Ear Pathology PDF

E Ear Atresia Introduction ▶ Congenital Aural Atresia Canal wall down mastoidectomy is an effective treat- ment option in the management of cholesteato...

E Ear Atresia Introduction ▶ Congenital Aural Atresia Canal wall down mastoidectomy is an effective treat- ment option in the management of cholesteatoma. Controversy remains, however, regarding how to Ear Canal Wall Replacement/ address the posterior canal wall. Removing the canal Reconstruction wall greatly improves successful elimination of middle ear and mastoid disease, but is not without disadvan- John T. McElveen Jr. and Calhoun D. Cunningham III tages. Canal wall down surgery results in an exterior- Carolina Ear & Hearing Clinic, P.C., Raleigh, ized mastoid cavity that tends to accumulate moisture NC, USA and debris and can predispose to otorrhea. This necessitates periodic cleaning of the mastoid cavity Synonyms and possibly water restrictions on the part of the patient. These patients may also experience a “caloric Canal wall reconstruction; Mastoid obliteration; effect” causing dizziness and vertigo when the ear is Reversible canal wall down mastoidectomy cleaned due to stimulation of the exposed lateral semicircular canal. Preserving the posterior canal wall, such as with Definitions intact canal wall surgery, preserves the normal ana- tomic dimensions of the middle ear thereby improving Cholesteatoma: Skin-lined cyst involving the middle hearing results with ossicular reconstruction. The need ear and mastoid. for periodic cleaning of the mastoid cavity is elimi- Tympanomastoidectomy: Surgical technique to nated as is the need for water precautions, which is remove cholesteatoma and repair the ear drum. especially important for pediatric patients. Preserva- Intact canal wall surgery: Surgical procedure that tion of the posterior canal wall, however, may impair maintains the integrity of the posterior external direct visualization of some areas within the middle ear auditory canal. and epitympanum during surgery, potentially leaving Canal wall down: Surgical procedure that removes the residual disease. posterior canal wall and connects the mastoid cavity Over the years, a variety of techniques have been to the external auditory canal. developed to either temporarily displace the posterior Mastoid obliteration: Surgical technique that fills in canal wall during cholesteatoma surgery, or to recon- the mastoid cavity. struct it following disease removal. S.E. Kountakis (ed.), Encyclopedia of Otolaryngology, Head and Neck Surgery, DOI 10.1007/978-3-642-23499-6, # Springer-Verlag Berlin Heidelberg 2013 E 732 Ear Canal Wall Replacement/Reconstruction Canal Wall Reconstruction/Displacement cuts with a Feldmann saw to temporarily remove the Techniques posterior canal wall. The superior cut was made ante- rior to the head of the malleus and the inferior cut along In 1963, Schnee first reported on his experience the inferior aspect of the facial recess. The bone was with temporarily displacing the posterior canal wall removed, replaced orthotopically, and fixed using to facilitate exposure for tympanic membrane ionomeric cement. grafting. In contradistinction to the Babighian technique, the Lapidot and Brandow (1966) used a small cutting reversible canal wall down technique developed by burr to create perforations in the posterior canal wall. McElveen beveled the canal cuts in such a manner The superior osteotomy was made at the level of the that the posterior surface of the canal segment was superior buttress, and the inferior osteotomy was made wider than the anterior segment, minimizing the like- at the bottom of the ear canal. A horizontal osteotomy lihood of the segment becoming displaced anteriorly connecting the two vertical cuts was made 1–2 mm into the external auditory canal. In addition, in suitable lateral to the mastoid segment of the facial nerve. The cases, the reversible canal wall down approach was posterior canal wall with its intact ear canal skin was combined with attempts to preserve the ossicular displaced anteriorly, exposing the ossicular chain and chain when the cholesteatoma had not engulfed the posterior tympanic cavity. ossicles. The technique of Richards (1972) differed only In 2005, Gantz et al. reported on canal wall slightly from that of Lapidot and Brandow (1966) in reconstruction tympanomastoidectomy with mastoid that placement of his superior osteotomy started ante- obliteration. They described their technique of pos- rior to the head of the malleus; otherwise, the proce- terior canal wall removal using a microsagittal saw dure was essentially the same. in order to increase intraoperative exposure for In 1969, Gerlach temporarily removed the bony ear cholesteatoma removal as well as removal of any canal wall in cases of extensive cholesteatoma. Using diseased and/or nitrogen-absorbing mastoid epithe- small cutting burrs to create his osteotomies, the lium. Using their technique, the canal wall was then superior osteotomy was anterior to the head of the replaced and the attic and mastoid were isolated malleus and the inferior osteotomy was toward from the middle ear space using a combination of the floor of the ear canal. The bony ear canal was bone chips and bone pâté to obliterate the mastoid. replaced and fixed with Histoacryl glue, and This technique was felt to improve the outcomes of a superiorly based fascia–muscle flap was placed chronic ear surgeries for cholesteatoma by enhanc- behind the canal wall. ing the surgeon’s ability to remove cholesteatoma Wullstein (1972) developed the osteoplastic through improved exposure, as well as preventing epitympanotomy approach using a 0.3–0.4-mm dia- the development of postoperative retraction pockets mond burr to create a groove in the anterior tympanic by obliterating the mastoid and epitympanum spine (Wullstein 1972). Her inferior cut appeared to be and removing the nitrogen-absorbing mastoid in the region of the incudal fossa. The bone was epithelium. In long-term follow-up of their patients, replaced and covered with bone pate and fibrin glue. 98.5% of ears remained safe without evidence of Fascia was used to cover the bone flap. recurrence. Feldmann (1978) used an oscillating saw to create In addition to reversible canal wall reconstruction four angled cuts, the superior cuts were above the short and mastoid obliteration, various reports describe process of the malleus and the inferior cuts were along the use of cartilage to reconstruct the posterior the inferior aspect of the facial recess. By angling the canal wall (Weber and Gantz 1998; Dornhoffer cuts, he was able to create grooves in the posterior 2004; Barbara 2008; Pennings and Cremers 2009). canal wall, allowing him to replace the canal wall For large defects or total canal wall reconstruction, without other means of fixation. cymba cartilage can be successfully employed Mercke (1987) had combined Feldmann’s (1978) to reconstruct the canal wall due to its rigidity and technique with a musculoperiosteal Palva flap and natural curvature. Cartilage is readily available, has obliterated the epitympanic space with bone chips. excellent biocompatibility, and is versatile and Babighian’s (1993) approach involved making canal easily shaped. Ear Canal Wall Replacement/Reconstruction 733 E Mastoid Obliteration Techniques obliteration using skin and muscle flaps with a Wullstein type IV tympanoplasty and Austin (1962) A variety of methods, both medical and surgical, have further advanced middle ear reconstruction in combi- been suggested for the management of the chronically nation with mastoid obliteration using a temporalis discharging mastoid cavity. The surgical alternatives muscle flap. In 1961, Guilford proposed combining have included: (1) lining the mastoid with skin grafts a musculoperiosteal flap as described by Meurman (Kerrison 1930; Lempert 1949; House 1949); (2) filling and Ojala with Rambo’s temporalis muscle flap to the cavity with various materials such as bone (Schiller provide a more complete obliteration of the cavity. 