Image Number 8 for United States Patent #7223246.
A procedure for diagnosing cochlear hydrops is based, in part, on an analysis of the patient's auditory brainstem response (ABR) to stimuli. The patient's ABR to a broadband click stimulus is recorded. A plurality of masked ABR's are also recorded, wherein the stimulus is masked by high-pass noise with a plurality of high-pass cut-off frequencies. The latency difference between the wave V component in the unmasked click alone response and the undermasked wave V component of a low cut-off frequency high-pass response is then calculated. If an undermasked component is not present, the normal wave V component is used. The measured latency difference is combined with another measure, such as the wave V amplitude ratio. A distribution of the combined measure is then plotted for the population and a threshold established for diagnosing cochlear hydrops. Alternatively, the joint distribution of the individual measures may be used in situations where the individual measures are known to be independent.