Mapping autonomic, mood and cognitive effects of hypothalamic region deep brain stimulation.

Because of its involvement in a wide variety of cardiovascular, metabolic and behavioural functions, the hypothalamus constitutes a potential target for neuromodulation in a number of treatment-refractory conditions. The precise neural substrates and circuitry subserving these responses, however, are poorly characterized to date. We sought to retrospectively explore the acute sequelae of hypothalamic region deep brain stimulation and characterize their neuroanatomical correlates. To this end we studied-at multiple international centres-58 patients (mean age: 68.5 ± 7.9 years, 26 females) suffering from mild Alzheimer's disease who underwent stimulation of the fornix region between 2007 and 2019. We catalogued the diverse spectrum of acutely induced clinical responses during electrical stimulation and interrogated their neural substrates using volume of tissue activated modelling, voxel-wise mapping, and supervised machine learning techniques. In total 627 acute clinical responses to stimulation-including tachycardia, hypertension, flushing, sweating, warmth, coldness, nausea, phosphenes, and fear-were recorded and catalogued across patients using standard descriptive methods. The most common manifestations during hypothalamic region stimulation were tachycardia (30.9%) and warmth (24.6%) followed by flushing (9.1%) and hypertension (6.9%). Voxel-wise mapping identified distinct, locally separable clusters for all sequelae that could be mapped to specific hypothalamic and extrahypothalamic grey and white matter structures. K-nearest neighbour classification further validated the clinico-anatomical correlates emphasizing the functional importance of identified neural substrates with area under the receiving operating characteristic curves between 0.67 and 0.91. Overall, we were able to localize acute effects of hypothalamic region stimulation to distinct tracts and nuclei within the hypothalamus and the wider diencephalon providing clinico-anatomical insights that may help to guide future neuromodulation work.

Pallidal Connectivity Profiling of Stimulation-Induced Dyskinesia in Parkinson's Disease.

OBJECTIVES: The aim of this study is to identify anatomical regions related to stimulation-induced dyskinesia (SID) after pallidal deep brain stimulation (DBS) in Parkinson's disease (PD) patients and to analyze connectivity associated with SID. METHODS: This retrospective study analyzed the clinical and imaging data of PD patients who experienced SID during the monopolar review after pallidal DBS. We analyzed structural and functional connectivity using normative connectivity data with the volume of tissue activated (VTA) modeling. Each contact was assigned to either that producing SID (SID VTA) or that without SID (non-SID VTA). Structural and functional connectivity was compared between SID and non-SID VTAs. "Optimized VTAs" were also estimated using the DBS settings at 6 months after implantation. RESULTS: Of the 68 consecutive PD patients who underwent pallidal implantation, 20 patients (29%) experienced SID. SID VTAs were located more dorsally and anteriorly compared with non-SID and optimized VTAs and were primarily in the dorsal globus pallidus internus (GPi) and dorsal globus pallidus externus (GPe). SID VTAs showed significantly higher structural connectivity than non-SID VTAs to the associative cortex and supplementary motor area/premotor cortex (P < 0.0001). Simultaneously, non-SID VTAs showed greater connectivity to the primary sensory cortex, cerebellum, subthalamic nucleus, and motor thalamus (all P < 0.0004). Functional connectivity analysis showed significant differences between SID and non-SID VTAs in multiple regions, including the primary motor, premotor, and prefrontal cortices and cerebellum. CONCLUSION: SID VTAs were primarily in the dorsal GPi/GPe. The connectivity difference between the motor-related cortices and subcortical regions may explain the presence and absence of SID. © 2020 International Parkinson and Movement Disorder Society.

Brain structures and networks responsible for stimulation-induced memory flashbacks during forniceal deep brain stimulation for Alzheimer's disease.

