Efficacy, stability and predictors of outcome of pallidotomy for Parkinson's disease. Six-month follow-up with additional 1-year observations.

We tested the efficacy, stability and predictors of outcome of unilateral pallidotomy used to treat patients with Parkinson's disease inadequately controlled with pharmacotherapy (IP). The surgical procedure was as simple as possible; we used CT rather than MRI, and we omitted microelectrode recording. We studied 24 patients with IP; 22 of these patients had drug-induced dyskinesias. There was a significant and stable improvement in all the major parkinsonian motor signs in the OFF (medication) state on the contralateral side. In the ON (medication) state peak-dose dyskinesias were alleviated on the contralateral side. The only significant and stable change on the ipsilateral side was improvement in dyskinesias less marked than on the contralateral side. The improvement in Unified Parkinson's Disease Rating Scale motor scores in the OFF state increased with age. The improvement in total dyskinesia scores occurred irrespective of age, but increased with duration of disease, duration of dyskinesias and baseline severity of dyskinesias. Five patients had transient neurological complications while facial paresis was permanent in one subject. Our results are similar to those obtained by others who used the time consuming microelectrode recording technique for localization. By simplifying the procedure in the way that we describe, the operation could become available to a greater number of patients.