JC100 (ENT) - Vertigo Flashcards
Inputs, integration and effectors to maintain balance
3 sensation inputs:
- Vision – 70%
- Proprioception – 15%
- Vestibular input – 15%
Integrated at central (brainstem, cerebellum)
Effector = motor system (lower limbs, core muscles) = postural support adjustment
Anatomical components of the peripheral and central vestibular system
Peripheral:
Semicircular canals - rotatory movement
Vestibule (saccule, utricle) - linear movement
Vestibular nerve
Central: Vestibular nuclei Brainstem Cerebellum Vestibular cortex Spinal cord
Anatomical components of the Labyrinth
Bony labyrinth surrounds membranous labyrinth containing perilymph and endolymph:
Semicircular canals (3 on each side) Otolithic organs: utricle and saccule
Semicircular canals
- Orientation and anatomical locations
- Connection to other structures in labyrinth
- physiological activation of vestibular nerve
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)
Describe the pairing of semicircular canals for vestibular nerve firing
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
Otolithic organs
- Function
- Anatomical positions
- Components for vestibular nerve firing
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)
Physiological activation of otolith organs
Trace the neural pathway from otolith organs to execute vestibular reflexes
Translational head movement in any particular direction will displace hair bundle
- Increase excitability of (depolarize) a subgroup of hair cells»_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)
Vestibular ocular reflex
- Function
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
Nystagmus
- ## Clinical definition
involuntary, rhythmic, oscillating movement of the eyes
Especially for saccadic eye movement (fast corrective movement to pick up next target)
Define the COWS reflex test for nystagmus
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.
4 main types of dizziness
Differentiate the 4 types’ description
- Nonspecific lightheadedness (無法分辨) = most common
- Vague, doesn’t fall - Pre-syncope (快昏倒了)
- Impeding faint/ LOC +/- generalised weakness
- Postural change
- Worse in morning - Disequilibrium (走路不穩)
- Impaired balance and gait
- No abnormal head sensation/ no illusion or movement or faintness - Vertigo (天旋地轉)
- Hallucination of movement
- Typically rotatory
Ddx non-specific light-headedness
Hyperventilation Hypoglycaemia Anaemia Head trauma Associated with psychogenic disorders (e.g. depression, anxiety, phobia)
Ddx pre-syncope
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
Ddx of disequilibrium
Ageing (most common) - multisensory deficits
- Deficit in vision, proprioception, vestibular organs, neural pathway…etc
Peripheral neuropathy
Musculoskeletal disorder
Gait disorder
Parkinson’s disease
Peripheral vs central vertigo
- Triggered by which type of movement
- Triggered by gaze or not
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
Peripheral vs central vertigo
- Compare onset and duration
- Fatigability
- Effect of gaze on vertigo
- Associated symptoms
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)
Causes of peripheral vertigo
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)
Causes of central vertigo
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)
BPPV - Benign paroxysmal postural vertigo
- Pathogenesis
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
BPPV
- Clinical presentation
- Duration of episodes
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
BPPV
Specific clinical test for Dx
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)
Compare the composition of perilymph and endolymph
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)
BPPV
Treatment options
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)
Meniere’s Disease
Pathogenesis
Specific signs
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
Meniere’s disease
Triad of clinical symptoms
Conditions to exclude in Dx
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
Define diagnostic criteria for definite meniere’s disease
>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
Define diagnostic criteria for Probable meniere’s disease
>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
Prognosis of Meniere’s disease
High spontaneous remission rate: >50% within 2 years; >70% after 8 years
Acute treatment of Meniere’s disease
Vestibular sedatives:
cinnarizine, diazepam (benzodiazepine)
Antiemetics: maxolon (= metoclopramide, dopamine receptor antagonist)), stemetil, ondansetron (5HT3 receptor antagonist)
Intratympanic steroid injection
Chronic prophylaxis for Meniere’s disease
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
Surgical treatment options for Meniere’s disease
- **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
Vestibular neuritis/ neuronitis
- Cause
- S/S
- Tx
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
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
Vestibular neuritis/ neuronitis
Most likely dx of peripheral vertigo:
Vertigo onset after trauma
Episodic vertigo attacks – worse on straining
Fluctuating hearing loss
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
Most likely dx of peripheral vertigo:
Severe vertigo
Hearing loss
Ear discharge
Suppurative labyrinthitis
Direct invasion of the inner ear by bacteria
Most likely dx of peripheral vertigo:
Mild vestibular dysfunction
Mild high-frequency hearing loss
Preceding AOM
Toxin labyrinthitis
Toxins penetrate the round window/ IAC/ cochlear aqueduct
Acute/chronic otitis media; or
Early bacterial meningitis
Most likely dx of peripheral vertigo:
Vesicles on pinnae/ external auditory canal
Facial weakness/ paralysis
Sensorineural hearing loss
Herpes zoster oticus»_space; Ramsay Hunt syndrome:
Perilymph fistula
- Preceding causes
- Pathogenesis
- S/S
- Tx
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
Toxin labyrinthitis
Preceding causes
S/S
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
Suppurative
labyrinthitis
Cause
S/S
Tx
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
Herpes zoster oticus
Cause
S/S
Diagnostic test
Tx
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
Vestibular migraine
Diagnostic criteria
Vestibular migraine (aka migrainous vertigo)
- > 5 episodes of vestibular symptoms, lasting 5min-72hr
- Current/previous history of migraines +/- aura
- > 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
Outline history taking questions for dx of dizziness
- Type: nonspecific lightheadedness, presyncope, postural imbalance, spinning vertigo
- Time course ***
- Episodic attack/ sustained acute/ sustained chronic - Triggering factors
e. g. social situation, bright light, URTI..etc - Associated symptoms
e. g. Meniere’s triad, photophobia, cerebellar signs
Ddx episodic attacks of dizziness (examples in 4 types of dizziness)
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
Ddx sustained acute and sustained chronic dizziness
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
Lis triggers for :
BPPV Migrainous vertigo Vestibular neuritis Perilymph fistula Superior canal dehiscence Vestibulopathy
- 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
Outline P/E for ddx cause of dizziness
- Neurological, vestibular, central, motor causes and tests
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
2 signs specific to Meniere’s disease
Hennebert’s sign (pressure on tragus induces vertigo)
Tullio phenomenon (sound induce vertigo)
Function of HINTS test to investigate dizziness
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)
Investigations for cause of dizziness (after clinical tests)
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
Treatment of chronic vestibular insufficiency
Group into sensory input, central, motor treatments…
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
Vestibular rehabilitation
Aims
Exercises
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
