) Otosclerosis--- Second most e) Viral infections (Measles, Mumps, common cause in Caucasian adults Herpes Zoster etc) (after wax impaction) Presbycusis – progressive, bilaterally symmetrical perceptive hearing loss occurring with age usually at the higher frequencies Sensorineural Hearing Loss in Childhood a) 50%--- genetic origin ---majority autosomal recessive e.g. Usher's Syndrome ---Sensorineural hearing loss (SNHL) and retinitis pigmentosa Pendred's Syndrome (SNHL and hypothyroidism) b) 25-30%---Environmental factors Rubella and other members of TORCHS (toxoplasma, rubella, cytomegalovirus, herpes, HIV, hepatitis, and syphilis) group Meningitis Kernicterus Hypoxia perinatally c) Idiopathic (Unknown cause) Audiological Testing 3 a) Free field testing using whispered voice, conversational voice and loud voice b) Tuning fork tests –Rinne's, Weber and Absolute Bone Conduction Test 50% of patients with a conductive hearing loss of 20 dB will have a negative Rinne's (bone conduction better than air conduction). 90% of patients with a 40 dB conductive hearing loss will have a negative Rinne's. A negative Rinne's test therefore usually indicates a substantial conductive hearing loss. A false negative Rinne's test is associated with profound hearing loss. In such cases, no significant perception of sound occurs when the tuning fork is placed beside the ipsilateral ear. When the tuning fork is placed on the ipsilateral mastoid, bone conduction allows detection of the sound by the opposite cochlea. In the Weber's test, sound typically lateralizes to the ear with a conductive hearing loss. In a patient with a false negative Rinne's test, sound lateralizes to the good ear. The Absolute Bone Conduction Test is useful in the bilateral, equal sensorineural loss, when the Rinne would be positive and the Weber not lateralized. Here a doctor (who has normal hearing) compares his bone conduction with the patient's. c) Pure Tone Audiometry Here the patient's Air and Bone Conduction are tested for different frequencies in a sound proof environment. The threshold for each frequency is charted. One can detect and quantify both conductive and sensorineural hearing loss. Children 2-4 years will not be suitable for this test. Instead Behavioural Audiometry is used. In the latter test, sound is introduced while the child is occupied playing and one expects alteration of behaviour if the sound is heard. d) Impedance Audiometry used to elucidate: Middle Ear Pressure Compliance of Conductive system Acoustic Reflexes, indirectly giving an idea of the threshold of hearing Type of lesion in sensorineural loss Patients with middle ear effusions usually have Type B tympanograms (flat tracings) while those with negative middle ear pressures will have Type C curves (peak in the negative range) e) Otoacoustic emissions test This is a very important objective tool in neonatal hearing screening. The test is quickly administered and it does not require highly trained personnel to operate and interpret the test. Sound is introduced into the ear and sound emanating from the cochlea is detected in patients with hearing better than 30 dB. f) Auditory Brain Stem Response or Evoked Response Audiometry This is another objective test that is useful in neonates, in infants and in people who cannot or will not cooperate for hearing tests (malingerers).An auditory stimulus is introduced into the ear and this will result in electrical activity sequentially in the cochlear nerve, the cochlear nucleus, the superior olivary nucleus, the lateral lemniscus and the inferior colliculus. The test is repeated while a computer subtracts the background EEG activity leaving behind the response to the sound stimulus. Thus one can objectively follow the stimulus throughout the auditory system, and can detect problems therein. 4  VERTIGO AND THE PHYSIOLOGY OF BALANCE The maintenance of equilibrium at rest and in motion is achieved by a complex interaction of peripheral receptors and the central coordinating areas in the brain. The whole balance mechanism serves to orient the individual in space. 5  The peripheral sensory systems are 1. Vestibular system (semicircular canals, utricle and saccule) 2. Visual Pathway 3. Proprioceptive system Central coordination occurs in the cerebellum and the vestibular nuclei. There are also important inputs from the cerebral cortex, limbic system, red nucleus and substantia nigra that modulate these centres. Usually a positive activity in one side of the body is balanced by a negative activity on the contralateral side. Disequilibrium occurs when the inputs from one system does not match with those from the other systems. The cerebellum has a mainly dampening effect on vestibular nuclear activity, inhibiting excessive electrical activity of the vestibular nuclei. The midbrain nuclei have a less negative effect and can be regarded as a finer adjuster of vestibular nuclear activity. The cerebrum has a positive or negative effect on vestibular nuclear activity and maybe under voluntary control. Vertigo is an abnormal sensation of rotation relative to one's environment or “a hallucination of movement”. Vertigo is specifically associated with the disorders of vestibular system. The vestibular receptors for the detection of angular acceleration are located in the semicircular canals. The semicircular canals lie at right angles to each other, occupying the three planes of space. Thus, in the semicircular canals, we have sensors to monitor circular movement in the three planes of space. The utricle and the saccule contain receptors oriented at right angles to each other for the detection of linear acceleration and tilt. A gelatinous matrix called the otoconial membrane covers these receptors. Embedded in the otoconial membrane are dense calcific bodies called, otoconia, which exert pressure on the hair cells. Since the otoconia and hair cells have different inertia, they will move differently if there is accelerating or decelerating force acting on them. This gives us the ability to sense linear movement with gravity or against gravity. The vestibular nerve carries information from these receptors to the vestibular nuclei. There are important connections between the vestibular system and the visual system via the medial longitudinal fasciculus. This accounts for the vestibulo-ocular reflex and for nystagmus in vestibular disorders. Patients who have disorders of the peripheral vestibular system are initially vertiginous, nauseous (and often vomit) and sweaty. In three to four weeks significant compensation occurs predominantly in the cerebellum so that the patient becomes much less symptomatic. Diagnostic pointers in the assessment of the dizzy patient Patients should be initially classified into one of the following groups: a) Patients with true vertigo (problem lies in the peripheral or central vestibular system) b) Patients with syncopal sensation or actual syncope (inadequate cerebral blood flow, oxygenation, or nutrition) c) Miscellaneous group of patients who experience imbalance, but no syncope or vertigo. This may be secondary to almost any medical disorder. Peripheral vestibular disorder/ Central vestibular disorder Nausea, vomiting, sweating with initial attack Nausea and vomiting occurs late (often with raised intracranial pressure) 6  Nystagmus only present when patients have Nystagmus often noted in the absence of significant systemic symptoms systemic symptoms Nystagmus is usually in the horizontal plane Nystagmus may occur in any plane Nystagmus worsened by the loss of visual Nystagmus not influenced by visual fixation fixation Compensation occurs in three to four weeks Compensation may not occur as the lesion is central If one has determined by the symptoms and signs that this is a peripheral vestibular disorder, one will next need to decide whether it is the left or right vestibular system that has been affected. The vestibular system and the hearing mechanism are closely related. If the patient has unilateral hearing loss it is reasonable to assume that the vestibular problem originates from the ipsilateral side. The caloric test is a good method of testing each vestibular system individually. The mnemonic “COWS” is useful in remembering the responses. Infusion of Cold water causes nystagmus to the Opposite side Infusion of Warm water causes nystagmus to the Same side. The commonest cause of vertigo in elderly patients is vertebrobasilar ischaemia. Some of the conditions that result in vertebrobasilar ischaemia are atherosclerosis, cervical spondylosis cardiac dysfunction including arrhythmias. Benign paroxysmal positional vertigo, labyrinthitis, vestibular neuronitis, eustachian tube dysfunction are important in all the age groups. Menière's Disease This disorder has stimulated much interest. It is however an uncommon cause of vertigo. It is characterized by recurrent episodes of vertigo, sensorineural hearing loss and tinnitus. The attacks last 1/2 hour to 12 hours and are often preceded by a sensation of aural fullness. This is a peripheral vestibular disorder and patients usually experience significant nausea and vomiting. The aetiology is unknown but the salient histopathologic finding is endolymphatic hydrops with marked increase in the volume of endolymphatic fluid. It is believed that symptoms occur when the endolymphatic compartment is so distended that Reissner's membrane ruptures. This results in the mixing of endolymphatic and perilymphatic fluid. In severe attacks, patients are admitted to hospital for intravenous hydration, anti-emetics and sedation. Most patients will never need surgical intervention. Patients who have frequent, disabling vertigo and very poor hearing in the affected ear are best managed by labyrinthectomy. This procedure is followed by compensation within three to four weeks. If the hearing is good, vestibular neurectomy is one useful surgical option. Benign paroxysmal positional vertigo This condition is thought to be due to cupulolithiasis. Calcium deposits from the otoconial membrane become dislodged and travel in the endolymphatic fluid to the posterior semicircular 7 canal. Transient vertigo is induced by certain head positions that place the posterior semicircular canal in the dependent position. After appropriate head positioning (Dix-Hallpike test), there is a latent period of 5-10 seconds. This is followed by vertigo and nystagmus that lasts 15-30 seconds. Nystagmus is rotary with the fast component in the direction of the dependent ear. Most cases of benign paroxysmal positional vertigo will resolve in 18 to 24 months. Many cases respond well to vestibular exercises. Occasionally surgery is necessary and this entails transection of the nerve to the posterior semicircular canal (the singular nerve). Otitis Media and Otitis Externa Definitions: Acute suppurative otitis media: Acute inflammation of the mucosal lining of the middle ear cleft [tympanic cavity, eustachian tube and the mastoid air cell system]. The features of acute inflammation are present. 