Sub-acute delayed failure of subthalamic DBS in Parkinson's disease: The role of micro-lesion effect

ObjectiveTo study delayed failure after subthalamic nucleus (STN) deep brain stimulation in Parkinson's disease (PD) patients.MethodsOut of 56 consecutive bilaterally STN-implanted PD patients, we selected subjects who, after initial clinical improvement (⩾1 month after surgery), lost benefit (delayed failure, DF).ResultsFive patients developed sub-acutely severe gait disorders (DF). In 4/5 DF patients, a micro-lesion effect, defined as improvement without stimulation, was observed; immediate post-operative MRI demonstrated electrode located above or behind to the STN.ConclusionsPatients presenting micro-lesion effect should be carefully monitored, as this phenomenon can mask electrodes misplacement and evolution in DF.