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Background: Subthalamic deep brain stimulation (STN-DBS) is a well-established therapy to treat Parkinson's disease (PD). However, the STN-DBS sub-target remains debated. Recently, a white matter tract termed the hyperdirect pathway (HDP), directly connecting the motor cortex to STN, has gained interest as HDP stimulation is hypothesized to drive DBS therapeutic effects. Previously, we have investigated EEG-based evoked potentials (EPs) to better understand the neuroanatomical origins of the DBS clinical effect. We found a 3-ms peak (P3) relating to clinical benefit, and a 10-ms peak (P10) suggesting nigral side effects. Here, we aimed to investigate the neuroanatomical origins of DBS EPs using probabilistic mapping. Methods: EPs were recorded using EEG whilst low-frequency stimulation was delivered at all DBS-contacts individually. Next, EPs were mapped onto the patients’ individual space and then transformed to MNI standard space. Using voxel-wise and fiber-wise probabilistic mapping, we determined hotspots/hottracts and coldspots/coldtracts for P3 and P10. Topography analysis was also performed to determine the spatial distribution of the DBS EPs. Results: In all 13 patients (18 hemispheres), voxel- and fiber-wise probabilistic mapping resulted in a P3-hotspot/hottract centered on the posterodorsomedial STN border indicative of HDP stimulation, while the P10-hotspot/hottract covered large parts of the substantia nigra. Conclusion: This study investigated EP-based probabilistic mapping in PD patients during STN-DBS, revealing a P3-hotspot/hottract in line with HDP stimulation and P10-hotspot/hottract related to nigral stimulation. Results from this study provide key evidence for an electrophysiological measure of HDP and nigral stimulation.

Introduction Differential target multiplexed spinal cord stimulation (DTM SCS) is a new stimulation paradigm for chronic pain management with the aim of modulating glial cells and neurons in order to rebalance their interactions. Animal studies revealed positive effects of this type of stimulation; however, studies in humans are still scarce, pointing towards the need for an evaluation of the effectiveness and safety of DTM SCS in clinical settings. Furthermore, the differential target multiplexed (DTM) algorithm consists of a combination of several programmes, which will presumably consume more energy from the spinal cord stimulation (SCS) battery. Therefore, the objective of DETECT is to investigate the feasibility, effectiveness and safety of DTM SCS in patients with Persistent Spinal Pain Syndrome Type II through a longitudinal cohort study.Methods and analysis DETECT is a prospective multicentre cohort study (n≥250) with a follow-up until 12 months after receiving DTM SCS. The study initiated in October 2021 and is currently still recruiting patients. Self-reporting outcome variables were evaluated at baseline (before SCS) and at 1, 6 and 12 months of DTM SCS. The primary effectiveness endpoint is overall pain intensity, measured with the visual analogue scale. Secondary effectiveness outcome measures are back pain intensity, leg pain intensity, disability, health-related quality of life, pain medication use, functional disability, clinical holistic responder status, self-management, impression of change, work status, pain catastrophising, symptoms of central sensitisation, anxiety, depression and healthcare utilisation. Time spent in different body postures and SCS stimulation parameters will be read out from the pulse generator. The prevalence of technical issues, recharge frequency, (serious) adverse events and the proportion of successful DTM trials will be collected as well. Longitudinal mixed models will be calculated to evaluate the effectiveness of DTM SCS over time.Ethics and dissemination The study protocol was approved by the central Ethics Committee of the Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel (B.U.N.1432021000563) and the Ethics Committees of each participating centre. Research findings will be disseminated to key stakeholders through peer-reviewed publications in scientific journals and presentations to clinical audiences.Trial registration number NCT05068011.