8 Acute suppurative otitis media may be complicated by perforation of the tympanic membrane. These perforations will generally heal within four weeks. Otitis media with effusion Presence of liquid behind an intact tympanic membrane, in the absence of the features of acute inflammation. Chronic suppurative otitis media: Characterized by the presence of a persistent (> 4 weeks) perforation of the tympanic membrane. Otorrhoea Otorrhoea may be secondary to a primary pathology in the external auditory canal or in the middle ear. Base of skull fractures involving the temporal bone may present with CSF otorrhoea. In some cases, visualization of the tympanic membrane is difficult because of exudate in the external auditory canal. Without seeing the tympanic membrane one can often still distinguish between acute otitis externa and acute otitis media. (Unfortunately the two sometimes co-exist) Otitis Externa Otitis Media Otalgia often severe. Severity of otalgia varies. Onset of otorrhoea not associated with Otalgia markedly reduced at onset of diminution of otalgia otorrhoea No mucus in otorrhea Discharge is mucopurulent Very mild hearing loss Mild to moderate hearing loss Pressure on the tragus and movement of Pain unrelated to movement of pinna the pinna cause significant pain Pathogenesis of middle ear infections The pathogenesis of middle ear infections is strongly linked to disorders of the eustachian tube. The eustachian tube has the following functions: Ventilation of the middle ear Equalization of the pressure in the middle ear with that of atmospheric pressure Drainage of middle ear secretions into the nasopharynx Protection of the middle ear from nasopharyngeal secretions and organisms Dysfunction of the eustachian tube is generally secondary to obstruction and or infection. Acute suppurative otitis media and otitis media with effusion are most commonly associated with children. Adenoidal hyperplasia is the commonest source of obstruction to the eustachian tube in this age group. The adenoids are an important source of ascending infection into the middle ear via the eustachian tube. Congenital cysts such as Thornwaldt's cysts can also obstruct the ostium of the eustachian tube. In male teenagers angiofibroma is an important cause of otitis media with effusion and severe epistaxis. One must always be on the alert for cases of nasopharyngeal carcinoma since this tumor 9  frequently presents with otologic complaints. The nasopharyngeal carcinoma directly obstructs the ostium of the eustachian tube but also has the effect of obstructing the lymphatic drainage of the eustachian tube, further perpetuating the otitis media with effusion. Infections of the nose, paranasal sinuses and the nasopharynx result in edema of the ostium of the eustachian tube and subsequent obstruction. These infections are more common in patients who have obstructive lesions in the nose such as nasal polyps, hypertrophied turbinates and marked septal deviation. Allergic rhinitis and vasomotor rhinitis produce obstruction of the nose and of the paranasal sinuses with subsequent frequent infections. Children who attend nurseries have a high incidence of upper respiratory tract infections and, consequently, frequent otitis media with effusion or acute suppurative otitis media. Passive smoking impairs mucociliary function by damaging the cilia. Otitis media with effusion occurs more frequently and is more difficult to eradicate in children who are exposed to smoking. Patients with cleft palate, those with cystic fibrosis and patients who are immunocompromised will obviously get frequent ear infections. Acute otitis media Chronic Suppurative Otitis Media This condition is characterized by the presence of a persistent (> 4 weeks) perforation of the tympanic membrane. Chronic suppurative otitis media can be divided into: a) Cholesteatoma or squamous disease ---- presence of keratinising squamous epithelium in the middle ear cleft. b) Tubotympanic or mucosal disease. Genesis of cholesteatoma 1. Retraction pocket---- commonest mechanism The external auditory canal is lined by squamous epithelium, which extends onto the tympanic membrane to form the external layer of the drum. Long-standing eustachian tube dysfunction can produce persistent negative pressure in the tympanic cavity. This can result in the weakest parts of 10 the tympanic membrane being pulled medially to form retraction pockets. Classically this affects the pars flaccida (which lacks a fibrous layer) or the postero-superior aspect of the pars tensa. These retraction pockets are lined by keratinising squamous epithelium and an accumulation of keratin occurs if the opening of the retraction pocket is relatively small. Secondary infection in the retraction pocket results in the production of collagenases and phosphatases that ultimately erodes surrounding bone and ligaments. 2. Squamous epithelial growth at the edge of a perforation In cases of long-standing perforation of the tympanic membrane, squamous epithelium can overgrow the edge of the perforation and extend into the middle ear. This is especially likely to occur if, in the region of the perforation, there is loss of mucosa from the medial aspect of the tympanic membrane. 3. Implantation cholesteatoma Squamous epithelium can be implanted by a penetrating injury to the tympanic membrane, or this can occur during surgery. 4. Squamous Metaplasia of the middle ear mucosa 5. Congenital cholesteatoma In this case congenital squamous epithelial rests are trapped in the middle ear. Chronic suppurative otitis media can be active or inactive. Cholesteatoma, by its very nature, is always considered active. Cholesteatoma is important because of the complications associated with this disorder. These include: 1. Hearing loss secondary to adhesions, granulation tissue, perforation of the tympanic membrane, exudate in the middle ear, and ossicular chain discontinuity 2. Facial nerve palsy 3. Acute and chronic mastoiditis 4. Sub periosteal abscess 5. Bezold's abscess-- along the sternomastoid 11  6. Citelli's Abscess-- along the digastric muscle 7. Perilabyrinthitis and labyrinthitis 8. Gradenigo's syndrome-- lateral rectus palsy, pain in the distribution of the fifth cranial nerve and a discharging ear. These features are noted when chronic suppurative otitis media involves the apex of the petrous temporal bone (petrous apicitis) 9. Sigmoid sinus thrombosis which can extend into the internal jugular vein 10. Meningitis 11. Extradural abscess 12. Subdural abscess 13. Temporal lobe or cerebellar abscesses are usually secondary to chronic suppurative otitis media 14. Benign intracranial hypertension It is clear that cholesteatoma is a serious disorder with the risk of life-threatening complications. Cholesteatoma is a surgical disease and all patients who are medically fit to undergo surgery should be given this option. Prior to surgery, an ear swab should be sent for culture and sensitivity and the condition of the ear optimized by using ❑ topical ear drops, ❑ aural suctioning plus or minus systemic antibiotics. The commonest organisms grown are Gram-negative organisms such as Pseudomonas and Proteus. Often the infection is a mixed infection involving anaerobes and gram negatives. Failure to control the ear discharge with medications should hasten rather than delay the surgical procedure. The actual surgery is usually a form of a modified radical mastoidectomy. In this procedure, the squamous lining in the mastoid cavity and middle ear is removed, the posterior wall of the external auditory canal is usually removed and the external auditory canal is widened (meatoplasty). At the end of the procedure, the mastoid cavity and middle ear can easily be visualised and cleaned through the external auditory canal. The ear would have been converted from an "unsafe ear" to a "safe ear". Once the cholesteatoma is controlled, the hearing mechanism can be reconstructed or a hearing aid can be utilised. OTITIS MEDIA WITH EFFUSION: AETIOLOGY AND MANAGEMENT IN CHILDREN INTRODUCTION Otitis media with effusion is defined as the presence of liquid behind an intact tympanic membrane, without any of the symptoms or signs of acute inflammation. It is thought to be the commonest cause of hearing loss in children. Otitis media with effusion is predominantly a disease 12 of children 1-9 years old. The peak incidence is found in children 6 months to 2 years old but as the diagnosis in this age group is difficult and the condition often asymptomatic, the peak incidence in children attending otolaryngology clinics is in the age group 3-6 years. In many developed countries, otitis media with effusion is the commonest indication in children for admission to hospital for elective surgery. In these countries, sixty percent of children will experience otitis media with effusion by the age of 2 years and 80% prior to school entry. The prevalence falls from 38 % at age 2 years to 1 % at 11 years. In Jamaica, the prevalence rate in children 5-7 years is 2 % There is a high incidence in North American Indians and Eskimos. OME is generally thought to be more common in Caucasians than in Blacks, even though most studies do not define the racial composition of the study group. Males are more frequently affected than females. There is a seasonal variation with the highest incidence in January, February and March and the lowest incidence in August, September and October. AETIOLOGY The major underlying factors are related to eustachian tube dysfunction and infection. The classic example of eustachian tube dysfunction occurs in cleft palate where the tensor palati muscle is abnormal and thus active opening of the eustachian tube is impaired. Patients with cleft palate also have a direct pathway for the passage of vomitus, sputum and drinks to gain access to the pharyngeal opening of the eustachian tube. The result is secondary infection. Otitis media with effusion is also very common in patients with a submucous cleft palate. Obstruction to the eustachian tube can either be intrinsic or extrinsic. In the intrinsic type, oedema and secretions associated with inflammation cause obstruction of the eustachian tube. This occurs in upper respiratory infections. The nose, sinuses and the adenoids can act as reservoirs for infection producing repeated intrinsic obstruction of the eustachian tube. A distinct possibility is that the lymphatic drainage of the eustachian tube becomes obstructed by peritubal inflammation and this causes otitis media with effusion. In the child who is less than 7 years old, abnormal compliance of the eustachian tube, due to a relative reduction in the amount and stiffness of the cartilage, can