1963; Shea and Gardner 1970), cartilage (Wullstein During this same period, Tauno Palva (1962a) began 1962), fat (Kuhweide and van Deninse 1960), acrylic using a postauricular flap for complete mastoid oblit- (Mahoney 1962), and recently hydroxylapatite eration in children and later for the reconstruction of E (Hartwein and Hoermann 1990); (3) lining or obliter- the ear canal and middle ear in adults (1962b, 1963). ating the mastoid cavity with pedicled soft tissue flaps, Palva developed an anteriorly pedicled either at the time of mastoidectomy or during revision. musculoperiosteal flap with a broad base toward the We focus on the development of soft tissue ablation of meatus. This flap was similar to that described by the mastoid cavity. Popper (1935), except that Palva included all of the The first use of a pedicled tissue flap after mastoid- subcutaneous soft tissues with the periosteum. The ectomy was reported by Passow in 1908, who used anterior broad base of this flap provided a rich vascular a temporalis musculoperiosteal flap to control persis- supply and preserved the innervation to the muscle. tent fistulae in two patients. In 1910, Gabe reported his These design advantages have made the Palva flap experience with this procedure in 28 patients. Mosher particularly useful in obliterating the mastoid cavity. (1911) independently described a superiorly based One of the problems with soft tissue mastoid oblit- musculoperiosteal flap derived from postauricular eration techniques was the potential for atrophy of the soft tissue that he used in an attempt to “shorten the soft tissue over time. As a result, interest developed in healing, to prevent deformity, and to lessen the fre- using bone to obliterate mastoid cavities. Several quency of secondary operations.” Mastoid obliteration authors have described techniques for harvesting was later advanced by Kisch (1928) who presented autogenous bone chips or bone pate to obliterate or three cases with conservative mastoid surgery and reconstruct the canal wall following primary or revi- a temporalis muscle flap to the Royal Society of Med- sion canal wall down mastoid surgeries (Shea and icine in 1928. Despite successful reports of Kisch’s Gardner 1970; Palva 1975; Mills 1987). These tech- technique in both England and the United States niques require the harvesting of cortical bone posterior (Almour 1930; Mill 1930), the otologic community to the mastoid cavity using a bone pâté collector. After was reluctant to adopt this new procedure. In 1935, complete exoneration of any diseased mastoid air cells, Popper introduced a periosteal flap with a broad base the bone pate is compressed into the mastoid defect to directed toward the auricle in an effort to provide obliterate the cavity and reconstruct the canal wall. It is a viable lining for the mastoid cavity. Meurman and important that the bone pate be covered with either Ojala (1949) incorporated the muscle with the perios- fascia or a local soft tissue flap at the time of recon- teum in an inferiorly pedicled flap designed to obliter- struction. Although there is a risk of reabsorption, with ate the mastoid tip. In spite of these independent proper technique, Roberson and colleagues (2003) reports of soft tissue mastoid ablation as an alternative reported a take rate of 95%. Bone pate is an excellent to a large open cavity, these methods were not gener- resource for mastoid obliteration as it is readily avail- ally accepted at the time. able and has excellent biocompatibility resulting in Interest in mastoid obliteration was revived in 1958, osteoinduction and osteoneogenesis. when Rambo described the use of a temporalis muscle Interest has also been expressed in the use of syn- flap followed by fenestration of the lateral semicircular thetic materials such as hydroxyapatite cement (Grote canal. Thorburn (1960) suggested that Rambo’s oblit- 1998). Although readily available and easy to work erative technique might be combined with a Wullstein with, these materials demonstrate a higher rate of tympanoplasty procedure, but this idea was rejected by extrusion or tissue breakdown over time and may Rambo. Richtnér (1960) later combined mastoid require coverage with a vascularized tissue flap. E 734 Ear Canal Wall Replacement/Reconstruction Conclusion Kisch H (1928) Temporal muscle grafts in the radical mastoid operation (with illustrative cases). J Laryngol Otol 43:735–736 Maintenance of the posterior canal wall facilitates Kuhweide W, van Deninse JB (1960) Surgical treatment of normal water activities for the patient and avoids the chronic otitis media. Acta Otolaryngol 52:143 need for periodic cleansing of the mastoid cavity. Lapidot A, Brandow E (1966) A method for preserving the A variety of techniques have proven successful in posterior canal wall and bridge in the surgery for cholesteatoma. Acta Otolaryngol 62:88–92 temporarily displacing the posterior canal wall during Lempert J (1949) Lempert endaural subcortical mastoidectomy chronic ear surgery. In addition, other techniques for the cure of chronic persistent supporative otitis media. have been developed to reconstruct the posterior Arch Otolaryngol Head Neck Surg 49:20–35 canal wall in patients with an exteriorized mastoid Mahoney JL (1962) Tympanoacryloplasty. Arch Otolaryngol Head Neck Surg 75:519 cavity. The use of foreign bodies to reconstruct the McElveen JT, Chung ATA (2003) Reversible canal wall down canal wall may result in tissue breakdown over mastoidectomy for acquired cholesteatomas: preliminary the implant with time. In light of this, soft tissue or results. Laryngoscope 113:1027–1033 autogenous cartilage or bone techniques are prefera- Mercke U (1987) The cholesteatomatous ear one year after surgery with obliteration technique. Am J Otol 8:534–536 ble and have proven to be effective with long-term Meurman Y, Ojala L (1949) Primary reduction of a large oper- follow-up. ation cavity in radical mastoidectomy with a muscle- periosteal flap. Acta Otolaryngol 37:245–251 Mill WA (1930) Three cases of conservative mastoid operation with temporal muscle graft. J Laryngol Otol 45(11):129–130 References Mills RP (1987) Surgical management of the discharging mas- toid cavity. Clin Otolaryngol 12:327–329 Almour R (1930) A method for the repair of persisting Mosher HP (1911) A method of filling the excavated mastoid postauricular openings. Laryngoscope 40:799 with a flap from the back of the auricle. Laryngoscope Austin DF, Sanabria F (1962) Mastoidplasty. Arch Otolaryngol 21:1158–1163 Head Neck Surg 76:414–421 Palva T (1962a) Mastoiditis in children. Laryngoscope Babighian G (1993) Posterior and attic wall ‘en bloc’ osteoplasty 72:353–360 in combined approach tympanoplasty. In: Nakano Y (ed) Palva T (1962b) Reconstruction of ear canal in surgery for Cholesteatoma and mastoid surgery. Kugler, Amsterdam, chronic ear. Arch Otolaryngol Head Neck Surg 75:329–334 pp 649–653 Palva T (1963) Surgery of chronic ear without cavity. Arch Barbara M (2008) Lateral attic reconstruction technique: pre- Otolaryngol Head Neck Surg 77:570–580 ventive surgery for epitympanic retraction pockets. Otol Palva T (1975) Mastoid obliteration. Arch Otolaryngol Neurotol 29(4):522–525 101:271–273 Dornhoffer JL (2004) Retrograde mastoidectomy with canal Passow A (1908) Uber€ den Verschluss der Knochenwunden wall reconstruction: a follow-up report. Otol Neurotol nach Antrumoperationen. Beitr Anat Physiol Path Therap 25(5):653–660 Ohres 1:67–75 Feldmann H (1978) Osteoplastic approach in chronic otitis Pennings RJE, Cremers CWRJ (2009) Postauricular approach media by means of a microsurgical reciprocating saw. Clin atticotomy: a modified closed technique with reconstruction Otolaryngol 3:515–520 of the scutum with cymbal cartilage. Ann Otol Rhinol Gabe E (1910–1911) Uber € den plastischen Verschluss Laryngol 118(3):199–204 persistierender retroaurikularer Öffnungen nach Popper O (1935) Periosteal flap grafts in mastoid operations. Antrumoperationen. Beitr Anat Physiol Path Therap Ohres S Afr Med J 9:77–78 18:354–375 Rambo JHT (1958) Musculoplasty: a new operation for suppu- Gerlach H (1969) Die hintere Gehorgangswand bei der rative middle ear deafness. Trans Am Acad Ophthalmol tympanoplastik. Monatsschr Laryngol Rhinol Otol Otolaryngol 62:166–177 48:214–218 Richards S (1972) Tympanoplasty results following the Grote JJ (1998) Results of cavity reconstruction with hydroxy- mobilebridge technique. Trans Am Acad Ophthalmol Otol apatite implants after 15 years. Am J Otol 19:551–557 76:153–159 Guilford FR (1961) Obliteration of the cavity and reconstruction Richtnér NG (1960) Reconstructive micro surgery of the ear, of the auditory canal in temporal bone surgery. Trans Am especially with the cavum minor technique. Laryngoscope Acad Ophthalmol Otolaryngol 65:114–122 70:1179–1197 Hartwein J, Hoermann K (1990) A technique for the reconstruc- Roberson JB, Mason TP, Stidham KR (2003) Mastoid oblitera- tion of the posterior canal wall and mastoid obliteration in tion autogenous cranial bone pÂte reconstruction. Otol radical cavity surgery. Am J Otol 11(3):169–173 Neurotol 24(2):132–140 House H (1949) Surgery for the chronically discharging ear. Saunders JE, Shoemaker DL, McElveen JT (1992) Reconstruc- Arch Otolaryngol Head Neck Surg 49:135–150 tion of the radical mastoid. Am J Otol 13(5):465–469 Kerrison P (1930) Diseases of the ear. JB Lippincott, Schiller A (1963) Mastoid osteoplasty. Arch Otolargyngol Head Philadelphia Neck Surg 77:475–483 Ectropion 735 E Schnee I (1963) Tympanoplasty: a modification in technique. Arch Otolaryngol 77:87–91 Ecchordosis Physaliphora Shea MC, Gardner G (1970) Mastoid obliteration using homo- graft bone. Arch Otolaryngol Head Neck Surg 92:358–365 Shea MC Jr, Gardner G Jr, Simpson ME (1970) Mastoid oblit- ▶ Chordoma eration using homogenous bone chips and autogenous bone paste. Arch Otolaryngol 92:413 Sheehy JL, Crabtree JA (1974) Tympanoplasty: staging the operation. Laryngoscope 83:1594–1621 Sheehy JL, Brackmann DE, Graham MD (1977) Cholesteatoma Ectatic Carotid Artery surgery: residual and recurrent disease. A review of 1024 cases. Ann Otol Rhinol Laryngol 86:451–462 ▶ Imaging for Parapharyngeal Space Masses, Ectatic Thorburn IB (1960) A critical review of tympanoplastic surgery. Internal Carotid Artery E J Laryngol Otol 74:453–474 Weber PC, Gantz BJ (1998) Cartilage reconstruction of the scutum defects in canal wall up mastoidectomies. Am J Otolaryngol 19(3):178–182 Wullstein A (1962) Tympanoplasty today. Arch Otolaryngol Head Neck Surg 76:295 Ectropion Wullstein S (1972) Die osteoplastische epitympanotomie und ihre