Basal ganglia neuronal discharge in primary and secondary dystonia in patients undergoing pallidotomy

Basal ganglia neuronal activity in patients undergoing posteroventral pallidotomy (PVP) for the treatment of primary genetic, secondary, or idiopathic dystonia (DYS) was studied to gain a better understanding of the pathophysiology of DYS.

Intraoperative neurophysiological data recorded from 15 DYS patients were compared with those from 78 patients with Parkinson's disease (PD) who underwent PVP.

Putamen neurons in both DYS and PD patients had low discharge rates. Globus pallidus externa (GPe) and globus pallidus interna (GPi) neurons in DYS patients had significantly lower discharge rates and more irregular discharge patterns than in PD patients. GPe and GPi neurons displayed similar discharge rates and patterns in DYS, whereas in PD, the discharge rate of GPe neurons was lower than that of the GPi neurons. The discharge rate and pattern of GPe and GPi neurons in patients whose DYS was ameliorated by PVP were similar to those in DYS patients who did not benefit from PVP. No significant differences in the rate or pattern of neuronal discharge in patients with DYS of different causes were discernible. PVP was most beneficial in patients with primary genetic DYS. Anesthesia with desflurane depressed the discharge rate of the GPe and GPi neurons, particularly in patients with PD.

Significant differences in the rates and patterns of discharge of GPe and GPi neurons exist in DYS and PD. The findings are discussed with reference to the current model of the functional connections of the basal ganglia.