Click- and short tone burst-evoked myogenic potentials in cerebellopontine angle tumors.

We report results of vestibular-evoked myogenic potentials (VEMPs) in patients with cerebellopontine angle tumors and compare results obtained using clicks with those obtained using 500 Hz short tone bursts (STB). We reviewed the records of 87 patients with cerebellopontine angle tumors. Clicks (0.1 ms, 95 dB nHL) were presented to all patients and STB (500 Hz, rise/fall time 1 ms, plateau time 2 ms, 95 dB nHL) were presented to 27 patients. Click-evoked VEMPs were abnormal in 69/87 patients (79%; no response in 55 patients, decreased response in 14 patients, normal response in 18 patients). STB-evoked VEMPs were abnormal in 22/27 patients (82%; no response in 18 patients, decreased response in 4 patients, normal response in 5 patients). Click- and STB-evoked VEMPs were identical in 23/27 patients (85%). Two patients showed normal STB-evoked VEMPs and decreased click- evoked VEMPs, and 2 patients showed decreased STB-evoked VEMPs and absent click- evoked VEMPs. These results confirm our previous study in a small number of patients. Vestibular afferents seem to respond better to 500 Hz STBs than to clicks.