Ear - 2 star Flashcards
Auditory pathway
Tympanic membrane middle ear ossicles (malleus --> incus --> stapes) Auditory hair cells in the cochlea Spiral (cochlear) ganglion cochlear nuclei Superior Olivary nucleus (contralateral) Lateral lemniscus inferior colliculus medial geniculate nucleus (thalamus) Primary auditory cortex (temporal lobe)
Olivocochlear bundles
send cholinergic signals to the cochlea causing contraction of the outer hair cells
–> stiffening of basilar membrane and sensitizing inner hair cells to particular frequency
Antibiotic that causes hearing loss
Amino glycosides (streptomycin, gentamicin) cause hearing loss by damaging outer hair cells
Weber Test
Normal –> midline (both ears hear it)
Conductive hearing loss –> materializes to side of affected ear
Sensorineural hearing loss –> materializes to the side opposite the affected ear (good ear hears it)
Rinne Test
Normal: AC>BC
Conductive hearing loss BC >AC
Diagnosis:
Weber: Midline
Rinne:
Left: AC>BC
Right: AC>BC
Normal
Diagnosis:
Weber: Right
Rinne:
Left: AC>BC
Right: BC>AC
Conductive loss on Right
Diagnosis:
Weber: Left
Rinne:
Left: AC>BC
Right: AC>BC
Sensorineural loss on right
Diagnosis:
Weber: Midline
Rinne:
Left: BC>AC
Right: BC>AC
B/L conductive loss
Acute otitis externa
“swimmer’s ear”
Inflammation/infection of ear canal
Pain w/ manipulation of pinna or instrumentation of canal
Most common: P. aeruginosa or S. aureus
Tx: irrigation and topical abx
Acute otitis media (AOM)
bacterial or viral infection of middle ear
TM: bulging, middle ear effusion (opacity, air-fluid level, pus), erythema, immobile under insuflation
MC bacteria: S. pneumo, nontypable H. flu, M. catarrhalis
Tx:
abx: amoxicillin, amoxicillin + clavulanic acid, cephalosporins
Tumpanostomy tubes
Complications: acute mastoiditis: AOM sx + post-auricular swelling, redness, mastoid tenderness
Cholesteatoma
overgrowth of desquamated keratin debris w/in middle ear –> erode ossicular chain and mastoid air cells
Causes: negative middle ear pressure - chronic retraction pocket from eustachian tube dysfunction or direct growth of epithelium through TM perforation
Assoc w/ chronic middle ear infection
TM: grayish-white, “pearly” lesion behind or involving the TM, conductive hearing loss, vertigo
Tx: surgical removal (tympanomastoidectomy) and reconstruction of ossicular chain
Benign paroxysmal positional vertigo (BPPV)
debris or misplaced otoliths w/in vestibular apparatus
Dix-Hallpike manuever and Epley maneuver used to dx/tx
Vestibular neuritis
inflammation of vestibular nerve
Meniere disease (endolymphatic hydrops)
imbalances of fluid and electrolyte composition of endolymph
Triad: intermittent vertigo, tinnitus, hearing loss
