28.3 Acute Dizziness, Benign Paroxysmal Positional Vertigo & Vestibular Neuritis

The Modern Approach to Acute Dizziness: The TiTrATE Framework

For decades, medical education taught clinicians to categorize dizziness by asking patients, 'What do you mean by dizzy?' and sorting responses into four distinct subjective silos: vertigo (spinning), presyncope (near-fainting), disequilibrium (imbalance), and lightheadedness (giddiness). Landmark clinical trials by Newman-Toker and colleagues demonstrated that this classical approach is fundamentally flawed, highly inaccurate, and clinically dangerous:

• Over 50% of patients change their primary descriptive category when questioned multiple times within the same emergency encounter;
• Patients frequently use 'spinning' to describe vasovagal presyncope, and 'lightheaded' to describe acute cerebellar stroke;
• Reliance on subjective descriptions fails to distinguish benign peripheral vestibular conditions from fatal posterior circulation strokes.

The TiTrATE Diagnostic Paradigm

The modern, validated evidence-based approach is TiTrATE: categorizing dizziness by Timing, Triggers, And Targeted Examination:

                          THE TiTrATE METHODOLOGY

     1. TIMING                        2. TRIGGERS
  ┌─────────────────────────────┐  ┌─────────────────────────────┐
  │ • Episodic (Seconds/Minutes)│  │ • Triggered (Positional/    │
  │ • Episodic (Hours)          │  │   Orthostatic change)       │
  │ • Continuous (Days/Weeks)   │  │ • Spontaneous (No trigger)  │
  └──────────────┬──────────────┘  └──────────────┬──────────────┘
                 │                                │
                 └────────────────┬───────────────┘
                                  ▼
                    3. TARGETED EXAMINATION
  ┌───────────────────────────────────────────────────────────────┐
  │ • Positional Testing (Dix-Hallpike Maneuver)                  │
  │ • Oculomotor / Vestibulo-Ocular Reflex (HINTS Examination)    │
  │ • Orthostatic Vital Signs & Cerebellar Motor Examination     │
  └───────────────────────────────────────────────────────────────┘

The Three Core Clinical Syndromes

Applying TiTrATE categorizes virtually every patient presenting with acute dizziness into one of three defined syndromes:

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The HINTS Examination: Differentiating Stroke from Vestibular Neuritis

Acute Vestibular Syndrome (AVS) represents an emergency diagnostic dilemma: distinguishing benign viral vestibular neuritis from a potentially fatal posterior circulation ischemic stroke (infarction of the cerebellum or brainstem, typically in the posterior inferior cerebellar artery [PICA] or anterior inferior cerebellar artery [AICA] territories).

The MRI Limitation vs. Bedside HINTS Accuracy

• Diffusion-Weighted Brain MRI (DWI-MRI) has an alarming false-negative rate of 12% to 20% in the first 24 to 48 hours for small posterior fossa ischemic strokes. A normal emergency brain MRI performed within 24 hours of onset does NOT rule out a stroke!
• The landmark HINTS to Diagnose Stroke in the Acute Vestibular Syndrome study (Kattah et al., Stroke 2009) demonstrated that a structured 3-component bedside oculomotor examination—the HINTS Exam (Head Impulse, Nystagmus, Test of Skew)—exhibits sensitivity of 100% and specificity of 96% for detecting stroke in acute AVS, outperforming early DWI-MRI!

CRITICAL CLINICAL PREREQUISITE: The HINTS examination is validated and clinically interpretable ONLY in patients with Continuous Vestibular Syndrome who have active, ongoing vertigo and observable spontaneous nystagmus. Performing HINTS on a patient with brief episodic dizziness (e.g., BPPV) or on a patient without nystagmus produces completely meaningless and dangerous results.

                      THE THREE COMPONENTS OF HINTS

  1. HEAD IMPULSE TEST (HIT)       2. NYSTAGMUS EVALUATION         3. TEST OF SKEW
  ──────────────────────────       ───────────────────────         ───────────────
  Checks Vestibulo-Ocular          Assesses Spontaneous &          Assesses Graviceptive
  Reflex (VOR) Integrity           Direction-Changing Gaze         Vertical Alignment

  • ABNORMAL HIT (Catch-up         • UNIDIRECTIONAL (Beats one     • NO SKEW (Eyes remain
    saccade back to nose):           direction only; horizontal-     conjugate upon alternate
    PERIPHERAL (Neuritis)            torsional; fixed fast phase):   covering): PERIPHERAL
                                     PERIPHERAL (Neuritis)
  • NORMAL HIT (Gaze remains                                       • SKEW DEVIATION (Vertical
    smoothly fixed on nose):       • DIRECTION-CHANGING (Beats       refixation saccade up
    CENTRAL (Stroke!)                right on right gaze, left on    or down upon cover): 
                                     left gaze; or pure vertical):   CENTRAL (Stroke!)
                                     CENTRAL (Stroke!)