Background & Aims: The goal of treatment in autoimmune hepatitis (AIH) is induction of remission to prevent the development of liver fibrosis, cirrhosis, and its related complications. Various definitions of treatment response and remission have been used. The International Autoimmune Hepatitis Group (IAIHG) recently defined consensus criteria for treatment response. We aimed to validate the IAIHG response criteria in our cohort and establish correlations with survival endpoints. Methods: We performed a retrospective, multicentric cohort study in one tertiary and seven secondary care centres in Belgium. Eligible patients were at least 18 years of age at data collection and were diagnosed with AIH by a simplified IAIHG score of ≥6. Complete biochemical response (CBR) was defined according to the IAIHG consensus criteria as normalisation of transaminases and serum IgG within the first 6 months of treatment. The primary endpoint was liver-related survival – defined as freedom from liver-related death or liver transplantation. Secondary endpoints were overall mortality and transplant-free survival. Outcomes were compared between patients attaining CBR and those with insufficient response. Results: Biochemical response status could be determined in 200 patients with AIH: CBR was achieved in 128 (64.0%) individuals. Patients not achieving CBR more frequently presented with cirrhosis on initial histology (22.2% vs. 10.9%, p = 0.036). Liver-related mortality or liver transplantation as a primary outcome occurred in 26 patients (13.0%). Patients achieving CBR exhibited superior liver-related (hazard ratio 0.118; 95% CI 0.052-0.267; p

Background: To maximize clinical benefit and minimize stimulation-induced side effects, optimising deep brain stimulation (DBS) parameters is paramount. Recent literature suggests a potential benefit of short pulse width DBS (spDBS; ≤40 μs) over conventional pulse width DBS (cDBS; ≥60 μs) in movement disorders. Objective: To compare therapeutic window (TW), therapeutic and side effects and energy consumption of spDBS and cDBS in movement disorders. Methods: We systematically searched Medline, Embase, Cochrane Library and Web of Science. Appropriate paired analyses were performed. Results: Nine Parkinson's disease (PD) (143 patients), 4 essential tremor (ET) (26 patients) and no dystonia studies were included in the meta-analysis. TW defined as therapeutic amplitude range was larger with spDBS vs. cDBS in PD (standardized mean difference (SMD) = -1.04, p

IntroductionSymmetric biphasic pulses have been shown to increase the therapeutic window compared to standard cathodic pulses in ET Vim-DBS patients. Furthermore, three hours of stimulation with biphasic pulses caused less stimulation-induced ataxia compared to cathodic pulses. Therefore, an investigation of the longer-term safety of biphasic pulses is warranted.MethodsSeven ET patients were included in a randomized double-blind, cross-over design of one week home-use of symmetric biphasic stimulation (anodic phase first) versus cathodic stimulation. Amplitude was set in a double-blinded way, at the tremor arrest threshold. The primary outcome was safety assessed by documenting the adverse events. Secondary outcome parameters were stimulation amplitude, tremor (Fahn-Tolosa-Marin Tremor Rating Scale) and ataxia (International Cooperative Ataxia Rating Scale) severity, quality of life (Quality of Life in Essential Tremor Questionnaire) and cognition (Montreal Cognitive Assessment). Three patients continued in the open-label extension phase for 3 months, during which biphasic stimulation-only was further assessed by the same outcome parameters.ResultsDuring the 1 week testing, no adverse effects were reported. To obtain equivalent tremor control, the amplitude of the biphasic pulse was significantly higher compared to that of the cathodic pulse (p = 0.003). The other outcome parameters were not significantly different. During the open-label study, one patient used the remote control to increase the amplitude, leading to two falls caused by stimulation-induced ataxia. No other adverse effects occurred.Discussion and conclusionIn a small cohort, when tested for one week, symmetric biphasic pulses suggest to be safe, but require higher stimulation amplitudes. Further follow-up studies are needed to investigate long-term effects and safety.

