Cross-correlation function in the analysis of auditory brainstem response in spinocerebellar degeneration.

Cross-correlation functions were derived from the analysis of auditory-evoked brainstem response (ABR) and compared with measurements of wave latency and computed tomography findings in the assessment of ABR findings in spinocerebellar degeneration (SCD). Gender-specific normative ABR templates were produced from 30 normal males and 30 normal females separately. The cross-correlation indices used were the correlation coefficient at time 0, the maximal correlation coefficient and the latency delay in milli-seconds. The technique was applied to 33 patients with SCD. The incidence of abnormal cross-correlation functions (81.8%) was greater than the incidence of abnormal ABR peak latencies assessed according to gender (75.8%) which, in turn, was more common than the abnormal peak latencies assessed conventionally (69.7%). Moreover, the incidence of abnormal cross-correlations and latencies in Menière's disease was much lower (less than 8%). These results suggest that the evaluation of ABR waveform characteristics with cross-correlation functions using normative ABR templates of the same gender contributes to the precise detection of abnormality in the brainstem auditory pathway.