Detailed Mechanics & Interpretation of HINTS Components

1. Head Impulse Test (HIT) of the Vestibulo-Ocular Reflex (VOR)

• Technique: The examiner sits directly facing the patient, asking the patient to maintain continuous visual fixation on the examiner's nose. The examiner holds the patient's head firmly and delivers a rapid, unpredictable, small-amplitude (10° to 20°), high-acceleration horizontal head rotation to one side.
• Peripheral Vestibular Lesion (Vestibular Neuritis):
  • The unilateral peripheral vestibular end-organ or nerve is damaged; the VOR cannot drive compensatory eye movement.
  • When the head is rapidly turned toward the affected side, the patient's eyes move with the head (drifting away from the examiner's nose).
  • The patient must then make a noticeable corrective catch-up saccade back to the examiner's nose.
  • Exam Pearl: An ABNORMAL Head Impulse Test (presence of a catch-up saccade) indicates a PERIPHERAL vestibular nerve lesion.
• Central Lesion (Posterior Circulation Ischemic Stroke):
  • In isolated cerebellar strokes, the brainstem vestibulo-ocular reflex arc (vestibular nerve, vestibular nuclei, CN III/VI pathways) remains structurally intact.
  • The eyes remain locked smoothly on the examiner's nose throughout the head thrust without any catch-up saccade.
  • Exam Pearl: A NORMAL Head Impulse Test in a patient with acute continuous spinning vertigo indicates a CENTRAL STROKE!

2. Nystagmus Assessment (Spontaneous & Eccentric Gaze)

• Peripheral Nystagmus (Vestibular Neuritis):
  • Unidirectional: The fast phase beats in ONE single direction regardless of which direction the patient looks (beats away from the hypofunctioning lesion ear; fast phase toward the healthy, hyperactive contralateral ear).
  • Horizontal-torsional: Predominantly horizontal with a small torsional component; never pure vertical or pure torsional.
  • Alexander's Law: The nystagmus intensifies in amplitude and frequency when the patient looks in the direction of the fast phase.
  • Suppression with Visual Fixation: Nystagmus diminishes or disappears when the patient fixates on a visual target, and intensifies when fixation is removed (e.g., behind Frenzel lenses or during penlight examination).
• Central Nystagmus (Posterior Fossa Stroke):
  • Direction-Changing Nystagmus: The fast phase changes direction based on gaze: beats to the right on rightward gaze, and beats to the left on leftward gaze (bidirectional gaze-evoked nystagmus).
  • Pure Vertical or Pure Torsional Nystagmus: Downbeat nystagmus (strongly indicates craniocervical junction or cerebellar vermis lesion) or upbeat nystagmus (pontomedullary junction).
  • Failure to Suppress: Does not suppress with visual fixation.

3. Test of Skew (Alternate Cover Test)

• Technique: The patient fixates straight ahead on the examiner's nose. The examiner alternately covers one eye and then the other in rapid succession, observing the newly uncovered eye for corrective vertical movement.
• Peripheral Lesion: The eyes remain conjugate in the horizontal plane; no vertical shift occurs.
• Central Lesion (Skew Deviation):
  • Disruption of graviceptive pathways traversing the brainstem produces vertical ocular misalignment.
  • When the cover is shifted, the uncovered eye makes an immediate, visible vertical corrective saccadic refixation (one eye shifts downward to acquire the target, the other eye shifts upward).
  • Indicates a central brainstem or cerebellar lesion.

The INFARCT Central Stroke Rule

To synthesize the HINTS examination, remember the mnemonic INFARCT:

• Impulse Normal;
• Fast-phase Alternating (direction-changing);
• Refixation on Cover Test (skew deviation).
• The Rule: If ANY SINGLE ONE of these three signs is central (Normal Head Impulse, Direction-Changing Nystagmus, OR Skew Deviation), the patient has a CENTRAL POSTERIOR CIRCULATION STROKE until proven otherwise! STAT emergency stroke activation, neurology consultation, and comprehensive neuroimaging are mandatory.

