Vestibular Neuritis

Definition & Etiopathogenesis - Dizzying Dilemma

• Definition: Acute, severe, prolonged vertigo from unilateral vestibular hypofunction. Crucially, no auditory or neurological symptoms.
• Etiology:
  • Predominantly viral (Herpes Simplex Virus type 1 (HSV-1) reactivation in vestibular ganglion is a leading theory).
  • Post-viral inflammation.
  • Less common: Ischemic (e.g., anterior vestibular artery).
• Pathogenesis: Inflammation of vestibular nerve (CN VIII), often selectively affecting the superior division.

  ⭐ Vestibular neuritis is distinguished from labyrinthitis by the absence of hearing loss or tinnitus.

Clinical Presentation - The World Spins

• Sudden, severe, persistent vertigo (rotational); lasts days to weeks.
• Associated with:
  • Intense nausea & vomiting.
  • Imbalance & gait ataxia (veers towards affected side).
• Symptoms worsen with head movements.
• Crucial negatives:
  • NO hearing loss.
  • NO tinnitus.
  • NO focal neurological signs.
• Nystagmus: Spontaneous, unidirectional (horizontal/horizontal-torsional); suppressed by visual fixation. Follows Alexander's Law.
• Positive Head Impulse Test (HIT) towards affected side.
• Often preceded by viral illness (URI) in ~50% cases.

⭐ Absence of auditory symptoms (hearing loss, tinnitus) is key to differentiate vestibular neuritis from labyrinthitis.

Diagnosis & Investigations - Pinpointing Vertigo

• Clinical: Acute, persistent vertigo, N/V, gait instability. NO hearing loss/tinnitus.
• Nystagmus: Spontaneous, unidirectional, horizontal-torsional; fast phase beats away from affected side; suppressed by fixation.
• Head Impulse Test (HIT): Positive - corrective saccade towards affected side.
• Test of Skew: Negative.
• 📌 HINTS exam (Head Impulse, Nystagmus, Test of Skew): Differentiates peripheral (VN) vs. central (stroke).
• Audiometry: Normal.
• MRI: If atypical or HINTS worrisome for central lesion.

⭐ The HINTS exam is highly sensitive for stroke when a patient presents with acute vestibular syndrome and at least one stroke risk factor; a reassuring (peripheral) HINTS makes stroke very unlikely.

Differential Diagnosis - Ruling Rivals Out

• Labyrinthitis:
  • Sudden vertigo WITH auditory symptoms (hearing loss, tinnitus). Full labyrinth inflammation.

  ⭐ Unlike vestibular neuritis (nerve only), labyrinthitis involves cochlear symptoms due to labyrinthine inflammation.

• Meniere's Disease:
  • Episodic vertigo (min-hrs), fluctuating low-frequency SNHL, tinnitus, aural fullness.
• BPPV (Benign Paroxysmal Positional Vertigo):
  • Brief, positional vertigo (sec-min); head movement trigger. Dix-Hallpike positive.
• Central Causes (Stroke/TIA - posterior circulation):
  • Sudden, severe, persistent vertigo; neurological signs (ataxia, dysarthria). HINTS exam vital.
• Vestibular Migraine:
  • Episodic vertigo with migraine history/symptoms (headache, aura).

Management & Prognosis - Steadying Steps

• Acute Phase:
  • Symptomatic relief: Antiemetics (ondansetron), vestibular suppressants (meclizine, diazepam; use <3 days to avoid delaying compensation).
  • Corticosteroids: E.g., Prednisolone 1mg/kg/day (max 60mg) tapered over 10-14 days, if within 72 hours of onset; may hasten recovery.
• Rehabilitation Phase:
  • Vestibular Rehabilitation Therapy (VRT): Crucial. Start as soon as tolerated.
    • Gaze stabilization, habituation, balance training (e.g., Cawthorne-Cooksey exercises).
• Prognosis:
  • Acute symptoms resolve in days; full recovery in weeks to months for most.
  • ~30% may have residual dizziness. Recurrence: ~2-10%.
  • Potential for post-neuritis BPPV.

  ⭐ Early initiation of VRT is paramount for optimal functional recovery and reducing chronic symptoms.

High-Yield Points - ⚡ Biggest Takeaways

• Viral infection (often URI) precedes vestibular nerve inflammation.
• Sudden, severe, persistent vertigo, nausea, vomiting; lasts days.
• No auditory symptoms (hearing preserved) - key differentiator from labyrinthitis.
• Unidirectional horizontal nystagmus (fast phase away from affected side).
• Positive Head Impulse Test (HIT) towards affected side is diagnostic.
• Treatment: Corticosteroids (early), vestibular suppressants, antiemetics, vestibular rehabilitation.
• Prognosis generally good; most recover fully with rehabilitation.