Using the continuous loop averaging deconvolution (CLAD) technique for conventional electrocochleography (ECochG) and auditory brainstem response (ABR) recordings, the effects of testing at high stimulus rates may have the potential to diagnose disorders of the inner ear and auditory nerve. First, a body of normative data using the CLAD technique must be established.
Extratympanic click ECochG and ABR to seven stimulus rates using CLAD were measured simultaneously from a tympanic membrane electrode and surface electrodes on the forehead and mastoid of 42 healthy individuals.
Results showed that the compound action potential (AP) of the ECochG and waves I, III, and V of the ABR decreased in amplitude and increased in latency as stimulus rate was increased from standard 7.1 clicks/s up to 507.81 clicks/s, with sharp reduction in AP amplitude at 97.66 clicks/s and reaching asymptote at 292.97 clicks/s. The summating potential (SP) of the ECochG, however, stayed relatively stable, resulting in increased SP/AP ratios with increasing rate. The SP/AP amplitude ratio showed more stability than AP amplitude findings, thus it is recommended for use in evaluation of cochlear and neural response.
Results of both amplitude and latency data from this normative neural adaptation function of the auditory pathway serves as guide for improving diagnostic utility of both ECochG and ABR using CLAD as a reliable technique in distinguishing inner ear and auditory nerve disorders.
1Department of Communication Sciences and Disorders, Missouri State University, Springfield, Missouri, USA; 2Intelligent Hearing Systems Corporation, Miami, Florida; and 3Otology and Neurotology Department, Mercy Clinic Springfield, Springfield, Missouri, USA.
Portion of this study was presented at the American Auditory Society Meeting in Scottsdale, AZ (March 2015).
R.E.D.'s company, Intelligent Hearing Systems, is the manufacturer of the equipment used in this study. R.E.D. has a direct financial interest in Intelligent Hearing Systems.
E.Y. was working as a Research Scientist at the Intelligent Hearing System Corporation.
Received September 15, 2015; accepted August 29, 2016.
Address for correspondence: Wafaa A. Kaf, Department of Communication Sciences and Disorders, Missouri State University, 901 S. National Ave., Springfield, MO 65897, USA. E-mail: WafaaKaf@MissouriState.edu