Nasal glial heterotopia (NGH), also known as nasal glioma, is a rare congenital malformation in which a mature glial cell mass is found in a location other than the central nervous system. These benign masses are divided into 3groups based on localization: the intranasal, extranasal, and mixed types. Here we present a case study of a young boy with an extranasal-located NGH who underwent surgical resection. Radiological examination is indispensable to differentiate between other midline masses (hemangiomas, dermoid cysts, and encephaloceles). Magnetic resonance imaging should exclude communication with the central nervous system. Computed tomography is used to verify the integrity of the anterior skull base. The proper management of NGH is a complete resection, often by a multidisciplinary approach involving otorhinolaryngology, neurosurgery, and reconstructive surgery.

ObjectiveSubthalamic deep brain stimulation (STN-DBS) is a neurosurgical therapy to treat Parkinson’s disease (PD). Optimal therapeutic outcomes are not achieved in all patients due to increased DBS technological complexity; programming time constraints; and delayed clinical response of some symptoms. To streamline the programming process, biomarkers could be used to accurately predict the most effective stimulation configuration. Therefore, we investigated if DBS-evoked potentials (EPs) combined with imaging to perform prediction analyses could predict the best contact configuration.MethodsIn 10 patients, EPs were recorded in response to stimulation at 10 Hz for 50 s on each DBS-contact. In two patients, we recorded from both hemispheres, resulting in recordings from a total of 12 hemispheres. A monopolar review was performed by stimulating on each contact and measuring the therapeutic window. CT and MRI data were collected. Prediction models were created to assess how well the EPs and imaging could predict the best contact configuration.ResultsEPs at 3 ms and at 10 ms were recorded. The prediction models showed that EPs can be combined with imaging data to predict the best contact configuration and hence, significantly outperformed random contact selection during a monopolar review.ConclusionEPs can predict the best contact configuration. Ultimately, these prediction tools could be implemented into daily practice to ease the DBS programming of PD patients.

Objective: To reveal clinical characteristics of suboptimal responses to deep brain stimulation (DBS) in a multi-country DYT1 dystonia cohort. Methods: In this multi-country multi-center retrospective study, we analyzed the clinical data of DYT1 patients who experienced suboptimal responses to DBS defined as 30% postoperatively; however, secondary worsening of dystonia commenced between 6 months and 3 years following DBS. The improvement at the last follow-up was less than 30% despite optimally-placed leads, a trial of multiple programming settings, and additional DBS surgeries in all patients. The on-/off-stimulation comparison at the long-term follow-up demonstrated beneficial effects of DBS despite missing the threshold of 30% improvement over baseline. Conclusion: Approximately 8% of patients represent a more aggressive phenotype of DYT1 dystonia characterized by younger age at onset, faster disease progression, and cranial involvement, which seems to be associated with long-term suboptimal responses to DBS (e.g., secondary worsening). This information could be useful for both clinicians and patients in clinical decision making and patient counseling before and following DBS implantations. Patients with this phenotype may have different neuroplasticity, neurogenetics, or possibly distinct neurophysiology.

BackgroundOne of the experimental neuromodulation techniques being researched for the treatment of Alzheimer's disease (AD) is deep brain stimulation (DBS). To evaluate the effectiveness of DBS in AD, we performed a systematic review and meta-analysis of the available evidence.MethodsFrom the inception through December 2021, the following databases were searched: Medline via PubMed, Scopus, Embase, Cochrane Library, and Web of Science. The search phrases used were “Alzheimer's disease,” “AD,” “deep brain stimulation,” and “DBS.” The information from the included articles was gathered using a standardized data-collecting form. In the included papers, the Cochrane Collaboration methodology was used to evaluate the risk of bias. A fixed-effects model was used to conduct the meta-analysis.ResultsOnly five distinct publications and 6 different comparisons (one study consisted of two phases) were included out of the initial 524 papers that were recruited. DBS had no impact on the cognitive ability in patients with AD [0.116 SMD, 95% confidence interval (CI), −0.236 to 0.469, p = 0.518]. The studies' overall heterogeneity was not significant (κ2 = 6.23, T2 = 0.053, df = 5, I2 = 19.76%, p = 0.284). According to subgroup analysis, the fornix-DBS did not improve cognitive function in patients with AD (0.145 SMD, 95%CI, −0.246 to 0.537, p = 0.467). Unfavorable neurological and non-neurological outcomes were also reported.ConclusionThe inconsistencies and heterogeneity of the included publications in various target and age groups of a small number of AD patients were brought to light by this meta-analysis. To determine if DBS is useful in the treatment of AD, further studies with larger sample sizes and randomized, double-blinded, sham-controlled designs are required.

