Value of the promontory stimulation test in predicting speech perception after cochlear implantation

To determine the role of the promontory stimulation test (PST) in cochlear implantation (CI), we evaluated the correlations between PST parameters and the results of speech perception tests after CI.

With use of a retrospective review of the medical records of 58 patients, the GAP50, GAP100, TDL50, and TDL100 parameters of the PST were compared with the results of speech perception tests at fixed time points after CI. Spearman's rank-order correlation coefficient was used in statistical analyses.

GAP100 scores were correlated with all results of speech perception tests at all time points after CI (r = 0.309-0.509, P = .001-0.010), and TDL100 scores were correlated with the results of open set one- and two-syllabic word tests at 1 month after CI (r = 0.288, P = .028); no other significant correlations were found. The GAP100 scores for postlingually deaf patients, especially for gap intervals up to 100 ms, were correlated with all results of speech perception tests after CI. A stepwise multiple regression analysis revealed that the GAP100 score is the only variable that was significantly correlated with the results of speech perception tests. The duration and onset age of deafness did not significantly affect the results.

The PST may be a useful tool for predicting the prognosis of CI. The GAP100 score, especially for gap intervals up to 100 ms, might be useful in predicting the results of speech perception tests after CI as well as in determining the optimal site for CI in postlingually deaf patients without residual hearing.