NEURAL CONDUCTION-VELOCITY OF THE HUMAN AUDITORY-NERVE - BIPOLAR RECORDINGS FROM THE EXPOSED INTRACRANIAL PORTION OF THE 8TH NERVE DURING VESTIBULAR NERVE-SECTION

We measured the conduction velocity of the intracranial portion of the auditory nerve in 3 patients undergoing vestibular nerve section to t reat Menieres disease. The conduction velocity varied from patient to patient. with an average value of 15.1 m/sec. The latency of peak III of the brain-stem auditory evoked potentials (BAEPs) increased by an a verage of 0.5 msec as a result of exposure of the eighth nerve, and if that increase is assumed to affect the entire length of the auditory nerve (2.6 cm) evenly, then the corrected estimate of conduction veloc ity would be 22.0 m/sec. Estimates of conduction velocity based on the interpeak latencies of peaks I and II of the BAEP, assuming that peak II is generated by the mid-portion of the intracranial segment of the auditory nerve, yielded similar values of conduction velocities (abou t 20 m/sec).