Neuro-Otology
Neuro-Otology
What Do You Need to Know?
- Peripheral vertigo = more symptomatic (severe spinning, nausea); central vertigo = more dangerous (stroke, subtle findings)
- HINTS exam has high sensitivity for posterior circulation stroke ONLY in acute vestibular syndrome (acute continuous dizziness/vertigo + spontaneous nystagmus + nausea/gait instability) AND when performed by a trained clinician; central or equivocal HINTS → MRI/MRA
- BPPV = most common cause of vertigo; posterior canal 80–90%; Dix-Hallpike → Epley maneuver
- Normal head impulse test in acute vertigo is alarming — suggests central cause (brainstem stroke)
- Vestibular migraine = most common episodic vertigo in young adults (after BPPV); can occur WITHOUT headache
- Meniere triad: episodic vertigo (20 min–12 h) + low-frequency SNHL + tinnitus ± aural fullness
- COWS: Cold Opposite, Warm Same (fast-phase direction of caloric nystagmus)
🚩 Don’t Miss — Test-Day Priorities
- HINTS exam in acute vestibular syndrome (and only AVS): normal head impulse + direction-changing/vertical nystagmus + skew deviation → CENTRAL (stroke) until proven otherwise. Validated >98% sensitivity applies only when performed by trained clinicians (GRACE-3); central or equivocal HINTS → MRI/MRA.
- Normal head impulse test in a patient with prolonged spinning vertigo is a red flag — suggests posterior circulation stroke (PICA/AICA/basilar), not vestibular neuritis.
- BPPV: brief positional vertigo with rolling over/looking up + torsional upbeating nystagmus on Dix-Hallpike (delay, fatigue, reversal) → treat with Epley; horizontal canal → Lempert/BBQ roll.
- Vestibular neuritis: monophasic prolonged vertigo days, NO hearing loss, positive head impulse with catch-up saccade ipsilateral to lesion; vestibular rehab; steroids controversial.
- Ménière triad: episodic vertigo (hours) + low-frequency SNHL + tinnitus ± aural fullness. AAO-HNS: clinicians MAY offer diuretics ± betahistine for maintenance; MAY offer intratympanic steroids if not responsive to noninvasive therapy; SHOULD offer intratympanic gentamicin if not responsive to nonablative therapy.
- Vestibular migraine can occur WITHOUT headache — recurrent minutes-to-days vertigo + migraine criteria + photo/phonophobia; treat with migraine prevention.
- Vestibular schwannoma: slowly progressive asymmetric SNHL + tinnitus + imbalance; MRI IAC; bilateral = NF2.
- Superior canal dehiscence: autophony + Tullio phenomenon (sound-induced vertigo) + bony defect on temporal bone CT + abnormal VEMP → surgical plugging.
- Vestibular paroxysmia: brief recurrent seconds-long vertigo from neurovascular conflict at CN VIII → carbamazepine (like trigeminal neuralgia).
- Episodic ataxia type 2: autosomal dominant, CACNA1A → acetazolamide responsive.
🔍 Buzzwords & Pathognomonic FindingsClinical / triggers · Bedside exam · Treatment
Clinical / triggers
- Brief vertigo triggered by rolling over or looking up → BPPV (posterior canal)
- Sudden prolonged vertigo for days, no hearing loss, recent URI → Vestibular neuritis
- Episodic vertigo (hours) + low-frequency SNHL + tinnitus + aural fullness → Ménière disease
- Recurrent minutes-to-days vertigo ± headache + photo/phonophobia → Vestibular migraine
- Autophony (hearing own voice/heartbeat) + Tullio (sound-induced vertigo) → Superior canal dehiscence
- Progressive asymmetric SNHL + tinnitus + imbalance → Vestibular schwannoma (bilateral → NF2)
- Brief seconds-long recurrent vertigo, neurovascular conflict CN VIII → Vestibular paroxysmia
- Vertigo + ipsilateral Horner + crossed sensory loss + dysphagia → Wallenberg (lateral medullary / PICA)
- Vertigo + ipsilateral hearing loss + facial weakness + ataxia → AICA stroke
- Childhood-onset episodic vertigo/ataxia, AD inheritance → EA2 (CACNA1A)
Bedside / HINTS / exam
- Torsional upbeating nystagmus on Dix-Hallpike with latency, fatigue, reversal → Posterior canal BPPV (peripheral)
- Downbeating torsional nystagmus on Dix-Hallpike → Anterior canal BPPV (rare)
- Geotropic or apogeotropic horizontal nystagmus on supine roll test → Horizontal canal BPPV (peripheral)
- Unidirectional horizontal-torsional nystagmus + abnormal head impulse + no skew → Peripheral (vestibular neuritis)
