Objective: To compare the range of stimulation amplitudes that can relieve symptoms without side effects, between directional and omnidirectional DBS.

Background: Published reports on directional DBS have been limited to small single-center investigations. Therapeutic window (TW) has been introduced in DBS to describe the range of stimulation amplitudes achieving symptom relief without side effects. The PROGRESS study evaluated whether directional DBS provides a wider TW in a large prospective trial.

Method: Participants receiving STN DBS for Parkinson’s disease were programmed with omnidirectional stimulation for 3 months, followed by directional stimulation for 3 months. The subject was blinded to stimulation type and a blinded evaluator assessed TW and motor symptoms. The primary endpoint was based on blinded off-medication evaluation of TW for directional vs. conventional stimulation at 3 months. Additional endpoints at 3, 6 and 12 months included adverse events, subject and clinician stimulation preference, therapeutic current strength (TCS), medication reduction, quality of life and UPDRS part III motor score.

Results: A directional DBS system was implanted in 234 subjects (62±8 years, 33% female). At 3 months, TW was wider using directional stimulation in 90.6% of subjects, satisfying the primary endpoint for superiority (p<0.001). The mean increase in TW with directional stimulation was 41% (2.98±1.38mA, compared to 2.11±1.33mA for omnidirectional, p<0.001). UPDRS part III motor score on medication was improved with either stimulation at each time point (p<0.001). After 6 months, 53% of subjects blinded to stimulation type (102/193) preferred the period with directional stimulation, 26% (50/193) preferred the omnidirectional period and 21% (41/193) had no preference. The directional period was preferred by 59% of clinicians (113/193) vs. 21% (41/193) who preferred the omnidirectional period. Additional results including 12-month data will be available.

Conclusion: A double-blind randomized comparison of directional and omnidirectional stimulation found that 90.6% of subjects had a wider TW using directional stimulation. There were improvements in the minimum amplitude required to achieve therapeutic benefit and the side effect threshold, leading to a 40% wider TW. For the first time, we demonstrated superiority of TW for directional stimulation over omnidirectional stimulation.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/directional-versus-omnidirectional-deep-brain-stimulation-results-of-a-multicenter-prospective-blinded-crossover-study/