Hearing

Question 1

physiology of the cochlea

Answer 1

sound causes resonant vibration of the basilar membrane
high freq–>base of the cochlea
low freq–>apex of cochlea

Question 2

Tonotopic encoding of sound

Answer 2

hair cells at one point of the cochlea respond maximally to one specific frequency

Question 3

factors in an ear Hx

Answer 3

hearing loss
otalgia (pain)
otorrhoea (discharge)
tinnitus
vertigo

Question 4

vertigo

Answer 4

the hallucination of movement. caused by:
BPPV (benign paroxysmal positional vertigo)
vestibular neuritis
labyrinthitis
meniere’s
migraine/stroke

Question 5

meniere’s

Answer 5

endolymphatic hydrops (abnormal fluctuations of the endolymph) causes recurrent attacks of vertigo with/without nausea and vomiting, fluctuating sensorineural hearing loss and tinnitus

Question 6

vestibulo-ocular reflex

Answer 6

VOR stabilises image on retina during head movement (doll’s eye test)

Question 7

vestibulo-spinal relfex

Answer 7

VSR maintains head in upright position

Question 8

Rinne’s

Answer 8

air conduction>bone conduction: positive (normal)
bone conduction>air conduction: negative (conductive hearing loss)

can be false negative in unilateral SNHL, as BC still heard in other ear

Question 9

Weber’s

Answer 9

central: hearing equal both sides
lateralises toward unilateral conductive hearing loss
lateralises away from unilateral SNHL

Question 10

meniere’s disease

Answer 10

endolymphatic hydrops causes recurrent episodes of vertigo lasting >20 mins (with or without N&V)
fluctuating (or permanent) sensorineural hearing loss, and tinnitus
sense of aural fullness
with or without drop attacks (no LOC or vertigo, but falling to one side)

Question 11

Tx meniere’s

Answer 11

acute attacks - reassurance and bed rest
antihistamines can be helpful in prolonged attacks
if very severe, consider endolymphatic sac surgery ir ablation of the vestibular organ with gentamicin