Vestibular neuronitis

What it is

Vestibular neuritis is inflammation of the vestibular portion of CNVIII, a disorder of the vestibulocochlear nerve with inflammation and swelling. Labyrinthitis is inflammation of both the vestibular and the cochlear portions, and unaffected hearing is what distinguishes vestibular neuronitis from labyrinthitis.

Causes and risk

Infections, that is measles, mumps and HSV, with an associated URTI in 30%. Also DM, autoimmune and microvascular events.

How it presents

The acute phase is severe disabling vertigo with nausea and vomiting and imbalance, lasting 1-5 days. The imbalance is towards the affected side and the nystagmus is irritative, its fast phase towards the offending ear. There are no auditory symptoms. In the convalescent phase the imbalance and motion sickness last days to weeks, the spontaneous nystagmus now beats away from the affected side, and gradual vestibular adaptation requires weeks to months.

Put together, the presentation is dizziness of sudden onset lasting a day or two, constant rather than intermittent, worse on head movement but not triggered by it, with nausea and vomiting, a cough or a cold in the week before, horizontal nystagmus on examination, and hearing that is normal bilaterally.

Set against central vertigo, vestibular neuritis is sudden in onset, severe initially and often decreasing over time, continuous and lasting for hours to days, with horizontal torsional nystagmus, vertigo worsened by head position, and no associated neurologic findings.

Labyrinthitis stands next to it: recent viral infection, sudden onset, nausea and vomiting, tinnitus and unilateral sensorineural hearing loss. Where there is ringing in the ears and Rinne's and Weber's tests show a hearing loss, the auditory symptoms point to labyrinthitis rather than to vestibular neuronitis.