- NORMAL head impulse + direction-changing/vertical nystagmus + skew deviation (INFARCT) → Central (posterior circulation stroke)
- Pure vertical or pure torsional nystagmus → Central until proven otherwise
- No fixation suppression of nystagmus → Central
- Downbeat nystagmus on chronic phenytoin/carbamazepine → Anticonvulsant cerebellar toxicity (central)
- Cannot sit/stand unsupported with acute vertigo → Cerebellar stroke/hemorrhage (central)
Treatment / maneuver
- Epley canalith repositioning maneuver → Posterior canal BPPV (Semont alternative)
- Lempert / BBQ roll maneuver → Horizontal canal BPPV
- Vestibular rehabilitation → Vestibular neuritis (recovery 1–3 wk)
- AAO-HNS Meniere ladder (graded recommendations): low-salt diet; diuretics ± betahistine (may offer) → intratympanic steroids (may offer if noninvasive-refractory) → intratympanic gentamicin (should offer if nonablative-refractory)
- Migraine prophylaxis (topiramate, propranolol, amitriptyline, CGRP) → Vestibular migraine
- Carbamazepine / oxcarbazepine → Vestibular paroxysmia
- Acetazolamide → Episodic ataxia type 2 (CACNA1A)
- Observation, stereotactic radiosurgery, or microsurgical resection → Vestibular schwannoma
- Surgical plugging / resurfacing of bony defect → Superior canal dehiscence
- Urgent MRI brain + posterior circulation stroke workup → Central HINTS pattern / suspected PICA/AICA/basilar stroke
Peripheral vs Central Vertigo
Master Comparison Table
| Feature | Peripheral | Central |
|---|---|---|
| Onset | Sudden | Sudden or gradual |
| Vertigo severity | Severe spinning | Mild-moderate (may be imbalance only) |
| Duration | Seconds to days (self-limited) | Variable; may be persistent |
| Nystagmus direction | Unidirectional (fast phase away from lesion); horizontal-torsional | Direction-changing, vertical, or purely torsional |
| Fixation suppression | Yes (nystagmus decreases) | No (nystagmus persists or worsens) |
| Hearing loss | May be present (labyrinthitis, Meniere) | Usually absent (except AICA stroke) |
| Nausea/vomiting | Prominent | Variable, often less severe |
| Neurologic signs | Absent | Present (diplopia, dysarthria, ataxia, weakness) |
| Gait | Unsteady but able to walk | Severe ataxia; may be unable to sit unsupported |
| Head impulse test | Abnormal (catch-up saccade) | Normal (no catch-up saccade) |
| Skew deviation | Absent | Present |
Red Flags for Central Vertigo
- Vertical nystagmus (downbeat or upbeat)
- Direction-changing nystagmus (changes with gaze direction)
- No fixation suppression
- Skew deviation (vertical misalignment on alternate cover test)
- New neurologic signs: diplopia, dysarthria, dysphagia, limb ataxia, weakness, numbness
- Normal head impulse test in acute sustained vertigo
- Inability to walk (cerebellar stroke/hemorrhage)
💎 Board Pearl
- Peripheral vertigo = more symptomatic; central vertigo = more dangerous — classic board teaching point
- Vertical nystagmus is always central until proven otherwise
HINTS Exam (Head Impulse, Nystagmus, Test of Skew)
HINTS Components
| Component | Peripheral (Vestibular Neuritis) | Central (Stroke) |
|---|---|---|
| Head Impulse Test (HIT) | Abnormal — catch-up saccade (positive) | Normal — no catch-up saccade |
| Nystagmus | Unidirectional (fast phase away from lesion) | Direction-changing or vertical |
| Test of Skew | Negative (no skew deviation) | Positive (vertical eye misalignment) |
Key Facts
- Sensitivity for posterior fossa stroke: >98% — superior to initial MRI (DWI can miss 12–20% within first 48 h)
- Only valid in acute vestibular syndrome (acute sustained vertigo + nystagmus + nausea/gait instability)
- Any ONE central finding = central until proven otherwise
InFARCT Mnemonic — Central Pattern
INFARCT = Impulse Normal, Fast-phase Alternating, Refixation on Cover Test — all 7 letters map to the 3 central HINTS findings:
| Letters | Component | Central Finding |
|---|---|---|
| I-N | Impulse Normal | Head impulse test normal (no catch-up saccade) |
| F-A | Fast-phase Alternating | Direction-changing nystagmus on lateral gaze |
| R-C-T | Refixation on Cover Test | Skew deviation present (vertical eye misalignment) |
Peripheral pattern (opposite of INFARCT): abnormal HIT (catch-up saccade), unidirectional nystagmus that does not change with gaze, and no skew deviation.
