FFS: Vestibular Neuronitis

Pathophysiology

Vestibular neuronitis is caused by decreased vestibular tone on one side.

Causes:

1. Viral infection
   • Reactivation of herpes simplex type 1 is suggested in many cases.
   • Damage results from swelling and mechanical compression of the vestibular nerve within the temporal bone (similar to Bell’s palsy).
2. Microvascular disturbances
   • Acute localised ischaemia of the vestibular nerve or labyrinth may be contributory.

Recovery is often incomplete on formal vestibular testing

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Epidemiology

• Most commonly occurs in middle-aged adults.

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Clinical assessment

The key early goal is to distinguish peripheral from central vertigo
(see also Vertigo document).

Clinical features:

1. Gradual onset of severe, prolonged vertigo:
   • Not sudden/maximal like stroke.
   • Unlike BPPV, it persists and may be slightly aggravated by movement.
2. Unidirectional mixed horizontal and torsional nystagmus
3. Vertigo persists at rest.
4. Autonomic features:
   • Nausea, vomiting, sweating
5. No central neurological signs (brainstem or cerebellar)
6. No hearing loss
7. Normal tympanic membrane
8. No fever
9. Vestibulo-ocular testing:
   • Positive head impulse test
   • Negative Dix-Hallpike

Symptoms typically peak on day one, improving over a few days.
Most recover within 1 week, but complete resolution may take weeks to months.
Some may have recurrent or persistent symptoms.

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Investigations

There are no definitive ED investigations for vestibular neuronitis.
Investigations aim to exclude central causes.

Maintain a low threshold for imaging in elderly or vascular risk patients.

• CT brain: useful to exclude posterior fossa bleed.
• CT angiogram: assess posterior circulation for thromboembolism.
• MRI/MRA: best for ruling out posterior fossa infarction.

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Management

1. IV fluids
   • Rehydration for patients with prolonged vomiting.
2. Antiemetics
   • Prochlorperazine (oral/IV/IM/PR)
   • Ondansetron / granisetron
3. Diazepam
   • 5–10 mg orally TDS
   • Titrated IV doses for very severe cases
4. Promethazine
   • May be helpful for symptom relief

(Refer to Therapeutic Guidelines for full prescribing information.)

5. Corticosteroids
   • Significantly improves function and speeds recovery:
     • Prednisolone 1 mg/kg (max 100 mg) PO daily x 5 days,
       then taper over 15 days.
6. Antivirals
   • Valacyclovir has no demonstrated benefit

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Disposition

Outpatient care may be appropriate in younger, well patients.

Admit if:

• Severe symptoms
• Significant comorbidities
• Elderly

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References

Publications

• Strupp M, Zingler VC, Arbusow V, Niklas D, Maag KP, Dieterich M, Bense S, Theil D, Jahn K, Brandt T. Methylprednisolone, valacyclovir, or the combination for vestibular neuritis. N Engl J Med. 2004 Jul 22;351(4):354-61. 
• Nelson JA, Viirre E. The clinical differentiation of cerebellar infarction from common vertigo syndromes. West J Emerg Med. 2009 Nov;10(4):273-7. 

FOAMed

• Nickson C. Ballistically Potent Vertigo. LITFL
• Cassidy T. Vertigo the Big 3. LITFL
• Baker C. Benign paroxysmal positional vertigo. LITFL
• Baker C. Dix-Hallpike Test. LITFL