Interleaving Stimulation in Parkinson Disease: Interesting to Whom?

Background: Interleaving stimulation (ILS) is a stimulation strategy that can help the physician manage more challenging cases of patients with deep brain stimulation (DBS) for Parkinson disease (PD). It consists of altering 2 different programs on the electrode with the same frequency.

Objectives: Our objective was to overview our patients' experience with ILS and explore clinical scenarios in which ILS should be considered when programming DBS in patients with PD.

Methods: We retrospectively reviewed medical charts from 120 patients with PD treated with DBS between 2011 and 2018.

Results: Eighteen patients received ILS. One was excluded because of the medical chart was incomplete. The remaining 17 patients had subthalamic nucleus DBS (n = 14) and globus pallidus internus DBS (n = 3). Eight patients (47%) received ILS to improve rigidity and bradykinesia, 4 to improve dyskinesias, 4 because of refractory tremor, and 1 for gait management. Until the end of data collection, 13 of 17 patients (70%) were still on ILS, with a mean duration time of 28.8 months (range, 2-44 months). Four patients reported no benefit from ILS and had their program changed.

Conclusions: Overall, ILS is useful 1) to use 2 contacts that optimally improve 2 specific symptoms but have different therapeutic windows; 2) to avoid side effects related to current spreading to nearby areas; 3) to increase frequency in a small region; or 4) to stimulate a larger target area.