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MBBS IV - Junior Clerkship WCS > JC100 (ENT) - Vertigo > Flashcards

JC100 (ENT) - Vertigo Flashcards

1
Q

Inputs, integration and effectors to maintain balance

A

3 sensation inputs:

  1. Vision – 70%
  2. Proprioception – 15%
  3. Vestibular input – 15%

Integrated at central (brainstem, cerebellum)

Effector = motor system (lower limbs, core muscles) = postural support adjustment

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2
Q

Anatomical components of the peripheral and central vestibular system

A

Peripheral:
 Semicircular canals - rotatory movement
 Vestibule (saccule, utricle) - linear movement
 Vestibular nerve

Central: 
 Vestibular nuclei
 Brainstem
 Cerebellum
 Vestibular cortex
 Spinal cord
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3
Q

Anatomical components of the Labyrinth

A

Bony labyrinth surrounds membranous labyrinth containing perilymph and endolymph:

Semicircular canals (3 on each side)
Otolithic organs: utricle and saccule
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4
Q

Semicircular canals

  • Orientation and anatomical locations
  • Connection to other structures in labyrinth
  • physiological activation of vestibular nerve
A

Semicircular canals at the superior part of labyrinth:
 3 canals perpendicular to each other: horizontal (aka lateral), posterior, superior (aka anterior)

 Open into the utricle, with dilation ampulla at anterior end

Activation:

  • A gelatinous mass called cupula cover the sensory epithelium (hair cells)
  • Flow of endolymphatic fluid relative to cupula cause shearing of hair cell cilia:

 Stereocilia bent towards kinocilium increase firing rate of vestibular nerve
 Stereocilia deflected away from kinocilium decrease firing rate (inhibition)

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5
Q

Describe the pairing of semicircular canals for vestibular nerve firing

A

The semicircular canals are paired:
 Horizontal canals
 Right superior / left posterior (in same plane)
 Left superior / right posterior

When head turns to the left, endolymph does not follow due to inertia:
o Left canal is excitatory
o Right canal is inhibitory

Brain interpret the difference in discharge as movement

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6
Q

Otolithic organs

  • Function
  • Anatomical positions
  • Components for vestibular nerve firing
A

Otolithic organs: Sense linear acceleration

Located at the macula in utricle and saccule:
 Macula of utricle lies in the horizontal plane
 Macula of saccule lies in the vertical position

Embedded in gelatinous layer are:
 Cilia from hair cells
 Otoconia (consists of CaCO3 or calcite crystals)

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7
Q

Physiological activation of otolith organs

Trace the neural pathway from otolith organs to execute vestibular reflexes

A

Translational head movement in any particular direction will displace hair bundle

  • Increase excitability of (depolarize) a subgroup of hair cells&raquo_space;release transmitter to vestibular nerve
  • Decrease excitability of (hyperpolarize) another subgroup on the same otolith organ

Pathway:

  • Hair cell (in semicircular canals, otolith organs)-
    vestibular nerve-
    Scarpa’s ganglion-
    vestibular nucleus (superior, lateral, inferior, medial)-
    spinal/ocular motor neuron-
    vestibular reflexes
  • Modulated by cerebellar Purkinje cells (innervate neurons in the vestibular nucleus)
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8
Q

Vestibular ocular reflex

  • Function
A

During rapid impulsive head movement, produce an equal but opposite amount of eye movement to stabilize images on the retina

Maintain visual acuity on object of interest during acute head movement

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9
Q

Nystagmus

  • ## Clinical definition
A

involuntary, rhythmic, oscillating movement of the eyes

Especially for saccadic eye movement (fast corrective movement to pick up next target)

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10
Q

Define the COWS reflex test for nystagmus

A

Cold-opposite:
Irrigated with COLD water: Eyes deviate to ipsilateral ear and the nystagmus beats away to the OPPOSITE ear.

Warm-same:
Irrigated with WARM water: Eyes deviate to contralateral ear and the nystagmus beats towards to the SAME ear.

