Cerebellar stimulation for spastic cerebral palsy: preliminary report; on-going double blind study

To date, June 1, 1986, 33 spastic cerebral palsy (CP) patients have taken part in a double blind study testing the safety and efficacy of chronic cerebellar stimulation (CCS) for reduction of spasticity and improvement in function. Seven U.S. surgical centers involving ten neurosurgeons have implanted the Neurolith 601 cerebellar stimulator supplied by Pacesetter Systems Inc. (Sylmar, CA). A pilot study was run with three patients at Stanford University (Stanford, CA) using taped-on real (strong) and dummy (weak) magnets to control the ON-OFF status. Following the pilot study, a magnetically controllable switch was placed in line between the Neurolith stimulator and the cerebellar lead to allow more reliable switching sequences for the study. The test battery included joint angle measurements (passive and active), motor performance testing, reaction time, hand dynamometry, grooved peg board placement, hand/foot tapping, and rotary pursuit testing. Testing only was done at presurgery. Testing and ON-OFF switching was performed following recovery from surgery and at one, two, and four months. After four months, the switch was left turned ON. Of the 30 patients using the implanted switch, 11 were dropped from the study and seven are still in progress. Of the 11 dropped from the study, four were due to switch problems and three were due to double blind protocol violations, i.e., the participants discovered the stimulus status. The remaining four were removed because of a broken lead, infection, or unrelated medical problems, or refusal to participate after implant. A preliminary analysis indicated that three-quarters of the patients have a demonstrable quantitative improvement during the time the stimulation was "ON." Three patients showed no significant change.