Background: Since the inception of DBS, cathodic pulses have been used. Objective: To investigate the effect of anodic and symmetric biphasic pulses on the therapeutic window (TW) in essential tremor (ET) patients. Methods: A randomized, doubled-blinded, cross-over design was used to test the effect of cathodic, anodic and symmetric biphasic pulses (cathode-first and anode-first) on the TW in an acute clinical setting. TW was defined as the difference between the minimal stimulation amplitude provoking side effects and minimal stimulation amplitude inducing tremor arrest. Results: 9 ET patients (10 hemispheres) were included. Anodic stimulation induced a significantly larger TW compared to cathodic stimulation (p = 0.008). Symmetric biphasic stimulation also widened the TW compared to cathodic stimulation for both cathode- (p = 0.047) and anode-first (p = 0.008) biphasic pulses. For both anodic and biphasic pulses, the effect on TW was mainly driven by the change in side effect threshold. The order of the phases in the biphasic pulse had a significant effect on the side effect threshold (p = 0.039), with biphasic-anode first having the highest value. All pulse shapes were safe in the acute setting. Conclusion: Anodic and symmetric biphasic pulses increase TW in ET patients.

BackgroundSubthalamic deep brain stimulation (DBS) is an established therapy to treat Parkinson’s disease (PD). To maximize therapeutic outcome, optimal DBS settings must be carefully selected for each patient. Unfortunately, this is not always achieved because of: (1) increased technological complexity of DBS devices, (2) time restraints, or lack of expertise, and (3) delayed therapeutic response of some symptoms. Biomarkers to accurately predict the most effective stimulation settings for each patient could streamline this process and improve DBS outcomes.ObjectiveTo investigate the use of evoked potentials (EPs) to predict clinical outcomes in PD patients with DBS.MethodsIn ten patients (12 hemispheres), a monopolar review was performed by systematically stimulating on each DBS contact and measuring the therapeutic window. Standard imaging data were collected. EEG-based EPs were then recorded in response to stimulation at 10 Hz for 50 s on each DBS-contact. Linear mixed models were used to assess how well both EPs and image-derived information predicted the clinical data.ResultsEvoked potential peaks at 3 ms (P3) and at 10 ms (P10) were observed in nine and eleven hemispheres, respectively. Clinical data were well predicted using either P3 or P10. A separate model showed that the image-derived information also predicted clinical data with similar accuracy. Combining both EPs and image-derived information in one model yielded the highest predictive value.ConclusionEvoked potentials can accurately predict clinical DBS responses. Combining EPs with imaging data further improves this prediction. Future refinement of this approach may streamline DBS programming, thereby improving therapeutic outcomes.Clinical trial registrationClinicalTrials.gov, identifier NCT04658641.