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11
Q

4 main types of dizziness

Differentiate the 4 types’ description

A
  1. Nonspecific lightheadedness (無法分辨) = most common
    - Vague, doesn’t fall
  2. Pre-syncope (快昏倒了)
    - Impeding faint/ LOC +/- generalised weakness
    - Postural change
    - Worse in morning
  3. Disequilibrium (走路不穩)
    - Impaired balance and gait
    - No abnormal head sensation/ no illusion or movement or faintness
  4. Vertigo (天旋地轉)
    - Hallucination of movement
    - Typically rotatory
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12
Q

Ddx non-specific light-headedness

A 
 Hyperventilation
 Hypoglycaemia
 Anaemia
 Head trauma
 Associated with psychogenic disorders (e.g. depression, anxiety, phobia)
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13
Q

Ddx pre-syncope

A

 Orthostatic hypotension

 Autonomic dysfunction
- secondary to diabetes, cardiovascular diseases (e.g. arrhythmias, myocardial infarction, carotid artery stenosis)

 Medications (esp elderly on multiple medication), e.g. anti-
hypertensive, anti-arrhythmic drugs

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14
Q

Ddx of disequilibrium

A

Ageing (most common) - multisensory deficits
- Deficit in vision, proprioception, vestibular organs, neural pathway…etc

Peripheral neuropathy

Musculoskeletal disorder

Gait disorder

Parkinson’s disease

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15
Q

Peripheral vs central vertigo

  • Triggered by which type of movement
  • Triggered by gaze or not
A

Peripheral

  • Horizontal or torsional (mixture of up or down with horizontal), never vertical
  • Same direction in all gazes
  • Looking in the direction of nystagmus makes nystagmus more obvious

Central:

  • Can be vertical or other direction
  • May change direction with change in gaze
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16
Q

Peripheral vs central vertigo

  • Compare onset and duration
  • Fatigability
  • Effect of gaze on vertigo
  • Associated symptoms
A

Peripheral = Acute onset and short duration, subsides in days

  • Visual fixation helps suppress vertigo
  • Fatigable vertigo: gets better after repeated episodes
  • Severe nausea and vomiting
  • Otological symptoms *** e.g. labyrinthitis
  • Mild instability only

Central = Subacute/ slow onset with long duration, persistent

  • Visual fixation does not suppress vertigo
  • Not-fatigable: persistently same severity
  • Variable nausea and vomiting
  • Neurological symptoms ***
  • Severe instability *** (can’t stand)
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17
Q

Causes of peripheral vertigo

A

In semicircular canals and vestibule:

1) Benign paroxysmal positional vertigo (BPPV) = commonest
2) Meniere’s Disease
3) Perilymph fistula
4) Labyrinthitis
5) Superior canal dehiscence
6) Vestibular insufficiency
7) Ototoxicity
8) Trauma (fracture temporal bone / vestibular concussion)

In vestibular nerve:

1) Vestibular neuritis/ neuronitis
2) Vestibular paroxysmia (vascular loop compression of CN VIII)

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18
Q

Causes of central vertigo

A

a) Central-vestibular vertigo (lesion of brainstem/ cerebellum, e.g. CVA/ tumour)
b) Migrainous vertigo
c) Cerebellar ataxia (e.g. infarction, Wilson’s disease, congenital)
d) Metabolic (dysthyroid, anaemia, electrolyte, hypoglycemia)
e) Medication (e.g. phenytoin overdose)

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19
Q

BPPV - Benign paroxysmal postural vertigo

  • Pathogenesis
A

Most commonly affects posterior semicircular canal

Etiology – canalolithiasis:
 Particulate from otoconia (for saccule or utricle) is
dislodged (after head injury/ idiopathic) then stuck in
posterior semicircular canal

 Inertia of crystal continues to stimulate the ampulla by a
plunger effect (piston-effect) >> continues to move the
endolymph when head is still
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20
Q

BPPV

  • Clinical presentation
  • Duration of episodes
A

 True vertigo provoked by turning over to particular position in bed or when reaching up

 No hearing symptom (cochlea not affected; no infection)

