Search

BACKGROUND Directional deep brain stimulation (DBS) allows for steering of the stimulation field, but extensive and time-consuming testing of all segmented contacts is necessary to identify the possible benefit of steering. It is therefore important to determine under which circumstances directional current steering is advantageous. METHODS Fifty two Parkinson's disease patients implanted in the STN with a directional DBS system underwent a standardized monopolar programming session 5 to 9 months after implantation. Individual contacts were tested for a potential advantage of directional stimulation. Results were used to build a prediction model for the selection of ring levels that would benefit from directional stimulation. RESULTS On average, there was no significant difference in therapeutic window between ring-level contact and best directional contact. However, according to our standardized protocol, 35% of the contacts and 66% of patients had a larger therapeutic window under directional stimulation compared to ring-mode. The segmented contacts warranting directional current steering could be predicted with a sensitivity of 79% and a specificity of 57%. CONCLUSION To reduce time required for DBS programming, we recommend additional directional contact testing initially only on ring-level contacts with a therapeutic window of less than 2.0 mA.

BACKGROUND The landscape of neurophysiological symptoms and behavioral biomarkers in basal ganglia signals for movement disorders is expanding. The clinical translation of sensing-based deep brain stimulation (DBS) also requires a thorough understanding of the anatomical organization of spectral biomarkers within the subthalamic nucleus (STN). OBJECTIVES The aims were to systematically investigate the spectral topography, including a wide range of sub-bands in STN local field potentials (LFP) of Parkinson's disease (PD) patients, and to evaluate its predictive performance for clinical response to DBS. METHODS STN-LFPs were recorded from 70 PD patients (130 hemispheres) awake and at rest using multicontact DBS electrodes. A comprehensive spatial characterization, including hot spot localization and focality estimation, was performed for multiple sub-bands (delta, theta, alpha, low-beta, high-beta, low-gamma, high-gamma, and fast-gamma (FG) as well as low- and fast high-frequency oscillations [HFO]) and compared to the clinical hot spot for rigidity response to DBS. A spectral biomarker map was established and used to predict the clinical response to DBS. RESULTS The STN shows a heterogeneous topographic distribution of different spectral biomarkers, with the strongest segregation in the inferior-superior axis. Relative to the superiorly localized beta hot spot, HFOs (FG, slow HFO) were localized up to 2 mm more inferiorly. Beta oscillations are spatially more spread compared to other sub-bands. Both the spatial proximity of contacts to the beta hot spot and the distance to higher-frequency hot spots were predictive for the best rigidity response to DBS. CONCLUSIONS The spatial segregation and properties of spectral biomarkers within the DBS target structure can additionally be informative for the implementation of next-generation sensing-based DBS. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for advanced Parkinson's disease. Stimulation of the hyperdirect pathway (HDP) may mediate the beneficial effects, whereas stimulation of the corticospinal tract (CST) mediates capsular side effects. The study's objective was to suggest stimulation parameters based on the activation of the HDP and CST. This retrospective study included 20 Parkinson's disease patients with bilateral STN DBS. Patient-specific whole-brain probabilistic tractography was performed to extract the HDP and CST. Stimulation parameters from monopolar reviews were used to estimate volumes of tissue activated and to determine the streamlines of the pathways inside these volumes. The activated streamlines were related to the clinical observations. Two models were computed, one for the HDP to estimate effect thresholds and one for the CST to estimate capsular side effect thresholds. In a leave-one-subject-out cross-validation, the models were used to suggest stimulation parameters. The models indicated an activation of 50% of the HDP at effect threshold, and 4% of the CST at capsular side effect threshold. The suggestions for best and worst levels were significantly better than random suggestions. Finally, we compared the suggested stimulation thresholds with those from the monopolar reviews. The median suggestion errors for the effect threshold and side effect threshold were 1 and 1.5 mA, respectively. Our stimulation models of the HDP and CST suggested STN DBS settings. Prospective clinical studies are warranted to optimize tract-guided DBS programming. Together with other modalities, these may allow for assisted STN DBS programming.

OBJECTIVE Decompressive hemicraniectomy (DCE) is the standard of care for space-occupying malignant infarction of the medial cerebral artery in suitable patients. After DCE, the brain is susceptible to trauma and at risk for the syndrome of the trephined. This study aimed to assess the feasibility of using temporary space-expanding flaps, implanted during DCE, to shield the brain from these risks while permitting the injured brain to expand. METHODS The authors performed a prospective feasibility study to analyze the safety of space-expanding flaps in 10 patients undergoing DCE and evaluated clinical and radiological outcomes. RESULTS The relatives of 1 patient withdrew consent, leaving 9 patients in the final analysis. No patients required removal of the space-expanding flap because of uncontrolled increase of intracranial pressure or infection. One patient required additional external ventricular drainage and 1 received mannitol. The mean (range) midline shift decreased from 6.67 (3–12) mm to 1.26 (0–2.6) mm after DCE with the space-expanding flap. The authors observed no cases of sinking skin flap syndrome, other complications, or deaths. One patient underwent further treatment due to infection of the reimplanted autologous bone flap. Two patients later refused cranioplasty, preferring to keep the space-expanding flap and thus avoid the potential risks of cranioplasty. CONCLUSIONS This feasibility study showed that the concurrent use of space-expanding flaps appeared to be safe in patients who underwent DCE for malignant infarction of the medial cerebral artery. Moreover, space-expanding flaps may permit patients to avoid a second surgery for reimplantation of the autologous bone flap and the risks inherent to this procedure.