cause collapse of the eustachian tube with resultant obstruction. Extrinsic obstruction of the eustachian tube is seen in patients with adenoidal hyperplasia or nasopharyngeal tumours that compress the eustachian tube. In patients with craniofacial abnormalities such as Down's, Hunter's and Hurler's syndromes, there is a relative disproportion of the adenoidal size to the nasopharyngeal space which predisposes to obstruction of the eustachian tube. When obstruction to the eustachian tube occurs, the air in the middle ear is gradually utilised or absorbed, leaving a vacuum. The result is transudation of fluid from the mucosa to the tympanic cavity. The situation is much more complex than mere obstruction to the eustachian tube. Infection plays a significant role. Cultures of aspirates from middle ear effusions have grown organisms in 30-60% of cases. The organisms that have been found are the same as those associated with acute suppurative otitis media. The most frequent organisms found are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella (Branhamella) catarrhalis. Although the adenoids can cause obstruction of the eustachian tube, it appears that the main role of the adenoids is as a source of sepsis. Ascending infection up the eustachian tube causes oedema and exudate with eventual obstruction. It is likely that otitis media with effusion and acute suppurative otitis media are different ends of a spectrum of manifestations of obstruction and inflammation of the eustachian tube. In patients with otitis media with effusion, the host mechanisms and the organisms have created a balance so that a latent infection is maintained. In acute suppurative otitis media, the host 13 mechanisms have been temporarily overwhelmed. It is known that otitis media with effusion can be a sequel to acute suppurative otitis media. In chronic otitis media with effusion, there is hyperplasia of the goblet cells and an increased number of mucous glands in the middle ear cleft. This will tend to perpetuate the effusion. Some patients have an inefficient mucociliary system, which predisposes them to otitis media with effusion. These include patients with the immotile cilia syndrome, Kartagener's syndrome and cystic fibrosis. Viral and bacterial infections can adversely alter the mucociliary system. The role of allergy in otitis media with effusion is uncertain. A true causal relationship has not been established. Some studies have found an increased incidence of atopic disease in children with otitis media with effusion. The adenoids have been shown to have a large number of mast cells and these can bind IgE with the resulting release of histamine. However, antihistamines and decongestants have not altered the course of otitis media with effusion. This casts doubts on the significance of allergy in these patients. CLINICAL FEATURES Otitis media with effusion is usually asymptomatic or presents with symptoms related to hearing loss. In the infants and young children, parents may complain that the child has delayed or impaired speech development. In the older child, his teacher may report that his academic performance is poor, that the child does not pay attention or that he has general behavioural problems. Excessive shouting and increasing the volume of the television may be subtle signs of hearing loss. Otalgia is uncommon in a pure otitis media with effusion. However some patients get recurrent acute suppurative otitis media and otalgia often heralds the onset of this complication. Disorders of balance may also occur. DIAGNOSIS The diagnosis is based on the clinical findings and audiological investigations. If the tympanic cavity is filled with fluid, the colour of the drum may suggest underlying liquid. Many patients have evidence of retraction of the tympanic membrane (horizontal handle of the malleus, fore-shortened malleus, and prominent lateral process of the malleus). If the fluid is opaque, the middle ear structures will be obscured. When the eustachian tube is partially patent or functioned recently, air bubbles or air-liquid levels may be identified. The most useful clinical signs are the reduction in the mobility of the tympanic membrane that is found on pneumatic otoscopy. The tuning fork tests may show features of a conductive hearing loss depending on the severity of deafness. Impedance tympanometry and pure tone audiogram are then performed. The impedance tympanometry is an objective assessment. It is the most sensitive audiological test for the presence of middle ear effusions. There is a high correlation between a Type B tympanogram and the presence of otitis media with effusion but this is not specific and clinical correlation is necessary. The pure tone audiogram can be performed in children older than 5 years. It assesses the severity of the hearing loss and is thus useful in the management of this disorder. 14  TREATMENT Treatment can be divided into the following categories a) Management of predisposing factors b) Medical treatment of otitis media with effusion c) Surgical management of otitis media with effusion It is important that identifiable predisposing factors are adequately addressed. Parental smoking has been linked to otitis media with effusion. The control of recurrent acute suppurative otitis media is important, as otitis media is frequently a sequel. Nasal or sinus infections must be treated. Although considerable controversy exists, in patients who are known to have allergies to inhaled or ingested allergens, appropriate measures should be taken in managing these allergens. Frequent hand washing and wearing an extra layer of clothing in winter can reduce the incidence of viral infections that may predispose the patient to secondary bacterial infection and otitis media with effusion. Medical management of otitis media with effusion Since 90% of the cases of otitis media with effusion will resolve within three months surgery is not indicated in this period. Medical therapy should be undertaken while the patient is being observed. Unfortunately, no medications have given long lasting results. Antibiotics In 30-60% of cases, cultures of middle ear effusions have grown organisms similar to those that cause acute suppurative otitis media. Antibiotic therapy should incorporate drugs that are effective against these bacteria. A -lactamase-stable antibiotic should be prescribed for patients who have persistent otitis media with effusion despite therapy with one of the medications above. Other medications Antihistamines, decongestants and non-steroidal anti-inflammatory drugs have efficacy comparable to placebo and are therefore not recommended. Systemic steroids have been used alone or in combination with antibiotics in the treatment of otitis media with effusion. The results have been inconsistent and, with the risk of significant complications, they should not be recommended. Surgical management of otitis media with effusion Surgery is indicated in cases that fulfil all of the following criteria: a) Hearing loss secondary to otitis media with effusion b) Persistence of the effusion for greater than 3 months c) Failed medical therapy Surgical management aims to 1) Reverse hearing loss and the associated disability 2) Prevent recurrent suppurative otitis media 3) Prevent complications such as cholesteatoma Surgery entails the insertion of grommets and adenoidectomy. Surgery may be required to eliminate potential causes of recurrent otitis media with effusion. This may include repair of cleft palate, antral washouts, turbinectomies and polypectomies. OTITIS EXTERNA The external ear consists of the external auditory canal and the pinna. The squamous lining of the 15 external canal extends unto the tympanic membrane to form the lateral surface of the drum. Inflammation of the external canal is therefore commonly associated with hyperaemia of the tympanic membrane. The skin of the external auditory canal is firmly adherent to the perichondrium laterally and to the periosteum medially. Infection involving the lining of the external auditory canal is therefore often extremely painful. Infection of the external canal occurs in three forms: a) Diffuse otitis externa b) Localized otitis externa (furuncle or carbuncle) c) Malignant otitis externa Diffuse otitis externa Normal skin is a good protective organ. Otitis externa is usually initiated by secondary infection of skin that has been traumatized by scratching, macerated in persistently moist conditions or affected by particular skin disorders. Factors commonly associated with diffuse otitis externa include: Seborrhoeic dermatitis Frequent swimming Hot, humid climates Repeated trauma to the external auditory canal (frequently produced by excess cleaning of the external auditory canal). Hypersensitivity reaction to otologic topical preparations The typical features of acute otitis externa include otalgia, pruritus, scant exudate, oedema and hyperemia of the external auditory canal wall. In the more severe cases, cellulitis of the peri- auricular soft tissue occurs and this is usually accompanied by pyrexia. The management of acute otitis externa aims to remove debris and exudate from the external auditory canal, eradicate the infective organism, remove predisposing conditions return the skin of the external auditory canal to normal. Ear swabs should be sent for culture and sensitivity prior to initiating antibiotic therapy. The commonest organisms associated with acute otitis externa are Pseudomonas, Proteus and Staphylococcus aureus. In severe cases the external canal can be virtually occluded by oedema. In such a case, a wick soaked in glycerine and ichthammol should be inserted. This can be changed 48 hours later. After the oedema has lessened significantly, treatment can be continued with topical drops containing a fluoroquinolone or gentamycin and a corticosteroid. Systemic antibiotics are generally unnecessary except in cases with cellulitis. Analgesic therapy is an important part of the treatment of this painful condition. Non- steroidal anti-inflammatory drugs are usually effective. Regular aural toilet, preferably by suctioning, is the most important treatment modality in these patients. In chronic otitis externa, Pseudomonas and Fungi are most commonly isolated. Treatment consists of aural toilet, topical gentamycin/steroid drops or anti-fungals (eg clotrimazole drops and ketoconazole orally). One should always search for predisposing conditions and identify cases of immnuosuppression in recurrent acute or chronic otitis externa. 