Background: Parkinson's disease (PD) is a common neurodegenerative disorder that results in movement-related dysfunction and has variable cognitive impairment. Deep brain stimulation (DBS) of the dorsal subthalamic nucleus (STN) has been shown to be effective in improving motor symptoms; however, cognitive impairment is often unchanged, and in some cases, worsened particularly on tasks of verbal fluency. Traditional DBS strategies use high frequency gamma stimulation for motor symptoms (∼130 Hz), but there is evidence that low frequency theta oscillations (5–12 Hz) are important in cognition. Methods: We tested the effects of stimulation frequency and location on verbal fluency among patients who underwent STN DBS implantation with externalized leads. During baseline cognitive testing, STN field potentials were recorded and the individual patients’ peak theta frequency power was identified during each cognitive task. Patients repeated cognitive testing at five different stimulation settings: no stimulation, dorsal contact gamma (130 Hz), ventral contact gamma, dorsal theta (peak baseline theta) and ventral theta (peak baseline theta) frequency stimulation. Results: Acute left dorsal peak theta frequency STN stimulation improves overall verbal fluency compared to no stimulation and to either dorsal or ventral gamma stimulation. Stratifying by type of verbal fluency probes, verbal fluency in episodic categories was improved with dorsal theta stimulation compared to all other conditions, while there were no differences between stimulation conditions in non-episodic probe conditions. Conclusion: Here, we provide evidence that dorsal STN theta stimulation may improve verbal fluency, suggesting a potential possibility of integrating theta stimulation into current DBS paradigms to improve cognitive outcomes.

Subthalamic deep brain stimulation (STN-DBS) is a well-established therapy to treat Parkinson's disease (PD). However, the STN-DBS sub-target remains debated. Recently, a white matter tract termed the hyperdirect pathway (HDP), directly connecting the motor cortex to STN, has gained interest as HDP stimulation is hypothesized to drive DBS therapeutic effects. Previously, we have investigated EEG-based evoked potentials (EPs) to better understand the neuroanatomical origins of the DBS clinical effect. We found a 3-ms peak (P3) relating to clinical benefit, and a 10-ms peak (P10) suggesting nigral side effects. Here, we aimed to investigate the neuroanatomical origins of DBS EPs using probabilistic mapping. EPs were recorded using EEG whilst low-frequency stimulation was delivered at all DBS-contacts individually. Next, EPs were mapped onto the patients' individual space and then transformed to MNI standard space. Using voxel-wise and fiber-wise probabilistic mapping, we determined hotspots/hottracts and coldspots/coldtracts for P3 and P10. Topography analysis was also performed to determine the spatial distribution of the DBS EPs. In all 13 patients (18 hemispheres), voxel- and fiber-wise probabilistic mapping resulted in a P3-hotspot/hottract centered on the posterodorsomedial STN border indicative of HDP stimulation, while the P10-hotspot/hottract covered large parts of the substantia nigra. This study investigated EP-based probabilistic mapping in PD patients during STN-DBS, revealing a P3-hotspot/hottract in line with HDP stimulation and P10-hotspot/hottract related to nigral stimulation. Results from this study provide key evidence for an electrophysiological measure of HDP and nigral stimulation. • Probabilistic mapping is proposed to investigate the origins of EEG-based EPs. • Probabilistic mapping revealed a P3-hotspot/tract indicative of HDP stimulation. • Probabilistic mapping revealed a P10-hotspot/tract indicative of nigral stimulation. • Topographic heat map analysis confirmed the probabilistic mapping analyses. [ABSTRACT FROM AUTHOR]

Introduction: Spinal cord ischaemia (SCI) is a devastating complication of the treatment of thoraco-abdominal aneurysms. Peri-operative cerebrospinal fluid (CSF) drainage, typically using a spinal catheter, is a possible preventive measure. There are no reports or guidelines on peri-operative CSF drainage for this indication in patients with a ventriculoperitoneal (VP) shunt. Report: A single case of a patient suffering SCI after fenestrated endovascular aortic repair for the treatment of a pararenal aneurysm after previous open repair of an infrarenal aortic aneurysm is presented. Despite the presence of a patent VP shunt, elevated CSF pressures were observed after placement of a CSF drain. Discussion: A VP shunt with a gravitational component may drain insufficiently in bedridden patients who often lie with their head tilted on a cushion. In this position, both the differential pressure component and the gravitational component become active, thereby increasing the overall resistance to CSF outflow, hence increasing intracranial and intraspinal pressure. VP shunts with gravitational components should be managed with caution in the setting of prophylactic or therapeutic drainage of CSF to prevent SCI in extensive aortic repair. For reliable CSF pressure monitoring or active drainage in case of symptoms, the insertion of a spinal drain is indicated.