Additional Central Red Flags in Acute Vestibular Syndrome

• Truncal Ataxia / Postural Instability Severity:
  • Grade 1 (Mild): Unsteady but walks unassisted (typical of peripheral neuritis);
  • Grade 2 (Moderate): Can sit unassisted, but requires support to walk;
  • Grade 3 (Severe): Unable to sit upright in bed without support, falling immediately like a lead weight (pathognomonic for cerebellar stroke);
• New Focal Neurological Signs: Dysarthria, dysphagia, facial numbness, limb dysmetria (finger-to-nose or heel-to-shin ataxia), or Horner syndrome (ptosis, miosis, anhidrosis in Wallenberg lateral medullary syndrome);
• New Severe Occipital Headache or Posterior Neck Pain: Suggests vertebral artery dissection.

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Benign Paroxysmal Positional Vertigo (BPPV)

Benign Paroxysmal Positional Vertigo (BPPV) is the single most common cause of peripheral vertigo in clinical practice, with a lifetime prevalence of 2.4%. It exhibits a female-to-male ratio of 2:1 and peaks in adults aged 50 to 70 years.

Pathophysiology: Canalithiasis vs. Cupulolithiasis

• Canalithiasis (>90% of cases): Calcium carbonate otoconia (otolith crystals) spontaneously detach from the macula of the utricle—due to degenerative aging, minor head trauma, or antecedent vestibular neuritis—and migrate into the semicircular canals.
• The posterior semicircular canal is involved in 85% to 90% of cases, owing to its gravity-dependent, lowest anatomical position in the inner ear. (The horizontal/lateral canal is involved in 5% to 10%; the anterior/superior canal in <2%).
• When the patient shifts the head relative to gravity, the free-floating, heavy otoconia debris moves within the canal like a piston, generating abnormal hydrodynamic endolymph flow that deflects the gelatinous cupula, sending false high-frequency acceleration signals to the brain.
• Cupulolithiasis (<5-10%): Otoconia adhere directly to the cupula itself, causing immediate, non-fatiguing positional vertigo.

Clinical Hallmarks

• Brief, violent episodes of spinning vertigo lasting strictly less than 60 seconds (typically 15 to 30 seconds);
• Triggered exclusively by changes in head position relative to gravity: rolling over in bed (the 'pillow turn'), tilting the head backward to look upward ('top-shelf vertigo'), or bending forward to tie shoes;
• Patients are completely free of spinning vertigo when keeping the head stationary, though a vague, non-specific background sense of floating or imbalance may linger between spells;
• Absence of cochlear symptoms (no hearing loss, no tinnitus) and absence of focal neurological deficits.

The Diagnostic Gold Standard: Dix-Hallpike Maneuver

                    DIX-HALLPIKE MANEUVER PROTOCOL

  1. Patient Seated Upright on Table
     Turn head 45° toward the side being tested (e.g., right).
                           │
                           ▼
  2. Rapidly Lower Patient Supine
     Maintain 45° head turn; extend neck 20° over the table edge.
     Eyes remain wide open, fixated on examiner's forehead.
                           │
                           ▼
  3. Observe Eyes for 30 to 60 Seconds
     Classic Positive Posterior Canal BPPV Response:
     • Latency: 2 to 20 second delay before vertigo/nystagmus starts
     • Torsional Upbeating Nystagmus: Top pole of eye beats TOWARD the
       lower affected ear, combined with vertical UPWARD beating
     • Transient Duration: Resolves in <60 seconds (crescendo-decrescendo)
     • Fatigability: Nystagmus diminishes with repeated maneuvers
     • Reversal: Upright return provokes transient reverse nystagmus

• If Dix-Hallpike testing produces pure horizontal nystagmus, the Supine Roll Test (Pagnini-McClure Test) is performed to evaluate for lateral (horizontal) semicircular canal BPPV.

Definitive Treatment: The Epley Maneuver (Canalith Repositioning)

