Electrocochleography and Auditory Brainstem Response in Normal Adults and Vestibular Migraine Patients Using Continuous Loop Averaging Deconvolution

Vestibular migraine (VM) is a disorder for which no objective tests exist to aid in diagnosis. Using the Continuous Loop Averaging Deconvolution (CLAD) technique in ECochG and ABR, the effects of testing at very high stimulus rates may have the potential to help diagnose VM, but first, a body of normative data using the CLAD technique must be established. Electrocochleography (ECochG) and auditory brainstem response (ABR) were measured simultaneously from a tympanic membrane electrode and surface electrodes on the forehead and mastoid. Participants included 20 healthy individuals for normative data and three VM patients for the pilot study. Normative data showed that the action potential (AP) of the ECochG and waves I, III, and V of the ABR decreased in amplitude and increased in latency as the stimulus rate was increased from the standard 7.1 clicks/s up to 507.81 clicks/s. The summating potential (SP) of the ECochG, however, stayed relatively stable, resulting in increased SP/AP ratios with increasing stimulus rate. The SP/AP amplitude ratio showed more stability than amplitude findings, thus it is recommended for use in evaluation of cochlear and neural response. Pilot results from the VM patients revealed similar trends to normative data. Results from this normative study and the pilot VM data may be helpful in improving the diagnostic utility of CLAD in distinguishing inner ear disorders.