ENT JC100: Vertigo: Peripheral And Central Flashcards
Balance mechanism
Sensation (3 inputs):
1. Vision (70%)
2. Proprioception (15%)
3. Vestibular input (15%)
—> ***>=2 sensory inputs should be intact to allow brain to identify which sensory input is abnormal
—> allow central adaptation
Processing:
- Central (Brainstem + Cerebellum)
Motor system:
- Body position / Postural support adjustment (lower limbs + core muscles)
Vestibular system
- Peripheral
- Vestibule
—> **SCC: Horizontal + Posterior + Superior —> **Rotational movement
—> **Otolith organs: Saccule + Utricle —> **Linear movement
- Vestibular nerve (project to brainstem then cortex) - Central
- Vestibular nuclei
- Brainstem
- Cerebellum
- Spinal cord
- Vestibular cortex
Labyrinth
- Bony labyrinth + Membranous labyrinth
- Bony labyrinth: hard protective case for Membranous labyrinth
—> Perilymph (**High Na, Low K): Fluid in space between the 2 labyrinth
—> Endolymph (Low Na, **High K): Fluid inside Membranous labyrinth
Semi-circular canals
- Superior part of labyrinth
- 90o to each other
- ALL 3 open into utricle
- Each has dilation **Ampulla at anterior end —> contain **Cupula (a gelatinous mass) covering Sensory epithelium
SCC are all paired:
- Horizontal canals
- Right superior + Left posterior (same plane)
- RIght posterior + Left superior (same plane)
Endolymph flowing inside SCC
—> Flow of Endolymph
—> Cupula (move in opposite direction due to lag)
—> Shearing of hair cell cilia
—> Towards Kinocilium ↑ firing rate (frequency not amplitude) (vice versa)
Example:
Head turns to **left
—> Endolymph not follow due to inertia (lag)
—> **Left canal excitatory + Right canal inhibitory
—> Brain interpret ***difference in discharge as movement
Otolith organs
- Located at the Macula in Utricle + Saccule
- Sense ***Linear acceleration
- Cilia from hair cells embedded in gelatinous layer
Otoconia:
- embedded on gelatinous layer (砸住)
- consists of **CaCO3 / **Calcite crystals
(記: HUVS)
Macula of utricle: Horizontal plane
Macula of saccule: Vertical plane
Vestibular-ocular reflex
Stabilise images on retina esp. during rapid impulsive head movement
—> produce equal but opposite amount of eye movement
—> maintain gaze during active head movement
Problem with either gain / phase —> blurred vision during head movement
Nystagmus
- Involuntary, rhythmic, oscillating eye movement
- Combination of:
1. Pursuit (slow phase: follow object)
2. Saccade (i.e. Nystagmus) (fast phase: corrective movement to pick up next target) (Nystagmus named after fast phase)
***COWS effect (Cold opposite, Warm same):
- Physiological response to temperature
- Warm water —> ↑ rate of firing (模擬頭部向暖水方向轉) —> both eyes turn to contralateral ear + horizontal nystagmus (fast phase) to ipsilateral ear
Dizziness
Dizzy: Non-specific term
- patient may use “dizzy” for LOC / headache
- importance of ***clarification with history taking
4 main types:
1. Non-specific lightheadedness (無法分辨)
2. Pre-syncope (快昏倒了)
3. Disequilibrium (走路不穩)
4. Vertigo (天旋地轉)
- Non-specific lightheadedness (無法分辨)
- most common
- vague complaint: patient just think something wrong with their sensation of balance but cannot describe
- ***never actually falls
Causes:
1. Hyperventilation
2. **Hypoglycaemia
3. **Anaemia
4. Head trauma
5. ***Associated with psychogenic disorders e.g. depression, anxiety, phobia
- Pre-syncope (快昏倒了)
- Sensation of ***impending faintness / LOC
- May also experience generalised weakness
- Often related to postural changes: Rises from lying / sitting position
- Typically worse in morning
Causes:
1. **Orthostatic hypotension
2. **Autonomic dysfunction secondary to DM, CVS diseases e.g. arrhythmia, MI, carotid stenosis
3. Medications e.g. Anti-HT, Anti-arrhythmic drugs
- Disequilibrium (走路不穩)
Impaired balance + gait ***without abnormal head sensation
—> Feeling of unsteadiness but there is no illusion of movement / sensation of faintness (好似坐船要扶住d野)
