CORRELATION OF ACOUSTIC THRESHOLD MEASURES AND SPIRAL GANGLION-CELL SURVIVAL IN SEVERE TO PROFOUND SENSORINEURAL HEARING-LOSS - IMPLICATIONS FOR COCHLEAR IMPLANTATION

In a temporal bone study of 26 ears from 13 patients who, in life, had severe sensorineural hearing loss, the segmental and total spiral gan glion cell (SGC) counts were correlated with hearing thresholds and wi th the difference between hearing thresholds in the two ears, the age at death, the duration of deafness, and the duration of hearing loss. A statistically significant correlation was found between the interaur al differences in total SGC counts and the interaural difference in pu re tone averages for 3, 4, and 5 frequencies. The total SGC count was higher in the ear with the better residual hearing in 11 of 12 cases. Approximately 41% of the variability in interaural difference in pure tone average was explained by the difference in SGC counts. The findin gs would suggest that in a given individual, selection of the ear with better residual hearing for cochlear implantation is likely to result in accessing a higher number of residual SGCs. This, in turn, may res ult in better speech recognition with the implant.