resultate. Arch Ohren Nasen Kehlkopfheilkd Michael M. Kim 202:655–658 Division of Facial Plastic & Reconstructive Surgery, Department of Otolaryngology-Head and Neck Surgery, Oregon Health & Science University, Portland, OR, USA Ear Drum Repair ▶ Tympanoplasty, Underlay and Overlay Techniques Introduction Ectropion is the outward turning or eversion of the lower lid margin where the mucosal surface of the lid Ear Popping is no longer in apposition to the globe. Untreated, this condition may result in conjunctivitis or exposure ▶ Barotrauma and Decompression Sickness keratophy. There are several types of ectropion includ- ing involutional (age-related laxity), cicatricial (scar), paralytic, and congenital. The appropriate medical or Ear Reconstruction surgical treatment for this condition is largely deter- mined by the etiology of the disease. ▶ Microtia and Atresia Patient Presentation and Evaluation Ear, Nose, Throat Surgery: Anesthetic Patients with ectropion may present with complaints Management related to conjunctival and corneal exposure such as epiphora (tearing), irritation, mattering, and edema ▶ Anesthetic Techniques for Otolaryngologic Patient (Frueh and Schengarth 1982). The practitioner should note the position of the lid margin and the position of the puncta compared to normal anatomy. In the normal lower eyelid, the lower lid rests at the limbus in appo- Early/Fast Response sition to the globe with no sclera visible between the lower lid margin and the limbus. ▶ Hearing Testing, Auditory Brainstem Response Patients with ectropion may present with con- (ABR) comitant lid retraction. Consequently, the margin E 736 Ectropion reflex distance 2 (MRD2) should be recorded. In Cicatricial ectropion results from a vertical short- patients with epiphora, the patency of the puncta ening of the anterior lamella of the lower lid and lacrimal drainage system can be evaluated by (orbicularis oculi and skin). Causes of anterior lamellar irrigation. In these cases of ectropion with punctal shortening include scarring after trauma, burns, skin eversion, the lack of apposition of the punctum can conditions, blepharoplasty complications, and after cause epiphora despite a functional tear drainage skin cancer defect repair. system. Paralytic ectropion is caused by a loss of orbicularis “Snap” and “distraction” testing are used to evalu- oculi function related to facial nerve paresis. There are ate the horizontal laxity of the lower lid. The “snap” myriad causes of facial nerve palsy including neoplas- test is performed by manual distraction of the lower lid. tic (cerebellopontine angle or parotid tumors), trauma, Normal support is indicated by a return of eyelid to iatrogenic (neurosurgery, otologic surgery, parotid sur- globe apposition after the lid is released either imme- gery), infectious (herpes zoster oticus), and Bell’s diately or at most after one blink. If the lid does not palsy. Problems related to paralytic ectropion exhibit return to the globe after one blink, it is said to exhibit additional complexity to that of the cicatricial and poor support. The “distraction” test also measures hor- involutional varieties due to the contribution of con- izontal laxity. This is performed by distracting the lid comitant upper eyelid dysfunction (Seiff 1998). in a caudal direction while measuring the change in position from normal. Distances of greater than 6 mm indicate laxity. Treatment Should there be any concern regarding corneal abnormalities, referral to an ophthalmologist who can Although massage and taping technique can be used perform a more detailed examination through the use with some success in temporary post-procedure of a slit lamp apparatus may be warranted. An exam- ectropion, the treatment of long-term, stable ectropion ination of the cornea, as well as the quantity and is primarily surgical. Additional conservative mea- quality of tears can be evaluated through fluorescein sures such as lubrication and moisturization may be administration. used to prevent corneal complications related to exposure. Many different techniques have been described for Classification the correction of ectropion. Appropriate selection of specific surgical strategies is largely based on the eti- Ectropion is classified depending on its etiology. First, ology and severity of ectropion. Although technically ectropion is grouped into the rare congenital types or possible to perform under local anesthesia, these pro- the more common acquired varieties. Primary congen- cedures are frequently done under Monitored Anesthe- ital ectropion results from a primary anomaly of the sia Care (MAC) or General Anesthesia (GA) for tarsus while secondary congenital ectropion includes patient comfort. cases caused by birth trauma, skin retraction, and ever- The lateral tarsal strip is widely considered the most sion from orbital tumors. useful procedure in surgical ectropion treatment Acquired ectropion occurs with much greater fre- because it is often utilized in all of the three major quency than congenital ectropion, and involutional types of acquired ectropion (involutional, cicatricial, ectropion is the most common acquired cause. Involu- and paralytic). The procedure provides support to the tional ectropion results from a progressive laxity of the lower lid through horizontal shortening of the tarsal lid support system with age or with extrinsic factors plate followed by fixation (Anderson and Gordy 1979). such as eyelid retraction for ophthalmic surgery (Shore After a lateral canthotomy and inferior lateral 1985). Factors such as medial or lateral canthal tendon cantholysis, the lateral portion of the tarsus is isolated laxity (Ousterhout and Weil 1982), attenuation of the and de-epithelialized. It is then tailored to the appro- lower lid retractors (capsulopalpebral fascia, M€ uller’s priate length and then fixated inside the lateral orbital muscle; Putterman 1978), diminishment of orbicularis rim at the approximate location of Whitnall’s tubercle. oculi function, and weakening of the tarsus and septum If the patient presents with epiphora due can all contribute to cause involutional ectropion. to punctal eversion, the medial spindle procedure Electrodiagnostic Test 737 E is utilized (Nowinski and Anderson 1985). A may need to release sutures and possibly perform lat- diamond-shaped excision of conjunctiva and lower eral canthotomy and cantholysis to decompress the lid retractor musculature is resected. This is then orbit. followed by suture techniques to invert the lid to a position whereby the medial lid and puncta are in apposition to the globe so that the lacrimal system Cross-References can drain normally. Since cicatricial ectropion results from a shortage of ▶ Bell’s Palsy anterior lamella, full thickness skin grafts can be used ▶ Canthal Positions as anterior lamellar replacement tissue. A subciliary ▶ Canthoplasty incision is made and the lower lid margin is released to ▶ Facial Paralysis E expose the posterior lamellar tissue. This is often done ▶ Static Facial Paralysis Rehabilitation in conjunction with a lateral tarsal strip procedure for horizontal support. A full thickness skin graft is then placed between the two sides of the subciliary incision References as a spacer in an overcorrected position. Bolstering techniques in addition to the use of a Frost suture to Anderson R, Gordy D (1979) The lateral tarsal strip procedure. Arch Ophthalmol 97:2192–2196 resist the contractile forces of healing are commonly Frueh B, Schengarth L (1982) Evaluation and treatment of the used. patient with ectropion. Ophthalmology 89:1049–1052 Paralytic ectropion is more difficult to correct since Nowinski T, Anderson R (1985) The medial spindle procedure the dynamic nature of the orbicularis oculi muscle is for involutional medial ectropion. Arch Ophthalmol 103:1750–1753 lost. In addition, the concomitant manifestations of Ousterhout D, Weil R (1982) The role of the lateral canthal upper lid paralysis typically require treatment of the tendon in lower eyelid laxity. Plast Reconstr Surg upper and lower lid in order to achieve full eye closure. 