Most common cause:
- **Ageing (∵ **multi-sensory deficit affecting balance)
Ageing related degeneration in:
1. Visual acuity
2. Proprioception + Muscle power
3. SCC + Otolith organs
4. Vestibular nuclei + brainstem pathways
5. Other causes: Peripheral neuropathy, MSS disorder, Gait disorder, PD
***4. Vertigo (天旋地轉) (True vertigo)
Hallucination of movement
- Typically **rotatory but not necessarily
- Suggest a **lesion in vestibular system
Causes:
Peripheral:
1. SCC + Vestibule
- **Benign Paroxysmal Positional Vertigo (BPPV) (commonest)
- **Ménière’s disease
- Superior canal dehiscence
- **Perilymph fistula
- **Labyrinthitis
- Ototoxicity
- ***Trauma (fracture temporal bone, vestibular concussion)
- Vestibular insufficiency
- Vestibular nerve
- ***Vestibular neuronitis
- Vestibular paroxysmia (vascular loop compression of CN8)
Central (Vestibular nuclei, Cerebellum, Brainstem, Spinal cord, Vestibular cortex):
1. **Central-vestibular vertigo (Lesion of Brainstem / Cerebellum e.g. **CVA, **Tumour)
2. Medication (e.g. phenytoin overdose)
3. Metabolic (e.g. dysthyroid, anaemia, electrolyte, hypoglycaemia)
4. **Vestibular migraine
5. **Tumour
6. **Cerebellar ataxia
Functional vertigo
***Peripheral vs Central vertigo
1 = Peripheral
2 = Central
Nystagmus (Fast phase) direction:
1. **Horizontal (only 1 direction) / Torsional (mixture of horizontal + upward/downward), never vertical, **same direction in all gazes
2. Can be **vertical / other direction, may **change direction with change in gaze
(∵ Horizontal and Vertical gaze centre at different locations
- Horizontal: PPRF (paramedian pontine reticular formation) —> **Pons
- Vertical: Rostral interstitial nucleus —> **Midbrain)
Onset:
1. Acute
2. Subacute / Slow
**Visual fixation:
1. **Suppressed (i.e. nystagmus can be suppressed upon fixation on target)
2. Not suppressed (∵ brain cannot coordinate)
N+V:
1. May be severe
2. Varies
Otological symptoms:
1. ***Common (∵ vestibule in labyrinth, Labyrinthitis can also affect hearing)
2. Rare
Neurological symptoms:
1. Rare
2. ***Common
Instability:
1. Mild - Moderate
2. Severe, unable to stand
Fatigability:
1. ***Fatigable (if keep same stimulus —> eventually stimulus suppressed by brain —> no vertigo)
2. Not fatigable
Duration:
1. Short, may decrease after a few days
2. Persist
Vertigo causes
Descending order:
1. **Benign paroxysmal positional vertigo (BPPV)
2. Functional vertigo
3. Central-vestibular vertigo
4. **Vestibular migraine
5. **Ménière’s disease
6. **Vestibular neuritis
7. Vestibular paroxysmia
8. **Perilymph fistula
9. **Labyrinthitis
10. ***Herpes zoster oticus
- Benign paroxysmal positional vertigo (BPPV) (良性陣發性姿勢性暈眩)
- Benign disease
- Paroxysmal: only happen sometimes
- Positional: related to postural change
- a True vertigo
- Commonest cause of ***Peripheral vertigo
***Posterior SCC most commonly affected
Etiology:
Canalolithiasis
- particulate from otoconia (from saccule / utricle) —> dislodged after head injury / idiopathic
—> lodged into posterior SCC (∵ more dependent position)
—> stimulate ampulla by ***plunger effect (piston effect)
—> move Endolymph
(fluid movement are due to crystal rather than head turn —> brain thinks there is head movement)
Presentation:
- **NO hearing symptom (∵ cochlea not affected)
- **usually last for ~3 weeks
- recurrence common
- provoked by turning over to ***particular position in bed / when reaching up
- wakes in sleep
Diagnostic test:
- **Dix-Hallpike’s maneuver (direct stimulatory effect on **posterior SCC)
—> right sided lesion: if move head upward + right —> eye move upwards + right (towards down ear) —> Torsional nystagmus (眼睛嘗試翻返正中位置)
(記住:
頭向右轉 —> fast phase to right (to catch up), slow phase to left
頭向右後轉 —> fast phase to right + upward (towards down ear), slow phase to left + downward
∴ if 頭向右後轉 —> Endolymph continue to stimulate —> nystagmus towards right + upward)
