A follow-up study of 26 patients with vestibular neuronitis is reported. The disease is characterized by an acute attack of severe vertigo with complete loss of unilateral caloric response. The following results were obtained:
1) The average period of spontaneous nystagmus was 136 days and the standard error was 39 days.
2) No correlation could be found between age and the period of spontaneous nystagmus.
3) Six patients showed direction reversal in their spontaneous nystagmus (recovery nystagmus), and their outcome was good.
4) On the most recent caloric test, 42% of the patients had bilateral normal responses, 27% displayed partial improvement on the affected side, and no reaction was observed in 31% of patients.
We suggest that three types of clinical courses may occur in vestibular neuronitis: i) complete recovery of the function of the affected vestibular nerve, ii) partial recovery of vestibular function, and iii) no recovery of the affected vestibular nerve, but central nervous system compensates for the vestibular imbalance.