a double-blind controlled trial of cerebellar stimulation in severe intractable epilepsy

Epileptic seizures probably terminate through a combination of neuronal fatigue and active inhibition. There is evidence that the cerebellum, along with other structures, may have such an inhibitory role. Animal work and human studies have suggested that electrical stimulation of the cerebellum can suppress or terminate seizure activity. In addition, the EEG and cortical evoked potentials can be modified and neurotransmitter levels in the CFS may be altered by cerebelllar stimulation. This study examined the effect of chronic cerebellar stimulation in twelve patients with severe and intractable epilepsy. Following implantation of the stimulation equipment, two-month phases of continuouse and contingent stimulation were compared with a phase of no stimulation in each patient. The trial was carried out and the results analysed double blind. Patients were assessed clinically with the help of fit charts. Psychometric testing was used to detect changes in cognitive function and ambularoty EEG monitoring was carried out as a measure of subclinical epileptogenic activity. CSF was analysed and neurotransmitter levels were measured. An examination was made of the acute effects of short bursts of cerebellar stimulation on the EEG and evoked potentials. There were no significant changes in the fit frequency and no objective psychological changes were found although eleven of the patients felt better as a result of cerebellar stimulation. Reduction in the amplitude of somatosensory evoked potentials occurred in some patients. A small but significant rise in CSF occurred during continuous stimulation but no changes were detected in CSF neurotransmitter levels. One patient died after the trial had finished and the post mortem findings are discussed in relation to implanted electrical stimulating devices.