Deep brain stimulation is an effective neurosurgical intervention for movement disorders such as Parkinson's disease. Despite its success, the underlying mechanisms are still debated. One tool to better understand them is the Volume of Tissue Activated (VTA), that estimates the region activated by electrical stimulation. Different estimation approaches exist, these typically assume isotropic tissue properties and modelling of anisotropy is often lacking.The present work was aimed at developing and testing a method for patient-specific VTA estimation that incorporated an anisotropic conduction model. Our method was implemented within the open-source toolbox Lead-DBS and is accessible to the public.The present method was further tested with two patient cases and compared to a standard Lead-DBS pipeline for VTA estimation. This showed encouraging similarities in one test scenario and expected differences in another test scenario. Further validation with a wider cohort is warranted.

BACKGROUND Different deep brain stimulation (DBS) targets have been suggested as treatment for patients with pharmacologically refractory Holmes tremor (HT). We report the clinical and quality of life (QoL) long-term (up to nine years) outcome in four patients with HT treated with DBS (in thalamic ventral intermediate nucleus-VIM or in dentato-rubro-thalamic tract-DRTT). MATERIALS AND METHODS The patients underwent routine clinical evaluations before and after DBS (typically annually). Tremor severity and activities of daily living (ADL) were quantified by the Fahn-Tolosa-Marin Tremor-Rating-Scale (FTMTRS). QoL was assessed using the RAND SF-36-item Health Survey (RAND SF-36). In addition, we computed, in all four patients, the VTA based on the best stimulation settings using heuristic approaches included in the open source toolbox LEAD-DBS. RESULTS In all patients, tremor and ADL improved significantly at one-year post-DBS follow-up (34-61% improvement in FTMTRS total score compared to baseline). In three out of four patients, the improvement of tremor was sustained no longer than two to three years and only in one patient was sustained up to nine years. In this patient, the largest intersection between VTA and DBS target has been observed. Scores for ADL deteriorated over the course of time, reaching worse levels compared to baseline already during the three-year post-DBS follow-up, in three out of four patients. Physical and mental health component scores of RAND SF-36 had very different outcome between patients and follow-ups and were not associated with tremor-related outcomes. CONCLUSIONS The benefits of DBS in HT might not be always long lasting. Although QoL slightly improved, this change seemed to be independent of the motor outcome following DBS. The estimation of DBS target and VTA proximity could be a useful tool for DBS clinicians in order to facilitate the DBS programming process and optimize DBS treatment.

OBJECTIVE Deep brain stimulation (DBS) is a treatment option for refractory chronic cluster headache (CCH). Despite several recent prospective case series reporting a good outcome, the effectiveness and the optimal stimulation target of DBS for CCH remain unclear. We aimed to obtain precise estimates and predictors of long-term pain relief in an individual patient data meta-analysis. Furthermore, we aimed to construct a probabilistic stimulation map of effective DBS. METHODS We invited investigators of published cohorts of patients undergoing DBS for CCH, identified by a systematic review of MEDLINE from inception to Febuary 15, 2019, to provide individual patient data on baseline covariates, pre- and postoperative headache scores at median (12-month) and long-term follow-up, in addition to individual imaging data to obtain individual electrode positions. We calculated a stimulation map using voxel-wise statistical analysis. We used multiple regression analysis to estimate predictors of pain relief. RESULTS Among 40 patients from four different cohorts representing ~50% of all previously published cases, we found a significant 77% mean reduction in headache attack frequency over a mean follow-up of 44 months, with an overall response rate of 75%. Positive outcome was not associated with baseline covariates. We identified 2 hotspots of stimulation covering the midbrain ventral and retrorubral tegmentum. INTERPRETATION This study supports the hypothesis that DBS provides long-term pain relief for the majority of CCH patients. Our stimulation map of the region of influence of therapeutic DBS identified an optimal anatomical target site that can help surgeons to guide their surgical planning in the future. ANN NEUROL 2020.

Supplemental Material for Deep brain stimulation of chronic cluster headaches: Posterior hypothalamus, ventral tegmentum and beyond by Andreas Nowacki, Liz Moir, Sarah LF Owen, James J Fitzgerald, Alexander L Green and Tipu Z Aziz in Cephalalgia

Objective: Chronic subdural hematoma (CSH) have high recurrence rates after surgical evacuation. Routine post-surgical CT scans often show substantial residuals, although the value of those scans to predict later symptomatic recurrences is questionable. Methods: The aim of the trial was to assess[for full text, please go to the a.m. URL], 69. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Mexikanischen und Kolumbianischen Gesellschaft für Neurochirurgie

BACKGROUND: Although recently introduced directional DBS leads provide control of the stimulation field, programing is time-consuming.OBJECTIVES: Here, we validate local field potentials recorded from directional contacts as a predictor of the most efficient contacts for stimulation in patients with PD.METHODS: Intraoperative local field potentials were recorded from directional contacts in the STN of 12 patients and beta activity compared with the results of the clinical contact review performed after 4 to 7 months.RESULTS: Normalized beta activity was positively correlated with the contact's clinical efficacy. The two contacts with the highest beta activity included the most efficient stimulation contact in up to 92% and that with the widest therapeutic window in 74% of cases.CONCLUSION: Local field potentials predict the most efficient stimulation contacts and may provide a useful tool to expedite the selection of the optimal contact for directional DBS. © 2017 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.