突発難聴を初発症状とした聴神経腫よう症例

Abstract

Acoustic tumor (AT) most commonly arises from the inferior vestibular nerve and its initial symptom is sensori-neural hearing loss. This hearing loss is progressive with a gradual onset in the majority of cases. Since Cushing's report (1917), however, it is also known that some patients present with sudden hearing loss which may or not be temporary. Since 1978, unilateral AT has been diagnosed in 157 patients in our clinic, and in 19 of them the hearing loss of sudden onset was the chief complaint. Hearing was restored in 6 but was permanent in 13 patients. Although there were no significant differences in clinical and otoneurological findings between AT patients with gradual onset and those with sudden hearing loss without recovery, the patients with sudden onset followed by recovery of hearing showed several findings different from the other two groups: smaller tumor, trough type hearing loss and higher percentage of normal or slightly abnormal responses in caloric tests, X ray examinations and auditory brainstem response. In a review of the available literature, we found 22 AT cases in which sudden onset hearing loss followed by recovery had been reported with sufficient clinical information. The clinical and otoneurological findings in those cases were quite similar to our own. The most common ear disease with hearing loss of sudden onset is sudden deafness and the estimated incidence is 16, 663 every year. Although AT patients with sudden onset of hearing loss followed by recovery are very few (estimated 31 to 62/year), it is extremely important for otolaryngologists to consider the possibility of AT, when patients present with sudden hearing loss.