Vestibular Neuritis

Intro & Causes - Dizzying Debut

• Definition: An acute peripheral vestibulopathy causing sudden, severe vertigo, often lasting days. It's an inflammation of the vestibular nerve.
• Affected Nerve: Vestibular nerve (a branch of CN VIII).
  • The superior division is more frequently affected. 📌 Superior division Suffers more.
• Presumed Etiology:
  • Viral infection is the most common theory.
  • Reactivation of Herpes Simplex Virus type 1 (HSV-1) is strongly implicated.
  • Can be post-viral inflammation.

⭐ The superior division of the vestibular nerve is more commonly affected than the inferior division.

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Clinical Picture - The World Spins

• Sudden, Severe Vertigo: Intense, debilitating spinning sensation.
• Associated: Significant nausea, vomiting; postural instability, gait ataxia.
• Duration: Several days to a few weeks.
• Key Differentiating Negatives:
  • NO Auditory Symptoms: Hearing preserved (no hearing loss/tinnitus). Distinguishes from labyrinthitis.
  • NO Neurological Deficits: (e.g., diplopia, dysarthria, weakness). Rules out stroke.
• Nystagmus Characteristics:
  • Spontaneous, unidirectional (horizontal/horizontal-torsional).
  • Fast phase beats away from affected ear.
  • Alexander's Law: Intensity ↑ with gaze towards fast phase. (📌 "Fast beat gaze, nystagmus stays!").
  • Suppressed by visual fixation.

⭐ Vestibular neuritis characteristically spares auditory function, a key clinical point differentiating it from labyrinthitis.

Diagnosis - Pinpointing the Problem

• Primarily clinical diagnosis.
• Bedside tests:
  • Head Impulse Test (HIT): Positive (corrective saccade towards affected side).
  • HINTS exam (Head Impulse, Nystagmus, Test of Skew) to differentiate stroke:
    • For VN: Positive HIT, Unidirectional Nystagmus, No Skew Deviation.
    • 📌 INFARCT (stroke): Impulse Normal, Fast-phase Alternating Nystagmus, Refixation on Cover Test (Skew present).

• Investigations:
  • Audiometry: Normal.
  • Caloric testing: Unilateral canal paresis (affected side).
  • MRI: If central pathology suspected or atypical features (e.g., HINTS suggestive of stroke).

⭐ A positive Head Impulse Test (HIT) is highly suggestive of a peripheral vestibular lesion like vestibular neuritis.

Management & Prognosis - Setting Things Straight

• Acute Phase (start within 72h of onset):
  • Corticosteroids: e.g., Prednisolone 1mg/kg/day (max 60mg), tapered over 10-14 days.
  • Symptomatic relief: Vestibular suppressants (e.g., Meclizine, Diazepam) short-term only, ≤3 days; Antiemetics (e.g., Ondansetron).
• Rehabilitation:
  • Vestibular Rehabilitation Therapy (VRT) is crucial for promoting central compensation.
  • Encourage early mobilization.
• Prognosis:
  • Generally good; most patients recover function within weeks to months.
  • Potential for residual dizziness, developing BPPV, or Persistent Postural-Perceptual Dizziness (PPPD).

⭐ Early initiation of corticosteroids (within 72 hours of symptom onset) can improve outcomes in vestibular neuritis.

High‑Yield Points - ⚡ Biggest Takeaways

• Viral/post-viral inflammation of the vestibular nerve (CN VIII), often superior part.
• Presents with acute, severe, spontaneous vertigo, nausea, vomiting, lasting days to weeks.
• Crucially, no auditory or neurological symptoms are present.
• Unidirectional, horizontal nystagmus (beats away from lesion), suppressed by visual fixation.
• Positive Head Impulse Test (HIT) towards affected side is key.
• Caloric testing confirms unilateral vestibular weakness (canal paresis).
• Management: Short-term vestibular suppressants (e.g., antihistamines, benzodiazepines), then vestibular rehabilitation.