Posteroventral pallidotomy for advanced Parkinson's disease

Provoked by the limitations and late complications of levodopa therapy, the advances in stereotactic surgery, and better understanding of the pathophysiology of the basal ganglia, the role of pallidotomy in the treatment of advanced Parkinson's disease (PD) has been revived.

We included 11 patients with advanced PD, who had a good response to levodopa but had late complications of motor fluctuation and severe dyskinesia. The internal globus pallidus was identified with computed tomography prior to posteroventral pallidotomy and it was reaffirmed by microelectrode recording during surgery. Clinical evaluations were carried out in both the "on" and "off" motor periods at baseline and at 1 week, 3 months, 6 months and 1 year postoperatively. Repeated measures ANOVA followed by multiple comparisons were used for statistical analysis.

Dyskinesia improved bilaterally but only significantly in the contralateral limbs. This benefit was sustained up to 1 year. Parkinsonism, particularly contralateral tremor and rigidity, improved in the "off" motor period but not in the "on" motor period. The average Unified Parkinson's Disease Rating Scale motor score was reduced 36% at 3 months and 26% at 1 year in the "off" motor period. Both of the mean Hoehn and Yahr staging and Schwab and England activities of daily living score improved in "off" motor period. Improvement in parkinsonism, however, did not reach a significant level. Mild dysarthria and unstable gait were observed temporarily in 2 patients. Mild weakness in the contralateral limbs was found in 1 patient.

Unilateral pallidotomy guided by microelectrode recording is helpful for severe levodopa-induced dyskinesia in advanced PD. Contralateral parkinsonian disabilities also improve in the "off" motor period.