Introduction: Programmable shunt valve settings can sometimes be difficult to assess using classic read-out tools, warranting a skull X-ray. Research question: Can we use available head computed tomography (CT) scans to determine the valve settings, in order to obviate the need for additional skull X-rays? Material and methods: The valve setting of two different programmable shunts (Codman Certas Plus® and Sophysa Polaris®) were assessed by two blinded observers in 24 patients using 65 head CT scans (slice thickness ≤2 ​mm). Using multi-planar reconstruction (MPR) tools, images were resliced according to the direction of the valve, allowing a direct readout of the valve settings. We validated our CT based method against 32 available skull X-rays. Results: For all CT scans it was possible to assess the valve setting. No interobserver variability was found and there was a 100 ​% concordance between the CT based method and skull X-rays. Discussion: CT based assessment of programmable shunt valve settings is feasible and reliable. It may obviate the need for additional skull x-rays when a head CT scan is available. Conclusions: This technique can reduce radiation exposure and can be applied to historical CT imaging with unknown valve settings.

Objective: To reveal clinical characteristics of suboptimal responses to deep brain stimulation (DBS) in a multi-country DYT1 dystonia cohort.Methods: In this multi-country multi-center retrospective study, we analyzed the clinical data of DYT1 patients who experienced suboptimal responses to DBS defined as 30% postoperatively; however, secondary worsening of dystonia commenced between 6 months and 3 years following DBS. The improvement at the last follow-up was less than 30% despite optimally-placed leads, a trial of multiple programming settings, and additional DBS surgeries in all patients. The on-/off-stimulation comparison at the long-term follow-up demonstrated beneficial effects of DBS despite missing the threshold of 30% improvement over baseline.Conclusion: Approximately 8% of patients represent a more aggressive phenotype of DYT1 dystonia characterized by younger age at onset, faster disease progression, and cranial involvement, which seems to be associated with long-term suboptimal responses to DBS (e.g., secondary worsening). This information could be useful for both clinicians and patients in clinical decision making and patient counseling before and following DBS implantations. Patients with this phenotype may have different neuroplasticity, neurogenetics, or possibly distinct neurophysiology.

Currently, the most common surgical treatment for Parkinson's disease is deep brain stimulation (DBS). This treatment strategy is typically reserved for bradykinesia, rigidity and tremor in patients who no longer respond to medication in a predictable manner or who suffer medication-induced dyskinesias. In addition to DBS, ablative procedures like radiofrequency, radiosurgery and focused ultrasound are also utilized for select tremor symptoms. In this review, we discuss evolving surgical techniques, targets, and emerging technology. In addition, we evaluate potential paradigm shifts in treatment, including gene therapy, immunotherapy and cell transplantation. While these new techniques and treatment options are still in their infancy, advances in Parkinson's disease treatment are rapidly expanding.