69:620–622 The lower lid can be treated with the aforementioned Putterman A (1978) Ectropion of the lower eyelid, secondary to Mueller’s muscle-capsulopalpebral fascia detachment. Am lateral tarsal strip procedure. A gold weight will often J Ophthalmol 85:814–817 need to be placed in the upper lid in order to provide Seiff S, Chang J (1992) Management of ophthalmic a mechanical load for closure. complications of facial nerve palsy. Otolaryngol Clin North Am 25:669–690 Shore J (1985) Changes in lower eyelid resting position, movement, and tone with age. Am J Ophthalmol 99:415–423 Complications Complications related to ectropion include dry eye, lagophthalmos, corneal ulceration, exposure Eighth Nerve Schwannoma keratopathies, and even blindness. Surgery to correct ectropion may result in complications such as ▶ Cochlear Schwannoma corneal abrasions, inadequate correction, contour abnormalities, and need for additional procedures. Care must be taken when performing lower lid tight- ening procedures on those with the “negative vector” Electroacoustic Stimulation (EAS)/Hybrid anatomic configuration. The “negative vector” is char- Implants acterized by relative proptosis of the globe in relation to the midface. This can be present due to any combi- ▶ Implantable Hearing Devices nation of proptosis and/or malar or orbital rim hypoplasia. Postsurgical hemorrhage should also be recognized and treated early. Patients should be warned to look for Electrodiagnostic Test increased swelling, bleeding, pain, and vision changes. If the patient has impending visual loss, the surgeon ▶ Electromyogram E 738 Electromyogram Polyphasic Potentials Electromyogram Electrophysiologically, a normal motor unit has a di- or triphasic configuration. One of the earliest signs of Kofi Derek O. Boahene muscle reinnervation is the increase in phases of the Department of Otolaryngology-Head and Neck motor units. Polyphasic potentials are abnormal action Surgery, Johns Hopkins University School of potential configurations of a motor unit with five or Medicine, Baltimore, MD, USA more phases and indicate neurological recovery and also establish the fact that there is axonal continuity. Synonyms Cross-References Electrodiagnostic test; EMG ▶ Facial Paralysis ▶ Nerve Grafting Definition Electromyogram (EMG) is electrodiagnostic record- References ing of electric potentials or voltage detected by a needle electrode inserted into skeletal muscle. EMG Anonymous (2001) American Association of Electrodiagnostic Medicine glossary of terms in electrodiagnostic medicine. records the variation in electrical potential of insertion, Muscle Nerve Suppl 10:S1–S50 spontaneous, and voluntary activity of muscles with Dale AJD, Kokmen E, Swanson JW et al (1991) Clinical exam- a recording needle electrode. The American Associa- inations in neurology, 6th edn. Mosby–Year Book, St. Louis, tion of Electrodiagnostic Medicine Glossary of Terms pp 395–396 provides a uniform agreed-upon framework for expressing electric phenomena encountered in study- ing patients with EMG. EMG of the facial muscles is used as an adjunct to Electromyography neurologic examination of the face to determine the state and function of the facial muscles following J. Edward Hartmann facial nerve injury. Georgia Health Sciences, University/Medical College of Georgia, Augusta, GA, USA Fibrillation Potential This is the action potential of a single muscle fiber occurring spontaneously or after movement of a Synonyms needle electrode. Fibrillation potentials usually fire at a constant rate and are indicative of muscle Electroneuromyography; Laryngeal electroneuro- denervation. In the early stage following facial myography; Needle electromyography nerve injury, fibrillation potentials are large in size but continue to decrease in amplitude over time. At 6 months the mean amplitude drops by 50–300 mV, Definition and at 1 year 100 mV or smaller. As a rule, larger amplitudes suggest nerve injury within the past few Electrodes are electrical devices that translate voltage months, whereas smaller amplitudes suggest that changes into electrical signals for analysis. The active injury occurred at least 6 months to a year ago. electrode is the electrode that records the voltages at The presence of fibrillation potentials and their the point of interest. Since voltage is a measurement of amplitude can be used as an indication of a the electrical potential difference between two points, physiologically responsive muscle that may respond a second electrode is needed for measurements. This to reinnervation from various nerve grafting second electrode is the reference electrode. A ground techniques. electrode is placed on the patient for electrical safety. Electromyography 739 E Electromyography (EMG) is the neurodiagnostic demonstrate whether a nerve based lesion is purely test which samples the electrical activity of a muscle. demyelinating (no increase in insertional activity) ver- The electromyographer places a needle intramuscu- sus wholly or partially involving the axon (when larly for recording for evaluation of its insertional increased insertional activity is seen). Axonal lesions activity at rest and its voluntary motor units during typically reflect more severe injury compared to demy- contraction. elinating lesions. Also, EMG can demonstrate if the Insertional activity is the electrical signal generated lesion is incomplete by the presence of voluntary when the recording needle is moved within the muscle. motor units versus complete in which no motor units Normal muscle will show a short period of electrical are seen when a patient is asked to contract the muscle changes. Abnormal insertional activity most com- of interest. EMG can help with prognosis, especially monly is increased. when it is performed serially, since the motor units’ E Interference pattern is the appearance of voluntary morphology and recruitment patterns change over time motor units on the display screen during contraction of in a reinnervated muscle. In addition, specialized a muscle. With submaximal contraction, individual hypodermic EMG needles guide the precise delivery motor units may be analyzed visually or quantitatively of chemodenervation agents such as botulinum toxin for parameters such as amplitude, duration, firing fre- (BT). Common disorders in which these purposes are quency, and recruitment. With full muscle contraction applied in Otolarygologic conditions include Bell’s of a normal muscle, the screen is filled with electrical Palsy, Acoustic Neuromas, Hemifacial Spasm, and activity and individual motor units cannot be distin- Spasmodic Dysphonia. guished. Nerve and muscle diseases cause change in EMG in Bell’s Palsy has been reported by several these patterns. authors. Eighty-one patients with Bell’s Palsy who EMG utilizes one of two types of needles for test- presented over a 4-year period were studied prospec- ing. A monopolar needle consists of a needle that is tively with several electrodiagnostic studies performed coated with a material shielding it from electrical on days 5, 20, and 90 after the clinical onset of symp- activity except at its tip which serves as the active toms (Ozgur et al. 2010). EMG of the orbicularis electrode. A reference electrode is placed on nearby oculus was performed, and results were reported as skin. A concentric needle consists of a needle housing abnormal when insertional activity was increased. both the active and reference electrodes. The needle tip Patients whose House-Brackman score was 3 or higher is beveled exposing a small wire which runs through were considered to have a poor prognosis. All EMGs the center of the needle and acts as the active electrode. were normal on day 5, reflecting a sample time too The wire within the needle is surrounded by an insu- early to detect denervation. All seven patients having lating material, with the outer surface of the needle a poor prognosis on day 90 showed increased inser- serving as the reference electrode. Advantages and tional activity on day 20 (100% sensitivity). Fifty-two disadvantages for each are discussed later in this entry. of fifty-eight patients with a good prognosis on day 90 Recruitment is the orderly fashion in which showed normal results on day 20 (90% specificity). a muscle increases its power. As a muscle begins to Their conclusion was EMG performed on day 20 pro- contract, only one motor unit fires. As the muscle needs vided statistically significant information for more power, this single motor unit fires more fre- predicting prognosis. Another publication evaluated quently. At a certain level of increasing force, 197 patients with four diagnostic tests performed, to a second motor unit begins firing (i.e., is recruited), include EMG (Hyden et al. 1982). EMGs were and more motor units activate as the contractile forces performed 7 days after the onset of symptoms. The increase. With nerve injury, recruitment is delayed, authors categorized the EMG results into five interfer- and with muscle injury, recruitment is early. ence patterns (no motor units, one motor unit, discrete activity, reduced and full interference pattern). If the EMG was showing no motor units, their data showed Purpose 13/13 patients demonstrated a bad (severe or moderate weakness) outcome (100% sensitivity). Alternatively, EMG has several purposes. EMG can show injury of if the EMG showed zero or one motor unit, then 32/41 the muscle due to muscle or nerve diseases. EMG can patients had a bad outcome (78% sensitivity). E 740 Electromyography Specificity with a “normal” EMG was not as strong – significantly improves the BT therapy in relieving the only 50% predictive of a good outcome if any motor myoclonic movements of HS. units were seen on the interference pattern (and 54% if Patients with Spasmodic Dysphonia (SD) undergo >1 motor units were seen). An EMG examination of EMG for two reasons – diagnostic testing and thera- the frontalis, mentalis, and orbicularis oculus (OO) on peutic injections. EMG can sample laryngeal muscles day 30 of symptoms on patients with Bell’s Palsy also used for phonation to assess for neuropathic changes. was published (Kokotis et al. 2006). Of the 54 patients, In addition chemodenervation agents are injected only 11 (20%) showed increased insertional activity in through a hypodermic EMG needle into the the OO, compared to 32 (59%) in the mentalis and 29 thyroarytenoid, lateral cricothyroid, and posterior (54%) in the frontalis. Patients with increased inser- cricothyroid muscles for treatment of SD. The etiology