Tissue damage after chronic cerebellar stimulation.

Two spastic patients undergoing chronic cerebellar stimulation are studied. Biopsies taken after three months of stimulation showed various tissue changes when compared with those taken at the moment of electrode implantation. The most important alterations in the cerebellar cortex were adhesions round the electrodes, with a scarring reaction, gliosis, and loss of Purkinje cells. These findings resemble those described in various experimental reports of chronic cerebellar stimulation.