16 Furuncles are most commonly located in the superior aspect of the cartilaginous canal. They are treated with topical and systemic antibiotics. It is usually unnecessary to incise and drain these. Incision and drainage can be complicated by perichondritis of the pinna. MALIGNANT OTITIS EXTERNA Malignant otitis externa is a progressive, necrotising infection of the external auditory canal, which is most commonly found in elderly diabetics. Most of the morbidity associated with malignant otitis externa is secondary to osteomyelitis of the temporal bone and the skull base which, when inadequately treated, result in cranial nerve palsies and intracranial complications. Chandler coined the term “malignant external otitis” in 1968 when he reported his experience with his first thirteen cases. Six of these cases died from this disease or underlying medical problems. Malignant otitis externa is an aggressive form of infection of the external auditory canal, which is most frequently detected in immuno-suppressed patients. Classically, it is found in elderly diabetics. Pseudomonas aeruginosa is the responsible organism in most cases. Males are affected twice as frequently as females. Malignant otitis externa has now been diagnosed in patients on cytotoxic therapy, acquired immune deficiency syndrome and in malnourished infants. The pathogenesis is an infection by a virulent organism in an immunosuppressed host. The organisms produce exotoxins that cause tissue necrosis at the advancing edge of the infection or produce substances that encapsulate the infection from host defences and from systemic antibiotics. Of importance in the diabetic is the microangiopathy, which makes the tissues ischaemic and impairs the effect of systemic therapy. The infection spreads in the base of skull predominantly as an osteomyelitis and periosteitis. It involves the cranial nerves as they exit the skull via their various foramina. The facial nerve is most frequently affected in an abscess cavity close to the stylomastoid foramen. The ninth, tenth and eleventh cranial nerves are affected close to the jugular foramen, while the hypoglossal nerve is affected at the hypoglossal canal. The osteitis and periosteitis spreads along the petrous temporal bone to involve the sixth cranial nerve close to the petrous apex. CLINICAL FEATURES Typically, the patient is an elderly diabetic who has purulent otorrhoea with otalgia disproportionate to the clinical signs. The otalgia is worse at nights and is associated with hearing loss. The discharge is usually yellow or green. Characteristically, granulation tissue is noted in the external auditory canal at the osseo-cartilaginous junction. The granulation tissue marks the site of abscess formation beneath the tympanic plate. Conductive hearing loss is found in almost fifty percent of patients. This hearing loss is secondary to obstruction to the ear canal or to otitis media with effusion. The inflammation at the skull base causes obstruction to the lymphatic and venous drainage of the eustachian tube and this will predispose the patient to otitis media with effusion. Marked tenderness is invariably present on palpation between the mastoid process and the ascending ramus of the mandible, just below the floor of the external auditory canal. In advanced cases, there may be trismus and tenderness over the temporo-mandibular joint. Cranial nerve palsies are common in advanced lesions. 17 Investigations Blood: A complete blood count and blood film should be requested. Neutrophilia represents the host response to bacterial infection but neutropaenia or abnormal white cells can be important clues to underlying immunosuppression, leukaemia or lymphoma. ESR: The ESR is usually markedly elevated. The ESR can be used to monitor the response to therapy. Urea and electrolytes must be monitored as patients may be placed on nephrotoxic drugs or diabetic nephropathy may be present. Glucose profile --- as most cases are found in diabetics. Pure tone audiogram --- as a baseline study, since the patient may be treated with ototoxic drugs. Ear Swab Microscopy and culture and sensitivity tests are done to guide antibiotic therapy. Cultures for aerobic, anaerobic and acid fast bacteria should be done. Histology Multiple biopsies are sent to rule out malignancy. The histopathologist should look for any evidence of fungal infection. Nuclear Scanning: Nuclear scanning of the temporal bone and the base of skull will show increased uptake. Technetium 99 (Tc 99) is commonly used. Technetium is absorbed by osteoblasts and osteocytes. Unfortunately, the Technetium scan may be positive for an indefinite period. The Technetium scan is therefore not useful in the follow-up of the patient. Gallium 67 citrate scan reverts to normal when active inflammation ceases and this scan can be done six-weekly to assess the patient's response to therapy CT Scans CT scans are less sensitive than nuclear scans in assessing the involvement of the temporal bone. CT however, is far more sensitive than plain x-rays TREATMENT The treatment of malignant otitis externa has undergone considerable changes as the pathogenesis of this disorder became clearer. Surgical management is limited to regular suction clearance of the ear, biopsy of the granulation tissue, drainage of abscesses and debridement of necrotic bone and cartilage. Patients who are deteriorating despite adequate medical therapy should be considered for debridement. Medical management is the mainstay of therapy. It is important to control underlying medical problems. The diabetes should be controlled. Anaemia and malnutrition should be treated. The patient's fluid and electrolyte status must be monitored. Intravenous aminoglycosides used to be the main antibiotic therapy. Ceftazidime is a useful parenteral cephalosporin that can be used empirically with oral fluoroquinolones in the initial management of the patient. This combination avoids the nephrotoxicity and ototoxicity of the aminoglycosides. The tissue necrosis seen in malignant otitis externa provides a good medium for the growth of anaerobic organisms. Daily suction toilet of the ear is performed and a gentamycin wick used or gentamycin drops administered. Treatment should continue for six to sixteen weeks. Treatment is discontinued when the external canal has returned to normal, the white blood cell count and ESR are normal, and the Gallium scan (if available) shows no evidence of active inflammation. 18  THE MANAGEMENT OF EPISTAXIS Epistaxis can be defined as bleeding emanating from the internal nose. Epistaxis is a frightening experience for the patient. Most cases are easily controlled and can be managed on an outpatient basis. On the other hand, epistaxis can be a life-threatening problem. It is important that the clinician has a logical approach to the management of epistaxis. Management will include the establishment of haemostasis, identification and treatment of hypovolaemia or circulatory shock 19 (when present) and the specific management of any aetiologic factor. BLOOD SUPPLY OF THE INTERNAL NOSE The nose is supplied by both the external carotid and internal carotid arterial systems and there are multiple anastomoses between these systems in the nose. The major blood supply is via the maxillary branch of the external carotid artery. Venous drainage The venous drainage of the central parts of the lateral nasal wall is to the pterygoid venous plexus. The anterior areas drain to the facial vein while posteriorly the drainage is to the pharyngeal venous plexus. The specific blood supply to the septum must be reviewed, as this is the commonest source of epistaxis. The blood supply of the nasal septum The major source of arterial blood to the nasal septum is the sphenopalatine branch of the maxillary artery. The ascending branch of the greater palatine artery passes through the incisive canal to anastomose with the sphenopalatine, the superior labial and the anterior ethmoidal arteries at Little's area on the antero-inferior portion of the septum. The plexus of arteries at this site is called Kiesselbach's plexus. The commonest site for epistaxis is Little's area. The posterior ethmoidal artery gives a small contribution to the antero-superior aspect of the septum. Venous drainage The septum drains anteriorly to the facial vein, posteriorly to the pterygoid venous plexus and superiorly via ethmoidal veins to the ophthalmic veins. In 1% of individuals, the nasal veins are connected to the superior sagittal sinus by a vein that passes through the foramen caecum in front of the crista galli. The retrocumellar vein is an important source of venous bleeding in children and young adults. There are important anastomoses across the midline between the two anterior ethmoidal vessels and also occurring in the nasopharynx. This can explain some of the cases in which arterial ligation fails to control epistaxis. Causes of epistaxis Local causes a) Trauma: trivial or major injuries, nasal fracture, surgical trauma, foreign body, excessive sneezing or coughing (with increased pressure in the nasal vessels). b) Inflammation, infection and allergy: e.g. acute and chronic, specific and non-specific rhinitis. c) Neoplasms (and tumour- like masses) of the nose, nasopharynx and sinuses: 1) Benign - angiofibroma, haemangioma, inverted papilloma, pyogenic granuloma (tumour- like), other granulomas. 2) Malignant - squamous cell carcinoma, adenocarcinoma, salivary gland tumours, melanocarcinoma, midline lethal granuloma (generally considered a lymphoma). d) Drugs - cocaine abuse. e) Congenital vascular malformation. In many cases of epistaxis the actual aetiology is never elucidated. These cases are often labelled as “spontaneous epistaxis” but a careful clinical assessment will often reveal contributory factors such as minor trauma and inflammation. 20 General causes Abnormal bleeding may result from a defective coagulation pathway, thrombocytopaenia, platelet function defects and vascular abnormalities. A) Congenital coagulopathies e.g. haemophilia, Christmas disease, von Willebrand's disease. B) Acquired defects in the coagulation pathway: heparin or warfarin therapy; hepatic or obstructive biliary diseases. C ) Thrombocytopaenia 1) Platelet production failure i) Selective depression of the megakaryocytes by drug toxicity (cotrimoxazole, phenylbutazone, thiazides, tolbutamide) or viral infections. ii) Generalised bone marrow failure: plastic anaemia, leukaemia, marrow infiltration or myelosclerosis. iii) Ineffective platelet production: megaloblastic anaemia. 2) Increased platelet destruction: i) Idiopathic thrombocytopaenic purpura ii) Secondary immune thrombocytopaenia ( post-infection, SLE, chronic lymphocytic leukaemia) iii) Disseminated intravascular coagulation iv) Drug- induced immune thrombocytopaenia (sulphonamides, quinine, PAS, rifampicin digitoxin). 3) Splenic pooling in patients with splenomegaly. 