• The Epley maneuver uses sequential 90-degree head rotations to guide free-floating otoconia debris from the posterior semicircular canal, around the common crus, and back into the utricular vestibule, where the debris is safely resorbed by dark cells within days to weeks:
  • Step 1: Perform Dix-Hallpike maneuver on the affected side (head turned 45°, extended 20°); hold position for 30 to 60 seconds (until nystagmus and vertigo subside);
  • Step 2: Slowly rotate the head 90° toward the unaffected side (head now 45° toward opposite side, neck still extended); hold for 30 to 60 seconds;
  • Step 3: Have the patient roll onto the shoulder of the unaffected side while turning the head another 90° in the same direction (patient's face is now angled 45° downward toward the floor); hold for 30 to 60 seconds;
  • Step 4: While maintaining head-turned position, assist the patient into an upright seated position on the side of the table with chin tucked slightly forward.
• Efficacy: Achieves >85% to 90% resolution of vertigo and nystagmus after just 1 or 2 treatment cycles!
• Why Vestibular Suppressants (Meclizine) are Contraindicated in BPPV:
  • The AAO-HNS and American Academy of Neurology guidelines explicitly state that vestibular suppressant medications (meclizine, dimenhydrinate, benzodiazepines) are NOT recommended for BPPV;
  • BPPV is a mechanical hydrodynamic disorder; medications do not reposition otoconia;
  • Antihistamines and benzodiazepines cause significant sedation, impair cognitive performance, increase fall risk in elderly patients, and blunts central adaptation.

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Vestibular Neuritis and Labyrinthitis: Acute Stabilization & Compensation

Vestibular neuritis is an acute, self-limiting inflammatory disorder of the vestibular division of cranial nerve VIII, representing the second leading cause of peripheral vertigo (after BPPV).

Vestibular Neuritis vs. Labyrinthitis

• Vestibular Neuritis: Inflammation is confined strictly to the superior division of the vestibular nerve. Manifests as sudden, severe, continuous spinning vertigo, nausea, vomiting, and gait ataxia. Cochlear function and hearing are ENTIRELY PRESERVED.
• Labyrinthitis: Inflammation involves both the vestibular and cochlear branches of CN VIII or the membranous labyrinth itself. Manifests as identical continuous vertigo, nausea, and vomiting PLUS acute unilateral sensorineural hearing loss, roaring tinnitus, and aural fullness.

               PERIPHERAL AVS: NEURITIS vs. LABYRINTHITIS

  CLINICAL FEATURE       VESTIBULAR NEURITIS           LABYRINTHITIS
  ───────────────────────────────────────────────────────────────────
  Pathology              Vestibular nerve alone        Vestibular AND Cochlear
  Vertigo Duration       Continuous (days)             Continuous (days)
  Hearing Status         100% PRESERVED & NORMAL       UNILATERAL SENSORINEURAL LOSS
  Tinnitus               Absent                        Present (roaring/ringing)
  HINTS Exam Pattern     Peripheral (Abnormal HIT,     Peripheral (Abnormal HIT,
                         Unidirectional Nystagmus)     Unidirectional Nystagmus)
  Treatment              Short-term suppressants,      Short-term suppressants,
                         Oral steroids, Early VRT      High-dose steroids, Urgent ENT

Medical Management: The 48-to-72-Hour Rule

1. Symptom Suppression (Acute Phase Only):
   • In the first 24 to 48 hours, patients experience profound nausea, emesis, and incapacitating vertigo.
   • Appropriate agents: Antihistamines (Meclizine 25 mg PO TID, Dimenhydrinate 50 mg), antiemetics (Ondansetron 4-8 mg IV/PO, Promethazine), or low-dose benzodiazepines (Diazepam 2-5 mg PO/IV).
   • THE CRITICAL CLINICAL MANDATE: Vestibular suppressants must be STRICTLY DISCONTINUED AFTER 48 TO 72 HOURS!
   • Mechanism of Harm: The brain achieves clinical recovery from vestibular injury through central neuroplastic vestibular compensation (the cerebellum and vestibular nuclei actively recalibrate by comparing sensory asymmetry between the healthy and damaged sides). Vestibular suppressants sedate the central vestibular nuclei, blocking this recalibration. Prolonged use transforms an acute self-limiting condition into chronic persistent postural-perceptual dizziness (PPPD), prolonged ataxia, and permanent unsteadiness.
2. Systemic Corticosteroids:
   • Oral methylprednisolone or prednisone (Prednisone 60-80 mg daily for 7 days followed by a 5-day taper) initiated within 3 days of symptom onset significantly accelerates peripheral vestibular recovery and reduces long-term caloric hypofunction.
3. Early Vestibular Rehabilitation Therapy (VRT):
   • Specialized physical therapy employing vestibulo-ocular reflex (VOR) gaze stabilization exercises (fixating on a target while rotating the head horizontally and vertically, 'VOR x 1' and 'VOR x 2' exercises), habituation drills, and balance-gait retraining.
   • VRT should be initiated as soon as acute severe emesis abates (typically day 3 to 5), directly stimulating central neuroplastic compensation.