[Trigeminal somatosensory evoked potentials: II. Some clinical experiences]

Compared to other somatosensory evoked potentials (SEP), little information has been published so far on trigeminal somatosensory evoked potentials (TSEP) in the various kind of disorders. This may be due to few recording technique suitable for clinical practice. We previously reported a new recording method and showed the normal pattern of TSEP. The purpose of this report is to examine its reliability for clinical use. Sixty patients, with either a complaint of facial numbness or an organic lesion supposed to involve facial sensory pathway, were investigated. Their age ranged from 13 to 74 years old (mean 47.0). They consisted of 34 organic lesions (30 brain tumors and 4 cerebrovascular diseases) and 26 non-organic lesions (16 hemifacial spasms, 6 trigeminal neuralgias and other miscellaneous disorders). TSEP was recorded by the stimulation of the half of the contralateral upper or lower lip with the clip-shaped electrode. C'5 or C'6 (midpoint between Cz and the external auditory porus) was used as an active electrode and Fz as a reference. Two hundred or four hundred responses were averaged by a Nicolet Pathfinder II. All recordings were repeated at least twice to confirm the reproducibility. (1) Among 21 patients with a complaint of facial numbness except for neuralgia, the abnormality rate of TSEP was significantly different (p less than 0.02) between organic and non-organic lesions. The former was 87.5% (14 out of 16 cases) and the latter was 20% (1 out of 5 cases).(ABSTRACT TRUNCATED AT 250 WORDS)