4) Massive transfusion of old blood: dilutional thrombocytopaenia D) Abnormal platelet function Aspirin therapy, hepatic and renal disease, multiple myeloma and Waldenstrom's macroglobulinaemia are all acquired causes of platelet dysfunction. E) Vascular abnormalities: Hereditary haemorrhagic telangiectasia, steroid-induced vascular weakness, scurvy, Monckeberg's sclerosis. Hypertension and anxiety tend to cause prolongation of epistaxis but the incidence of epistaxis is not increased in these patients. Hypertension is associated with vascular changes, which inhibit vasoconstriction thus prolonging epistaxis. The increased arterial pressure will also increase the severity of the epistaxis. Thus hypertensive patients are more frequently admitted to hospital for the control of epistaxis. The control of hypertension is an essential part of the management of epistaxis in the hypertensive patient. Management of active epistaxis History A brief history is obtained from the patient or a relative while preparations are being made to control the epistaxis. It is useful to inquire: 1. Whether the epistaxis is predominantly an anterior or posterior bleed 2. Whether the epistaxis is unilateral. If the bleeding is reported as bilateral, one should still inquire as to the side that initially bled (often blood is entering the opposite nasal passage at the posterior choanae by passing around the border of the septum). 3. Syncopal sensation, which may be indicative of cardiovascular decompensation. 4. Estimate of the blood loss in terms of common utensils such as cups or tablespoonfuls. Patients tend to exaggerate the blood loss, but often have containers with them that they have used to collect the blood and these can be very helpful in estimating the blood loss. 21  5. Nasal trauma( including nose-picking), upper respiratory tract infections, recent medications, history of bleeding diathesis and any significant medical illness. It should be clear that the thoroughness of the initial history would depend on the clinical status of the patient. The patient who is in hypovolaemic shock will require emergency resuscitation while attempts are made to control the bleeding. The patient whose cardiovascular system is stable but who is bleeding heavily is best managed by controlling the bleeding and then completing the history. Examination 1. Pulse and blood pressure should be taken. If the cardiovascular system is stable the patient should be examined sitting up or in the semi-recumbent position. Strong suction and a good headlight are prerequisites for an adequate assessment of the patient with epistaxis. It is useful to attempt a preliminary assessment of the nose without vasoconstriction because this can sometimes stop the bleeding and prevent identification of the bleeding point. After 2. Suction the clots, local anaesthetic & vasoconstrictive nasal drops or sprays will facilitate examination of the nose and assist with haemostasis in patients who are not bleeding profusely. Cocaine is a very potent vasoconstrictor and local anaesthetic and is therefore frequently used in this setting. The maximum dose should be 1.5mg/kg. An alternative preparation is a mixture of 0.1% xylometazoline and lignocaine. While local measures are being undertaken, it is important that 3. Resuscitation of the circulatory volume with intravenous fluid and blood transfusion (if necessary) is carried out. 4. Sedation should be prescribed as this relieves the patient's anxiety, reduces the blood pressure and facilitates nasal cautery and packing. Anterior epistaxis Effective treatment for anterior epistaxis includes: 1. Tamponade of the nasal vessels between the fingers, 2. Nasal cautery, 3. Nasal packing, and 4. Surgery with ligation of the anterior ethmoidal artery. Most patients who are being assessed by an otolaryngologist will have already attempted to tamponade the nasal vessels between the fingers, but may not have applied pressure properly and so the otolaryngologist should give the relevant instructions. The patient can attempt to tamponade the nasal vessels while preparations are being made to examine the nose. If the source of an anterior epistaxis is identified, the treatment of choice is nasal cautery. This treatment is usually successful unless the bleeding is profuse. The commonest site of epistaxis is Little's area on the antero-inferior nasal septum. The immediate area around the focus of bleeding should first be cauterised before cautery to the actual bleeding site is attempted, otherwise there would be a significant risk of aggravating the epistaxis. Successful nasal cautery has the advantage of avoiding nasal packs. Silver nitrate, trichloro-acetic acid and electrocautery are highly effective. Electrocautery is the more effective than chemical cautery in the presence of active bleeding, but would require general anaesthesia in children Patients who have not had major bleeds with cardiovascular decompensation can often go home after a short period of 20- 30 minutes of observation for recurrent bleeding. There is a risk of septal perforation when unilateral cautery is overzealously performed. 22 Bilateral nasal cautery at equivalent sites on the nasal septum should be avoided, as this is associated with a high incidence of perforations. Nasal packs will be required in cases of profuse anterior epistaxis and in cases where the focal bleeding point cannot be identified. A half- inch petrolatum gauze-strip soaked in antibiotic ointment or bismuth iodoform paraffin paste (BIPP) packing is commonly used. The nasal packing should be applied meticulously, in loops, from the nasal floor to the nasal roof and extending as far posteriorly as is feasible. Patients often find the insertion and the removal of these packs very uncomfortable. Adequate local anaesthesia and analgesia should be administered. Merocel sponges can be inserted easily and are better tolerated. These are especially useful in children. Experience with Merocel sponges suggest that they are less effective than BIPP or gauze strip packs. They are most useful in mild epistaxis. Gauze strip packs, BIPP and Merocel all adhere to the nasal mucosa to varying degrees and epistaxis may resume on removal of the nasal packs. Nasal balloons are easy to insert and to remove, but are slightly less effective than traditional nasal packs in controlling epistaxis because they do not adapt very well to the irregularity of the lateral nasal wall. Anterior nasal packs should be left in situ for 24-48 hours. During this period the patient should be on antibiotics and should be nursed propped up so that that the head is elevated.. Nasal endoscopy Nasal endoscopy has increased the frequency with which the actual bleeding point is identified. This has facilitated both chemical and electro-cautery. Nasal endoscopy has been particularly helpful in epistaxis that is relatively posterior in location. The 0 and the 30 degrees rigid telescopes or the flexible fibreoptic scopes can be used. The flexible fibreoptic scope is particularly useful in identifying bleeding points that are posterior to septal deviations. Occasionally septoplasty (operation to straighten the septum) must be performed to facilitate access to a bleeding point so that cautery or effective nasal packing can be accomplished. Treatment options for posterior epistaxis Posterior epistaxis can be very difficult to manage. Identification of the bleeding point is sometimes impossible and one has to rely on post- nasal packs or balloon tamponade initially if significant active bleeding is occurring. Sometimes the patient presents with mild posterior epistaxis. In these cases the nose should be: Decongested and Topical anaesthesia applied This facilitates examination endoscopically or microscopically. It is worthwhile to attempt a preliminary nasal examination without the use of vasoconstriction as the latter occasionally stops the bleeding and prevents identification of the bleeding point. If the bleeding point is identified, the site should be cauterised. In cases where heavy posterior bleeding is occurring, the initial management should be: Insertion of a double-lumen balloon to apply nasal as well as postnasal tamponade since one would not be certain of the exact source of the bleeding. This method also increases the efficiency of the tamponade. Under local anaesthesia, nasal balloons can be inserted quickly and easily with minimal discomfort to the patient. Nasal balloons are tolerated much better than the traditional anterior and posterior nasal packs. The nasal balloons should remain in situ for 48 - 72 hrs. If bleeding persists despite the insertion, or on the removal, of the nasal balloons, endosopic or microscopic examination of the nose should be performed. If the epistaxis is not controlled by 23 posterior endoscopic microscopic cautery, then a Foley's catheter should be inserted and the balloon inflated with 15 ml of air or saline. Saline does carry with it the tiny theoretical risk of aspiration but has the advantage that it does not leak as easily as air. Bilateral anterior nasal packs (petrolatum gauze strips) should also be inserted to maximise the tamponade effect. When posterior endoscopic cautery (under local anaesthesia) and nasal packs fail to control epistaxis, or epistaxis recurs on removal of the packs, the nasal passages and the postnasal space should be examined under general anaesthesia. Any bleeding point that is identified should be cauterised. Identification of the bleeding point may require fracturing the turbinates to allow access to the meati. If the bleeding site cannot be identified, the maxillary artery should be ligated. The alternative is to insert firm anterior and posterior nasal packs under general anaesthesia, leave these in situ for 72- 96 hrs and to proceed to ligate the maxillary artery if bleeding recurs on removal of the packs. It is perhaps a better choice to avoid two general anaesthesias and to proceed with ligation of the maxillary artery at the first general anaesthesia. Ligation of the maxillary artery is effective in 95% of cases. Embolization of the maxillary artery using gelfoam, has been successful in controlling epistaxis, but has a higher failure rate than ligation of the maxillary artery and its sphenopalatine and greater palatine branches. It is rarely necessary to ligate the anterior ethmoidal vessels when adequate ligation of the maxillary arteries and its main branches has been performed. Special conditions There are many possible causes for epistaxis. In the management of epistaxis one should be careful not to miss a malignancy of the nose, sinuses or the nasopharynx. Careful clinical assessment and radiologic studies will identify these malignancies. The male teenager may have an angiofibroma requiring angiography and CT scanning to plan the surgical approach to be utilised after embolization of the major feeding vessels. Patients who have hereditary haemorrhagic telangiectasia are difficult to manage. Septodermoplasty has produced transient success but telangiectactic vessels tend to grow into the split skin graft with resultant