Microsubthalamotomy: an immediate predictor of long-term subthalamic stimulation efficacy in Parkinson disease

A microsubthalamotomy (mSTN) effect is commonly described after implantation that improves Parkinson's motor disability and is considered to be an obvious sign of good placement of the definitive electrode within the subthalamic nucleus (STN). There has been no formal study, however, demonstrating whether this mSTN effect can predict the long-term efficacy of STN stimulation in Parkinson Disease. The mSTN effect was defined by the percentage improvement of unified parkinson's disease rating scale (UPDRS III) baseline score assessed the third day morning following STN implantation, after at least a 12 hour withdrawal of dopaminergic treatment and before the programmable pulse generator was switched on. It was assessed in 30 consecutive patients with PD submitted for STN stimulation. Multiple stepwise regression analysis showed that mSTN effect (P = 0.005) and global mean intensity of stimulation (P = 0.004) were accurate independent predictors of the 6-month postoperative UPDRS III motor score improvement in the off-drug/on-stimulation condition.