Vestibular Neuritis

Definition & Pathophysiology - Nerve Gone Wild

• Definition: Acute, prolonged vertigo (hours-days) with nausea, vomiting, and gait imbalance. Crucially: no hearing loss or other neurological signs.
  • Caused by unilateral vestibular hypofunction.
• Pathophysiology:
  • Inflammation of the vestibular nerve (CN VIII), often viral (HSV-1 reactivation suspected) or post-viral.
  • Typically affects the superior division of the vestibular nerve.
    • Innervates: Utricle, Superior & Horizontal Semicircular Canals (SCCs).
  • This leads to a sudden ↓ in tonic neural input from the affected side, creating an imbalance in vestibular signals to the brainstem.

  ⭐ Vestibular neuritis is characterized by acute vestibular syndrome (vertigo, nystagmus, head motion intolerance) without cochlear involvement, distinguishing it from labyrinthitis.

Clinical Features - Dizzy Patient Tales

• Sudden, severe, persistent vertigo: Acute onset, lasts hours to days; often bedridden.
• Intense nausea & vomiting: Frequently accompanies vertigo.
• Gait instability & imbalance: Difficulty walking, veers/falls towards affected side.
• Symptoms aggravated by head movements.
• Spontaneous nystagmus:
  • Horizontal or horizontal-torsional.
  • Unidirectional: fast phase beats away from affected side.
  • Suppressed by visual fixation (Alexander's Law).
• Positive Head Impulse Test (HIT): Corrective saccade when head turned rapidly to affected side.
• No auditory symptoms: Hearing preserved (no hearing loss/tinnitus).
• No other neurological deficits: (e.g., weakness, dysarthria).
• Often preceded by viral URI.

⭐ Hallmark: Acute vertigo without auditory or other neurological symptoms, distinguishing from labyrinthitis or stroke.

Diagnosis & DDx - HINTS to Diagnosis

• HINTS Exam (Head Impulse, Nystagmus, Test of Skew): Key for differentiating peripheral (e.g., Vestibular Neuritis) vs. central (e.g., stroke) causes in Acute Vestibular Syndrome (AVS).

  • HI (Head Impulse): Abnormal (corrective saccade present) suggests Peripheral. Normal HI is a Central concern.
  • N (Nystagmus): Unidirectional, horizontal, fast-phase away from lesion suggests Peripheral. Direction-changing (gaze-evoked), vertical, or pure torsional nystagmus is a Central concern.
  • TS (Test of Skew): Absent suggests Peripheral. Present (vertical ocular misalignment) is a Central concern.

• 📌 HINTS to INFARCT Mnemonic for central (stroke) signs:

  • Impulse Normal (Normal Head Impulse)
  • Fast-phase Alternating Nystagmus (Direction-Changing)
  • Refixation on Cover Test (Skew deviation present)

  ⭐ Any single "INFARCT" sign is highly sensitive for stroke. A benign HINTS profile (Abnormal HI, Unidirectional Nystagmus, No Skew) strongly points to a peripheral cause like vestibular neuritis.

• Key DDx:
  • Stroke (Posterior circulation) - Critical to exclude!
  • Labyrinthitis (vertigo + acute hearing loss)
  • Meniere's disease (episodic vertigo, hearing loss, tinnitus, aural fullness)
  • BPPV (brief, positional vertigo, no hearing loss)
  • Migrainous vertigo (headache, photophobia, phonophobia may be present)
  • Multiple Sclerosis

Management - Stop The Spin!

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High‑Yield Points - ⚡ Biggest Takeaways

• Characterized by sudden, severe vertigo, nausea, and vomiting, lasting days.
• Crucially, no auditory symptoms like hearing loss or tinnitus are present.
• Typically due to viral inflammation of the vestibular nerve (superior part often).
• Leads to unilateral peripheral vestibular hypofunction.
• Positive Head Impulse Test (HIT) is a key diagnostic sign.
• Spontaneous, unidirectional, horizontal nystagmus beating away from the affected side.
• Management includes corticosteroids (early), antiemetics, and vestibular rehabilitation exercises.