recurrent epistaxis. Oestrogens and local radiotherapy have been useful in some cases. Recurrent bleeding from the edges of a septal perforation can be controlled with cautery. NASOPHARYNGEAL CARCINOMA INTRODUCTION Nasopharyngeal carcinoma is a tumour of epidermoid origin that is endemic in certain ethnic groups. It constitutes 90% of all malignancies found in the nasopharynx. Nasopharyngeal carcinoma is prevalent in the Cantonese Chinese in Southern China, Hong Kong and Singapore. The age-adjusted incidence in males in Hong Kong is 26: 100,000. In Jamaica it is found in 1.4: 100,000 males and 0.5: 100,000 females. This cancer is uncommon among Caucasians. In North 24  America the incidence is 1: 100,000. In Northern China nasopharyngeal carcinoma has an incidence of only 3 per 100,000. There is a moderately high incidence in the Malays, Indonesians, Thais and Filipinos. In North African countries such as Tunisia, Algeria and Sudan the incidence is less than that in South-east Asia but still appreciably higher than in North America and Europe. The Eskimos in Alaska have an incidence that is 15 times that of the general USA population. The aetiology is multifactorial and includes genetic, viral and environmental factors. Although this carcinoma has its highest incidence in particular racial groups, it occurs universally. Clinicians must have a high index of suspicion in order not to miss this lesion since the presentation can be subtle and varied. Nasopharyngeal carcinoma is more commonly found in males. The male to female ratio is 2- 3: 1. In high risk regions the incidence of nasopharyngeal carcinoma rises from the end of the second decade to reach a peak in the fourth decade and then remains at a plateau. In low risk countries such as Jamaica, a high proportion of cases have their onset in the second decade of life with a second peak occurring in the sixth decade. Aetiology Nasopharyngeal carcinoma is an interesting tumour that demonstrates the interaction of several factors in carcinogenesis. The important aetiologic factors are viral, genetic and environmental. Exciting data has been collected from the continued research into the aetiology of this carcinoma. The role of the Epstein-Barr virus The Epstein-Barr virus has been associated with Burkitt's lymphoma, infectious mononucleosis, non-Hodgkin's lymphoma in immunosuppressed individuals, some cases of Hodgkin's lymphoma and nasopharyngeal carcinoma. Antibodies to the Epstein-Barr virus have been strongly associated with nasopharyngeal carcinoma. In high risk regions there is a rise in the titres of certain antibodies to the Epstein-Barr virus prior to the onset of the malignancy. The association of the Epstein-Barr virus and nasopharyngeal carcinoma was subsequently confirmed by demonstrating that the DNA of this virus ( EBV DNA) was present in biopsy material from nasopharyngeal carcinoma In situ hybridisation is considerably more sensitive for the detection of EBV-encoded RNA than it is for EBV DNA because of the high levels of the former in specimens from nasopharyngeal tumours. Genetic factors The high incidence of nasopharyngeal carcinoma among certain ethnic groups strongly suggests a genetic link, which possibly interacts with environmental factors. The major histocompatibility gene complex on the short arm of chromosome six comprises six recognised loci called HLA-A, -B, -C, -DR, -DQ, -DS. There are now well-established associations between HLA (human leukocyte antigen) and nasopharyngeal carcinoma. Deletion of the short arm of chromosome 3 (3p) has been noted in these cancers and this may reflect the loss of a tumour suppressor gene. Environmental factors Ingestion of Cantonese- style salted fish, especially in childhood, has been linked to nasopharyngeal carcinoma. It is known that carcinogenic nitrosamines are present in such salted fish. Histopathology The World Health Organisation Classification recognises three histologic types a) Keratinising squamous cell carcinoma (WHO-1) -30-50 % of the cases in non-endemic regions but only 5 % in endemic areas. b) Non- keratinising squamous cell carcinoma (WHO-2) 25 c) Undifferentiated carcinomas that have abundant non-neoplastic, lymphocytic infiltrate (WHO-3). This latter histologic type has often been called “lymphoepithelioma”most commonin endemic areas. It is squamous cell ( cytokeratin is present) Anatomy The nasopharynx has dimensions of 4 cm x 4 cm x 3 cm. The anterior “wall” is really the posterior choanae separated by the posterior border of the nasal septum. The floor consists of the superior surface of the soft palate and the nasopharyngeal isthmus. The roof and the posterior wall form one continuous sloping surface formed by the body of the sphenoid, the basiocciput and the first two cervical vertebrae. The prevertebral fascia and muscles separate the adenoids from the vertebrae. The lateral wall contains the pharyngeal end of the eustachian tube, the tubal tonsils and the Fossa of Rosenmuller. Most cases of nasopharyngeal carcinoma seem to arise in the region of the Fossa of Rosenmuller. In the adult this cleft-like space may be as deep as 1.5 cm. Its base lies superomedial to the pharyngeal opening of the eustachian tube and it extends posterolaterally to its apex which reaches the petrous apex and the anterior margin of the carotid canal. The foramen ovale and the foramen spinosum lie lateral to the apex of the Fossa of Rosenmuller. Lateral to the fossa lie the mandibular division of the trigeminal nerve, the tensor palatini, the parapharyngeal space with the internal carotid artery, the internal jugular vein and the lower four cranial nerves. Above the superior border of the superior constrictor muscles (at the sinus of Morgagni), the nasopharynx is separated from the parapharyngeal space by the pharyngobasilar fascia and the pharyngeal mucosa only, allowing easy spread of tumour in the parapharyngeal space. Clinical features Symptoms may be due to the local effects of the tumour mass in the nasopharynx, direct spread into contiguous structures (including erosion of the skull base), regional or distant metastases, cranial nerve involvement or paraneoplastic syndromes. Sixty percent of patients present with palpably enlarged cervical nodal metastases. CT scans have detected nodal metastases in 75% to 90% of nasopharyngeal carcinomas of histologic types WHO 2 and WHO 3. The initial spread of nasopharyngeal carcinoma is to the retropharyngeal nodes (nodes of Rouviere) but the first palpable nodes are the jugulodigastric nodes followed by apical nodes deep to the superior aspect of the sternomastoid. Metastases to submandibular and parotid nodes are relatively common. The tumour can directly invade the deep lobe of the parotid. Bilateral cervical nodal metastases frequently occur. Fifty percent of undifferentiated carcinoma of the nasopharynx will present with bilateral cervical lymphadenopathy. Nasal symptoms are common but may be quite subtle. Nasal obstruction along with bloodstained postnasal discharge is common. Epistaxis may only occur after hawking. Secondary infection or obstruction to the drainage of the paranasal sinuses can cause the symptoms of sinusitis. Aural symptoms are frequently present. The tumour obstructs the eustachian tube or infiltrates the tensor or levator palati muscle, interfering with the function of the eustachian tube. Otitis media with effusion is commonly the end result. Recurrent acute suppurative otitis media may also be found. One must always be suspicious of nasopharyngeal carcinoma in any teenager or adult who has unilateral otitis media with effusion (although this lesion can also cause bilateral otitis media with effusion). Other aural symptoms include otalgia and tinnitus. Cranial nerve palsies are found in 15-20 % of patients. At the University Hospital of the West Indies, cranial nerves VI and XII are most commonly involved. Nasopharyngeal carcinoma can easily invade the fifth cranial nerve since the foramen ovale lies lateral to the apex of the Fossa of Rosenmuller. Cranial nerves V and VI can both be affected at 26 the petrous apex. Nasopharyngeal carcinoma can spread superiorly through the foramen lacerum and along the internal carotid artery to the cavernous sinus. In this way cranial nerves III, IV, Va, Vb and VI may be invaded or compressed. Spread to the parapharyngeal space, the jugular foramen and/or the hypoglossal canal can cause cranial nerve palsies involving the last four cranial nerves. The tumour can spread anteriorly to the pterygopalatine fossa and the maxillary sinus with subsequent involvement of the orbit and the optic nerve. It is conceivable that the olfactory nerve may rarely be affected by further spread into the roof of the nose or the anterior cranial fossa. All cranial nerves except for 7 and 8 can be involved The fossa of Rosenmuller is where most of the nasopharengeal carcinomas arise. Other symptoms and signs include trismus due to invasion of the pterygoid muscles and severe headaches resulting from erosion of the skull base or secondary sinusitis. Distant metastases can be detected in 20- 30 % of nasopharyngeal carcinomas. Skeletal metastases (especially to the thoracolumbar spine) account for 50 % of these lesions. Intracranial spread has been found in 3-12 % of cases. Diagnosis The nasopharynx can be assessed by nasopharyngeal mirrors or by endoscopes in the Outpatients' Department. The diagnosis is confirmed by the histology of nasopharyngeal biopsies under local or general anaesthesia. One must stress that the lesion may be almost entirely submucosal and deep biopsies may be required to obtain adequate samples. These cases are best biopsied under general anaesthesia. The CT scan or MRI can often alert one of the need for deep biopsies. Assessment of the extent of the tumour Clinical and radiological studies are the main methods of assessing the tumour extent. CT scans of the base of the skull and the neck should be the minimum investigations. Plain X-ray can demonstrate erosion of the skull base and the foramina but is too insensitive a method to accurately assess the extent of the lesion. Plain X-rays of the head and neck are only indicated when CT or MRI is unavailable. Chest X-rays are used in the general evaluation of the patient and also to detect pulmonary metastases ( CT scan more accurate for the latter). Immuno-cytochemistry used to determine what the cancer developed from TREATMENT Nasopharyngeal carcinoma is predominantly treated with radiotherapy. The use of Cobalt 60 and megavoltage linear accelerator has decreased the incidence of complications while at the same time improving the results. Imaging studies have allowed better delineation of the tumour extent and therefore better planning of radiotherapy. Doses of 65-70 Gy are now given. Hyperfractionation is being utilised but there are no