HISTOPATHOLOGY OF THERMOCOAGULATION OF THE CEREBRAL CORTEX

Abstract

Surgical removal of a cortical region for the relief of epilepsy or tremors is frequently more extensive than planned owing to the interference with the blood supply of adjacent gyri, thrombus formation, and softening of the subjacent white matter. In hope of finding a technique which would eliminate the neuronal elements only, an exptl. study was made of the histopathology of thermocoagulation of the cerebral cortex. The application of a metallic rod heated to 80[degree]C to the cerebral cortex of cats and monkeys for 5 secs. caused an outer zone of thermocoagulation, an adjacent area of capillary thrombosis, and myelin destruction in the white matter of the gyrus. Studies made at intervals varying from 1 hr.-12 mos. after such coagulation revealed direct thermocoagulation of layers I to IV, V, or VI. There was interference with vascular supply from the pial arteries with patchy demyelination of the white matter of the injured gyrus, softening of the region, phagocytosis, thickening of the arachnoid over the injury, proliferation of astrocytes, and scar formation with contraction. Except for the zone of thermocoagulation, the reparative process is very similar to that induced by surgical interference with the pial arteries.