Clinical Pearl
HINTS sensitivity is operator-dependent. The >98% sensitivity figure was validated in trained neuro-otologists and stroke neurologists. Emergency physician sensitivity is much lower; HINTS performed by non-experts has not reliably outperformed clinical gestalt. Train the technique before relying on it.
⚠ Warning
A normal head impulse test in a patient with acute vertigo means the VOR is intact — the brainstem is likely the problem, NOT the inner ear. Do NOT be reassured by a normal HIT.
💎 Board Pearl
- HINTS beats early MRI for posterior fossa stroke detection — a classic board question
- INFARCT = Impulse Normal, Fast-phase Alternating, Refixation on Cover Test — all 3 central findings in one acronym; peripheral is the mirror image (abnormal HIT, unidirectional nystagmus, no skew)
Benign Paroxysmal Positional Vertigo (BPPV)
Overview
- Most common cause of vertigo overall
- Pathophysiology: free-floating otoconia (calcium carbonate crystals) displaced from utricle into semicircular canal
- Posterior canal = 80–90% of cases; horizontal canal = 5–15%; anterior canal = rare
- Recurrence rate: ~15–20% per year
Dix-Hallpike Test (Posterior Canal)
| Feature | Peripheral (BPPV) | Central Mimic |
|---|---|---|
| Latency | 2–5 seconds | None (immediate onset) |
| Duration | <60 seconds (transient) | Persistent (>60 s) |
| Nystagmus type | Upbeating + torsional (toward affected ear) | Downbeating or pure vertical |
| Fatigability | Yes (diminishes with repetition) | No (does not fatigue) |
| Vertigo | Intense, brief | Variable |
Horizontal Canal BPPV
| Variant | Mechanism | Nystagmus on Supine Roll Test | Stronger Side |
|---|---|---|---|
| Geotropic | Canalithiasis (free debris) | Horizontal, toward ground (both sides) | Affected ear (more intense) |
| Apogeotropic | Cupulolithiasis (debris on cupula) | Horizontal, away from ground (both sides) | Unaffected ear (more intense) |
Treatment by Canal
| Canal | Diagnostic Test | Treatment Maneuver |
|---|---|---|
| Posterior | Dix-Hallpike | Epley (canalith repositioning) |
| Horizontal (geotropic) | Supine roll test | Lempert (BBQ roll / 360° roll) |
| Horizontal (apogeotropic) | Supine roll test | Gufoni maneuver or forced prolonged position |
| Anterior | Dix-Hallpike (downbeat nystagmus) | Yacovino (deep head-hanging) maneuver — primary treatment; does not require identification of affected side |
💎 Board Pearl
- Dix-Hallpike nystagmus with no latency or non-fatigable = think central lesion, NOT BPPV
- Posterior canal BPPV = upbeating + torsional; downbeating nystagmus on Dix-Hallpike suggests anterior canal or central pathology
- Meclizine does NOT treat BPPV — repositioning maneuvers are the treatment
Vestibular Neuritis & Labyrinthitis
Comparison
| Feature | Vestibular Neuritis | Labyrinthitis |
|---|---|---|
| Vertigo | Acute, severe, sustained (days) | Acute, severe, sustained (days) |
| Hearing loss | No | Yes (SNHL) |
| Tinnitus | No | Yes |
| Etiology | HSV-1 reactivation in vestibular ganglion (Scarpa’s) | Viral/bacterial infection of labyrinth |
| Anatomy | Vestibular nerve (superior division most common) | Vestibular nerve + cochlea |
| Head impulse test | Abnormal (catch-up saccade toward affected ear) | Abnormal |
| Nystagmus | Fast phase away from affected ear; suppressed by fixation | Same |
| Caloric testing | Reduced/absent on affected side | Reduced/absent on affected side |
Treatment
| Phase | Treatment | Duration |
|---|---|---|
| Acute (1–3 days) | Vestibular suppressants: meclizine, diazepam, promethazine | Limit to ≤3 days |
| Steroids | Methylprednisolone taper or prednisone (within 72 h) | Short course (1–3 weeks) |
| Rehabilitation | Vestibular rehabilitation therapy (VRT) — most important long-term treatment | Weeks to months |
⚠ Warning
Do NOT use vestibular suppressants (meclizine, benzodiazepines) beyond 3 days — they delay central compensation and prolong recovery. Early vestibular rehab is key.
