Objective: To report the outcome of a novel interleaving stimulation (ILS) DBS programming paradigm (PP).

Background: DBS of the STN using conventional high frequency (130-185Hz) stimulation (HFS) is more effective in treating appendicular than axial symptoms. In fact, HFS-STN DBS may worsen gait and balance. This could be due to current spread outside the target area (STN) or alternatively HFS may not be the optimal rate for locomotion. Low frequency stimulation (LFS) of the STN has been reported to ameliorate freezing episodes possibly because of the indirect low frequency effect on PPN. However, stimulation at lower frequencies often results in loss of benefit on appendicular symptoms, limiting its clinical usefulness. Medtronic DBS offers an interleaving option which allows delivery of two individual programs on each DBS lead. We took advantage of this option to create a paradigm with two different frequencies.  

Methods: The novel PP (interlink-interleave, IL-IL) consisted of two overlapping LFS programs on each DBS lead, with the overlapping area focused around the optimal electrode contact. Consequently, this area receives HFS which allows for appendicular symptom control, whereas the non-overlapping areas receive LFS to reduce SE, such as dysarthria, and potentially reduce FOG and balance impairment. The amplitude of stimulation was empirically determined by the programmer and the pulse width was left unchanged.  

Results: Thus far 70 PD patients were switched from their optimized conventional HFS settings to the IL-ILS. The majority of patients were stimulated with two bi-polar overlapping programs at (i.e. 0-2+, 1-3+) and the remainder with a combination of mono-polar and bi-polar programs at a frequency of 60-90Hz. 87% of patients remain on the IL-ILS PP after 16 months (range 4-45). Approximately half of this group chose to remain on IL-ILS because of improved dysarthria, balance or gait. The remainder was unable to identify specific improvements, but confirmed their PD symptoms had not deteriorated.

Conclusions: In this preliminary study a significant number of patients chose to remain on IL-ILS because of subjective improvements in balance, gait or dysarthria. Some of those who chose to return to their original HFS settings may have done so before amplitude adjustments had been made. Formal assessment with objective/quantitative outcome measures is under way.  

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MDS Abstracts - https://www.mdsabstracts.org/abstract/a-novel-deep-brain-stimulation-programming-paradigm-for-parkinsons-disease/