We read with interest the comments from Drs Minguez-Castellanos and Escamilla-Sevilla regarding dyskinesia threshold among patients participating in their open-label comparison study of pallidal and subthalamic DBS for Parkinson disease,1 in which they found presurgical levodopa dose to be the major predictor of postsurgical motor efficacy. In our study, we found no association of presurgical levodopa dose and improved motor efficacy (Unified Parkinson’s Disease Rating Scale motor or 24-point dyskinesia score) after 12 months of DBS.2 However, we also noted no significant differences in presurgical levodopa dose between the 2 groups, a factor that the letter’s authors correctly identify as a potential confounder. We agree with the authors that larger, randomized studies will be required to detect the important predictors of motor efficacy for a given surgical target. We further believe that measures of the nonmotor effects of DBS and secondary medication adjustments will offer additional insights into the value of this treatment modality.
Hogarth P, Anderson V, Hammerstad J. Pallidal vs Subthalamic Deep Brain Stimulation for Parkinson Disease: Winner and Loser or a Sharing of Honors?—Reply. Arch Neurol. 2005;62(10):1643. doi:10.1001/archneur.62.10.1643-a