💎 Board Pearl
- Vestibular neuritis = vertigo without hearing loss; labyrinthitis = vertigo with hearing loss
- Long-term vestibular suppressants impair compensation — classic board question on what NOT to do
- Superior vestibular nerve is most commonly affected (supplies superior + horizontal canals and utricle)
Vestibular Schwannoma (Acoustic Neuroma) & CPA Lesions
Classification — Peripheral, Not Central
- Vestibular schwannoma is a PERIPHERAL lesion — arises from Schwann cells of CN VIII (usually the superior vestibular division) within the internal auditory canal (IAC) or cerebellopontine angle (CPA)
- Most common CPA tumor (~80–90% of CPA masses)
- Can produce central signs only when large (>2.5–3 cm) via brainstem and cerebellar compression — does not change the underlying peripheral origin
Clinical Features
| Feature | Detail |
|---|---|
| Hearing loss | Progressive unilateral high-frequency SNHL (most common presenting symptom) |
| Tinnitus | Unilateral, often high-pitched |
| Imbalance | Chronic disequilibrium > acute vertigo (slow growth allows central compensation) |
| CN V involvement | Facial numbness, decreased corneal reflex (with larger tumors extending into CPA) |
| CN VII involvement | Late finding; facial weakness uncommon early despite proximity (myelin sheath relatively resistant) |
| Brainstem/cerebellar signs | Only with large tumors — ataxia, hydrocephalus, long-tract signs |
NF2-Related Schwannomatosis
- Bilateral vestibular schwannomas = pathognomonic for NF2
- Gene: NF2 on chromosome 22q12; encodes merlin (schwannomin) — tumor suppressor
- Updated nomenclature (2022): NF2-related schwannomatosis (replaces "neurofibromatosis type 2")
- Associated tumors: meningiomas, ependymomas, peripheral schwannomas; juvenile posterior subcapsular cataracts
- Presents earlier (teens/20s) with bilateral SNHL; any young patient with bilateral vestibular schwannomas needs NF2 genetic testing
Diagnosis & Management
- MRI with gadolinium (IAC protocol) — intracanalicular or CPA enhancing mass; "ice cream cone" appearance when extending from IAC into CPA
- Audiometry: asymmetric high-frequency SNHL; reduced word recognition out of proportion to pure-tone loss
- Management options: observation with serial MRI (small tumors), stereotactic radiosurgery (Gamma Knife), or microsurgical resection (translabyrinthine, retrosigmoid, middle fossa)
💎 Board Pearl
- Vestibular schwannoma is a peripheral CN VIII lesion — do not file it under central causes of vertigo
- Bilateral vestibular schwannomas = NF2 until proven otherwise (chromosome 22q12, merlin/schwannomin)
- Asymmetric SNHL with poor word recognition → get MRI with gadolinium of IACs to rule out schwannoma
Meniere Disease
Diagnostic Criteria
- Definite Meniere: ≥2 spontaneous vertigo episodes (20 min–12 h) + audiometrically documented low-to-mid frequency SNHL + fluctuating aural symptoms (hearing, tinnitus, fullness) in affected ear
- Pathophysiology: endolymphatic hydrops (distention of endolymphatic compartment)
Key Features
| Feature | Detail |
|---|---|
| Classic triad | Episodic vertigo + fluctuating low-frequency SNHL + tinnitus (± aural fullness) |
| Attack duration | 20 min to 12 hours (never seconds, never days) |
| Hearing loss pattern | Low-frequency SNHL initially → all frequencies with progression |
| Bilateral disease | 25–40% over time |
| Tumarkin crisis | Sudden drop attack without LOC (otolith-mediated) |
| Lermoyez variant | Hearing improves during vertigo attack (reverse Meniere) |
| MRI role | Exclude vestibular schwannoma (acoustic neuroma); endolymphatic hydrops visible on 3T delayed gadolinium |
Treatment Ladder
| Step | Intervention | Notes |
|---|---|---|
| 1 | Low-sodium diet (<2 g/day); diuretics (HCTZ/triamterene) may be offered for maintenance (AAO-HNS) | Reduces endolymph volume; lifestyle baseline |
| 2 | Betahistine may be offered for maintenance (AAO-HNS) | Used widely outside US; modest evidence |
| 3 | Intratympanic dexamethasone — clinicians may offer if active disease not responsive to noninvasive therapy (AAO-HNS) | Non-ablative; reduces vertigo frequency |