Treatment:
1. ***Reassurance
- usually go away by itself
-
**Waiting
- avoid driving
- avoid precipitating position
—> **45o prop up / 2 high pillows
—> don’t sleep on side of bad ear
—> keep head still at vertical position (i.e. do not bend forward / backward) - Repositioning maneuvers - ***Epley
- while holding patient’s head on lesion side (e.g. right)
—> turn to opposite side (left) (for 30 seconds)
—> lie on lateral position (left lateral) on shoulder with head keep still (for 30 seconds)
—> crystal in posterior SCC will move more anteriorly drop back to utricle
—> sit back up (may have falling sensation ∵ crystal deposit back on macula)
—> 令到crystal由另一面跌出返黎, 唔會塞住條管
Endolymphatic hydrops (耳水不平衡)
Pathogenesis:
***Accumulation of fluid inside Endolymph area
2 theories:
1. Malabsorption of Endolymph theory (more accepted)
2. Glycoprotein theory
—> Physical distortion in Membranous labyrinth
—> Distortion of saccule (Bulging of saccule against footplate + Rupture of membranous labyrinth)
Causes:
1. Idiopathic = ***Ménière’s disease (diagnosis of exclusion)
2. Metabolic (hyperglycaemia, hyperlipidaemia, hypothyroidism)
3. Infectious (Syphilis, Viral: Measles, Mumps)
4. Autoimmunity (SLE, RA)
5. Developmental (Mondini dysplasia)
6. Otosclerosis (Cochlear involvement —> disturbed endolymph flow)
- ***Ménière’s disease (耳水不平衡 / 美尼爾氏症)
Idiopathic syndrome of Endolymphatic hydrops (a diagnosis of exclusion!)
**Triad +/- Aural **fullness:
1. **Vertigo
2. **Tinnitus
3. ***Hearing loss
Epidemiology:
- 0.1% in UK
- F:M = 3:2
- Family history 20%
- Young (<65)
Pathogenesis:
- Malabsorption theory
—> over-accumulation of fluid within inner ear
—> distension of Cochlear duct
—> distension of Saccule may be touching footplate causing:
1. **Hennebert’s sign (pressing on tragus —> pressure-induced vertigo)
2. **Tullio phenomenon (loud sound —> sound-induced vertigo)
—> Above actually tests for fistula: Ménière’s disease: False-positive (positive Hennebert’s sign + Tullio phenomenon without presence of fistula)
Fluctuating / Episodic course:
- Attacks of hydrops caused by ***↑ in endolymphatic pressure
—> microrupture of membranous labyrinth
—> break in membrane separating perilymph (low K extracellular fluid) + endolymph (high K intracellular fluid)
—> healing of rupture —> return of hearing
Prognosis:
- ***Self-limiting
- Spontaneous remission rate high (>50% within 2 years, >70% after 8 years)
- Some patients left with poor balance + hearing (∵ repeated attack + mixture of perilymph and endolymph —> hair cells in cochlear and saccule destroyed)
Diagnostic categories:
Definite Ménière’s disease (all 4 criteria):
1. >=2 spontaneous episodes of vertigo each lasting 20 mins - 12 hours
2. Audiometrically documented low-medium frequency sensorineural hearing loss of affected ear (>=1 occasion during / after an episode of vertigo)
3. Fluctuating aural symptoms (hearing, tinnitus, fullness) in affected ear
4. Not better accounted for by another vestibular diagnosis (other causes of Endolymphatic hydrops / Vertigo)
Probable Ménière’s disease (***if no Audiometrical documentation to show sensorineural hearing loss):
1. >=2 episodes of vertigo / dizziness, each lasting 20 mins - 24 hours
2. Fluctuating aural symptoms (hearing, tinnitus, fullness) in affected ear
3. Not better accounted for by another vestibular diagnosis (other causes of Endolymphatic hydrops / Vertigo)
Treatment:
Active
1. **Vestibular sedatives (Cinnarizine, Diazepam)
2. **Antiemetics (Metoclopramide, Prochlorperazine, Ondansetron)
3. Intratympanic steroid injection
Chronic (for prophylaxis)
1. Avoid caffeine, smoking
2. Low salt diet
3. Diuretics (**↓ Na load)
4. **Betahistine (CI for peptic ulcer / asthma) —> inner ear vasodilation —> ↑ inner ear circulation
(NO conclusive studies showing efficacy of drugs intended to alter disease course of Ménière’s disease)
