Hearing Loss Types PDF

Hearing loss  Hearing HEARING : Hearing refers to the reception of sound by the ear, its analysis, and its transmission to the brain. IMPAIRMENT: An impairment is any loss or abnormality of psychological, physiological or an...

Hearing loss  Hearing HEARING : Hearing refers to the reception of sound by the ear, its analysis, and its transmission to the brain. IMPAIRMENT: An impairment is any loss or abnormality of psychological, physiological or anatomical structure or function.  RANGES OF HEARING LOSS  Sound levels of common noises Safe range Risk Rane 30 Whisper 85 Heavy city traffic, school cafeteria 40 Refrigerator 95 Motorcycle 60 Normal conversation 100 Snowmobile 75 Dishwasher 110 Chain saw 110 Jackhammer, rock concert, symphony 115 Sandblasting 120 Ambulance siren, thunder 140-165 Firecracker, firearms  Maximum job-noise exposure allowed by law National Institute for Occupational Safety and Health (NIOSH) AGE OF HEARING IMPAIRMENT Post lingual: is loss of Pre lingual :is the loss hearing after of hearing before spontaneous speech speech and language and language has developed developed  Types of Hearing Loss Mixed hearing loss - refers to Conductive hearing loss - Sensorineural hearing loss a combination of conductive when hearing loss is due to and sensorineural hearing loss. problems with the ear canal, (SNHL) - when hearing loss is due to problems of the inner This means that there may be ear drum, or middle ear and its ear, also known as nerve- damage in the outer or middle little bones (the malleus, incus, ear and in the inner ear and stapes). related hearing loss. (cochlea) or auditory nerve Conductive Hearing Loss Sensorineural Hearing Loss (SNHL) Mixed Hearing Loss  Causes of Hearing Impairment Hereditary Prenatal, Physiological Congenital and Non- perinatal and and and acquired hereditary postnatal psychological  Risk Factors of Hearing Impairment Loud Aging Infection Genetics Noise Illness Injury  Microtia Causes of Congenital Conductive Absence or malformation of auricle( pinna) absence of external ear : Microtia refers to the spectrum of Hearing Loss deformities of the external ear. It is typically categorized into four different grades. External ear canal atresia/stenosis is the absence or closure of the external auditory canal. Most often unilateral Usually with other craniofacial abnormalities Treacher-Collins syndrome Robin sequence Crouzon syndrome Tympanic membrane abnormality: Congenital cholesteatoma (2- 3% of all cholesteatomas). The tympanic membrane is intact and overlies a white mass Ossicular malformation: Ossicular chain abnormalities may also be seen in association with craniofacial anomalies. Most common is stapes malformation/atresia Osteogenesis Imperfecta :also known as brittle bone disease, is a group of genetic disorders that mainly affect the bones. Approximately 50% of people with osteogenesis imperfecta (OI), While not everyone who has OI develops hearing loss.  Causes of Acquired Conductive Hearing Loss Otitis Externa :Otitis externa (OE) is an inflammation or infection of the external auditory canal (EAC), the auricle, or both. Bacteria, fungi Otitis media with effusion: Otitis media with effusion (OME) is thick or sticky fluid behind the eardrum in the middle ear. Fluid obstructs TM movement Effusion persists after therapy Asymptomatic effusion is present in 40% of patients 1 month post treatment Fluid present in 10% of patients 3 months post treatment Hearing loss is 25dB and persists until fluid disappears  Cholesteatoma : A cholesteatoma is an abnormal, noncancerous Causes of Acquired skin growth in the middle ear, behind the eardrum. Unless treated, it can cause hearing loss as it continues to grow in size. Benign growth made of cells and keratin Conductive Hearing Loss As it enlarges, it compresses ossicles, and occludes external auditory canal Furuncle Trauma Temporal bone fractures TM perforation Otosclerosis: is the abnormal growth of bone of the MIDDLE ear. Overgrowth of bone (near stapes usually) Foreign body Cerumen : The soft, brownish yellow, waxy secretion (a modified sebum) of the ceruminous glands of the external auditory canal. Synonym(s): ear wax, earwax  Causes of Congenital Sensorineural Hearing Loss Prenatal infections Cytomegalovirus (CMV) infection : Cytomegalovirus (CMV) is a common virus that can infect almost anyone. Once infected, your body retains the virus for life. Leading cause of sensorineural hearing loss Usually progressive/delayed onset Toxoplasmosis: Congenital toxoplasmosis can mimic disease caused by organisms such as herpes simplex virus, cytomegalovirus, and rubella virus. Delayed hearing loss Can be prevented by treating with pyrimethamine and sulfonamide Rubella Usually, bilateral Syphilis: Is a bacterial infection. Pregnant people who have syphilis can pass the disease to their babies. Unborn babies can become infected through the organ that provides nutrients and oxygen in the womb, called the placenta. Infection also can happen during birth. Hearing loss usually occurs around 2 years of age Can be prevented by treatment of disease before 3 months of age  Genetic Abnormalities Autosomal Recessive: is one of several ways that a trait, disorder, or disease can be passed down through families. Causes of An autosomal recessive disorder means two copies of an abnormal gene must be present in order for the disease or trait to develop. (80% of genetic causes) Congenital Autosomal Dominant (20% of genetic causes) Sensorineural Both can occur as: Nonsyndromic refers to hearing loss that is not associated with other signs and symptom. Hearing Loss Syndromic refers to hearing loss that occurs with abnormalities in other parts of the body.  Anatomic abnormalities Michel aplasia: is a congenital abnormality of the inner ear and is characterized by bilateral absence of differentiated inner ear structures, complete lack of inner ear before the 3rd week of gestation. Also known as Complete labyrinthine aplasia Mondini dysplasia is a type of inner ear malformation that is present at birth (congenital).partial development and malformation Causes of inner ear Scheibe: membranous cochleosaccular Congenital degeneration of the inner ear Alexander: malformation of the cochlear membranous labyrinth system Sensorineural Prenatal exposure to ototoxic drugs Hearing Loss Prematurity Hypoxia, acidosis (impairment in gas exchange resulting in decreased blood oxygen levels and excess of carbon dioxide (hypercapnia) leading to acidosis), incubator noise  Hypoxia, acidosis: Renal tubular acidosis with deafness is a disorder characterized by kidney (renal) problems and hearing loss. Hyperbilirubinemia Causes of Bilirubin toxic to cochlear nuclei and central auditory pathways Acquired Ototoxic drugs Aminoglycosides: Sensorineural gentamycin>tobramycin>amikacin>neomycin Chemotherapy: cisplatin, 5-FU, bleomycin, nitrogen Hearing Loss mustard Salicylates, quinines (reversible)  Infection Bacterial meningitis Trauma Causes of Blunt or penetrating trauma to the temporal bone Acquired Radiation to head and neck Sensorineural Tumor: acoustic neuroma Hearing Loss Neurodegenerative/demyelinating disorders  Noise Exposure Noise causes direct damage to cochlear structures Causes of Noise causes over-stimulation of cochlear structures Acquired increased metabolic demand causes Sensorineural increased nitric oxide release--toxic to hair cells Hearing Loss Increased metabolic demand causes generation of free radicals  History: Risk Factors for Hearing Loss Neonate: Family History utero infections Birth weight