Cerebellar Implant Studies

Electrical currents were applied to the cerebellum of anesthetized monkeys using techniques similar to those employed in human cerebellar electrode implant systems. Alterations in the bloodbrain barrier were not observed. Histological damage, when present, appeared secondary to mechanical injury rather than to application of current. Measurement of current density in the monkey and human cerebellum indicated that with the electrode configuration employed, most of the current is retained in the vicinity of the electrodes. In human patients with spasticity and dyskinesia, application of current through implanted cerebellar electrode units relieves spasticity and also has been associated with reduction of somatosensory evoked potential amplitude. The amount of current required for clinical improvement and for alteration of evoked potential amplitude has remained stable in all patients, even those followed for more than a year. These observations suggest that the methods described do not produce appreciable cerebellar damage.