1
Q
3 segments of the ear?
A
- outer ear
- middle ear
- inner ear
2
Q
When does hearing loss occur?
A
- usually happens when flying or traveling
- infection
- aging
- 538 mill people have hearing loss
- in US 43% of people 65-84
3
Q
Physiology of hearing?
A
- 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
4
Q
Classification of hearing loss?
A
- SNHL: involving inner ear, cochlea, or auditory nerve
- CHL: any cause that limits external sound into inner ear
- mixed: combo of sensorineural and conductive
5
Q
Outer ear causes of hearing loss?
A
- 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
6
Q
Middle ear causes of hearing loss?
A
- 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
- barotrauma
7
Q
Inner ear causes of hearing loss?
A
- congenital
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
8
Q
Sxs of hearing loss?
A
- unilateral/bilateral hearing deficit
- difficulty understanding speech, conversations, TV/radio
9
Q
Weber test?
A
- 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
10
Q
Rinne test?
A
- 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
11
Q
Purpose of using Weber and Rinne together?
A
- 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)
12
Q
Weber will lateralize to what ear if it is sensorineural loss?
what about CHL?
A
- to good ear in SNHL
- bad ear in CHL (also will have BC is greater than AC in Rinne test in bad ear)
13
Q
What may you see on exam of pt complaining of hearing loss? What tests should be done?
A
- 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
14
Q
Tx of CHL?
A
- congenital: surgery if possible, bone conduction hearing aid
- infections: abx
- trauma: surgery if possible
- otosclerosis: surgery to replace immobile stapes with mobile prosthesis
hearing aid
15
Q
Tx of SNHL?
A
- trauma (acoustic trauma): corticosteroids
- viral origin: corticosteroids
- menieres disease: low sodium diet, diuretics, corticosteroids
- tumors: surgery or radiation
- irreversible: hearing aids, cochlear implants
16
Q
How does a cochlear implant work?
A
- sounds are picked up by microphone
- signal is then coded into electrical pulses
- these pulses are sent to coil and are then transmitted across the skin to the implant
- the implant sends a pattern of electrical pulses to electrodes in cochlea
- auditory nerve picks up these pulses and sends them to the brain. The brain recognizes these signals as sound