Surgical treatment (only if medical therapy fails + severe symptoms)
1. Intratympanic ***gentamicin (ototoxic) injection (i.e. Medical labyrinthectomy —> preferential vestibulotoxic —> stop signals transmitted to brain)
2. Endolymphatic sac decompression
3. Labyrinthectomy
4. Vestibular neurectomy
- Vestibular neuritis
Lesion at Vestibular nerve:
- ***Viral infection / Post-viral inflammation —> Swelling of Vestibular nerve —> a lot of stimulatory signal
Symptoms:
- **Sudden severe vertigo
- N+V
- Gait instability
- **Hearing usually spared (∵ only vestibular nerve affected)
P/E:
- **↓ Caloric response in involved ear
- **Positive head thrust test in direction of affected side (right vestibular neuritis —> when head thrust to right —> catch up saccade back to left) (∵ abnormal vestibuloocular reflex)
Natural course:
- Vertigo (lasted for days) —> Period of unsteadiness (up to 3 months)
Treatment:
- **Vestibular sedative (e.g. Prochlorperazine) for acute phase (avoid prolong use)
- **Early mobilisation + ***Vestibular rehabilitation
- Vestibular migraine
- > =5 episodes, lasting 5 min - 72 hours
- ***Current / Previous history of migraine (with / without aura)
S/S:
- >=1 ***Migraine features in >50% of vertigo episodes
—> Headache (unilateral / pulsating)
—> Photophobia / Phonophobia
—> Visual aura
- Labyrinthitis
Labyrinthitis = Inflammation of inner ear
Causes:
1. Toxin labyrinthitis
- result from **sterile inflammation of inner ear (without bacteria in inner ear) (following acute/ chronic otitis media or early bacterial meningitis)
- **less severe symptoms
- toxins penetrate round window / IAC (internal auditory canal) / cochlear aqueduct
- produce mild high frequency **hearing loss / mild **vestibular dysfunction
- treatment: Antibiotics
- Suppurative labyrinthitis
- direct **invasion of inner ear by bacteria from otitis / meningitis
- more severe symptoms
- **severe vertigo + hearing loss + ear discharge
- treatment: Hospitalisation, Hydration, Vestibular suppressants (e.g. Stemetil), IV antibiotics, Early surgical treatment of underlying CSOM
- Perilymph fistula
- Damage of barrier between middle + inner ear (round window / ***oval window commonest)
Causes:
1. **Cholesteatoma
2. **Trauma
3. Iatrogenic (e.g. stapedectomy)
4. Idiopathic
S/S:
- Vertigo onset **after trauma (including barotrauma)
- **Fluctuating hearing loss + **Episodic vertigo attacks —> worse on straining
- **Hennebert’s sign (pressing on tragus —> pressure-induced vertigo)
- ***Tullio phenomenon (loud sound —> sound-induced vertigo)
Treatment:
- Urgent surgical repair of fistula
- Herpes zoster oticus
- VZV reactivation —> Zoster
Ramsay Hunt syndrome:
- Vesicles on pinna / EAC (external auditory canal)
- **Facial weakness / paralysis
- **Sensorineural hearing loss
Diagnosis:
- Clinical diagnosis
- Culture of vesicular fluid
Treatment:
- **Antiviral therapy
- **Steroids (for facial palsy)
- Analgesics
Approach to a Dizzy patient
Detailed history (***Type, Time, Trigger, Association)
1. Type
- Non-specific lightheadedness (無法分辨)
- Pre-syncope (快昏倒了)
- Disequilibrium (走路不穩)
- Vertigo (天旋地轉)
- Time course (**most valuable)
- **episodic attacks vs sustained
- few second / mins / hours / days - Triggering factors
- Associated symptoms
P/E: confirm working diagnosis + ***rule out central causes
***Time course of dizziness
3 types:
1. Episodic attack
second - mins:
- ***BPPV
- Vestibular paroxysmia, Superior canal dehiscence
- Postural hypotension, Anaemia etc. —> Presyncope, Non-specific dizziness
mins - hours:
- **Ménière’s disease (20 min - 12 hours)
- Endolymphatic hydrops
- **Vestibular migraine (5 min - 72 hours)
- Sustained acute (days - weeks)
- **Vestibular neuritis
- **Brainstem / Cerebellar lesion (infarct, tumour) - Sustained chronic (months - years)
- Bilateral vestibulopathy
- **Functional
- **Neurodegenerative disorders