tional activity of the OO showed small amplitude of SD remains unknown, but current theories attribute responses after facial nerve stimulation and poorer its pathophysiology to the extrapyramidal pathways recovery. In summary, an abnormal EMG within similar to other movement disorders. Adductor SD is 1 month of the onset of Bell’s Palsy is helpful in more common and produces a strained or “strangled” determining which patients have a poor prognosis. voice due to forced glottal closure. Abductor SD pro- Forty-five preoperative patients with Acoustic Neu- duces a breathy whisper due to forced glottal opening, romas were studied with EMG to determine prognostic and patients have trouble with the “voiceless” conso- factors (Normand and Daube 1994). The following nants – d, f, h, k, p, s, and t. Many agree that BT is the groups showed abnormalities on EMG: Three of “gold standard” of treatment for SD, compared to other seven patients with facial weakness and 13/38 without treatments such as muscle relaxants, anxiolytics, anti- facial weakness. Four of nine patients with facial sen- cholinergic agents, beta-blockers, and recurrent laryn- sation changes showed EMG abnormalities of the mas- geal nerve resection (Meyer and Blitzer 2007). seter muscle (i.e., assessment of the Trigeminal nerve). Unfortunately, no publications have met the stringent Among their conclusions, they noted that increased standards of evidenced based recommendations to insertional activity was infrequent and less sensitive prove that EMG guidance for injections is the best than the Blink Reflex and Electroneuronography. method for chemodenervation agent delivery. In Hemifacial Spasm (HS) is the condition in which 2003, the American Association of Electrodiagnostic muscles of facial expression involuntarily contract in Medicine (with other organizations) reviewed the a twitching-like movement. HS is a form of segmental published data on laryngeal EMG (LEMG). The arti- myoclonus involving the facial nerve and most com- cle’s recommendation was that LEMG was possibly monly affects the orbicularis oculus and zygomaticus (Level C) equally effective for directing BT for the muscles. Various causes have been described and can treatment of SD when compared to injection guided by be idiopathic or due to any insult to the facial nerve endoscopic techniques based on Class III or IV articles (such as compression from a nearby vascular structure, (i.e., most often retrospective articles; but even if pro- trauma, or demyelination from Bell’s Palsy). Although spective, not blinded, randomized, or with a control a number of medical and surgical therapies have been group). The task force recommended a prospective, reported, BT has become the treatment of choice for randomized, and controlled study to compare BT HS. The available literature was recently reviewed delivery via laryngoscope versus LEMG. Among sev- (Kenney and Jankovic 2008). They cited eight articles eral articles published on LEMG guided BT injections, as being randomized and double-blind studies in sup- the largest and longest followed group of patients with port of BT use for HS, although acknowledged that SD were reported by Blitzer on 901 patients receiving only one of these papers met the Cochrane’s review 6,300 injections over the 14 years (Blitzer et al. 1998). criteria for recommended therapy. Injection sites and Eight-two percent of the cohort had Adductor SD. For doses vary considerably, presumably due to which Adductor SD, the averages for onset effect was muscles are involved with HS. Generally, the duration 2–3 days, reaching a peak effect was 9 days, and lasted of benefits lasted between 3 and 10 months. Many use 15 weeks. The typical dosing of BT for Adductor SD EMG guidance for injections as this can direct the was 1.0 unit to each thyroarytenoid. For Abductor SD, delivery of BT to the most active areas of involved typical dosing was 3.75 units to one posterior muscles. No one has studied if EMG guidance cricoarytenoid, administered unilaterally to avoid Electromyography 741 E stridor or even airway obstruction. Its averages for Electromyography, Table 1 onset effect was 4 days, to peak effect was 10 days, Muscle Needle insertion point Use and lasted 10–11 weeks. Only one article has been Orbicularis Superior and inferior to orbit BP, published with a double-blind, placebo-controlled oculus HS design for the study of BT for SD (Truong et al. Orbicularis oris Lateral to mouth BP, 1991). In it, 13 patients with Adductor SD underwent HS Frontalis Above lateral eyebrow BP speech analysis prior to and 4 days following bilateral Thyroarytenoid Through cricothyroid membrane in an SD injections of either 5.0 units of BT or saline. Voices antero-lateral direction analysis showed significant improvement with BT. Posterior Posterior to posterior edge of thyroid SD cricoarytenoid cartilage, advanced almost to circoid cartilage E Principle Zygomaticus Half way between corner of mouth and BP, major midpoint of zygomatic arch HS Zygomaticus Half way between outer ¼ of mouth and BP, EMG Equipment minor outer corner of eye HS EMGs are performed with an Electromyographic/ Nerve Conduction Study (EMG/NCS) machine equipped with a screen to visualize the waveforms and a speaker to listen to them. Newer models have the capability to record short portions of the exam. Several reputable companies manufacture such machines. EMG needles can be monopolar or concen- tric as described in the definitions section above. Elec- trodes for the reference and ground leads are most commonly disposable and self-adhesive, although reusable electrodes can be applied with a conductive Frontalis gel and secured with tape. Exam rooms with EMG capabilities should be electrically shielded in order to minimize radiofrequency interference. Orbicularis oculi EMG Technique Zygomaticus minor With the EMG needle properly connected to the EMG Zygomaticus machine, the needle is inserted into the muscle of major Orbicularis interest. Low- and high-frequency filter settings are oris usually preset, but one should insure that their settings are 10 Hz and 20 KHz, respectively. Muscles that are typically used for EMG recording or injecting BT are listed in Table 1 and diagramed in Fig. 1. -needle insertion sites -BT injection sites Possible EMG Results -needle insertion & BT injection sites EMG has two stages – assessment of the insertional activity with the muscle at rest and analysis of volun- Electromyography, Fig. 1 Locations of needle insertion sites tary motor units during contraction. Insertional activity or botulinum toxin injection sites (or both) for muscles of the can be normal, indicated by a short burst of electrical face (Illustration by Colon Polonsky) activity only during needle movements. An increase of insertional activity is the most common abnormality in which abnormal waveforms either are present without insertional activity is reduced due to fibrotic replace- needle movement or persist for a prolonged time after ment of the muscle. For assessment of voluntary motor needle movement stops. It is due to either muscle units, the electromyographer visually analyzes the disease or injury in the muscle’s nerve supply. Rarely, morphologic characteristics of the waveforms. E 742 Electromyography Parameters evaluated include the motor unit’s ampli- interference. Thus, electrical activity from a reference tude, duration, and complexity. Neurogenic lesions electrode which is relatively distant from the muscle usually cause an increase in these variables. Also, of interest is negated. However, concentric needles neurogenic lesions cause late (or delayed) recruitment usually are larger in diameter, and thus can be of other motor units when resistance against the tested more painful. muscle is increased. EMG will not distinguish the etiology of an abnor- mality, but it can give important clinical information regarding localization and severity of injury. Thus any Indication injury, whether from trauma, Bell’s Palsy, a tumor, or other reason, will result in similar abnormalities. Some EMG can be performed in any clinical situation in EMG findings can help with prognosis. Abnormalities which one suspects a lesion of the muscle or nerve of on EMG evolve over time, reflecting different stages of interest. It can also assist in the delivery of denervation and reinnervation of a muscle. Insertional chemodenervating agents for therapy. For activity usually is not increased until
