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Neurology and Special Senses > Inner Ear > Flashcards

Inner Ear Flashcards

1
Q

Where is the inner ear?

A

Petrous part of temporal bone

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2
Q

What does the inner ear consist of?

A

Vestibule and semicircular canals

Cochlea

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3
Q

What is the function of the oval window?

A

Transmit vibrations from stapes into cochlea. This moves perilymph which causes hair cells on the tectorial membrane to vibrate at different frequencies and send impulses down CNVIII. The pressure change is compensated by the round window

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4
Q

What is the membranous labyrinth?

A

Labyrinth of endolymph that is surrounded by a bony labyrinth. It is suspended in perilymph

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5
Q

What is the difference between endolymph and perilymph?

A

Endolymph resembles intracellular fluid

Perilymph resembles CSF

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6
Q

How can the vestibular system be divided?

A

Semicircular canals
Utricle
Saccule

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7
Q

How do the semicircular canals exist with respect to one another? What do they detect?

A

3 canals all 90 degrees from one another

They detect rotatory movement

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8
Q

What to the utricle and saccule detect?

A

Linear motion

Utricle - point up - detect horizontal motion
Saccule - stick out to Side - verticle motion

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9
Q

How is balance maintained?

A

Input from vestibular system integrated centrally with proprioceptive and visual inputs

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10
Q

What is vertigo?

A

“Hallucination of movement” -symptom of dizziness associated with vestibular system

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11
Q

What central causes could lead to vertigo?

A 
Stroke
Migraine
Neoplasms
Demyelination
Drugs
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12
Q

What are possible peripheral causes of vertigo?

A

BPPV
Meniere’s disease
Vestibular neuritis

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13
Q

What is BPPV?

A

Benign Paroxysmal Positional Vertigo

Vertigo associated with particular head movements that last a short time

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14
Q

What causes BPPV?

A

Otoliths (crystals) in the semicircular canals (commonly posterior) leading to abnormal stimulation of hair cells

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15
Q

How is BPPV described?

A

Spinning sensation upon moving head
Associated with nausea
Rapid onset, last 30s then stop

No vomiting, pain, tinnitus or hearing loss

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16
Q

How is BPPV diagnosed?

A

Dix-Hallpike test

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17
Q

How is BPPV treated?

A

Epley manoevre

Brandt Daroff exercises

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18
Q

What is Dix Hallpike test?

A

Patient lowered quickly to supine and neck extended to 30 degrees

If vertigo symptoms + nystagmus –> BPPV

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19
Q

What is epley manoevre?

A

Manoeuvring into various positions to treat BPPV by relocating particles in the semicircular canals

https://en.wikipedia.org/wiki/Epley_maneuver

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20
Q

What is the pathophysiology of Meniere’s disease?

A

Increased endolymph causes distention of membranous labyrinth which compress vestibular system

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21
Q

What are the clinical features of Meniere’s?

A

Tinnitus in affected ear

Episodic vertigo with N&V - last minutes to hours

Fluctuating sensorineural hearing loss which can become permanent

Aural fullness

Lasts minutes to hours

Well between attacks

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22
Q

How does Meniere’s disease progress?

A

Initially patients are well between attacks

As it progresses patients feel unsteady between attacks.
Reduced vestibular function and progressive sensorineural hearing loss

Over time, disease burn itself out so don’t get acute vertigo but still have reduced hearing and general unbalanced feeling

23
Q

What are the 3 parts of management for Meniere’s disease?

A

Dietary changes
Medical intervention
Surgical intervention

Safety advice and support

24
Q

What dietary changes are suggested for Meniere’s disease?

A

Reduce SACCC:

Salt
Alcohol
Chocolate
Caffeine
Chinese food
25
Q

What medical interventions are used in Meniere’s disease?

A

Thiazides - bendroflumathiazide
Betahistine (antivertigo)
Antiemetic - prochlorperazine

26
Q

What surgical interventions are used in Meniere’s disease?

A 
Grommets
Dexamethasone middle ear injection
Endolymph sac decompression
Vestibular destruction using middle ear gentamicin injection
Surgical labyrinthectomy (rare)
27
Q

How does vestibular neuritis/labyrinthitis cause vertigo?

A

Vestibular neuritis - herpes simplex affects the vestibular nerve

Labyrinthitis - inflammation of the membranous labyrinth due to prior URT infection

Inflammation of the middle ear cause severe incapacitating vertigo with N&V lasting several days

28
Q

What would you see on examination of a patient suffering from vestibular neuritis?

