Vestibular Evoked Myogenic Potentials and Wideband Acoustic Immittance as Screening Tools for Large Vestibular...

Background: Large vestibular aqueduct syndrome (LVAS) is the most common inner ear malformation in children with hearing loss; however, imaging is required to determine the definitive diagnosis. Purpose: This study aimed to preliminarily determine the sensitivity and specificity of air-conducted and bone-conducted cervical vestibular evoked myogenic potentials (VEMPs) and ocular VEMPs and wideband acoustic immittance (WAI) as screening tools for LVAS and identify candidates for imaging. Research Design: This was a prospective observational study. Study Sample: The sample included 10 participants (17 ears) with LVAS and 15 control participants. Intervention: All participants completed cervical and ocular VEMP testing in response to air-conducted and bone-conducted stimuli and WAI testing. Results: Ears with LVAS had significantly higher air-conducted cervical and ocular VEMP amplitudes but reduced bone-conducted VEMP amplitudes. Because of this pattern reversal, air-conducted amplitudes were subtracted from bone-conducted amplitudes. This novel outcome was the best individual factor for differentiating ears of the control group from ears with LVAS and is a sensitive clinical indicator of LVAS, with 82 percent sensitivity and 80 percent specificity for cervical VEMP and 88 percent sensitivity and 80 percent specificity for ocular VEMP. Ears with LVAS exhibited significant differences in WAI absorbance of control ears at select low, mid, and high frequencies, and they also exhibited characteristic low-frequency peaks in individual responses that could be detected using an automated algorithm with moderate sensitivity (64 percent) and specificity (72 percent). Conclusions: This is the first report of the use of VEMP and WAI responses of individuals as screening tools for LVAS. VEMP and WAI could be used to determine which individuals are good candidates for radiographic imaging and decrease the time required to determine a diagnosis. The test results also demonstrated patterns that differed from those of other third window disorders. Therefore, important physiologic differences between LVAS and other third window disorders require further investigation.