Introduction
Our group has taken the ventral posterior thalamus as an initial target for stereotactic surgical intervention in the treatment of chronic severe pain. We have done this for several reasons.Clinically, we were often faced with the problem of treating terminal cancer patients with subjective head and neck pain in areas supplied by several cranial and upper cervical nerves. These patients, if not relieved by narcotic medication, often required a section of multiple posterior roots. We felt that any less drastic operative procedure, such as a stereotactic surgical maneuver which could effectively relieve chronic pain, would be a welcome addition to the surgical armamentarium.From a research point of view, the sensory relay nucleus of the thalamus offered us a unique opportunity to check the accuracy of our stereotactic method. We were able to stimulate peripherally and record evoked thalamic potentials; we also stimulated with intrathalamic electrodes in the