The effects of pallidotomy on Parkinson's disease: study design and assessment techniques

Lesions of the internal segment of the globus pallidus are increasingly being utilized in the surgical treatment of advanced Parkinson's disease, yet studies to demonstrate the safety and efficacy of these procedures are only now being completed. The importance of procedural variations between centres in the outcome of pallidotomy is not yet known. In order to compare accurately results between centres, carefully designed, prospective studies are needed. The authors utilized blinded, randomly evaluated videotaped examinations of pre- and post-operative patients undergoing microelectrode-guided GPi pallidotomy. Their results demonstrate significant effects on contralateral akinesia and tremor in the "off" state, and striking attenuation of levodopa-induced dyskinesias in the "on" state. More modest effects on postural stability and gait disturbance were seen only in non-blinded evaluations. This type of study design should enable many of the outstanding issues related to pallidotomy indications, procedures and outcomes to be addressed.