VEMP正常を示した下前庭神経由来聴神経腫瘍の一例
2003 年 62 巻 1 号 p. 43-46
詳細
2003 年 62 巻 1 号 p. 43-46
Vestibular-evoked-myogenic-potentials (VEMP) have been considered to reflect the function of saccular and inferior vestibular nerve tracts. We encountered a patient with inferior vestibular schwannoma who showed severely damaged hearing, with normal caloric tests and VEMP results. A 54-year-old woman with no contributing history or family history consulted with a complaint of hearing loss and tinnitus. On brain MRI, she was found to have an acoustic tumor in her right internal auditory meatus, about 8mm in diameter. Audiometry results showed severe hearing loss, 106.3 dB in right ear. Caloric test and VEMP result showed normal responses. The tumor was considered to originate from the cochlear nerve, but operation revealed an inferior vestibular schwannoma origin. After schwannoma enucleation with section of inferior vestibular nerve, VEMP results showed no response, confirming VEMP may be conducted by the inferior vestibular nerve, and showing that it is difficult to estimate neuron origin from preoperative caloric tests and VEMP results. In addition, it showed that VEMP may be conducted via the cochlear nerve as well as in the inferior vestibular nerve. Thus, evaluation of inferior vestibular nerve function should be performed carefully. Additional accumulation of cases and data are necessary for better understanding.