| 4 | Intratympanic gentamicin — clinicians should offer if active disease not responsive to nonablative therapy (AAO-HNS) | Ablative (vestibulotoxic); effective but risk of hearing loss |
| 5 | Surgery: endolymphatic sac decompression | Controversial efficacy |
| 6 | Labyrinthectomy / vestibular nerve section | Definitive; destroys residual vestibular function |
💎 Board Pearl
- Meniere duration = 20 min to 12 h; seconds = BPPV; days = vestibular neuritis — duration is the key differentiator
- Tumarkin crisis = sudden falls without LOC in Meniere — favorite board distractor from epileptic drop attacks
- Always get MRI with gadolinium to rule out vestibular schwannoma before diagnosing Meniere
Superior Canal Dehiscence Syndrome (SCDS)
Key Concepts
- Bony dehiscence over the superior (anterior) semicircular canal → creates a third mobile window (oval window, round window, + dehiscence)
- Sound/pressure energy diverted through dehiscence rather than through cochlea normally
Clinical Features
| Feature | Description |
|---|---|
| Tullio phenomenon | Vertigo/nystagmus triggered by loud sounds |
| Hennebert sign | Vertigo/nystagmus with tragal pressure or pneumatic otoscopy |
| Autophony | Hearing own voice, breathing, or heartbeat amplified |
| Conductive hyperacusis | Hearing internal body sounds (eye movements, footsteps) |
| Pulsatile tinnitus | From transmitted vascular pulsations |
| Apparent conductive hearing loss | Audiometry may show air-bone gap (bone conduction supranormal) — mimics otosclerosis |
Diagnosis
| Test | Finding |
|---|---|
| High-resolution CT temporal bone | Bony dehiscence over superior canal (coronal + Pöschl reformats) |
| cVEMP | Reduced threshold (≤65–70 dB nHL) + increased amplitude |
| oVEMP | Increased amplitude (most sensitive VEMP measure) |
| Audiometry | Low-frequency air-bone gap with supranormal bone conduction |
| ECoG | Elevated SP/AP ratio |
Treatment
- Conservative: avoidance of triggers, symptom management
- Surgical: canal plugging or resurfacing via middle fossa approach (definitive)
💎 Board Pearl
- Tullio phenomenon (sound-induced vertigo) + autophony = think SCDS until proven otherwise
- Air-bone gap on audiometry with normal tympanogram — do NOT confuse with otosclerosis; check VEMP and CT temporal bone
- SCDS = third mobile window; VEMPs show reduced threshold + increased amplitude (opposite of vestibular neuritis)
Vestibular Migraine
Diagnostic Criteria (International Classification)
- A. ≥5 episodes of vestibular symptoms (moderate/severe, 5 min–72 h)
- B. Current or previous history of migraine (with or without aura)
- C. ≥50% of vestibular episodes associated with ≥1 migraine feature: headache (migraine-type), photophobia, phonophobia, visual aura
- D. Not better accounted for by another diagnosis
Vestibular Migraine vs Meniere Disease
| Feature | Vestibular Migraine | Meniere Disease |
|---|---|---|
| Duration | 5 min to 72 h (variable) | 20 min to 12 h |
| Hearing loss | Usually absent | Low-frequency SNHL (fluctuating) |
| Migraine features | Present in ≥50% of episodes | May coexist but not required |
| Headache | Common (but NOT required) | Not typical |
| Aural fullness | Can occur (overlap) | Classic feature |
| Audiometry | Usually normal | Low-frequency SNHL |
| Caloric testing | Usually normal | Reduced unilateral response |
| Triggers | Migraine triggers (sleep, stress, diet) | Salt intake, stress |
Treatment
| Approach | Options |
|---|---|
| Acute | Triptans (if headache present), vestibular suppressants (short-term), anti-emetics |
| Prophylaxis | Same as migraine: topiramate, venlafaxine, propranolol, amitriptyline, nortriptyline |
| Non-pharmacologic | Lifestyle modification (sleep hygiene, trigger avoidance), vestibular rehabilitation |
Clinical Pearl
Vestibular migraine can present without headache in up to 30% of episodes. A history of migraine (even remote) plus episodic vestibular symptoms with photophobia or visual aura should raise suspicion.
