Movement and reaction times and fine coordination tasks following pallidotomy.
The effect of a unilateral, microelectrode-guided lesion in the globus pallidum internum (GPi) was evaluated in 41 patients (21 women) with moderately advanced Parkinson's disease (PD). The mean age was 60.3+/-9.0 years (range, 40-74) and the mean symptom duration was 14.7+/-5.3 years (range, 4-25). In addition to clinical ratings, movement time (MT) and reaction time (RT) tests were performed at baseline and 3 months after surgery during the "practically defined off" state (more than 12 hours after the last dose of levodopa). Improvement occurred bilaterally with more robust and statistically significant improvement on the contralateral side in all RT tests. Simple reaction time (SRT) improved by 14.5% (p<0.001) and the choice reaction time (CRT) by 12.2% (p<0.001) when the arm contralateral to the pallidotomy side was tested. There was a trend toward improvement in the ipsilateral arm. The MT, determined by repetitive movement between two adjacent targets, improved by 24% contralaterally (p<0.0001) and by 12% ipsilaterally (p<0.005). In addition, the Purdue Pegboard (PP) test scores, used to evaluate hand dexterity, improved on the contralateral side by 35.5% (p<0.0002) but there was no statistically significant ipsilateral improvement. To the extent that MT and RT are quantitative measures of bradykinesia, our study provides evidence that this parkinsonian feature improves after pallidotomy.