ABSTRACT
OBJECTIVE: To assess levodopa dose effect on pain thresholds in Parkinson's disease (PD) patients using an experimental nociceptive thermal stimulation. PATIENTS AND METHODS: We evaluated pain thresholds in 20 PD patients treated by dopaminergic drugs. We assessed heat and cold pain thresholds by using 2 different methods (method of limits and method of levels), intensity-response curve and tolerance threshold. Each PD patient was evaluated in two conditions: ON (after administration of leovdopa and OFF (after acute levodopa withdrawal). The order was randomized. RESULTS: The mean age of patients was 652+/-9.9 years and the mean duration was 9.3+/-3.3 years. Heat pain thresholds were statistically higher in ON versus OFF condition using both methods (44.1+/-3,6 degrees C versus 42.3+/-3,1 degrees C, method of levels, p=0.02). Cold pain thresholds were statistically higher in ON versus OFF condition only using method of levels (17.9+/-4,4 degrees C versus 19.6+/-4,2 degrees C, p=0.02). Heat pain tolerance was statistically higher in ON versus OFF condition (21.4+/-21.6 seconds versus 14.7+/-20.3 seconds, p=0.02). CONCLUSION: This study showed that levodopa increased heat and cold pain thresholds and heat pain tolrance in PD patients. This suggests that dopaminergic drugs could have an analgesic effects on PD related pain.
