What are the diagnostic criteria and steps for diagnosing vestibular neuritis?

Diagnosing Vestibular Neuritis

Vestibular neuritis is diagnosed clinically based on acute vestibular syndrome (sustained vertigo lasting ≥24 hours) with spontaneous peripheral vestibular nystagmus, unilateral vestibulo-ocular reflex (VOR) deficit on testing, and critically—the absence of any central neurological, audiological, or otological symptoms or signs 1.

Core Diagnostic Criteria

The Bárány Society established definitive diagnostic criteria that require ALL of the following 1:

A. Clinical Presentation

• Acute or subacute onset of sustained spinning or non-spinning vertigo of moderate to severe intensity
• Duration ≥24 hours (if <24 hours but >3 hours, classify as "Acute Unilateral Vestibulopathy in Evolution")
• Associated nausea/vomiting, gait instability, and head-motion intolerance 2

B. Nystagmus Characteristics

• Spontaneous peripheral vestibular nystagmus that is:
  • Direction-fixed (beats in one direction)
  • Generally horizontal-torsional trajectory
  • Enhanced by removal of visual fixation (use Frenzel goggles or video-oculography)
  • Fast phase beats away from the affected side 1

C. Vestibular Function Testing

• Unambiguous evidence of reduced VOR function on the side opposite to the fast phase of nystagmus
• This is confirmed by:
  • Video head impulse test (vHIT): Reduced VOR gain in affected semicircular canals with corrective saccades 3
  • Caloric testing: Canal paresis on affected side 4
  • VEMPs to differentiate superior vs. inferior nerve involvement 5, 3:
    • Superior vestibular neuritis: Abnormal oVEMP, preserved cVEMP
    • Inferior vestibular neuritis: Reduced/absent cVEMP, preserved oVEMP

D. Critical Exclusions (Must Rule Out)

• No acute central neurological symptoms: No diplopia, dysarthria, dysphagia, focal weakness, or sensory deficits 1
• No acute audiological symptoms: No hearing loss or tinnitus (these suggest labyrinthitis instead) 2
• No central vestibular signs on examination:
  • No pronounced skew deviation
  • No gaze-evoked nystagmus
  • No direction-changing nystagmus 1

Algorithmic Approach to Diagnosis

Step 1: Establish Acute Vestibular Syndrome

Confirm the patient has continuous vertigo with nausea/vomiting, gait instability, and nystagmus lasting >24 hours 2.

Step 2: Perform Bedside Examination

• Check for spontaneous nystagmus with and without visual fixation
• Perform HINTS examination (Head Impulse, Nystagmus, Test of Skew) if trained—this distinguishes peripheral from central causes with high accuracy 2
• Assess for any focal neurological deficits (cranial nerves, motor, sensory, cerebellar signs)
• Perform Dix-Hallpike testing to exclude BPPV 2

Step 3: Vestibular Function Testing

• vHIT: Demonstrates reduced VOR gain and corrective saccades in affected canals 3
• Caloric testing: Shows canal paresis (>25% asymmetry typically diagnostic) 4
• VEMPs: Identifies which division of vestibular nerve is affected 5, 3

Step 4: Imaging Decision

Imaging is NOT routinely indicated for isolated acute vestibular syndrome with normal neurological examination and peripheral HINTS findings 2. The detection rate of central pathology in this population is <1% 2.

MRI head and internal auditory canals WITH and WITHOUT IV contrast is indicated when 2:

• Any focal neurological signs are present
• HINTS examination suggests central pathology
• Atypical features (direction-changing nystagmus, severe skew deviation)
• Recurrent episodes
• Associated hearing loss (suggests different diagnosis)

Common Pitfalls to Avoid

Pitfall #1: Ordering unnecessary imaging In patients with isolated acute vestibular syndrome and normal neurological examination, CT has essentially no diagnostic yield (<1%) and MRI yield remains very low (4%) 2. The diagnosis is clinical.

Pitfall #2: Missing central causes While vestibular neuritis is peripheral, approximately 25% of acute vestibular syndrome cases are due to posterior circulation stroke 2. The key differentiator is the presence of ANY central neurological signs or symptoms—these mandate immediate MRI with DWI sequences 2.

Pitfall #3: Confusing with labyrinthitis Vestibular neuritis has no hearing loss or tinnitus. If audiological symptoms are present, the diagnosis is labyrinthitis, not vestibular neuritis 1.

Pitfall #4: Inadequate examination of nystagmus The nystagmus must be enhanced by removal of visual fixation—examining without Frenzel goggles or video-oculography may miss subtle cases 1.

Diagnostic Categories

The Bárány Society classification allows for diagnostic certainty 1:

• "Acute Unilateral Vestibulopathy": Meets all criteria above
• "Probable Acute Unilateral Vestibulopathy": Identical except VOR deficit not clearly documented
• "Acute Unilateral Vestibulopathy in Evolution": Symptoms >3 hours but <24 hours when examined
• "History of Acute Unilateral Vestibulopathy": For patients examined after acute phase with documented unilateral VOR deficit and appropriate history

Special Considerations

Inferior vestibular neuritis is frequently misdiagnosed because caloric responses remain normal (caloric testing only assesses lateral canal/superior nerve) 5. Diagnosis requires:

• Reduced posterior canal gain on vHIT
• Absent cVEMP
• Normal caloric responses
• Preserved oVEMP 5

Bilateral sequential vestibular neuritis is exceptionally rare but can occur with 2-5 year intervals between episodes 6. The second attack typically presents with milder symptoms due to central compensation 6.