Suppression of pain in trigeminal neuropathy by electric stimulation of the gasserian ganglion.

Lesions of the peripheral part of the trigeminal nerve may cause trigeminal neuropathy associated with severe pain. Such pain usually does not respond to carbamazepine and analgesics, and it is continuous and lacks the characteristic paroxysmal character of tic douloureux. These patients often present with complex changes of facial sensibility in the form of dysesthesia, hyperalgesia, and allodynia. The pain sometimes responds favorably to transcutaneous nerve stimulation, but direct stimulation of the trigeminal ganglion and rootlets via an implanted electrode provides a greater likelihood of pain relief. Fourteen patients diagnosed as having painful trigeminal neuropathy received implants of a gasserian ganglion-stimulating electrode. The mean follow-up period is 4 years (range, 1 to 7 years). Eleven of the patients have retained the pain-relieving effect, and 1 had pain disappear without further stimulation. Eight of the patients estimated their pain relief to be complete or very good. There were no serious complications, but in several of the patients the electrode had to be exchanged because the insulation of the lead wires broke. For the selection of patients for permanent electrode implantation, a method has been developed for trial stimulation via a percutaneous electrode introduced into the trigeminal cistern. Temporary trial stimulation can be performed for several days. It is concluded that stimulation of the trigeminal ganglion and rootlets with the aid of an implanted electrode may effectively relieve certain forms of trigeminal pain that are otherwise extremely difficult to manage.