To maximize clinical benefit and minimize stimulation-induced side effects, optimising deep brain stimulation (DBS) parameters is paramount. Recent literature suggests a potential benefit of short pulse width DBS (spDBS; ≤40 μs) over conventional pulse width DBS (cDBS; ≥60 μs) in movement disorders. To compare therapeutic window (TW), therapeutic and side effects and energy consumption of spDBS and cDBS in movement disorders. We systematically searched Medline, Embase, Cochrane Library and Web of Science. Appropriate paired analyses were performed. Nine Parkinson's disease (PD) (143 patients), 4 essential tremor (ET) (26 patients) and no dystonia studies were included in the meta-analysis. TW defined as therapeutic amplitude range was larger with spDBS vs. cDBS in PD (standardized mean difference (SMD) = -1.04, p < 0.001) and ET (SMD = −0.71, p < 0.001), but the TW in terms of charge per pulse (CPP) did not differ. In PD, no differences were found in therapeutic and side effects (MDS-UPDRS-III, speech and gait, dyskinesia, non-motor symptoms and quality of life). In ET, Fahn-Tolosa-Marin Tremor Rating Scale was lower with spDBS vs. cDBS (SMD = 0.36, p < 0.001). A qualitative analysis suggested fewer stimulation-induced side effects with spDBS. CPP was lower with spDBS vs. cDBS in PD (SMD = 0.79, p < 0.001) and ET (MD = 46.46 nC, p < 0.001), but real-world data on battery longevity are lacking. Although spDBS enlarges the TW as a wider amplitude range in both PD and ET, it does not alter TW defined by CPP. The therapeutic efficacy of spDBS is not different from cDBS in PD, but spDBS apparently induces more tremor reduction in ET. • Short pulse width DBS (spDBS) in movement disorders widens the amplitude-based therapeutic window. • SpDBS in movement disorders does not alter the therapeutic window defined by CPP. • In Parkinson's disease, spDBS seems non-inferior as to therapeutic and side effects. • In essential tremor (ET), spDBS appears superior as to therapeutic and side effects. • Future long-term studies on spDBS should address dystonia, battery longevity and ET habituation. [ABSTRACT FROM AUTHOR]

Since the inception of DBS, cathodic pulses have been used. To investigate the effect of anodic and symmetric biphasic pulses on the therapeutic window (TW) in essential tremor (ET) patients. A randomized, doubled-blinded, cross-over design was used to test the effect of cathodic, anodic and symmetric biphasic pulses (cathode-first and anode-first) on the TW in an acute clinical setting. TW was defined as the difference between the minimal stimulation amplitude provoking side effects and minimal stimulation amplitude inducing tremor arrest. 9 ET patients (10 hemispheres) were included. Anodic stimulation induced a significantly larger TW compared to cathodic stimulation (p = 0.008). Symmetric biphasic stimulation also widened the TW compared to cathodic stimulation for both cathode- (p = 0.047) and anode-first (p = 0.008) biphasic pulses. For both anodic and biphasic pulses, the effect on TW was mainly driven by the change in side effect threshold. The order of the phases in the biphasic pulse had a significant effect on the side effect threshold (p = 0.039), with biphasic-anode first having the highest value. All pulse shapes were safe in the acute setting. Anodic and symmetric biphasic pulses increase TW in ET patients. [Display omitted] • In the acute setting, both anodic and symmetric biphasic pulses are safe in ET patients. • Therapeutic windows are larger with anodic and symmetric biphasic compared to cathodic pulses. • The effects are mostly driven by increasing side effect thresholds. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is a common neurodegenerative disorder that results in movement-related dysfunction and has variable cognitive impairment. Deep brain stimulation (DBS) of the dorsal subthalamic nucleus (STN) has been shown to be effective in improving motor symptoms; however, cognitive impairment is often unchanged, and in some cases, worsened particularly on tasks of verbal fluency. Traditional DBS strategies use high frequency gamma stimulation for motor symptoms (∼130 Hz), but there is evidence that low frequency theta oscillations (5–12 Hz) are important in cognition. We tested the effects of stimulation frequency and location on verbal fluency among patients who underwent STN DBS implantation with externalized leads. During baseline cognitive testing, STN field potentials were recorded and the individual patients' peak theta frequency power was identified during each cognitive task. Patients repeated cognitive testing at five different stimulation settings: no stimulation, dorsal contact gamma (130 Hz), ventral contact gamma, dorsal theta (peak baseline theta) and ventral theta (peak baseline theta) frequency stimulation. Acute left dorsal peak theta frequency STN stimulation improves overall verbal fluency compared to no stimulation and to either dorsal or ventral gamma stimulation. Stratifying by type of verbal fluency probes, verbal fluency in episodic categories was improved with dorsal theta stimulation compared to all other conditions, while there were no differences between stimulation conditions in non-episodic probe conditions. Here, we provide evidence that dorsal STN theta stimulation may improve verbal fluency, suggesting a potential possibility of integrating theta stimulation into current DBS paradigms to improve cognitive outcomes. • Verbal fluency was assessed in PD patients with externalized STN DBS electrodes. • Dorsal theta and gamma, ventral theta and gamma, and off were compared. • Dorsal theta stimulation improves episodic verbal fluency vs all other settings. • Stimulation did not affect nonepisodic verbal fluency. • Dorsal STN theta stimulation could be integrated into clinical DBS paradigms. [ABSTRACT FROM AUTHOR]