💎 Board Pearl
- Most common cause of episodic vertigo in young adults (after BPPV) — frequently tested
- No headache required for diagnosis — only migraine history + migraine features during ≥50% of vestibular episodes
- Overlap with Meniere exists — if audiometry shows progressive SNHL, favor Meniere
Central Causes of Vertigo
Vascular Syndromes
| Syndrome | Artery | Key Features |
|---|---|---|
| AICA stroke | Anterior inferior cerebellar artery | Vertigo + hearing loss + facial weakness + cerebellar signs; AICA supplies labyrinth via internal auditory artery |
| PICA / Lateral medullary (Wallenberg) | Posterior inferior cerebellar artery / vertebral artery | Vertigo, nystagmus, Horner syndrome, dysphagia, hoarseness, ipsilateral facial numbness + contralateral body pain/temperature loss |
| Cerebellar hemorrhage/infarction | SCA, AICA, or PICA | Severe vertigo, inability to walk/sit, headache; may need emergent decompression (hydrocephalus, brainstem compression) |
| Basilar artery occlusion | Basilar artery | Vertigo, bilateral motor/sensory signs, decreased consciousness, locked-in syndrome |
Non-Vascular Central Causes
| Condition | Key Features | Nystagmus Pattern |
|---|---|---|
| Multiple sclerosis | Vertigo can be presenting symptom; INO common; brainstem/cerebellar plaques | Variable; INO = impaired adduction + contralateral abducting nystagmus |
| Episodic ataxia type 2 (EA-2) | CACNA1A mutation; episodic vertigo + ataxia lasting hours; responds to acetazolamide | Interictal downbeat nystagmus |
| Chiari I malformation | Tonsillar herniation >5 mm; headache + vertigo worse with Valsalva/cough | Downbeat nystagmus (especially on downgaze) |
| Cerebellar degeneration | Paraneoplastic (anti-Yo, anti-Hu), alcoholic, or hereditary | Gaze-evoked, downbeat, or positional |
Clinical Pearl
AICA stroke is the only central vertigo syndrome that commonly causes hearing loss (internal auditory artery supplies the labyrinth). This mimics peripheral vertigo and is a classic board trap.
