Optimizing ocular vestibular evoked myogenic potential testing for superior semicircular canal dehiscence syndrome: electrode placement.

OBJECTIVE To compare the sensitivity and specificity of ocular vestibular evoked myogenic potentials (oVEMPs) using 2 electrode montages for the diagnosis of superior canal dehiscence syndrome (SCDS). SUBJECTS 16 SCDS patients (17 affected-SCDS ears, 15 contralateral-SCDS ears) and 12 controls (24 ears). METHODS oVEMPs were recorded in response to 500-Hz tone bursts using 2 electrode montages. For both montages the active electrode was placed approximately 5 mm below each eye and a ground electrode on the sternum. For montage 1 (standard), the reference electrode was centered 2 cm below each active electrode. For montage 2, the reference electrode was placed on the chin. RESULTS For either montage, the separation between oVEMP amplitudes in affected-SCDS ears and controls was significant (p < 0.001), with excellent sensitivity and specificity (>90%). CONCLUSION oVEMP recordings with the standard montage remain a reliable method for evaluation of SCDS.