Flexible vs. standard subthalamic stimulation in Parkinson disease: A double-blind proof-of-concept cross-over trial

BackgroundDeep brain stimulation (DBS) of the subthalamus (STN) is effective for the treatment of cardinal motor signs of Parkinson disease (PD). Structures around the STN can suppress dyskinesia and tremor (zona incerta) and improve gait and balance (substantia nigra pars reticulata).ObjectiveIs the newer 8-contact linear lead connected to a ‘flexible’ DBS system superior to standard 4-contact stimulation in PD patients receiving STN DBS?MethodsAfter 3 months of open label programming, 10 patients were randomized to standard or flexible stimulation before crossing over to the other arm (3 months each period). Patients and assessors were blinded.ResultsA trend to improvement in Patient Global Impression of Change scores was seen with standard to flexible stimulation and worsening from flexible to standard stimulation (mean ± SD: 0.7 ± 1.2 and ?0.4 ± 1.5 respectively, p = 0.152). There was a significant reduction in the number of troublesome symptoms reported prior to DBS (2.6 ± 3.3 per patient), more so with flexible stimulation (0.4 ± 0.6 vs. 1.5 ± 1.6 with standard stimulation, p = 0.001 and p = 0.034). There was no significant difference between the flexible and standard stimulation groups.ConclusionFurther studies confirming that flexible stimulation is superior to standard DBS are warranted.