💎 Board Pearl
- Downbeat nystagmus = Chiari malformation, EA-2, cerebellar degeneration — always think craniocervical junction
- CACNA1A = EA-2, FHM1, SCA6 — same gene, three phenotypes; EA-2 responds to acetazolamide
- Cerebellar hemorrhage with hydrocephalus = neurosurgical emergency — do not just place EVD (risk of upward herniation); needs suboccipital decompression
Vestibular Testing
Caloric Testing
| Stimulus | Fast Phase Direction | Mnemonic |
|---|---|---|
| Cold water (30°C) | Away from stimulated ear (contralateral) | COWS: Cold Opposite, Warm Same |
| Warm water (44°C) | Toward stimulated ear (ipsilateral) |
- Tests horizontal canal VOR (lateral semicircular canal → CN VIII → vestibular nuclei)
- Canal paresis: >25% reduced response on one side = unilateral vestibular hypofunction
- Absent bilateral calorics = bilateral vestibular loss (think ototoxicity, bilateral Meniere)
- In comatose patients: only slow phase remains (fast phase requires cortex) → cold water = eyes deviate toward stimulated ear
Vestibular Test Summary
| Test | What It Measures | Key Finding |
|---|---|---|
| Video HIT (vHIT) | Individual canal VOR (high-frequency) | Catch-up saccades (overt/covert) = peripheral deficit |
| Caloric testing | Horizontal canal VOR (low-frequency) | Canal paresis = unilateral loss; COWS for direction |
| Rotary chair | Bilateral VOR across frequencies | Gold standard for bilateral vestibular loss |
| cVEMP (cervical) | Saccule + inferior vestibular nerve | Absent = inferior nerve dysfunction; low threshold = SCDS |
| oVEMP (ocular) | Utricle + superior vestibular nerve | Absent = superior nerve dysfunction; increased amplitude = SCDS |
| ENG/VNG | Nystagmus recording, positional testing, calorics | Documents nystagmus patterns, positional vertigo |
| Audiometry | Hearing function (air + bone conduction) | Low-frequency SNHL (Meniere), high-frequency SNHL (schwannoma), air-bone gap (SCDS, otosclerosis) |
VEMP Quick Reference
| VEMP Type | Receptor | Nerve | Muscle Recorded | SCDS Finding |
|---|---|---|---|---|
| cVEMP | Saccule | Inferior vestibular nerve | SCM (ipsilateral) | ↓ Threshold, ↑ amplitude |
| oVEMP | Utricle | Superior vestibular nerve | Inferior oblique (contralateral) | ↑ Amplitude (most sensitive) |
💎 Board Pearl
- COWS (Cold Opposite, Warm Same) = fast-phase direction; in comatose patients only slow phase persists (eyes deviate toward cold)
- Rotary chair = gold standard for bilateral vestibular loss (bilateral gentamicin ototoxicity, bilateral Meniere)
- Audiometry is mandatory in all vertigo workups — differentiates BPPV (normal), Meniere (low-freq SNHL), schwannoma (high-freq SNHL), and SCDS (air-bone gap)
Persistent Postural-Perceptual Dizziness (PPPD)
Overview
- Chronic functional vestibular disorder defined by the Bárány Society (2017)
- Replaces older terms: phobic postural vertigo, chronic subjective dizziness, space-motion discomfort, visual vertigo
- Often triggered by an acute vestibular event (vestibular neuritis, BPPV, vestibular migraine, panic attack, mTBI) that resolves but leaves persistent symptoms
Diagnostic Criteria (Bárány 2017)
- A. Dizziness, unsteadiness, or non-spinning vertigo on most days for ≥3 months
- B. Persistent symptoms occur without specific provocation but are exacerbated by:
- Upright posture (standing, walking)
- Active or passive motion (self or environment)
- Exposure to complex visual stimuli (busy patterns, scrolling screens, crowds, grocery aisles)
- C. Precipitated by an event that caused acute vertigo, unsteadiness, or balance problems
- D. Symptoms cause significant distress or functional impairment
- E. Not better explained by another disease
Treatment
| Modality | Detail |
|---|---|
| SSRIs / SNRIs | First-line pharmacotherapy; sertraline, escitalopram, venlafaxine; start low, titrate slowly |
| Vestibular rehabilitation | Habituation-based; gradual exposure to provocative visual/motion stimuli |
| Cognitive behavioral therapy (CBT) | Targets anxiety, avoidance behaviors, and catastrophizing |
💎 Board Pearl
- PPPD = chronic dizziness ≥3 months worsened by upright posture, motion, and complex visual environments — classic post-acute vestibular event
- Triad of treatment: SSRI/SNRI + vestibular rehab + CBT
Perilymph Fistula
Pathophysiology
- Abnormal communication between perilymph-filled inner ear and middle ear (typically via oval or round window)
- Triggers: barotrauma (flying, diving), Valsalva, heavy lifting, head trauma, stapes surgery, chronic otitis
