Recruitment in the diagnosis of small PCA tumors

Acoustic brainstem response (ABR) waveforms were preoperatively analyzed in 86 cases of pontocerebellar angle (PCA) tumors. Absolute (APL) and interpeak latencies (IPL) ipsilateral to the tumor and interaural absolute latency differences of wave V (IAAPLD V) were normal in two patients with small intracanalicular tumors. However, results of latency-intensity studies were abnormal. So, if PCA tumor is suspected, and standard ABRs are normal by usual criteria, the latency-intensity functions should be examined before the test result is reported as negative for an acoustic nerve tumor.