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Sven's Flashcards > 208 - Hearing Loss > Flashcards

208 - Hearing Loss Flashcards

1
Q

what sort of pathologies cause conductive deafness?

A

Outer ear and middle ear

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2
Q

what sort of pathologies cause sensorineural deafness?

A

inner ear

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3
Q

What is the purpose of the external ear and what pathologies affect it?

A

the pinna collects and amplifies sound so any deformities affect conduction into EAM
The EAM may abnormally closed or absent (Canal atresia) due to skin growing over entrance

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4
Q

name some EAM abnormalities

A
  • otitis externa (swimmer’s ear) - swelling of skin lining EAM causing stenosis/occlusion
  • wax plug obstruction - wax produced by outer 1/3 EAM hindering conduction
  • Exostoses (surfer’s ear) - benign growth of bone surrounding EAM causing stenosis/obstruction after repeated exposure to cold water
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5
Q

what are the 3 types of eardrum perforation?

A
  • central - perforation of pars tensa that has some pars tensa or annulus (rim) all the way round
  • marginal - pars tensa perforation that has no annulum between it and the canal wall on at least one side - risk of cholesteatoma on repair
  • attic - perforation of pars flaccida - risk of cholesteatoma
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6
Q

what management options are available for eardrum perforation?

A
  • heal on its own
  • hearing aid
  • surgery - paper patcg, fat plug, tympanoplasty
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7
Q

what is a cholesteatoma, what causes it and what can it lead to?

A
  • growth of solid ball of skin into middle ear
  • caused by normal skin growth being sucked into middle ear by low P
  • complications - conductive hearing loss as erodes ossicles, facial palsy as damages CNVII, inner ear sensorineural hearing loss (vertigo & labyrinthitis), posterior expansion (mastoiditis, menigitis, cerebellar abscess), superior expansion (menigitis, temporal lobe absecss, extradural abcess)
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8
Q

what is otosclerosis?

A

development of small focus of bone that obstructs stapes vibration into oval window (footprint) leading to conductive hearing loss. manages by stapedotomy where part of stapes removed and piston added to connect incus to oval window. F:M 2:1

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9
Q

What is glue ear?

A

effusion in middle ear usually in children as inefficient drainage by eustachian tube causing conductive deafness, retraction of ear drum due to low P. Risk factors - measles/mumps (adenoid infection), family smokers, downs syndrome. In adults can be due to nasopharyngeal carcinoma

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10
Q

what management techniques can be used for glue ear?

A
  • watch and wait
  • grommets
  • adenoidectomy
  • hearing aid
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11
Q

what are the possible complications of glue ear?

A

can become ASOM (acute supprative ottitis media) then spread:

  • posteriorly - mastoiditis
  • into middle ear - CNVII paralysis
  • medially - labyrinthitis
  • superiorly - menigitis & brain abscess
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12
Q

what is presbyacusis?

A

age related hearing loss - bilateral and symmetrical
males affected earlier. Affects high frequencies more than low (consonants lost before vowels). MAnaged by hearing aid/tactics

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13
Q

What are the iatrogenic causes of hearing loss?

A
  • ototoxic drugs - aminoglycosides (gentamycin)
  • chemotherapy drugs - cisplatin, carboplatin
  • loop diuretics - furosemide
  • surgical trauma
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14
Q

what is acoustic neuroma?

A

neural pathology where a schwannoma compresses nerves in internal acoustic meatus. Cochlear nerves affected, vestibular and facial more resistant to compression. unilateral hearing loss +/- tinitus with later facial palsy, vertigo, brainstem compression

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15
Q

what explanations can be given for different results in weber’s and rinne’s tests?

A
  • weber - hearing goes towards deaf ear = conductive loss, hearing goes away from deaf ear = sensorineural loss
  • rinne - AC>BC = normal or sensory deafness (+ve result), BC>AC = conductive deafness (-ve result)
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16
Q

by how much approximately does the external ear amplify sound?

A

20 dB at 2.5 kHz

17
Q

what is the purpose of the middle ear and how does it do this?

A
  • it amplifies sound and converts sound waves to mechanical energy for transmission into fluid
  • eardrum hit by sound waves and vibrates, malleus attached to eardrum vibrates and bangs on incus which levers stapes, stapes footplate sits in oval window and vibrations cause endolymph in cochlear duct to vibrate
18
Q

what are the 2 main structures of the inner ear and what do they contain?

