Ｇａｌｖａｎｉｃ ｂｏｄｙ ｓｗａｙ ｔｅｓｔ異常症例における前庭性頚筋電位（ＶＥＭＰ）

Abstract

In order to clarify whether the galvanic body sway test (GBST) is useful for differential diagnosis of lesions in patients with absent vestibular evoked myogenic potentials (VEMP), clinical records of patients with absent GBST were reviewed. Patients were 4 men and 10 women. Their ages ranged from 32 to 81. Diagnoses were vestibular neuritis in 6 patients, acoustic neuroma in 7 patients, and temporal bone fracture in one patient. GBST were performed using a stabilometer. As stimulation, 0.6 mA electrical stimuli were presented for 3 seconds. Electrodes were placed on the mastoid and the forehead. For recording VEMPs, electrodes were placed on the upper half of the sternocleidomastoid muscle and the lateral end of the upper sternum. As stimulation, 95 dBnHL clicks were presented at the rate of 5 Hz. Signals were amplified and bandpass-filtered (20-2000 Hz). One hundred responses were averaged. Whereas all of the 14 patients showed abnormal caloric responses, 4 patients (29%) showed normal VEMPs. These results suggested that GBST is not always useful for differential diag-nosis of retro-labyrinthine lesions from labyrinthine lesions in patients with abnormal VEMPs, while GBST could be useful for differential diagnosis in patients with abnormal caloric responses. We should establish other clinical testing for differential diagnosis of retro-labyrinthine lesions from labyrinthine lesions in patients with abnormal VEMPs.