In defense of SISIs. The short increment sensitivity index.

We review the Short Increment Sensitivity Index (SISI) in terms of its performance with a variety of sites of lesion and its likely physiologic basis. We conclude that its original schema can be broadened to extend its clinical application if changes are made in the parameters of its routine use. The two major changes involve (1) a presentation level of no less than 90 dB hearing threshold level (HTL) and (2) a bimodal interpretation of results based on the premise that high scores indicate normal cochlear function and low scores indicate extensive cochlear damage or neural dysfunction. We suggest that routine use of the modifications suggested here can provide useful diagnostic information and bring to light a group of neurally impaired patients that has been relatively ignored.