A

Sudden, constant severe vertigo

Worse with head movement

Horizontal Nystagmus during attacks

Lasts for days

Hearing loss and tinnitus

29
Q

How is an acute vestibular neuritis investigated?

A

MRI to exclude acoustic neuroma

30
Q

What is labyrinthitis?

A

Inflammatory disorder of the membranous labyrinth that effects the cochlear and vestibular end organs

31
Q

Describe the process of sound transmission to hearing in the cochlea

A

Stapes articulate with oval window with pass vibrations into Scala vestibuli

Movement of perilymph and pressure changes (compensated by round window)

Vibrations transmit endolymph to tectorial membrane

Movement of tectorial membrane move hair cells

Inner hair cells move in response to endolymph to detect sound, Outer stereocilia amplify sound

32
Q

What risk factors are associated with Menieres disease?

A

Genetics
Allergy
Autoimmune

33
Q

How is vestibular neuritis managed?

A

Urgent ENT referral if sudden onset unilateral hearing loss

Encourage to be as active as possible

Antiemetic - prochlorperazine

34
Q

What is an acoustic neuroma?

A

Tumour of vestibular cochlear nerve arising from Schwann cells

35
Q

What risk factors are associated with acoustic neuromas?

A

Neurofibromatosis

High dose head/neck radiation

36
Q

How does acoustic neuroma present?

A

Unilateral progressive hearing loss

Fluctuations in hearing

Balance disturbance

Tinnitus

37
Q

How are acoustic neuromas managed?

A

Wait and see if it grows

Surgery

Targeted radiation

38
Q

What is the Unterberger Test?

A

Patient walk on spot with eyes shut - rotate head to side of labyrinth lesion

39
Q

What is Romberg’s test?

A

Feel together, eyes closed

Taken away sight leaves only vestibular and proprioception. If dysfunction in one of these then likely to become unbalanced - e.g. dorsal columns issue or vestibular issue

40
Q

How is degree of hearing loss characterised?

A

Mild - 20-40dB - can’t hear whispers

Moderate - 40-70dB - can’t hear conversation

Severe 70-90dB - can’t hear shouting

Profound - >95dB - can’t hear sounds that would normally be painful

41
Q

What key questions may you ask if someone has hearing loss?

A

How well do you cope with background noise

How well do you hear someone sat next to you

Secondary symptoms

Past ear history

Ototoxic drugs

Exposure to noisy environments

42
Q

What conductive causes may there be for hearing loss??

A

External canal - obstruction (painless), growths, infection

TM - rupture (painful), tympanosclerosis

Middle ear - cholesteatoma (progressive), otosclerosis (painless, progressive), infection

Other - adenoids (painless, bilateral), TMJ syndrome (pain in ears, jaw, neck and head)

43
Q

What sensorineural causes may lead to hearing loss?

A

Presbyacusis

Noise induced

Ototoxic - aminoglyocsies, cisplatin, salicylates, quinine,
loop diuretics

Autoimmune - present like menieres

Idiopathic

Perilymph fistula

Systemic - meningitis, diabetes, MS, MD

44
Q

What pattern of hearing loss is seen with noise induced?

A

Bilateral gradual

or Acute with tinnitus

45
Q

What pattern of hearing loss is seen with ototoxic drug induced?

A

Gradual
Fullness
Tinnitus
Balance problems

46
Q

How does autoimmune sensorineural hearing loss present?

A

Like Menieres disease

47
Q

How does idiopathic hearing loss present?

A

Sudden onset, unilateral
Tinnitus
Fullness
Vertigo

48
Q

When should hearing loss be referred?

A

Sudden onset unilateral - ENT

50-80 no underlying pathology - hearing aids

Slight hearing difficulty and unwilling to have hearing aid - watchful waiting

Tinnitus >5mins - audiology

Mix of problems or under 50 - ENT

49
Q

What characterises sudden onset hearing loss?

A

> 30dB in 72 hours

50
Q

What may idiopathic sudden onset hearing loss be associated with?

A

Vertigo
Aural fullness
Tinnitus

Diagnosis of exclusion but don’t delay management with investigations

51
Q

How is idiopathic sudden onset hearing loss managed?

A

14 days oral prednisolone

If it doesn’t work then refer for intratympanic steroids

50% get hearing back within 2 weeks

52
Q

What are the red flags for sudden onset hearing loss?

A

Concurrent head trauma

Neurological signs

Unilateral middle ear effusion

53
Q

How is sudden onset hearing loss investigated?

A

Examine - lymph nodes, cranial nerves, otoscope, tuning fork

Pure tone audiometry

Tympanometry

Flexible nasoendoscopy

MRI

Neurology and Special Senses (28 decks)

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