Dual threshold neural closed loop deep brain stimulation in Parkinson disease patients

BackgroundClosed loop deep brain stimulation (clDBS) in Parkinson's disease (PD) using subthalamic (STN) neural feedback has been shown to be efficacious only in the acute post-operative setting, using externalized leads and stimulators.ObjectiveTo determine feasibility of neural (N)clDBS using the clinical implanted neurostimulator (Activa? PC + S, FDA IDE approved) and a novel beta dual threshold algorithm in tremor and bradykinesia dominant PD patients on chronic DBS.Methods13 PD subjects (20 STNs), on open loop (ol)DBS for 22 ± 7.8 months, consented to NclDBS driven by beta (13–30 Hz) power using a dual threshold algorithm, based on patient specific therapeutic voltage windows. Tremor was assessed continuously, and bradykinesia was evaluated after 20 min of NclDBS using a repetitive wrist flexion-extension task (rWFE). Total electrical energy delivered (TEED) on NclDBS was compared to olDBS using the same active electrode.ResultsNclDBS was tolerated for 21.67 21.10–26.15] minutes; no subject stopped early. Resting beta band power was measurable and similar between tremor and bradykinesia dominant patients. NclDBS improved bradykinesia and tremor while delivering only 56.86% of the TEED of olDBS; rWFE velocity (p = 0.003) and frequency (p < 0.001) increased; tremor was below 0.15 rad/sec for 95.4% of the trial and averaged 0.26 rad/sec when present.ConclusionThis is the first study to demonstrate that STN NclDBS is feasible, efficacious and more efficient than olDBS in tremor and bradykinesia dominant PD patients, on long-term DBS, using an implanted clinical neurostimulator and driven by beta power with a novel dual threshold algorithm, based on customized therapeutic voltage windows.