Vestibular neuronitis and labyrinthitis

These are considered to be a viral infection of the vestibular nerve and labyrinth respectively, causing a prolonged attack of vertigo that can last for several days and be severe enough to require admission to hospital.

• acute vertigo with nausea and vomiting = vestibular neuronitis
• same symptoms + hearing loss ± tinnitus = acute labyrinthitis

It is analagous to a viral infection of the 7th nerve causing Bell’s palsy. The attack is similar to Ménière’s syndrome except that there is no hearing disturbance. Characteristic features are:

• single attack of vertigo without tinnitus or deafness
• usually preceding upper respiratory tract infection
• mainly in young adults
• abrupt onset with vertigo, nausea and vomiting
• may take 6 weeks or so to subside
• examination shows nystagmus—rapid component away from side of lesion (no hearing loss)
• caloric stimulation confirms impaired vestibular function

Note: Acute labyrinthitis has a similar pattern. It is the diagnosis if hearing loss is present.

Treatment

The following drugs can be used:

• dimenhydrinate (Dramamine) 50 mg 4-6 hourly
  or
• prochlorperazine (Stemetil) 12.5 mg IM (if severe)
  or (recommended as best)
• diazepam (which decreases brain-stem response to vestibular stimuli), 2 5-10 mg IM for the acute attack, then 5 mg (o) tds and possibly droperidol.

Outcome

Both are self-limiting disorders and usually settle over 5-7 days or several weeks. Labyrinthitis usually lasts longer and during recovery rapid head movements may bring on transient vertigo.