Flashcards in Hearing loss Deck (16)
3 segments of the ear?
- outer ear
- middle ear
- inner ear
When does hearing loss occur?
- usually happens when flying or traveling
- 538 mill people have hearing loss
- in US 43% of people 65-84
Physiology of hearing?
- auricle catches sound waves and funnels them into external auditory canal
- sound waves vibrate TM, causing motion of ossicles resulting in piston like action of the stapes
- piston motion pushes inner ear fluid around in cochlea
- frequency specific movement sets up fluid waves in cochlea which sets motion of organ of corti
- ogran of court movement bends the stereo cilia, depolarizing the action of auditory message traveling through hair cells via the auditory nerve to the brain
- the brain organizes the information
Classification of hearing loss?
- SNHL: involving inner ear, cochlea, or auditory nerve
- CHL: any cause that limits external sound into inner ear
- mixed: combo of sensorineural and conductive
Outer ear causes of hearing loss?
- congenital:microtia - absence or malformation of auricle
- infection: otitis externa - inflammation of EAC, or debri
- trauma: penetrating trauma to EAC
- tumor: most common malignant tumor of EAC is SCC
- benign growths: most common are exostosis and osteoma
- systemic diseases: DM or other immunocompromised state
- cerumen: using Q-tips
Middle ear causes of hearing loss?
- congenital: malformation or fixation of ossicles
- ET dysfxn: viral URI or sinusitis, and allergies
- infection: otitis media
- tumors: cholesteatoma
- otosclerosis: bony overgrowth of footplate of stapes
- TM perforation
Inner ear causes of hearing loss?
non-hereditary: insult to developing cochlea, or viral infections: CMV, hepatitis, rubella, toxoplasmosis, HIV and syphilis
hereditary: 90% auto recessive (SNHL), most common is mondini - cochlea only turns 1 1/2 times instead of 2 1/2 times
- presbycusis: most common cause of hearing loss worldwide
- infection: most common in adults - viral cochleitis
MC in children - meningitis
- meniere disease
- trauma: skull fracture
- tumors: most common tumor to cause SNHL is acoustic neuroma
- ototoxic substances: abx - aminoglycosides, erythromycin, tetracyline
- chemo: cisplatin
Sxs of hearing loss?
- unilateral/bilateral hearing deficit
- difficulty understanding speech, conversations, TV/radio
- tuning fork test performed by pressing handle of fork to bridge of forehead, nose or teeth and ask pt if sound is louder in one ear or the other
- sound is heard equally in both ears in pts with normal hearing or symmetric hearing loss
- allows comparison of sound when tuning fork is placed on mastoid bone (BC) versus when fork is held near ear (AC)
- abnormal results occur when sound is at least equally loud or louder when fork is placed on bone as compared to when held near ear, BC being greater than AC
- normal is when AC is greater than BC
Purpose of using Weber and Rinne together?
- distinguish b/t CHL and SNHL
- in pts with unilateral decrease in hearing, weber test suggest SNHL if sound lateralizes to good side, CHL if sound lateralizes to bad side
- abnormal rinne when BC greater than AC is consistent with conductive especially if weber also lateralizes to that side
- when weber lateralizes to ear when rinne is normal, rinne test in opposite ear should be performed, a normal rinne test in contralateral ear suggest SNHL in this ear (weber lateralizes to normal ear)
Weber will lateralize to what ear if it is sensorineural loss?
what about CHL?
- to good ear in SNHL
- bad ear in CHL (also will have BC is greater than AC in Rinne test in bad ear)
What may you see on exam of pt complaining of hearing loss? What tests should be done?
- on pneumoscopy:
nonmobile TM - fluid or mass in middle ear cavity, or stiff or sclerotic TM
- or will see a hypermobile TM - ossicular chain disruption
- formal audiologic assessment:
done in sound proof room, audiologic workup, head CT or MRI
Tx of CHL?
- congenital: surgery if possible, bone conduction hearing aid
- infections: abx
- trauma: surgery if possible
- otosclerosis: surgery to replace immobile stapes with mobile prosthesis
Tx of SNHL?
- trauma (acoustic trauma): corticosteroids
- viral origin: corticosteroids
- menieres disease: low sodium diet, diuretics, corticosteroids
- tumors: surgery or radiation
- irreversible: hearing aids, cochlear implants