Pratt, Terri L.

Purpose Ocular vestibular evoked myogenic potentials (oVEMPs) are used to describe utricular/superior vestibular nerve function; however, optimal recording parameters have not been fully established. This study investigated the effect of repetition rate on air-conducted oVEMPs. Method Ten healthy adults were evaluated using 500-Hz tone bursts (4-ms duration, Blackman gating, 122 dB pSPL). Four repetition rates were used (1.6, 4.8, 8.3, and 26.6 Hz) and resulting oVEMP response presence, amplitude, amplitude asymmetry, and n1/p1 latency were assessed. Results Response presence was significantly reduced for 26.6 Hz using monaural stimulation and for 8.3 Hz and 26.6 Hz for binaural stimulation. For monaural stimulation using 1.6, 4.8, and 8.3 Hz, no significant differences were noted for amplitude or latency. Responses obtained using binaural stimulation demonstrated a significant effect of rate on amplitude, with 8.3 Hz producing significantly reduced amplitude. Binaural amplitudes were significantly larger than monaural contralateral responses but with reduced response presence. No significant differences were noted for latency or amplitude asymmetry. Conclusion Using repetition rates of approximately 5 Hz or less may produce more consistent oVEMP response presence with minimal effects on amplitude for monaural or binaural recordings.

Simultaneous four-channel (ipsilateral, contralateral, horizontal, and noncephalic) ABR recordings were reviewed by three audiologists for 187 ears of nontumor patients, and 13 ears of patients having eighth nerve tumors. Waveforms from a subgroup of 63 ears were reexamined by the same audiologists to assess inter- and intra-judge consistency. For nontumor ears, the ipsilateral tracings provided the best identification of Waves I and III; the ipsilateral and noncephalic recordings allowed equal identification of Wave V. Waves I, III, and V generally were more robust from the ipsilateral electrode array than from any of the other electrode montages for the tumor ears. Three-way inter-judge agreement ranged from 82% to 87% for ipsilateral Waves I, III, and V and for noncephalic Wave V. Agreement between pairs of judges ranged from 86% to 100%. Intra-judge agreement ranged from 87% to 94% for ipsilateral Waves I, III, and V, and from 92% to 95% for noncephalic Wave V.

Multichannel ABR recordings for 30 otoneurologic patients were reviewed independently by three audiologists to assess interjudge consistency in determining absolute latencies and overall interpretation of ABR results. Four months later, the tracings were reviewed a second time to evaluate intrajudge consistency in interpretation of ABR waveforms. Interjudge agreement in marking latencies for waves I, III, and V within 0.2 ms was on the order of 90% or better. Intrajudge consistency was slightly higher. Only rarely did inter- or intrajudge differences in latency measurements exceed 0.3 ms. Agreement in overall interpretation of ABR results as "normal" or "abnormal" was unanimous for 90% of the patients. Across pairs of judges, the agreement for "normal" and "abnormal" classification of the ABR tracings was 97%. Intrajudge consistency for "normal" and "abnormal" categorization of the ABR results was 100% for one judge, 97% for the other two judges.