GLOBUS-PALLIDUS INTERNUS PALLIDOTOMY FOR GENERALIZED DYSTONIA

The authors present a young boy with severe generalized dystonia treat ed with bilateral simultaneous pallidotomy. Microelectrode recordings with the patient under propofol anesthesia showed that the mean discha rge rate of globus pallidus internus (GPi) neurons was between 21 and 31 Hz. This contrasts sharply with the mean GPi neuronal firing rates of approximately 80 Hz that are characteristic of Parkinson's disease. The patient had no immediate benefit from surgery, but a progressive improvement in both axial and limb dystonia began within 3 days. The B urke-Fahn-Marsden scores were 75 (maximum possible = 120) at baseline, 52 at 5 days, and 16 at 3 months after surgery. The mechanism of acti on of pallidotomy for dystonia and the reasons for the delayed and pro gressive improvement are unknown. Nevertheless, the magnitude of the i mprovement and the safety of the procedure in this one patient warrant a careful evaluation of pallidotomy for dystonia.