Somatosensory Reports from Electrical Stimulation of the Brain during Therapeutic Surgery

Abstract

THE history of electrical stimulation of the human brain incidental to its use for therapeutic purposes extends back almost a century¹. The recent exploration of the discovery that stimulation of the brain can elicit verbal descriptions of sensations was ushered in by Foerster² and also by the extensive investigations of Penfield and his colleagues³, who were primarily limited to the cortex by the limited techniques of the day. The advent of human stereotaxic surgery⁴, especially for dystonias and dyskinesias such as Parkinson's disease—which can be ameliorated by lesions placed in the thalamus or basal ganglia⁵—has extended the possibility of obtaining reports of sensory phenomena as a result of stimulation deep within the brain. In the conscious patient this stimulation is a necessary part of the therapeutic surgical procedure. It provides information on the locus of the probe tip which must ultimately be placed in the site of the future therapeutic lesion. If the tip happens to be slightly off course in the internal capsule, the response to stimulation can prevent the disastrous error of severing this tract and resulting hemiplegia.