well-controlled, prospective studies assessing the efficacy of this technique, in nasopharyngeal carcinoma, when compared to that of traditional radiotherapy. Intracavitary and interstitial radiotherapy may be particularly useful in recurrent lesions. Surgery is generally limited to biopsies and radical neck dissections for residual tumour following radiotherapy. In patients with massive lymphadenopathy, surgery to reduce the tumour mass, is sometimes advocated prior to radiotherapy. The rational for this is that radiotherapy is less effective in these cases since the centre of the lesion is likely to be hypoxic. When there is recurrent tumour in the nasopharynx, intracavitary radiotherapy or surgery may be initiated. Grommets have been inserted to treat the otitis media with effusion that is often associated with nasopharyngeal carcinoma 27  Prognosis Major prognostic factors adversely influencing the outcome of treatment include large size of the tumour, higher T stage, and the presence of involved neck nodes (especially nodes > 8 cm diameter and supraclavicular nodes). Cranial nerve palsies, bone invasion and intracranial spread significantly affect survival. Small cancers of the nasopharynx are highly curable by radiotherapy with survival rates of 80%-90%. Moderately advanced lesions without clinical evidence of spread to cervical lymph nodes are often curable with survival rates of 50%-70%. The overall 5-year survival is 57 %. Patients with advanced lesions, especially those associated with clinically positive cervical lymph nodes, cranial nerve involvement, and bone destruction, are poorly controlled locally by radiotherapy with or without surgery and often develop distant metastases despite local control. Most present very late in Jamaica. MANAGEMENT OF SINUSITIS Acute sinusitis is defined as an acute inflammation of the paranasal sinuses, which resolves without residual mucosal change following appropriate medical therapy. Children who meet the following criteria are categorised as having chronic sinusitis: a) Persistent symptoms and signs for twelve weeks or six episodes per year of recurrent acute sinusitis 28 b) in association with persistent mucosal change on CT scan four weeks after medical therapy (International Conference on Sinus Disease: terminology, staging, therapy ---- 1993) The paranasal sinuses develop as outgrowths from the lateral wall of the nose starting at the 40th gestational day. At birth, only the maxillary and the ethmoidal sinuses are readily identifiable. Most of the subsequent growth of the maxillary sinus depends on the eruption of the dentition. The frontal sinus usually develops from anterior ethmoidal air cells called the frontal recess. The majority of the paranasal sinuses drain into the middle meatus. Normal physiology of the paranasal sinuses depends on the patency of the ostia of the sinuses, good mucociliary function and adequate immune function. Sinusitis is often initiated by obstruction of the ostiomeatal complex, which results in hypoxia of the sinus mucosa and ciliary dysfunction. This produces stasis of the sinonasal secretions and multiplication of bacteria. The inflammatory response perpetuates the obstruction of the ostia. Thus patients may have a primary lesion obstructing the ostia or inflammation may produce secondary obstruction of the ostia. Chronic sinusitis develops if the obstruction is not relieved. Persistent disease in the sinuses is usually secondary to disease in the anterior ethmoids and the ostiomeatal complex (middle meatus and adjoining areas). Medical and surgical management must attempt to correct the abnormalities in these key areas. A thorough history and a full examination are essential in each patient. However it is often difficult to examine the middle meatus without the use of nasal endoscopes. When the middle meatus is not seen and symptoms and signs of purulent rhinorrhoea, postnasal discharge and nasal obstruction persist for more than ten days a presumptive diagnosis of rhinosinusitis should be made. It is also reasonable to make a diagnosis of rhinosinusitis in the patient who has nasal symptoms associated with pain in the region of the sinuses. In the past we relied heavily on plain X-rays in the investigation of the sinuses. Mucosal thickening, sinus opacification and fluid levels are often indicative of sinusitis. It is now possible to assess the sinuses with great precision. The state of the art techniques in the assessment of the sinuses are nasal endoscopy and high resolution computerised tomography. Nasal endoscopy has allowed us to examine areas that were previously inaccessible without general anaesthesia. Patients with suspected complications of sinus disease (e.g. orbital and intracranial complications) and those with persistent symptoms and signs despite adequate medical therapy require computerised tomography. This will allow precise planning of the surgical approach in each patient. Complications of Sinusitis 29 Local Orbital complications Intracranial Spread 1. Chronicity and 1. Dacrocystitis because of 1. Epidural Abscess irreversible mucosal change obstruction of the Naso- 2. Meningitis 2. Mucocele lacrimal Duct. 3. Subdural Abscess 3. Osteomyelitis 2. Conjunctivitis 4. Frontal lobe especially of the diploic 3. Subperiosteal abscess Abscess anterior wall of frontal sinus 4. Periorbital cellulitis 5. Cavernous sinus 5. Orbital Cellulitis thrombosis 6. Orbital abscess 7. Ophthalmoplegia 8. Blindness Note that the paranasal sinuses are the commonest source of frontal lobe abscess. Medical therapy of Sinusitis aims to control infection, establish patency of the ostia, relieve symptoms and treat predisposing conditions. Streptococcus pneumoniae and Haemophilus influenzae are responsible for 76% of cases of community-acquired sinusitis. Anaerobes, other streptococcal species, Moraxella catarrhalis and Staphylococcus aureus each account for 3-7% of cases. Amoxicillin plus Clauvulanic acid, and Cefuroxime are considered as good first line antibiotics. 30  True vocal cords During phonation the true vocal cords are adducted. When the expiratory respiratory muscles contract, the subglottic air pressure increases. The subglottic air pressure will eventually be high enough to force the true vocal cords apart allowing the egress of expiratory air. The resultant fall in the subglottic pressure, the elastic recoil of the tissue and the Bernoulli effect will restore the true vocal cords to their original adducted position. Once again, the cycle of increasing subglottic pressure and separation of the true vocal cords will begin again. Studies have demonstrated that throughout the cycle of phonation, the vocal cord ligaments remain in an adducted position. Adduction and separation predominantly involves the mucosa. Thus we can speak about a mucosal wave of vibration. This explains the marked deterioration of the voice that is associated with disease of the mucosa of the true vocal cords. Normal vocal cord mobility requires intact recurrent laryngeal nerves, neuromuscular junction, glottic muscles and cricoarytenoid joints. CAUSES OF HOARSENESS Intrinsic lesions of larynx Acquired lesions Congenital lesions Vocal cord nodules Vocal cord palsy Vocal cord polyps Vocal cord webs Reinke's oedema (marked oedema in Laryngeal cysts the submucosa of the true cords) Laryngocoele Acute and chronic laryngitis Haemangioma or lymphangiomas Granulomas of the vocal cords: intubation granulomas, pyogenic granulomas, and tuberculosis Myxoedema: a dry waxy type of swelling (non pitting oedema) with abnormal deposits of mucin in the skin and other tissues associated with hypothyroidism the facial changes are distinctive with swollen lips and thickened nose Benign tumours: Laryngeal papillomatosis Malignant tumours: Squamous cell carcinoma (95%) Trauma with haematoma and oedema Foreign bodies at the glottis Recurrent laryngeal Supranuclear lesions of Posterior fossa lesions nerve palsy the vagus Acoustic neuroma 20 lesion of the vagus or Cerebrovascular accident Meningioma directly 31  Nuclear lesion Jugular foramen lesions Cervical lesions Bulbar poliomyelitis Glomus jugulare Penetrating neck injuries Motor neuron disease Metastatic carcinoma of Carotid body surgery Lateral medullary the nasopharynx Radical neck dissection syndrome Thoracic lesions Carcinoma of esophagus Tuberculous or metastatic nodes Aortic aneurysm or aneurysmal surgery Lesions of the recurrent laryngeal nerve in the neck Invasion by malignancies of the thyroid, cervical oesophagus, pyriform sinus. (Carcinoma of the larynx typically causes vocal cord palsy by infiltration of the intrinsic laryngeal muscles) Thyroidectomy Pharyngeal pouch surgery Repair of tracheal stenosis or tracheo-oesophageal fistula Viral infections and disorders such as vasculitis (e.g. associated with diabetes and autoimmune disorders) can affect either the vagus or the recurrent laryngeal nerve. Hoarseness can also occur because of: Disorders at the neuromuscular junction: myasthena gravis Muscular disorders: muscular dystrophies Cricoarytenoid joint dysfuntion: Perichondritis, arthritis, post-traumatic adhesions The assessment of the patient would require a thorough history and examination, special radiologic studies and blood investigations. It is essential that the vocal cords be visualised if hoarseness persists beyond two weeks. CARCINOMA OF THE LARYNX Carcinoma the larynx usually presents in the sixth or seventh decades of life. It 32 is strongly associated with cigarette smoking and alcohol intake. Polycyclic aromatic hydrocarbons derived from cigarette smoking are converted by aryl hydrocarbon hydroxylase to epoxides, which bind DNA and are the true carcinogens. Other associated factors include human papilloma virus types 16 and 18, nickel and asbestos, mate tea in Latin America, and prior radiation. Genetic factors may be important, as there is a higher incidence of laryngeal cancer in some families than the incidence found in the general population. Men are affected five times as frequently as women are. In the United States of America 10,000 to 12,000 cases of laryngeal cancer are reported annually. In men, laryngeal carcinoma occurs in 9 per 100,000 while women have a reported incidence of 1.5 per 100,000. In Jamaica, the incidence is 4 per 100,000 males annually. Worldwide, ethnic differences have been noted in the incidence of laryngeal cancer. Blacks are affected more often than Caucasians, while Japanese and the Chinese have lower incidences than both groups. There is a higher incidence in urban than in rural populations. This may be related to urban pollution. Ninety-five percent of cases are squamous cell carcinomas. Most are moderate to well differentiated. In Jamaica, United States, and Great Britain sixty percent of cases arise at the glottis, thirty-five percent at the supraglottis