 Usually lasts for ~3 weeks

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21
Q

BPPV

Specific clinical test for Dx

A

Dix- Hallpike’s maneuver

Series of postural changes:
» settling particles from otoconia in posterior semicircular canal should stimulate ampulla
» eyes should have torsional nystagmus (down-beating vertically towards the ground)

22
Q

Compare the composition of perilymph and endolymph

A

Perilymph- Between the bony and membranous labyrinth
High in Na, low in K

Endolymph - Inside the membranous labyrinth
High in K, low in Na (opposite)

23
Q

BPPV

Treatment options

A

Epley’s Maneuvre: make crystals in semicircular canal move anteriorly and drop into utricle

Reassurance

Spontaneous recovery:
o 45deg propped up or 2 high pillows
o Not to sleep on the side of the bad ear
o Keep the head still at vertical position (i.e. not bent forward/backward)

24
Q

Meniere’s Disease

Pathogenesis
Specific signs

A

idiopathic syndrome of endolymphatic hydrops:
- overaccumulation of endolymph fluid in inner ear increase
endolymphatic pressure + malabsorption of endolymph
- physical distortion (bulging) of membranous labyrinth (distension of scala media)

Distension of saccule causes:

i. Hennebert’s sign (pressure on tragus induces vertigo)
ii. Tullio phenomenon (sound induce vertigo)

Micro-ruptures of membranous labyrinth causes episodic, recurrent attacks

25
Q

Meniere’s disease

Triad of clinical symptoms

Conditions to exclude in Dx

A

triad: vertigo, tinnitus, hearing loss +/- aural fullness

Rule out DDx of endolymph hydrops first:
Metabolic 
 Hyperglycemia
 Hyperlipidemia
 Hypothyroidism

Infectious
 Syphilis
 Viral – measles, mumps

Autoimmune: SLE, RA

Development: Mondini dysplasia

Advanced otosclerosis with cochlear involvement

26
Q

Define diagnostic criteria for definite meniere’s disease

A

 >2 spontaneous episodes of vertigo lasting 20 min to 12 hours

 Audiometrically (pure tone audiogram) documented low- to
medium-frequency sensorineural hearing loss in one ear around vertigo episode

 Fluctuating aural symptoms (hearing, tinnitus or aural fullness) in the affected ear

 Not better accounted by another vestibular diagnosis

27
Q

Define diagnostic criteria for Probable meniere’s disease

A

 >2 episodes of vertigo or dizziness, each lasting 20 minutes to 24 hours (longer duration than definite Dx)

 Fluctuating aural symptoms (hearing, tinnitus or aural fullness) in the affected ear (same as definite dx)

 Not better accounted for by another vestibular diagnosis (same as definite dx)

 no pure tone audiogram = cannot make definite Dx

28
Q

Prognosis of Meniere’s disease

A

High spontaneous remission rate: >50% within 2 years; >70% after 8 years

29
Q

Acute treatment of Meniere’s disease

A

 Vestibular sedatives:
cinnarizine, diazepam (benzodiazepine)

 Antiemetics: maxolon (= metoclopramide, dopamine receptor antagonist)), stemetil, ondansetron (5HT3 receptor antagonist)

 Intratympanic steroid injection

30
Q

Chronic prophylaxis for Meniere’s disease

A

Lifestyle:
 Avoid caffeine
 Quit smoking
 Low salt diet, diuretics to reduce sodium load

Betahistine:
 Inner ear vasodilation = improve inner ear circulation
 Contraindicated for peptic ulcer / asthma

31
Q

Surgical treatment options for Meniere’s disease

A
  • **Intratympanic gentamicin injection (medical labyrinthectomy) ***
  • preferential vestibulotoxic (stop projection of vestibular signal to brain)

Less commonly performed:
o Endolymphatic sac decompression
o Labyrinthectomy
o Vestibular neurectomy

32
Q

Vestibular neuritis/ neuronitis

  • Cause
  • S/S
  • Tx
A

Cause: Post-viral infection, swelling of vestibular nerve

S/S:
 Sudden severe vertigo
 Nausea, vomiting
 Gait instability
 Hearing usually spared
 Poor caloric response in the involved ear
 Positive head thrust test@ in the direction of the involved side

