[Electrical stimulation of the posterior limb of the internal capsule for treatment of thalamic pain].
Electrical stimulation of the posterior limb of the internal capsule was performed in six patients with central pain due to vascular lesions of the thalamus. Three patients suffered from thalamic hemorrhage and the other three from ischemic insult. These patients developed dysesthesia, hyperpathia and spontaneous burning pain several months after cerebral vascular diseases. These severe pain were not relieved by any trials of anticonvulsants, psychopharmacological and analgesic drugs. Stimulating electrode system manufactured by Medtronic, Co. was implanted stereo-taxically in the posterior limb of the internal capsule which was 25 mm lateral to the posterior commissure. Ramped bipolar stimulation with a square pulse 2-3 V, 0.2 msec, 50 Hz elicited sensory response such as warm or comfortable sensation. Satisfactory relief of pain was obtained in most cases by 30-minutes-long stimulation twice or three times a day for various period of time ranging from 10 to 14 days. Long-term follow-up ranging from three months to two years showed that three patients had a good result (incomplete pain relief by stimulator with no medication required), two had a fair (incomplete pain relief by stimulator with decreased doses of medication) and another one had a poor result in which the pain had not been relieved with the stimulation in one month. No remarkable side effects were seen. These results indicate that the internal capsule stimulation is more effective and lasts longer than the various ablative methods to relieve central pain.(ABSTRACT TRUNCATED AT 250 WORDS)