Interleaving Stimulation in Parkinson Disease: Interesting to Whom?

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.

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.

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

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.

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.