and the five percent in the subglottis. Wine producing countries such as Italy, Spain and France have a higher incidence of supraglottic than glottic cancers and patients tend to present in middle age at the time of diagnosis. Glottic cancers tend to present early with persistent hoarseness, which becomes progressively worse. Any adult patient who has persistent hoarseness for more than two weeks must be assumed to have malignancy until proven otherwise. Examination of the larynx is mandatory. Early laryngeal cancer can be treated with minimal morbidity and good preservation of voice. Late diagnosis on the other hand may result in a relatively uncomfortable and unpleasant death. Dyspnoea and stridor may be the presenting features in patients with advanced laryngeal cancer. These symptoms may be present without hoarseness in the patient with a supraglottic or subglottic tumour. Cervical nodal metastases are common in supraglottic cancers but are uncommon in glottic cancers until the late stages. This is a reflection of the poor lymphatic drainage of the mucosa of the true vocal cords. The larynx can be examined by a number of methods in the clinic: Indirect laryngoscopy using a mirror Flexible fiber-optic nasolaryngoscopy Rigid telescope (70 degree) The lesion usually arises in the anterior one-third of the vocal cords. Often it appears as warty excrescences on the true vocal cords. Areas of leukoplakia may be present. Vocal cord palsy may be present in the more advanced lesion. In cases where the diagnosis has been greatly delayed, tumour may extend from the supraglottis to extend across the glottis into the subglottis (transglottic tumour). These patients often present with stridor because of the compromised airway. Deep jugular chain cervical lymphadenopathy may be present. This is especially likely in supraglottic tumours where 30% of patients present with palpable nodes (often bilaterally). The lymphatic 33  drainage tends to follow the arteries. (Superiorly along the superior laryngeal vessels to pass through the thyrohyoid membrane to mid deep jugular chain nodes and inferiorly along the inferior laryngeal and inferior thyroid vessels to jugulo-omohyoid nodes). There is also anterior lymphatic spread to prelaryngeal (Delphian node) and pretracheal nodes. Once the diagnosis is suspected the patient should be assessed for his/her fitness for surgery and for the possibility of metastatic spread. Chest Xray and CT examination of the neck and chest should be done. If a CT scan cannot be done because of cost constraints, ultrasound examination of the neck can be substituted. The diagnosis is confirmed by biopsies at direct laryngoscopy or microlayngoscopy. Prior to taking biopsies, the extent of the tumour must be assessed endoscopically and also by palpation of the base of the tongue. There is a 10% incidence of an associated second primary tumour in the head and neck or bronchus. Panendoscopy (laryngoscopy, tracheobronchoscopy, oesophagoscopy and nasophayngoscopy) is often performed. Fine needle aspiration cytology should be perfomed if nodal enlargement is present. However, even if FNA is negative, the neck must still be treated in patients with cervical lymphadenopathy since there is a small false negative rate and all nodes may not have been adequately sampled. Treatment Early laryngeal cancer is best treated with radiotherapy. When the lesion is confined to one vocal cord and there is no impairment of cord mobility, the ten-year survival is 90%. Partial laryngectomy is the second choice for early lesions but results in a poorer voice than when radiotherapy is the treatment modality. Advanced lesions may require total laryngectomy and radiotherapy. Metastases to cervical nodes are treated by neck dissection. The radical neck dissection entails resection of all the lymph nodes in the anterior and posterior triangles of the neck along with the sternomastoid muscle, the accessory nerve and the internal jugular vein. A functional neck dissection spares the non-lymphatic structures. Extranodal spread (into non-lymphoid tissue) is more common in patients with nodes> 3 cm diameter and in patients with multiple nodes. Functional neck dissection would not be advisable in these patients. Chemotherapy is still experimental---- 30-50% respond but no increase in survival rate has been demonstrated. 30 % also become resistant to the treatment. Voice Rehabilitation There are a number of methods of achieving speech after total laryngectomy: a) Oesophageal speech b) Electronic larynx c) Tracheo-oesophageal puncture and insertion of Blom- Singer or Provox valve d) Neoglottic techniques The tracheo-oesophageal puncture with insertion of a one- way valve is now most popular. The valve allows air to go into the oesophagus while the patient is expiring but will not allow food or drinks to get into the trachea. 34  SALIVARY GLAND TUMOURS The major salivary glands are the parotid, submandibular and sublingual glands. Hundreds of minor salivary glands are found in the palate, buccal mucosa, tongue, vallecula, larynx, trachea and paranasal sinuses. 35 The parotid gland is the largest of the salivary glands. Relations The parotid gland is a serous gland, which has three surfaces: anteromedial, posteromedial and lateral or superficial. The anteromedial surface embraces the ascending ramus of the mandible, which is sandwiched between the masseter externally and the medial pterygoid muscle medially. Posteromedial surface is related to the mastoid with the associated attachments of the sternomastoid and the posterior belly of the digastric. The external carotid artery grooves this surface before entering the gland. The styloid process and its associated muscles separate the internal carotid artery and the internal jugular vein from this surface of the gland. This superficial or lateral surface is covered by skin and superficial fascia. The gland extends superiorly to the level of the zygomatic arch. Inferiorly the gland extends into the neck, overlapping the superior aspect of sternomastoid. Anteriorly it extends to overlap the masseter muscle. The facial nerve traverses the gland and the portion of the gland superficial to the nerve is called the superficial lobe while that lying deep to the nerve is called the deep lobe of parotid. The parotid gland has a true capsule formed by condensation of the investing layer of the deep cervical fascia. This explains why acute inflammatory conditions of the parotid are so painful. The greater auricular nerve supplies the skin overlying the parotid and its posterior branch supplies the ear lobe. This posterior branch can sometimes be saved during parotidectomy but the anterior branch has to be sacrificed. The submandibular gland is a mixed salivary gland; which is divided into superficial and deep lobes by the mylohyoid muscle. The marginal mandibular branch of the facial nerve is a lateral relationship to the gland. The lingual and the hypoglossal nerves are closely related to the medial aspect of the gland. The submandibular duct (Wharton's duct) emerges from the deep lobe and courses anteriorly between the hyoglossus and mylohyoid muscles. While occupying this plane the duct is crossed twice by the lingual nerve, once on its lateral aspect near its origin and again on the medial aspect of the duct near its termination at the lingual frenulum. The facial artery and vein supplies the gland and are intimately linked to the submandibular gland. Tumours of the salivary glands The diversity of histopathologic lesions that are expressed in the salivary glands make these tissues truly unique. Salivary gland tumours constitute 3-6 % of all head and neck tumours. Sixty-five to eighty-five percent of all salivary gland tumours occur in the parotid gland. The majority (80 %) of parotid tumours are benign; while 50% to 60% of submandibular tumours and 40% of sublingual and minor salivary gland tumours are benign. Parotid neoplasms are slightly more common in females. There is a slight racial predilection for African - Americans over Caucasians. In Kingston, Jamaica, the incidence of malignant tumours of the salivary gland is 1.2 per 100 000 males and 0.5 per 100 000 females. Salivary gland tumours have an annual incidence of 1 per 100 000 in the United States of America. The majority of patients present in the age range 30 to 70 years. 36 CLASSIFICATION Parotid tumours can be classified as tumours of epithelial or non-epithelial origin. The tumours may be benign or malignant. The malignancies may be primary or metastastatic parotid tumours. Tumours of epithelial origin Benign: Mixed tumour (pleomorphic adenoma) Papillary cystadenoma lymphomatosum (Warthin's tumour) Oncocytoma Monomorphic tumours e.g. Basal cell adenoma and Myoepithelioma Primary Malignant Parotid Tumours: Mucoepidermoid carcinoma (low, intermediate and high grade): 15 % of all salivary gland tumours Adenoid cystic carcinoma: 10 % of all salivary gland tumours Adenocarcinoma: 8% of all salivary gland tumours Carcinoma ex pleomorphic adenoma (carcinoma arising in a mixed tumour) and Malignant mixed tumour (biphasic tumour): 6% of all salivary gland tumours Acinous cell (acinic cell) carcinoma: 3% of all salivary gland tumours Oncocytic carcinoma Secondary or Metastatic Parotid tumours Tumour-like swellings of the parotid Sjogren's syndrome Benign lympho-epithelial lesion Sialosis The malignant tumours can also be classified into low and high-grade carcinomas according to their aggressiveness. Acinic cell carcinoma is a good example of a low- grade carcinoma. The malignant mixed tumour is usually a high-grade carcinoma. There are also aggressive subtypes of mucoepidermoid and adenoid cystic carcinoma. Pleomorphic adenoma This is the commonest benign tumour of the parotid, submandibular and sublingual glands. It is responsible for 70 percent of parotid tumours. It occurs slightly more frequently in females (female to male ratio of 3: 2). It occurs most commonly in the 5th decade of life. The tumour is slow growing with occasional growth spurts. Facial nerve palsy is extremely rare and the presence of any facial weakness should suggest malignant transformation. Pleomorphic adenomas that have been present for greater than 10 years undergo malignant transformation in 2-10 percent of cases (carcinoma ex- pleomorphic adenoma). Grossly the tumour is firm and grey-white with variegated myxoid and blue translucent areas of chondroid. 37 The tumour is pleomorphic in a number of ways. The stroma may show chondroid, osteoid, myxomatous or fibrous features the ratio of stroma to epithelial component varies from tumour to tumour and from site to site within any one tumour. The epithelial cells may be polygonal, cuboidal or columnar and may form nests or cords of cells The tumour has an incomplete capsule with pseudopodial projections extending thr