Intraoperative test stimulation of the subthalamic nucleus aids postoperative programming of chronic stimulation settings in Parkinson's disease.

BACKGROUND: It is unknown whether intraoperative testing during awake Deep Brain Stimulation (DBS) of the subthalamic nucleus (STN) can be used to postoperatively identify the best settings for chronic stimulation. OBJECTIVE: To determine whether intraoperative test stimulation is indicative of postoperative stimulation results. METHODS: Records of consecutive Parkinson's Disease patients who received STN DBS between September 2012 and December 2017 were retrospectively analyzed. The best depth identified after intraoperative stimulation via the microelectrode's stimulation tip was compared with the depth of the contact selected for chronic stimulation after a standard monopolar contact review. Moreover, thresholds for induction of clinical effects (optimal improvement of rigidity and induction of side-effects) were compared between stimulation at the postoperatively selected contact and at the corresponding intraoperative depth. RESULTS: Records of 119 patients were analyzed (mean (SD) age 60.5 (6.5) years, 31.9% female, 238 STNs). In 75% of cases, the postoperatively selected contact corresponded with the intraoperative depth with the largest therapeutic window or was immediately dorsal to it. Higher stimulation intensities were required postoperatively than intraoperatively to relieve rigidity (p = 0.002) and induce capsular side-effects (p = 0.016). CONCLUSION: In the majority of cases, the postoperative contact for chronic stimulation was at a similar level or immediately dorsal with respect to the identified best intraoperative depth. Postoperatively, relief of rigidity and induction of capsular side-effects occur at higher stimulation intensities than during intraoperative test stimulation.

Stimulation challenge test after STN DBS improves satisfaction in Parkinson's disease patients.

OBJECTIVE: Although subthalamic Deep Brain Stimulation (STN DBS) is proven effective in improving symptoms of Parkinson's Disease (PD), previous literature demonstrates a discrepancy between objective improvement and patients' perception thereof. We aimed to examine whether postoperative stimulation challenge tests (SCT) alters patients' satisfaction after STN DBS for PD. METHODS: Fifty-four PD patients underwent preoperative levodopa challenge tests and were routinely invited for SCT 1-2 years postoperatively. SEverity of predominantly Nondopaminergic Symptoms in PD (SENS-PD) scores quantified non-dopaminergic disease severity. Motor functioning was quantified using Movement Disorders Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) III scores; a ratio between conditions ON and OFF (preoperative Med-ON vs. Med-OFF, and postoperative Med-ON/Stim-ON vs. Med-OFF/Stim-OFF) reflected treatment benefit. 'Global Impression of Change' (GIC) and 'Global Satisfaction with Surgery' (GSS) Likert scales were filled out before and immediately after SCT. RESULTS: Postoperative Med-ON/Stim-ON severity was lower than preoperative ON severity. Disease severity scores were not different between assessments. GIC and GSS scores were higher after SCT versus before (GIC: Z = -3.80, r = 0.37, subjects indicating maximum scores before SCT: 32.1%, after SCT: 57.1%; GSS: Z = -3.69, r = 0.35, maximum scores before SCT: 25.0%, after SCT: 46.4%). Higher non-dopaminergic disease severity was associated with lower GIC and GSS scores (GIC: OR 1.2 (95%CI 1.0-1.3); GSS: OR 1.2 (95%CI 1.1-1.3), while motor-scores and magnitude of DBS-effects were not. CONCLUSION: SCT improves patients' satisfaction and is recommended especially in case of suboptimal subjective valuations. This information should be considered in clinical practice and in the context of clinical trials.