Microvascular decompression for trigeminal neuralgia with special reference to delayed recurrence.

Thirty-five patients with trigeminal neuralgia underwent microvascular decompression. Complete remission was obtained in 33 patients, while one was fair and another unchanged postoperatively. The clinical and operative findings were reviewed, analyzing the direction of vascular compression of the trigeminal nerve and the distribution of pain in the peripheral regions. There were some weak correlations between the direction of vascular compression and the distribution of pain. Neuralgia in the region of second branch of the trigeminal nerve (V2) or in the regions of V2 and third branch of the nerve (V3) was caused by compression from the ventral or ventro-rostral direction, in the region of first branch of the nerve from the ventro-caudal direction, and in the V3 region from the ventral, rostral, and dorsal directions of the nerve in general. In two patients who had had complete remission after first operation, trigeminal neuralgia recurred. They had typical intermittent painful attacks with a background of continuous dull pain or painful dysesthesia caused by Ivalon sponges inserted between the nerve and the offending vessel. Complete remission was again obtained after removal of these sponge pieces. We would like to stress continuous dull pain or painful dysesthesia in cases of delayed recurrence as indicators for re-exploration.