Reaction time and movement time after embryonic cell implantation in Parkinson disease.

Background: Embryonic nigral cell implants are a novel treatment for Parkinson disease (PD). Reaction time (RT) and movement time (MT) analysis, validated quantitative measures of premovement neural processing and motor execution, can be used as objective physiological markers of motor performance in PD.

Objectives: To gauge the change in motor performance in patients with PD who received implants, and to determine whether the physiological findings correlate with clinical outcome measures after transplantation.

Design: Double-blind, placebo-controlled trial. Patients Forty patients with levodopa-responsive, Hoehn and Yahr stage III or greater PD.

Interventions: Random assignment to embryonic tissue implants or placebo (sham) operation.

Main Outcome Measures: Combined RT + MT scores measured preoperatively and at 4 and 12 months postoperatively in the "off" state.

Results: The difference in mean RT + MT scores between the sham and implant groups was statistically significant (P =.005) and was greatest in those 60 years or older (P =.003). Changes correlated with Unified Parkinson's Disease Rating Scale off scores at 4 (r = 0.87, P =.001) and 12 (r = 0.75, P =.01) months in those younger than 60 years. There was a significant deterioration in the sham surgery group at 12 months (P =.03) that was thought to be due to worsening in subjects 60 years and older (P<.001).

Conclusions: The physiological measures detected significant changes in patients undergoing embryonic nigral cell implants and correlated directly with clinical outcome measures. Comprehensive analyses of RT paradigms can document subtle changes in motor performance over time, making them useful outcome measures in therapeutic trials of PD. These findings support further research into nigral cell implantation for PD.