INTRODUCTION: Fornix deep brain stimulation (fx-DBS) is under investigation for treatment of Alzheimer's disease (AD). We investigated the anatomic correlates of flashback phenomena that were reported previously during acute diencephalic stimulation. METHODS: Thirty-nine patients with mild AD who took part in a prior fx-DBS trial (NCT01608061) were studied. After localizing patients' implanted electrodes and modeling the volume of tissue activated (VTA) by DBS during systematic stimulation testing, we performed (1) voxel-wise VTA mapping to identify flashback-associated zones; (2) machine learning-based prediction of flashback occurrence given VTA overlap with specific structures; (3) normative functional connectomics to define flashback-associated brain-wide networks. RESULTS: A distinct diencephalic region was associated with greater flashback likelihood. Fornix, bed nucleus of stria terminalis, and anterior commissure involvement predicted memory events with 72% accuracy. Flashback-inducing stimulation exhibited greater functional connectivity to a network of memory-evoking and autobiographical memory-related sites. DISCUSSION: These results clarify the neuroanatomical substrates of stimulation-evoked flashbacks.

Gait worsening and the microlesion effect following deep brain stimulation for essential tremor.

OBJECTIVE: To investigate the effects of unilateral thalamic deep brain stimulation (DBS) on walking in persons with medication-refractory essential tremor (ET). METHODS: We performed laboratory-based gait analyses on 24 persons with medication-refractory ET before and after unilateral thalamic DBS implantation. Normal and tandem walking parameters were analysed across sessions (PRE-DBS/DBS OFF/DBS ON) by repeated measures analyses of variance. Pearson's correlations assessed whether changes in walking after DBS were global (ie, related across gait parameters). Baseline characteristics, lead locations and stimulation parameters were analysed as possible contributors to gait effects. RESULTS: DBS minimally affected gait at the cohort level. However, 25% of participants experienced clinically meaningful gait worsening. Walking speed decreased by >30% in two participants and by >10% in four others. Decreased walking speed correlated with increased gait variability, indicating global gait worsening in affected participants. The worsening persisted even after the stimulation was turned off. Participants with worse baseline tandem walking performance may be more likely to experience post-DBS gait worsening; the percentage of tandem missteps at baseline was nearly three times higher and tandem walking speeds were approximately 30% slower in participants who experienced gait worsening. However, these differences in tandem walking in persons with gait worsening as compared with those without worsening were not statistically significant. Lead locations and stimulation parameters were similar in participants with and without gait worsening. CONCLUSION: Global gait worsening occurred in 25% of participants with unilateral DBS for medication-refractory ET. The effect was present on and off stimulation, likely indicating a microlesion effect.

A pilot trial of square biphasic pulse deep brain stimulation for dystonia: The BIP dystonia study.

BACKGROUND: Dystonia often has inconsistent benefits and requires more energy-demanding DBS settings. Studies suggest that squared biphasic pulses could provide significant clinical benefit; however, dystonia patients have not been explored. OBJECTIVES: To assess safety and tolerability of square biphasic DBS in dystonia patients. METHODS: This study included primary generalized or cervical dystonia patients with bilateral GPi DBS. Square biphasic pulses were implemented and patients were assessed at baseline, immediately postwashout, post-30-minute washout, 1 hour post- and 2 hours postinitiation of investigational settings. RESULTS: Ten participants completed the study. There were no patient-reported or clinician-observed side effects. There was improvement across time on the Toronto Western Spasmodic Torticollis Rating Scale (χ2 = 10.7; P = 0.031). Similar improvement was detected in objective gait measurements. CONCLUSIONS: Square biphasic stimulation appears safe and feasible in dystonia patients with GPi DBS. Further studies are needed to evaluate possible effectiveness particularly in cervical and gait features. © 2016 International Parkinson and Movement Disorder Society.

Current Practice and the Future of Deep Brain Stimulation Therapy in Parkinson's Disease.