10 days after otolaryngologic purposes, one performs EMG of the a nerve lesion develops. facial or laryngeal muscles when patients present with Bell’s Palsy, Spasmodic Dysphonia, Hemifacial Spasm, or having an Acoustic Neuroma. Other condi- Cross-References tions may warrant EMG testing based on the physical exam, as the strength of EMG is to extend the exam ▶ Bell’s Palsy ability to localize the lesion as well as to assist with ▶ Electroneurography prognosis. ▶ Facial Nerve ▶ Hemifacial Microsomia ▶ Intraoperative Neurophysiologic Monitoring of the Contraindication Facial Nerve (VII) ▶ Spasmodic Dysphonia EMG should not be performed on a patient who is unwilling to have the procedure performed. Also, post- operative wounds or bandages may obstruct typical References insertion sites. The electromyographer should ask if AAEM Laryngeal EMG Task Force (2003) Laryngeal electro- a patient is taking anticoagulants. The myography: an evidence-based review. Muscle Nerve electromyographer should account for the patient’s 28:767–772 level of anticoagulation, the compressibility of the Blitzer A et al (1998) Botulinum toxin management of spas- site tested, and the size of the needle used in determin- modic dysphonia (laryngeal dystonia): a 12 year experience in more than 900 patients. Laryngoscope 108(10):1435–1441 ing if it is safe to perform an EMG. Guidelines for Hyden D et al (1982) Prognosis in Bell’s Palsy based on symp- patients taking anticoagulation have been published by toms, signs and laboratory data. Acta Otolaryngol the American Association of Neuromuscular and 93:407–414 Electrodiagnostic Medicine. Kenney C, Jankovic J (2008) Botulinum toxin in the treatment of blepharospasm and hemifacial spasm. J Neural Transm 115:585–591 Kimura J (2001) Electrodiagnosis in diseases of nerve and mus- Advantages/Disadvantages cle: principles and practice. Oxford University Press, New York Kokotis P et al (2006) Denervation pattern of three mimic Monopolar needles are typically smaller, and thus less muscles in Bell’s Palsy. Neurophysiol Clin 36:255–259 painful, but it generates a greater amount of electrical Meyer TK, Blitzer A (2007) Spasmodic dysphonia. In: Stacy interference with the signal output. Monopolar needles MA (ed) Handbook of dystonia. Informa Healthcare USA, can be inserted into smaller muscles more reliably. In New York Normand MM, Daube JR (1994) Cranial nerve conduction and addition, monopolar needles can be hypodermic to needle electromyography on patients with acoustic neuro- allow for the delivery of medications such as BT. mas: a model of compression neuropathy. Muscle Nerve Concentric needles minimize external electrical 17:1401–1406 Embryology of Ear (General) 743 E Ozgur A et al (2010) Which electrophysiological measure is appropriate in predicting prognosis of facial paralysis? Clin Elite Neurol Neurosurg 112:844–848 Truong D et al (1991) Double-blind controlled study of botuli- num toxin in adductor spasmodic dysphonia. Laryngoscope ▶ Surgical Approaches and Anatomy of the Lateral 101(6):630–634 Skull Base Electroneurography Embryology ▶ Evoked EMG E ▶ Embryology of Ear (General) Electroneuromyography ▶ Electromyography Embryology of Ear (General) Eric R. Oliver1 and Bradley W. Kesser2 1 Department of Otolaryngology-Head and Neck Electronystagmography Surgery, Wake Forest University School of Medicine, Winston-Salem, NC, USA ▶ ENG/VNG 2 Department of Otolaryngology-Head and Neck Surgery, University of Virginia Health System, Charlottesville, VA, USA Elevated Upper Airway Resistance ▶ Snoring Without Apnea, Evaluation Synonyms Developmental anatomy; Embryology; Ontogeny ELISA Definition Johnathan Sataloff and Robert T. Sataloff Department of Otolaryngology-Head and Neck Embryologic development from the primitive fetus to Surgery, Drexel University College of Medicine, a fully functioning organ system Philadelphia, PA, USA Basic Characteristics Definition Introduction A method of serologic testing. It is used to screen for The ear is composed of three anatomic divisions, each Lyme disease but produces false-positive and false- with unique embryologic origins: (1) the external ear, negative results. It is commonly ordered as a “Lyme which consists of the auricle (pinna), the external titer.” Western blot provides more definitive testing. acoustic meatus and canal, and the external layer of the tympanic membrane; (2) the middle ear, an air-containing space lined by respiratory epithelium Cross-References housing the three ossicles and containing the internal layer of the tympanic membrane; and (3) the inner ear, ▶ Otologic Manifestations of Lyme Disease which includes the bony and membranous labyrinth E 744 Embryology of Ear (General) Embryology of Ear a b c (General), Fig. 1 Transverse Wall of rhombencephalon sections through the rhombencephalon demonstrating formation of Invaginating Statoacoustic the otic vesicles. (a) 24 days placode ganglion Otic pit (b) 27 days (c) 4.5 weeks (Sadler 2000) Otic vesicle Pharynx Endoderm Dorsal aorta Tubotympanic recess and cochlea. Because inner ear development occurs Saccule, Cochlea, and Organ of Corti independent of that of the middle and external ears, By day 26 in the fourth week, the ventral otic vesicle congenital sensorineural hearing loss typically differentiates into the saccule. During the fifth week, occurs in the presence of a normal outer and middle the lower pole of the saccule starts to lengthen and ear, while congenital defects of the middle and/or coil. This projection, the cochlear duct, penetrates external ear most often occur in the setting the surrounding mesenchyme in a spiral fashion. of a structurally and functionally normal cochlea and By completion of the eighth week, the duct has made vestibular system. 2.5 turns. The developing membranous cochlea and saccule maintain their connection via the ductus Inner Ear reuniens. In the auditory system, the inner ear develops earli- During the seventh week, cochlear duct epithelial est. A thickening of the surface ectoderm on each cells differentiate to form the Organ of Corti. side of the rhombencephalic region (the caudal part Initially, these epithelial cells are similar, but with of the hindbrain) of each neural fold on embryonic further development, they form two ridges: an inner day 22 or 23 heralds the development of the ear. (the future spiral limbus) and outer ridge. The outer Formation of this ectodermal thickening, the otic ridge forms one row of inner auditory sensory cells placode, is induced by signaling from the paraxial (hair cells) and 3–4 rows of outer hair cells. mesoderm and notochord. Head growth translocates The stereocilia of the hair cells are contacted by the the otic placode caudally to the level of the second tectorial membrane, which attaches to the spiral branchial arch region. During the fourth week, the limbus. The hair cells, their supporting cells, and the otic placode invaginates deep to the surface ecto- tectorial membrane together constitute the Organ of derm into the underlying mesenchyme, forming the Corti. Spiral ganglion cells also differentiate from otic pit. The margins of each otic pit subsequently cells in the wall of the cochlear duct, which migrate fuse to form the otic vesicle (otocyst), the primor- along the coiled membranous cochlea to form the dium of the membranous labyrinth. Two regions ganglion. Neuronal projections extend from the spiral of the otic vesicle become distinguishable: ganglion to the Organ of Corti, terminating at the calyx A ventral portion that gives rise to the saccule and adjacent to individual hair cells. The cells of the spiral the cochlear duct (pars inferior), and a dorsal ganglion retain their embryonic bipolar character. portion that forms the utricle and semicircular Mesenchyme surrounding the cochlear duct soon canals (pars superior), and endolymphatic differentiates into cartilage. During the tenth week, duct (Fig. 1). this cartilaginous tissue undergoes vacuolization Embryology of Ear (General) 745 E Embryology of Ear b (General), a Cartilaginous shell Scala vestibuli Fig. 2 Development of the scala tympani and scala Basement membrane vestibuli. (a) The cochlear duct is surrounded by a Cochlear duct cartilaginous shell (b) During the 10th week, large vacuoles Spiral ligament appear in the cartilaginous shell (c) The cochlear duct Outer ridge (scala media) is separated Inner ridge from the scala tympani and the Vestibular membrane scala vestibuli by the basilar E and vestibular membranes, respectively (Sadler 2000) c Cochlear duct Scala tympani Modiolus (scala media) Scala vestibuli Spiral ligament Auditory nerve fibers Basilar membrane Spiral ganglion Scala tympani and forms the two perilymphatic spaces: the scala utricular portion of the otic vesicle. The central region vestibuli and scala tympani. The vestibular of the walls of these projections appose each other, (Reissner’s) membrane separates the cochlear duct fuse, and disappear, giving rise to the three membra- from the scala vestibuli, and the basilar membrane nous semicircular canals. One end of each canal separates the cochlear duct from the scala tympani. dilates to form the ampulla. Since two non-ampullated The lateral wall of the cochlear duct remains attached ends fuse, only five total crura enter the utricle. to the surrounding cartilage by the spiral ligament, The cristae ampullares, containing hair cells, form whereas its medial aspect is supported by the cartilag- as crests within the ampullae of the membranous inous modiolus, which later serves as the bony semicircular canals. Similar specialized receptor cochlea’s axis. The cochlea is structurally developed areas, the maculae acousticae develop in the walls of by the 26th week (Fig. 2). the utricle and saccule. Utricle, Endolymphatic Sac, and Semicircular Canals Otic Capsule and Perilymphatic Space The dorsal region of the otic vesicle begins to elongate by In the ninth week, the otic vesicle stimulates the embryonic day 26, forming an endolymphatic append- mesenchyme around the otic vesicle to condense and age. Concurrently, the remaining otic vesicle begins to differentiate into a cartilaginous otic capsule. differentiate into the utricle. The