A
  • Bony labyrinth - fluid filled cavity within otic capsule made of hard bone including spiral canal, vestibule & semicircular canals. Filled with perilymph (high Na low K)
  • membranous labyrinth - membrane encased ducts and sacs (vestibular labyrinth, semicircular canals & cochlear labyrinth) containing endolymph (high k low Na) and surrounded by perilymph
19
Q

how does the inner ear cause us to hear?

A

waves of hydraulic pressure in the scala vestibuli by stapes and displace scala media (cochlear). High freq causes displacement near oval window and low freq away from it. Organ of corti on basilar membrane converts waves to neuronal signals via movement of tectorial membrane and hairs. Impulses travel up vestibulocochlear nerve (CN8) to auditory cortex. Waves in perilymph continue along scala vestibuli round to scala tympani back to round window

20
Q

what detects rotational movements and linear movements & gravity?

A
  • rotational (head turn/look up & down)- semicircular canals

* linear & gravity - utricle & saccule

21
Q

what are the causes of vertigo?

A
  • peripheral - caused by ear (isolated vertigo)
  • central - caused by brain (accompanied by facial weakness/slurring
  • other - psych, CV, drug
22
Q

what causes benign paroxysmal positional vertigo (BPPV)?

A

most common cause of isolated vertigo (no cochlear symptoms- no deafness, tinnitus, ottorhoea, otlagia). Lasts for seconds after specific movements. Otoconia become detached from macula in utricle and sacclule and migrate due to gravity into semicircular canals and are trapped behind cupula which is overstimulated (more impulses to brain from affected ear = sensation of movement in that direction)

23
Q

what are the diagnosis test and cure for BPPV?

A

diagnosis - dix hallpike test - shows rotatory nystagmus with fast beat towards diseased ear
*cure - epley mannoevre -helps trapped otoconia escape semicircular canals. relapse in 30%

24
Q

what causes merniere’s disease (vertigo)?

A

vertigo associated with hearing loss and tinnitus as affects inner ear. Lasts hrs to a day and more common in >40. caused by a stenosis of endolymphatic acqueduct causing incr. P in endolymphatic system which ruptures. Perilymph and endolymph mox and ionic imbalance causes damage to neuroepithelia. symptoms include nausea, vomitting, sweating. diagnosed clinically but MRI excludes acoustic neuroma & bloods rule out syphilis, anaemia

25
Q

what are the treatments for mernieres?

A
  • reduce salt intake
  • betahistine prophylaxis and antiemetics
  • surgical - grommets, gentamycin instillation, saccus decompression, vestibular nerve section
26
Q

what causes vestibular neuritis (vertigo), what are the symptoms and management?

A

vertigo lasts for weeks and has no cochlear symptoms (no hearing loss/tinnitus). Caused by inflammation of superior vestibular nerve cause by viral infection (herpes) or vascular occlusion. Brain learns to compensate. Associated with nausea, vomiting, pallor, sweats, diarrhoea. Give vestibular sedatives (prochlorperazine)

27
Q

what causes labyrinthitis (vertigo), what are the symptoms and management?

A

like vestibular neuritis but cochelar symptoms (HEARING LOSS, TINNITUS - usually permanent) as well. caused by viral infection, vascular ischaemia, autoimmune. lasts weeks. nausea, vomit, sweats, pallor, diarhorrea. Give vascular sedatives (prochlorperazine)

28
Q

what parts of the vestibular apparatus detect movement?

A
  • linear - by maculae in utricle & sacule - movement of head causes neuroepithelium to move, otoconia and gel lag moving cilia
  • rotational - by cupulae in ampullae of semicircular canals - endolymph in canal moves distorting cupula which distorts cilia
  • hair cells (cilia) detect movement (longest cilia called kinocilium) - bending towards kinocilium incr. firing rate and bend away decr. firing rate
29
Q

what is functional pairing in the vesitbular apparatus?

A

movement in one vestibule has opposite effect in other ear. when turn head to left - incr. neural activity from left and decr. neural activity in right. Brain looks at net movement - looking straight ahead should give equal impulse from both. If one not working only receiving from one side (feels like turning to that side)
L&R semicircular ducts paired. Left sup with right inf and vice versa.

30
Q

what is the vestibular-ocular reflex?

A

movement of eyes in opposite direction to head rotation to fix vision on something ahead - connections between semicircular cannals and extraocular muscles

31
Q

what is nystagmus?

A

involuntary eye movement -slow phase to affected side followed by fast phase to other side. right beating nystagmus means fast phase to right but pathology on left

Sven's Flashcards (32 decks)

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