Neuro-Otological Analysis in Vestibular Neuronitis.

Five patients with typical manifestations of vestibular neuronitis were examined repeatedly for spontaneous nystagmus, positional nystagmus, caloric responses and Contraves rotation test results determined by electronystagmography.1) Spontaneous nystagmus was observed for more than 2 months. The duration of spontaneous nystagmus in patients with vestibular neuronitis was longer than patients in those with other acute vestibular disorders.2) No patient showed direction-changing positional nystagmus, but in 2 cases, nystagmus amplitude was increased in the supine healthy-ear-downn position.3) Four of 5 patients showed no caloric reaction on the affected side in the early stage of the disease; however, at the follow-up examination after several months, all patients showed reappearance of the caloric responses.4) In the rotation test, all patients showed directional preponderance to the healthy side, but the “recruitment type”, which is observed exclusively in disturbances of the vestibular organ, was not observed in any patient.5) It was thought that vestibular neuronitis represented a neuropathy due to a viral infection, such as varicella zoster or herpes simplex.