endolymphatic Vacuoles develop within this cartilaginous otic capsule appendage elongates over the next week, and its distal as the membranous labyrinth enlarges. These vacuoles portion expands to form the endolymphatic sac. Its coalesce to form the perilymphatic space, which connection to the utricle is maintained by a narrow endo- suspends the membranous labyrinth in perilymph. lymphatic duct. The cartilaginous otic capsule ossifies by periosteal During the sixth week of development, semicircu- and endochondral ossification between 16 and lar canals appear as flattened diverticulae from the 23 weeks to form the bony enclosure that houses the E 746 Embryology of Ear (General) Embryology of Ear a b (General), Fig. 3 (a) Roof of rhombencephalon Transverse section of a 7 week Auditory ossicles embedded Endolymphatic in loose mesenchyme embryo in the region of the duct rhombencephalon, showing Wall of the tubotympanic recess, the Utricular portion inner first branchial cleft, and of otic vesicle mesenchymal condensation, preceding development of the Saccular portion ossicles (b)Middle ear Mesenchymal showing the cartilaginous condensation Auditory precursors of the ossicles tube (Sadler 2000) 1st pharyngeal cleft Tubotympanic recess External auditory Meatal Primitive tympanic meatus plug cavity membranous labyrinth and the perilymph, the bony mesenchyme of the first and second branchial labyrinth. The inner ear reaches its adult size arches near the tympanic cavity. The malleus head and morphology by the midpoint of the fetal period and neck, incus body and short process, and ante- (20–22 weeks). rior malleal ligament are derived from cartilage of the first branchial arch (Meckel’s cartilage). The Middle Ear second branchial arch (Reichert’s cartilage) gives Tympanic Cavity and Eustachian Tube rise to the manubrium of the malleus, long process Outpouchings within the endoderm of the embryo of the incus, and the stapes (except the vestibular form the pharyngeal pouches. The distal part of the portion of the footplate which arises from the first pharyngeal pouch endoderm elongates to form otocyst). the tubotympanic recess and widens further distally The ossicles remain enveloped in mesenchyme to give rise to the tympanic cavity (middle ear until the eighth month, when the surrounding tissue space). The proximal part remains narrow and involutes. The endodermal epithelial lining of the forms the Eustachian (pharyngotympanic or audi- tympanic cavity extends along the middle ear space tory) tube, through which the tympanic cavity and connects the ossicles in a mesentery-like fashion communicates with the nasopharynx. During the to the wall of the cavity. The supporting ligaments ninth month, the tympanic cavity expands into of the ossicles develop within these mesenteries. Dur- the mastoid portion of the temporal bone to form ing the ninth month, the suspended ossicles assume the mastoid antrum. The mastoid antrum is close their definitive locations and relationships to adjacent to its adult size at birth. However, no mastoid air structures. Because the malleus develops from the cells are typically present in newborns. After birth, first branchial arch, its associated muscle, the tensor the epithelium of the tympanic cavity extends to tympani, is innervated by the mandibular branch of the bone of the developing mastoid process, and the trigeminal nerve. Similarly, the stapedius muscle respiratory epithelium-lined air cells are formed is innervated by the nerve to the second arch, the facial (pneumatization). nerve (Fig. 3). Ossicles External Ear On the lateral, cranial aspect of the embryo swell- External Auditory Canal ings arise from the surface ectoderm – the branchial Between the branchial arches, the surface ectoderm arches. During the seventh week, the cartilaginous grows medially, pinching in to form clefts. The precursors of the three ossicles condense in the external auditory canal precursor develops through Embryology of Ear (General) 747 E Embryology of Ear b c (General), Fig. 4 (a) Lateral a view of the head of the embryo showing the six auricular hillocks surrounding the Auricular dorsal end of the first branchial hillocks cleft (b-g) Fusion and progressive development of the hillocks into the adult auricle (Sadler 2000) Cymba conchae d Helix Concha E Antihelix Tragus Antitragus e f g a deepening of the distal portion of the first branchial pouch (endoderm). As development proceeds, cleft during the sixth week. At the beginning of the mesenchyme intervenes between the two portions of third month, epithelial cells lining the deep portion of this membrane. Thus, the tympanic membrane is the canal proliferate to form a solid epithelial core, the comprised of an outer lining of ectoderm, an inner meatal plug. The meatal plug completely fills lining of endoderm, and an intermediate mesodermal the medial end of the external auditory canal by layer (the fibrous stratum). week 26. In the seventh month the epithelial cells recanalize by apoptosis in a medial to lateral direction, Auricle and the epithelial lining of the floor participates in the Around the sixth week of gestation, the auricle arises formation of the definitive tympanic membrane. from three pairs of mesenchymal proliferations at The external acoustic canal, relatively short at the dorsal ends of the first and second branchial birth, reaches its final length by approximately the arches, surrounding the first branchial cleft. These ninth year. swellings (auricular hillocks, Hillocks of His), three on each side of the external auditory canal, Tympanic Membrane begin to enlarge, differentiate, and fuse to produce The primordium of the tympanic membrane is the definitive form of the auricle during the seventh the pharyngeal membrane, which separates the first week. The first branchial arch gives rise to Hillocks branchial cleft (ectoderm) from the first pharyngeal of His 1–3 (1. tragus; 2. helical crus; 3. helix), and E 748 Embryology of Ear (General) Embryology of Ear (General), Fig. 5 Timeline of development of the inner, middle and external ears (Larsen 2001) the second branchial arch gives rise to Hillock of His the lower neck region to the side of the head at the 4–6 (4. antihelical crus; 5. antihelix; 6. lobule and level of the eyes (Fig. 4). antitragus). As the face and mandible develop, the For an illustrated overview of the developmental auricle gradually ascends from its original location in timeline of the ear, see Fig. 5. Emergency Airways 749 E Cross-References airway. Therefore, before managing the emergency air- way, it is necessary to be competent with routine airway ▶ Balance (Anatomy: Embryology) situations and all intubating techniques. ▶ Balance (Anatomy: Vestibular Nerve) ▶ Cochlea, Anatomy ▶ Congenital Aural Atresia Characteristics ▶ Microtia and atresia Evaluation of the Emergency Airway Airway evaluations are necessary in preparing for an References emergency airway. Assessment of the patient will help formulate a coherent and succinct plan to approach E Larsen WJ (2001) Human embryology. Churchill Livingstone, securing the airway. This may be the most vital and Philadelphia, pp 392–398 crucial part, and will ensure the most success. This Moore KL, Persaud T (2008) The developing human. WB Saunders, Philadelphia, pp 431–434 initial assessment will help in determining whether Sadler TW (2000) Langman’s medical embryology. Lippincott there will be potential difficulty with intubation and Williams & Wilkins, Baltimore, pp 382–392 possibly mask ventilation. Many predictors of the dif- ficult airway have been established, which include the Mallampati score, thyromental distance, mouth opening, dentition, and head extension. Used individ- Emergency Airway ually, these predictors are of relatively limited value, but when used together, provide better correlation ▶ Emergent Airway (Miller et al. 2009). The strongest predictor of the difficult airway is a history of previous difficult airway. Especially in the ENT patient, emergency airways tend to have underlying airway pathology such as a tumor, Emergency Airways infection, congenital abnormality, stenosis, edema, traumatic injury, and foreign object. Therefore, a David Furgiuele and Michael Wajda very cautious approach must be taken in every Department of Anesthesiology, NYU Langone situation. Medical Center, New York University, New York, NY, USA Preparation in the Emergency Airway In an emergency airway, preparedness is always criti- cal. Even though time is of the essence, a well- Synonyms prepared environment will aid in securing an airway. In all airways, a well-thought-out plan is needed, as is Airway Management; Difficult Airway certain equipment. At every airway there should be an ambu bag connected to oxygen, a mask, and working suction with a yankauer tip. Additionally, all devices Introduction that are to be used in the airway should be prepped so that they are readily available when needed. It is also The emergency airway can be approached in the same advised that there be someone available when securing way as the difficult airway. In the emergency airway, the airway to aid in any way possible. because of the risk of compromise, there is an inherent urgency in securing the airway. No two situations can The Difficult Airway Algorithm be approached the same way. Whether