Deep brain stimulation (DBS) is an effective therapy for Parkinson's disease patients experiencing motor fluctuations, medication-resistant tremor, and/or dyskinesia. Currently, the subthalamic nucleus and the globus pallidus internus are the two most widely used targets, with individual advantages and disadvantages influencing patient selection. Potential DBS patients are selected using the few existing guidelines and the available DBS literature, and many centers employ an interdisciplinary team review of the individual's risk-benefit profile. Programmed settings vary based on institution- or physician-specific protocols designed to maximize benefits and limit adverse effects. Expectations should be realistic and clearly defined during the evaluation process, and each bothersome symptom should be addressed in the context of building the risk-benefit profile. Current DBS research is focused on improved symptom control, the development of newer technologies, and the improved efficiency of stimulation delivery. Techniques deliver stimulation in a more personalized way, and methods of adaptive DBS such as closed-loop approaches are already on the horizon.

Neurologic Care for Transgender and Gender-Diverse People: A Review of Current Evidence and Clinical Implications.

Purpose of Review: To summarize the literature on neurologic care for transgender and gender-diverse (TGD) people and provide implications for clinical practice. Recent Findings: There are limited data on the frequency and management of neurologic conditions among TGD people. TGD people have a higher prevalence of various neurologic conditions compared with cisgender or general population cohorts, including migraine, subjective cognitive decline, sleep disturbances, functional disorders, and cerebrovascular disease. Gender-affirming hormone therapy interacts with commonly prescribed neurologic medications and increases stroke risk among transfeminine people. Sex hormones and sex chromosomes may play a role in neurodegeneration and disability progression in neuroimmunologic diseases. Clitoral reduction surgeries on intersex children can cause neurologic disability and sexual dysfunction in adulthood. Socioeconomic disparities among TGD people contribute to health care barriers. Summary: Neurologists should consider the unique experiences and health care needs of TGD people in their clinical practice and research protocols.

WarpDrive: Improving spatial normalization using manual refinements.

Spatial normalization-the process of mapping subject brain images to an average template brain-has evolved over the last 20+ years into a reliable method that facilitates the comparison of brain imaging results across patients, centers & modalities. While overall successful, sometimes, this automatic process yields suboptimal results, especially when dealing with brains with extensive neurodegeneration and atrophy patterns, or when high accuracy in specific regions is needed. Here we introduce WarpDrive, a novel tool for manual refinements of image alignment after automated registration. We show that the tool applied in a cohort of patients with Alzheimer's disease who underwent deep brain stimulation surgery helps create more accurate representations of the data as well as meaningful models to explain patient outcomes. The tool is built to handle any type of 3D imaging data, also allowing refinements in high-resolution imaging, including histology and multiple modalities to precisely aggregate multiple data sources together.

Scoping Review of Multidisciplinary Care in Tourette Syndrome.

Objective: To review current multidisciplinary care practices in patients with Tourette syndrome (TS). Background: Individuals with TS can have multiple symptoms and comorbidities and require treatment to encompass all of their needs. A multidisciplinary research or care model approaches the situation/problem from all sides and uses multiple perspectives. Methods: A database search of Medline (using Pubmed), PsychINFO, and Scopus was performed using keywords related to multidisciplinary care and TS. The authors then screened the results for relevant information using a standardized extraction form to collect data. Next, relevant codes from text analysis were extracted with a final list agreed on with author consensus. Finally, we inferred common themes. Results: The search revealed 2304 citations, and 87 were selected for full-text analysis. One additional article was identified by manual search. Thirty-one citations were deemed relevant. Multidisciplinary team members typically included a psychiatrist or child psychiatrist, a neurologist or child neurologist, and a psychologist or therapist at the core. Four primary benefits were associated with multidisciplinary care: establishing the diagnosis, managing the complexity of TS and its associated comorbidities, averting complications, and evaluating advanced therapies. Limitations include possible poor team dynamics and rigidity in the approach leading to an algorithmic treatment plan. Conclusions: A multidisciplinary care model for TS is the preferred model advocated by patients, physicians, and organizations. This scoping review reveals that the impetus for multidisciplinary care rests on four primary benefits, but there is a lack of empirical evidence for defining and evaluating its use.

