[Thalamic relay nucleus stimulation for relief of intractable pain. Clinical results and beta-endorphin immunoreactivity in cerebrospinal fluid].

Chronic implantation of a stimulating electrode in the thalamic relay nucleus (11 cases), in the periaqueductal gray (1 case) and in the internal capsule (2 cases) was performed in fourteen cases which suffered from intractable pain. All these cases could get pain relief at least initial two months. Ventricular fluids were collected before and after stimulation with optimal combination of parameters, and measurements of beta-endorphin were performed by radio-immunoassay. Intrathecal morphine (1mg) injection was performed in eight cases. Cerebrospinal fluids were collected by lumbar tap before and 24 hours after morphine injection. beta-endorphin immunoreactivity was measured by the same method. Pain relief was judged to be excellent if the patient so claimed, and if he discontinued analgesics. Pain relief was thought to be good when it was not completely controllable by stimulation but was sufficiently improved that the patient could do without analgesics. It was thought to be fair when patient could not discontinue analgesics, and poor when patient could not get pain relief. We usually attempt to prevent the stimulation-tolerance by administration of the monoamine precursors , i.e., 1-dopa and 1-tryptophan, on the basis of the experimental observation reported previously. In somatogenic pain patients, the thalamic relay nucleus stimulation was performed in 7 cases (excellent; 3, good; 1, fair; 3) and the periaqueductal gray stimulation in one case (good).(ABSTRACT TRUNCATED AT 250 WORDS)