there is struc- “The difficult airway represents a complex interaction tural pathology or traumatic injury, clear understand- between patient factors, the clinical setting and the ings of airway anatomy and airway skills are necessary skills of the practitioner” (American Society of Anes- in order to be successful. There is no absolute tech- thesiologists [ASA] 2003). The American Society of nique that will guarantee successful intubation in any Anesthesiologists (ASA) developed a difficult airway E 750 Emergency Airways algorithm in 1993, which was updated in 2003, in anesthetic induction can be followed. If there is any which they defined the difficult airway as the “clinical concern that the patient may be a difficult intubation, situation in which a conventionally trained anesthesi- then an awake approach should be taken. ologist experiences difficulty with face mask ventila- tion of the upper airway, difficulty with tracheal Awake Intubation intubation, or both” (ASA 2003). The algorithm is The awake intubation is a technique that allows for the used as a model for the approach to the emergency maintenance of spontaneous respirations accompanied and difficult airways, and was created to decrease the with a patent airway. In difficult airways, especially rate of adverse outcomes with the more complex air- those with significant pathology, the awake intubation way. When approaching any airway, a clear plan of may be the only option for a successful and safe intu- action is necessary in case any difficulty is encoun- bation. When approaching this technique, there are tered. The algorithm provides a clear stepwise many points to consider, including the route of anes- approach to the various considerations in attempting thetizing the airway, patient positioning to maintain to secure an airway. The algorithm also considers patent airway, the extent of patient cooperation, and awake versus asleep approaches, and noninvasive ver- whether or not any sedation is feasible. To provide an sus invasive techniques. optimized environment for the awake intubation, 0.2 mg of glycopyrrolate may be given. Glycopyrrolate Approaches to the Emergency Airway inhibits salivation and the production of respiratory Asleep Intubation tract secretions (Morgan et al. 2006). The determination of whether to manage a patient’s Techniques for anesthetizing the airway include airway asleep rather than awake is a critical decision. nebulizers, topical spray, transtracheal injection, and In emergency airway situations, if the decision has nerve blocks. Usually a combination of these tech- been made to intubate the patient asleep, predictors niques provides the most successful results. Nebulized of a difficult intubation should be relatively small. In 2% or 4% lidocaine can be use to anesthetize the entire these cases, patient’s status should be evaluated to airway; however, results often vary, and it can take assess the risk for regurgitation and pulmonary aspira- 20 min to completely anesthetize the airway, which tion. High-risk patients include those that have a full can be an issue in the emergent airway. Aerosolized stomach, intra-abdominal processes, or gastroparesis. and viscous lidocaine are other approaches to anesthe- These patients would necessitate a rapid sequence tizing the airway and, when done in a sequential man- intubation (RSI), in which a secured airway is ner, can successfully result in an anesthetized upper established in the shortest amount of time to minimize airway (Miller et al. 2009). Cocaine is a common local the chance of aspiration of gastric contents. The essen- anesthetic used by otolaryngologists when anesthetiz- tial principles of RSI include preoxygenation, induc- ing the upper airway because of local anesthetic prop- tion of anesthesia, rapid neuromuscular blockade, and erty and vasoconstrictor ability (Barash et al. 2009). It intubation, while maintaining cricoid pressure (Barash is possible to increase the extent of topicalization by et al. 2009). Cricoid pressure, also known as the Sellick spraying lidocaine into the trachea while doing an maneuver, is thought to compress the esophagus initial laryngoscopy. The transtracheal approach is against the vertebra in order to prevent pulmonary accomplished by injecting 4ml of 4% lidocaine aspiration (Miller et al. 2009). Once the airway is through the cricothyroid membrane. After the needle secured and confirmed, cricoid pressure can be makes contact with the skin, constant aspiration of the released. Rapid neuromuscular blockade can be syringe should be performed until aspiration of air achieved with either succinylcholine or double the occurs. At this point, the local anesthetic should be standard dose of rocuronium, a fast non-depolarizing injected and needle removed. The patient will typically muscle relaxant. The onset of succinylcholine, cough, which aids in the spread of the anesthetic and a depolarizing muscle relaxant, is about 30 s and dura- blockade of the sensory nerve endings of the recurrent tion is between 5 and 10 min. This gives the ability to laryngeal nerve (Hadzic 2006). Another common awaken a patient if a difficulty arises, and proceed with nerve block used in awake intubations is the superior an awake approach if needed. In situations where there laryngeal nerve block. This requires a bilateral nerve is no increased risk of aspiration, a straightforward block, which anesthetizes the area between epiglottis Emergency Airways 751 E and vocal cords. This block is accomplished by locat- ing greater cornu of the hyoid bone with a 25G needle, then retracting slightly, and injecting 3 ml of 2% lido- caine after aspiration for air and blood. This will effec- tively block the internal and external portions of the superior laryngeal nerve (Hadzic 2006). When dealing with the airway, patient positioning is critical to successful intubations. The sniffing position is the traditional position for successful intubations, and should be used when the emergency airway is encountered. A problem that may occur is when the E awake patient cannot tolerate lying flat, and the awake intubation is necessary. In these cases, optimizing the position most tolerated by the patient is necessary. Patient positioning may also dictate which techniques of intubations can be used. During awake airways, patient cooperation is nec- Emergency Airways, Fig. 1 An endotracheal tube connected essary. Without it, awake intubations are impossible. end to end in preparation for a blind intubation Patients should be informed of what an awake intuba- tion entails, and should be sure that they are able to cooperate during the procedure. Sedation, especially in sounds are heard again. To aid in a blind intubation, the emergency airway, can be very dangerous. Even prior to placing the tube, connect the tube end to end the smallest amount of sedation may cause airway (Fig. 1). This will give the tube a curve, which makes it to be compromised and can make the situation more likely to pass anteriorly and end up in the trachea a critical one. (Morgan et al. 2006). Inflation of the cuff of the tube while in the oropharynx and head flexion are other Techniques for Intubation maneuvers that can be done to aid the placement of Careful planning must occur when considering the the tube (Miller et al. 2009). emergency airway. A logical and succinct plan must be established to have the highest probability for suc- Laryngoscopy cess. The difficult airway algorithm is not only a great The most standard and commonly used way to intubate example of planning when dealing with the difficult is by using direct laryngoscopy. This can be accom- airway, but is a useful tool when dealing with any plished by using a laryngoscope with an appropriately airway, especially the emergency airway. The ASA sized blade attached, most commonly the Macintosh or difficult airway algorithm dictates a clear and struc- Miller. Direct laryngoscopy can be done in either an tured way to deal with the difficult airway and can act asleep or awake patient, if given adequate anesthetic to as a guide in any situation. the airway. Another form of laryngoscopy is done by video laryngoscopy, for example, using the Glidescope Blind Intubation (Fig. 2). This involves a specialized laryngoscope and The blind intubation technique requires no equipment blade that has an optical lens at the end. This is espe- other than an endotracheal tube. It is usually performed cially useful in patients for whom intubation with through the nasal route in a spontaneously breathing direct laryngoscopy is not successful due to limited patient. In emergency situations, sedation should be view. The technique of use is similar to that of direct avoided. The nose and upper airway should be ade- laryngoscopy, and competence can be achieved rap- quately anesthetized, after which an endotracheal tube idly (Miller et al. 2009). Another example of a portable should be slowly advanced while listening to the breath version of an optical laryngoscope is the Airtraq. The sounds coming from the tube. If breath sounds are no Airtraq is a single use laryngoscope with an endotra- longer heard, it means that the tube has entered into the cheal tube–guiding channel that can be used in difficult esophagus and should be pulled back until breath airways (Barash et al. 2009). E 752