[Trigeminal sensory evoked potential in retrogasserian glycerol injection for trigeminal neuralgia]

Since Dr. Håkanson reported retrogasserian glycerol injection method for treatment of idiopathic trigeminal neuralgia, its effectiveness for pain relief has been documented in a few reports. However, effects of glycerol in nervous tissue and mechanism of pain relief of the trigeminal neuralgia have not been elucidated yet. So we attempted to make clear what changes happen in trigeminal sensory evoked potential (TEP) of the patients with trigeminal neuralgia after retrogasserian glycerol injection. For this purpose we had to obtain normal TEP from 12 normal subjects in the beginning. The TEP by upper lip stimulation and recorded at contralateral C5 or C6 (TEP.V2) was consisted of 4 positive and 2 negative potentials in the analysis time of 40 msec which were named P3, N10, P14, P20, N30 and P40. The TEP.V3 that was obtained by lower lip stimulation was consisted of 3 positive and 3 negative potentials that were named N3, P10, N14, P20, N30 and P40. Most remarkable change of the TEP.V2 after glycerol injection in the pain relief group of patients with trigeminal neuralgia involving second division was amplitude attenuation of N10. There was no significant prolongation of peak latencies of P3, N10 and P20. It was remarkable that this amplitude decrease (about 38% of the pre-injection value) was recognized only in the pain relief group. On the contrary the mean amplitude of no relief group decreased only to 86% of the pre-injection value.(ABSTRACT TRUNCATED AT 250 WORDS)