Clinical Features
| Feature | Detail |
|---|---|
| Episodic vertigo | Triggered by pressure changes (Valsalva, sneezing, straining, altitude change) |
| Hearing loss | Fluctuating or progressive SNHL, often unilateral |
| Tinnitus / aural fullness | Frequently present |
| Pressure-induced symptoms | Vertigo or nystagmus with pneumatic otoscopy or tragal pressure |
| Hennebert sign | Vertigo/nystagmus with external auditory canal pressure (also seen in SCDS — same sign, different mechanism) |
Diagnosis & Treatment
- Largely clinical diagnosis; high-resolution CT may show pneumolabyrinth or fluid in middle ear
- Initial management: bed rest, head elevation, avoid Valsalva for 1–2 weeks
- Surgical repair (middle ear exploration with patching of oval/round window) if symptoms persist or hearing deteriorates
💎 Board Pearl
- Suspect perilymph fistula with episodic vertigo + hearing loss after barotrauma, Valsalva, or heavy lifting
- Positive Hennebert sign (pressure-induced vertigo) overlaps with SCDS — CT temporal bone helps distinguish
Orthostatic Dizziness (Differential from Vertigo)
Key Concepts
- Lightheadedness or presyncope on standing — NOT true spinning vertigo
- Caused by transient cerebral hypoperfusion, not vestibular dysfunction
- Two main mechanisms: orthostatic hypotension (OH) and postural tachycardia syndrome (POTS)
Comparison
| Feature | Orthostatic Hypotension | POTS |
|---|---|---|
| BP change on standing | ≥20 mmHg systolic or ≥10 mmHg diastolic drop within 3 min | No significant drop (<20/10) |
| HR change on standing | Variable (blunted in neurogenic OH) | ≥30 bpm increase (≥40 bpm in adolescents) within 10 min |
| Demographics | Older adults; autonomic failure, diabetes, Parkinson, medications | Young women (15–50); often post-viral |
| Symptoms | Lightheadedness, syncope, fatigue | Palpitations, lightheadedness, tremor, brain fog, exercise intolerance |
Workup & Differentiation from Vertigo
- Orthostatic vitals (supine, 1 min, 3 min standing) — first-line bedside test
- Tilt-table testing if orthostatic vitals are equivocal or to distinguish POTS, neurally mediated syncope, and delayed OH
- Absence of nystagmus, normal HINTS, and reproduction of symptoms only on standing point away from a vestibular cause
💎 Board Pearl
- "Dizziness on standing" without spinning = orthostatic, not vestibular — check orthostatic vitals before chasing BPPV
- HR ↑ ≥30 bpm without BP drop = POTS; BP drop ≥20/10 within 3 min = orthostatic hypotension
- Tilt-table is the definitive test when bedside orthostatics are non-diagnostic
References
- Kattah JC, Talkad AV, Wang DZ, et al. HINTS to diagnose stroke in the acute vestibular syndrome: three-step bedside oculomotor examination more sensitive than early MRI diffusion-weighted imaging. Stroke. 2009;40(11):3504-3510.
- Bhattacharyya N, Gubbels SP, Schwartz SR, et al. Clinical practice guideline: benign paroxysmal positional vertigo (update). Otolaryngol Head Neck Surg. 2017;156(3_suppl):S1-S47.
- Lempert T, Olesen J, Furman J, et al. Vestibular migraine: diagnostic criteria. J Vestib Res. 2012;22(4):167-172.
- Lopez-Escamez JA, Carey J, Chung WH, et al. Diagnostic criteria for Meniere disease. J Vestib Res. 2015;25(1):1-7.
- Minor LB. Superior canal dehiscence syndrome. Am J Otol. 2000;21(1):9-19.
- Strupp M, Mandalà M, López-Escámez JA. Peripheral vestibular disorders: an update. Curr Opin Neurol. 2019;32(1):165-173.
- Bisdorff A, Von Brevern M, Lempert T, Newman-Toker DE. Classification of vestibular symptoms. J Vestib Res. 2009;19(1-2):1-13.
- Staab JP, Eckhardt-Henn A, Horii A, et al. Diagnostic criteria for persistent postural-perceptual dizziness (PPPD): consensus document of the Committee for the Classification of Vestibular Disorders of the Bárány Society. J Vestib Res. 2017;27(4):191-208.
- Plotkin SR, Messiaen L, Legius E, et al. Updated diagnostic criteria and nomenclature for neurofibromatosis type 2 and schwannomatosis: an international consensus recommendation. Genet Med. 2022;24(9):1967-1977.
- Yacovino DA, Hain TC, Gualtieri F. New therapeutic maneuver for anterior canal benign paroxysmal positional vertigo. J Neurol. 2009;256(11):1851-1855.
- Freeman R, Wieling W, Axelrod FB, et al. Consensus statement on the definition of orthostatic hypotension, neurally mediated syncope and the postural tachycardia syndrome. Clin Auton Res. 2011;21(2):69-72.
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