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IntroductionDeep brain stimulation (DBS) of the subthalamic nucleus (STN) using high-frequency (130–185 Hz) stimulation (HFS) is more effective for appendicular than for axial symptoms. Low-frequency stimulation (LFS) of the STN may reduce gait/balance and speech impairment but can result in worsened appendicular symptoms, limiting its clinical usefulness. A novel dual-frequency paradigm (interleave–interlink, IL–IL) was created in order to reduce gait/balance and speech impairment while maintaining appendicular symptom control in Parkinson’s disease (PD) patients chronically stimulated with DBS.MethodsTwo overlapping LFS programs are applied to each DBS lead, with the overlapping area focused around the optimal electrode contact. As a result, this area receives HFS, controlling appendicular symptoms. The non-overlapping area receives LFS, potentially reducing gait/balance and speech impairment. Patients were separated into three categories based on their chief complaint(s): gait/balance impairment, speech impairment, and/or incomplete PD symptom control. The Clinical- Global Impression of Change scale (CGI-C) was completed retrospectively based on patient/caregiver feedback in patients who remained on IL–IL (at 3 months and at the last follow-up).ResultsSeventy-six patients were switched from optimized HFS to IL–IL. Fifty-five (72%) patients remained on IL–IL after 22 ± 8.7 months. The median (range) CGI-C for gait was 2 (1–5) at 3 months and 3 (1–4) at last follow-up, for dysarthria it was 4 (1–4) at 3 months and 4 (1–5) at last follow-up, and for PD motor it was 2 (1–3) at 3 months and 2 (1–3) at last follow-up.ConclusionA substantial number of patients remained on IL–IL because of subjective improvements in gait/balance, speech, or PD symptoms. A prospective, double-blind, crossover study with objective/quantitative outcome measures is underway.

A BS TRACT: Background: High-frequency (130-185 Hz) deep brain stimulation (DBS) of the subthalamic nucleus is more effective for appendicular than axial symptoms in Parkinson's disease (PD). Low-frequency (60-80 Hz) stimulation (LFS) may reduce gait/balance impairment but typically results in worsening appendicular symptoms. We created a "dual-frequency" programming paradigm (interleave-interlink, IL-IL) to address both axial and appendicular symptoms. In IL-IL, 2 overlapping LFS programs are applied to the DBS lead, with the overlapping area focused on the optimal cathode. The nonoverlapping area (LFS) is thought to reduce gait/balance impairment, whereas the overlapping area (highfrequency stimulation, HFS) aims to control appendicular symptoms. Methods: We performed a randomized, double-blind crossover trial comparing patients' previously optimized IL-IL and conventional HFS paradigms. Each arm was 2 weeks in duration. The primary outcome measure was the patient/caregiver Modified Clinical Global Impression Severity (CGI-S). Secondary outcome measures included blinded motor evaluations, timed tests, patient/caregiver questionnaires, and Personal KinetiGraphs (PKG). Results: Twenty-five patients were enrolled, and 20 completed. The patient/caregiver CGI-S for gait/balance (P = 0.01) and appendicular symptom control (P = 0.001), and the blinded rater MDS-UPDRS-III (−5.22, P = 0.02), CGI-S gait/balance (P = 0.01), and CGI-S speech (P = 0.02) were better while on IL-IL. Scores on Parkinson's Disease Quality of Life (P = 0.002) and Freezing-of-Gait Questionnaires (P = 0.04) were better on IL-IL. The Timed-Up-and-Go was 9.8% faster (P = 0.01), with 11.8% reduction in steps (P = 0.001) on IL-IL. There was no difference in PKG bradykinesia (P = 0.18) or tremor (P = 0.23) between paradigms. Conclusions: Our results prompt consideration of this novel programming paradigm (IL-IL) for PD patients with axial symptom impairment as a new treatment option for both axial and appendicular symptoms.

Bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) is an effective and proven treatment option for patients with advanced Parkinson’s disease (PD). Long-term outcomes (>5 years) have demonstrated sustained improvement in objective motor symptoms; however, few studies have evaluated patient-centered outcomes other than quality of life (QOL). A locally developed DBS-patient-centered outcomes questionnaire was administered to PD patients >5 years post-DBS. All questions were scored on a ten-point scale, whereby 0 represented the most ‘positive’ answer and 10 the most ‘negative’ answer. Pre-operative scales were repeated at the time of survey. Fifty-two patients (mean 8.2 ± 2.6 years post-DBS) were included. Satisfaction was high with median score (range) of 1/10 (0–8) at the time of survey. Patients endorsed having made the correct decision by undergoing DBS, with a score of 0 (0–10), would choose to have DBS again, with a score of 0 (0–10), and would recommend DBS to others, with a score of 0 (0–10). Pre-operative expectation target was set at a high level with a score of 2 (0–10). Parkinson’s Disease QOL (PDQ-39) Questionnaire Summary Index (SI) scores were, mean (SD), 2.1 (18.2) above baseline (p = 0.44). Those with worsening in PDQ-39-SI scores had less satisfaction with DBS (rs = 0.57, p ≤ 0.0001). This is the first study to assess long-term patient satisfaction with STN DBS. We are currently collecting data prospectively to confirm the results of these preliminary findings.

Lead edema is a rare complication after DBS surgery. It is important to recognize the benign clinical course of DBS lead edema to counsel patients and avoid unnecessary treatment such as hardware removal.