Trigeminal sensory evoked potentials in patients with trigeminal neurinoma: report of two cases.

The trigeminal sensory evoked potentials (TEPs) in two patients with trigeminal neurinoma are reported. In contrast to the two cases previously reported by others, in which the preoperative TEPs were normal, the two cases reported herein showed significant changes on the affected side: the sensory thresholds were greater and the peak latencies of P19 and N28 were longer on the affected side than those on the normal side. Our results confirm that a TEP measurement is very useful in a preoperative examination of patients with trigeminal neurinoma, when the function of the trigeminal nerve should be evaluated objectively.