Tx: self-limiting in days, unsteadiness for 3 months max
vestibular sedative, stemetil (antiemetic) for acute phase

33
Q

Most likely dx of peripheral vertigo:

 Sudden severe vertigo
 Nausea, vomiting
 Gait instability
 Hearing usually spared
 Poor caloric response in the involved ear
 Positive head thrust test@ in the direction of the involved side

A

Vestibular neuritis/ neuronitis

34
Q

Most likely dx of peripheral vertigo:

 Vertigo onset after trauma
 Episodic vertigo attacks – worse on straining
 Fluctuating hearing loss

A

Perilymph fistula

Violation of barrier between middle and inner ear (most commonly round window/ oval window)

 Cholesteatoma
 Trauma (including barotrauma)
 Iatrogenic (e.g. stapedectomy)
 Idiopathic

35
Q

Most likely dx of peripheral vertigo:

 Severe vertigo
 Hearing loss
 Ear discharge

A

Suppurative labyrinthitis

Direct invasion of the inner ear by bacteria

36
Q

Most likely dx of peripheral vertigo:

 Mild vestibular dysfunction
 Mild high-frequency hearing loss
Preceding AOM

A

Toxin labyrinthitis

Toxins penetrate the round window/ IAC/ cochlear aqueduct
 Acute/chronic otitis media; or
 Early bacterial meningitis

37
Q

Most likely dx of peripheral vertigo:

 Vesicles on pinnae/ external auditory canal
 Facial weakness/ paralysis
 Sensorineural hearing loss

A

Herpes zoster oticus&raquo_space; Ramsay Hunt syndrome:

38
Q

Perilymph fistula

  • Preceding causes
  • Pathogenesis
  • S/S
  • Tx
A 
Causes: 
 Cholesteatoma
 Trauma (including barotrauma)
 Iatrogenic (e.g. stapedectomy)
 Idiopathic

Pathogenesis:
Violation of barrier between middle and inner ear (most commonly round window/ oval window)

S/S:
 Vertigo onset after trauma
 Episodic vertigo attacks – worse on straining
 Fluctuating hearing loss

Tx: Urgent surgical repair of fistula

39
Q

Toxin labyrinthitis

Preceding causes
S/S

A

Causes:
 Acute/chronic otitis media; or
 Early bacterial meningitis
Toxins penetrate the round window/ IAC/ cochlear aqueduct

S/S:
 Mild vestibular dysfunction
 Mild high-frequency hearing loss

Tx: Abx

40
Q

Suppurative
labyrinthitis

Cause
S/S
Tx

A

Cause: Direct invasion of the inner ear by bacteria

S/S:
 Severe vertigo
 Hearing loss
 Ear discharge

Tx:
 Hospitalization
 Hydration
 Vestibular suppressants (stemetil)
 IV antibiotics
 Early surgical treatment of underlying CSOM/ cholesteatoma
41
Q

Herpes zoster oticus

Cause
S/S
Diagnostic test
Tx

A

Cause:
Reactivation of varicella zoster

S/S: 
Ramsay Hunt syndrome:
 Vesicles on pinnae/ external auditory canal
 Facial weakness/ paralysis
 Sensorineural hearing loss

Diagnosis:
 Clinical presentation
 Culture of vesicular
fluid (HSV)

Tx:
 Antiviral therapy (acyclovir)
 Steroids
 Analgesics

42
Q

Vestibular migraine

Diagnostic criteria

A

Vestibular migraine (aka migrainous vertigo)

  1. > 5 episodes of vestibular symptoms, lasting 5min-72hr
  2. Current/previous history of migraines +/- aura
  3. > 1 of the following migraine features in >50% of vertigo episodes:
    - Headache with at least 2 of: unilateral/ pulsating/ photophobia/ phonophobia/ moderate or severe pain intensity
    - Visual aura
43
Q

Outline history taking questions for dx of dizziness

A
  1. Type: nonspecific lightheadedness, presyncope, postural imbalance, spinning vertigo
  2. Time course ***
    - Episodic attack/ sustained acute/ sustained chronic
  3. Triggering factors
    e. g. social situation, bright light, URTI..etc
  4. Associated symptoms
    e. g. Meniere’s triad, photophobia, cerebellar signs
44
Q