Abstract Background Several different surgical procedures targeting the limbic circuit have been utilized for severe, treatment resistant obsessive-compulsive disorder; however, there has only been limited exploration of the inferior thalamic peduncle (ITP). The aim of this study was to determine the safety and initial efficacy of ITP deep brain stimulation (DBS) in patients with severe obsessive-compulsive disorder. Methods Patients with severe, treatment-refractory obsessive-compulsive disorder were enrolled into this open-label phase 1 DBS pilot study. Bilateral ITP DBS devices were implanted between November 2010 and December 2015. The primary outcome was safety. The initial efficacy was determined by Yale-Brown Obsessive-Compulsive scale (YBOCs) scores. Component Y-BOCs scores, Hamilton Depression Severity Scale, Quality of Life Assessment (SF-36), Oxford Happiness Questionnaire, Warwick-Edinburgh Mental Well-Being Scale, and Sheehan Disability Scale were also analyzed for a minimum of 2 years after surgery. Additionally, preoperative and three-month postoperative FDG-PET studies were performed on two patients. Results Five patients (2 males, 3 females; age range 25–48 years) received ITP DBS. All five patients were considered responders at one year (52% improvement in YBOCs scores compared to baseline (range 39–73%, p < 0.01) and last follow-up (54% improvement; range 38–85%; p < 0.01). At two years follow-up, there were three adverse events that occurred in two patients. One patient had his DBS system removed after one year due to the device becoming the object of his obsession. The other two adverse events were not related to the device. Post-operative FDG-PET imaging in two patients demonstrated decreased glucose uptake within the right caudate, right putamen, right supplementary motor area, and right cingulum and increased glucose uptake in bilateral motor areas, left temporal pole, and left orbitfrontal cortex. Conclusions ITP DBS has a favorable safety profile and is potentially an efficacious treatment for severe obsessive-compulsive disorder. Larger clinical trials are necessary to determine efficacy. Highlights • Inferior thalamic peduncle deep brain stimulation for treatment refractory obsessive-compulsive disorder has a favorable safety profile. • ITP DBS is a potentially efficacious treatment, as all five patients in this study were considered treatment responders. • After three months of chronic ITP DBS, PET imaging was consistent with network engagement. [ABSTRACT FROM AUTHOR]

• Normal-range electrical impedances can be measured from fractured DBS electrodes. • Only combining impedance measurements and imaging can rule out electrode fractures. • This is probably the first reported open DBS electrode fracture resulting from a fall. [ABSTRACT FROM AUTHOR]

In this work a new type of foldable neural electrode is presented. The microfabricated electrode is specifically designed for Deep Brain Stimulation of the cavity wall of thalamic lesions resulting from brain infarcts. On implantation, the electrode is introduced through a cannula, after which the flower-like structure unfolds, contacting the cavity walls and allowing stimulation at different anatomical locations. A three-layer microfabrication process based on UV-lithography and Reactive Ion Etching (RIE) is presented. In-Vivo experiments have also been performed in which the implantation procedure and the unfolding of the electrode are tested and visualized. [ABSTRACT FROM AUTHOR]