Ddx episodic attacks of dizziness (examples in 4 types of dizziness)

A

In seconds to minutes:

Nonspecific lightheadedness: Anaemia, hypoglycaemia..etc
Presyncope: Postural hypotension
Postural imbalance: /
Peripheral vertigo: 
 BPPV
 Perilymphatic fistula
 Superior canal dehiscence
 Vestibular paroxysmia
In minutes - hours 
Peripheral vertigo: 
 Meniere’s Disease (20min-12h)
 Other endolymph hydrops
 Perilymphatic fistula
Central vertigo:  Migrainous vertigo
45
Q

Ddx sustained acute and sustained chronic dizziness

A

Sustained acute (days-weeks)

  • Vestibular neuritis/neuronitis
  • Brainstem/ cerebellar lesion (infarct/ tumor)

Sustained chronic (months- years)

  • Functional non-specific lightheadedness
  • Postural imbalance: Neurodegenerative disorders
  • Peripheral vertigo: Bilateral vestibulopathy
46
Q

Lis triggers for :

BPPV 
Migrainous vertigo 
Vestibular neuritis 
Perilymph fistula 
Superior canal dehiscence 
Vestibulopathy
A
  • Supine/ sleep on specific side: BPPV
  • Bright light (photophobia): Migrainous vertigo
  • URTI (viral infection): Vestibular neuritis/neuronitis
  • Head injury, Post-concussion, fractured temporal bone
     perilymph fistula, BPPV
  • Loud sound/ ear pressure
     Perilymph fistula
     Superior canal dehiscence
  • Ototoxic drugs (antibiotics, chemotherapeutics, e.g. cisplatin) Vestibulopathy
47
Q

Outline P/E for ddx cause of dizziness

  • Neurological, vestibular, central, motor causes and tests
A

Neurological exam for vision, proprioception

Vestibular causes:

  • Otoscopy: r/o middle ear infection, cholesteatoma…etc
  • Pure tone audiogram (Definite Meniere’s)
  • Dix-Hallpike (BPPV)
  • Fistula test (perilymph fistula, superior canal dehiscence)

Central causes:

  • Cerebellar signs
  • CN exams: Wallenberg/ Lateral medullary
  • Gait exam
  • HINTS: Head-Impulse test, Nystagmus, Test of Skew

Motor: Romberg test

48
Q

2 signs specific to Meniere’s disease

A

 Hennebert’s sign (pressure on tragus induces vertigo)

 Tullio phenomenon (sound induce vertigo)

49
Q

Function of HINTS test to investigate dizziness

A

Most important!!!
Rule out central causes of dizziness (untreated = high mortality)

HINTS*:

1) Head-impulse test@
2) Nystagmus (test with Frenzel goggles to eliminate visual fixation)
3) Test of Skew (detect skew deviation of eye by alternating cover test)

50
Q

Investigations for cause of dizziness (after clinical tests)

A

Imaging/ radiological for central causes:
o CT/MRI Brain & Brainstem
o MRI brain and internal auditory canal (with contrast) - acoustic neroma

Audiological tests if not sure peripheral/ dx definite Meniere's 
o Pure tone audiometry
o Electronystagmography (ENG) with caloric test or rotary chair 
o Posturography
51
Q

Treatment of chronic vestibular insufficiency

Group into sensory input, central, motor treatments…

A

Vision: wear glasses, treat cataracts…

Proprioception: use walking stick, physiotherapy

Vestibular: Vestibular sedatives for acute attack, Betahistine (meniere’s), Cawthorne-Cooksey exercises

Central: Move slower

Motor: Physiotherapy for motor training, TaiChi, yoga

52
Q

Vestibular rehabilitation

Aims
Exercises

A

Aims:
 Improve postural stability and gaze stability
 Decrease subjective complaints of disequilibrium and oscillopsia (sensation that surrounding environment is constantly moving)
 Return to normal activities

Exercises:
 Vestibular adaptation
 Substitution exercises
 Balance and gait activities
 General conditioning

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