Craniocervical junction intradural extramedullary meningioma with cord compression.

Craniocervical spine meningiomas are rare. They often present with non-specific motor or sensory symptoms. Presenting symptoms can include gait ataxia, radiculopathy, myelopathy, back pain and sensory deficits. Spinal meningiomas are slow-growing tumours, with an insidious onset. Due to the critical location of craniocervical meningiomas, severe symptoms such as respiratory distress and quadriparesis are possible. We describe the clinical presentation of a craniocervical junction meningioma, its relevant neuroimaging findings, diagnostic challenges and management. A woman in her 30s presented with a subacute onset of neck pain, headaches, paresthesia and a Hoffman's sign of the left upper extremity. A cervical spine MRI revealed an intradural extramedullary craniocervical junction meningioma involving the C1 segment with cord compression. The tumour measured 1.4×2×2.2 cm. A mid-line suboccipital craniectomy, tumour resection (Simpson grade II) with cervical laminectomy, and dural grafting were completed for definitive management. A brief literature review was conducted yielding a total of 24 cases.

Hematoma-induced Twiddler-like phenomenon as a presentation of DBS hardware failure: Case report.

Deep brain stimulators (DBS) may fail for a multitude of reasons. We present a 79-year-old Parkinson's disease patient who suffered a DBS failure following impulse generator (IPG) replacement surgery due to the IPG flipping within an expanded capsular pocket. This creation of the pocket was unintentional, and the pocket formed around an undiagnosed postoperative hemorrhage. The syndrome could be considered "Twiddler-like" because it resulted in device flipping. There were, however, many characteristic differences between our case and classical Twiddler's syndrome. DBS neurostimulator failure due to hematoma induced device flipping should be suspected when device interrogation is impossible or there are abnormally high impedances across multiple DBS lead contacts. A plain film X-ray series should be ordered and can be useful in providing radiological evidence of device flipping. In cases like ours the extensive braiding encountered in Twiddler's syndrome may be absent. Anchoring the IPG to a deep fascial layer as well as the use of an antimicrobial pouch are two methods that may be employed to prevent or to treat this complication.

Course of Impulse Control Disorder Symptoms in Parkinson's Disease: Deep Brain Stimulation Versus Medications.

Background: The effect of surgery on impulse control disorders (ICDs) remains unclear in Parkinson's disease (PD) patients undergoing deep brain stimulation (DBS). Objective: To examine changes in ICD symptoms in PD patients undergoing DBS compared to a medication-only control group. Methods: The study was a 2-center, 12-month, prospective, observational investigation of PD patients undergoing DBS and a control group matched on age, sex, dopamine agonist use, and baseline presence of ICDs. Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease-Rating Scale (QUIP-RS) and total levodopa equivalent daily dose (LEDD) were collected at baseline, 3, 6, and 12 months. Linear mixed-effects models assessed changes in mean QUIP-RS score (sum of buying, eating, gambling, and hypersexuality items). Results: The cohort included 54 participants (DBS = 26, controls = 28), mean (SD) age 64.3 (8.1) and PD duration 8.0 (5.2) years. Mean baseline QUIP-RS was higher in the DBS group at baseline (8.6 (10.7) vs. 5.3 (6.9), P = 0.18). However, scores at 12 months follow-up were nearly identical (6.6 (7.3) vs. 6.0 (6.9) P = 0.79). Predictors of change in QUIP-RS score were baseline QUIP-RS score (ß = 0.483, P < 0.001) and time-varying LEDD (ß = 0.003, P = 0.02). Eight patients (four in each group) developed de novo ICD symptoms during follow-up, although none met diagnostic criteria for an impulse control disorder. Conclusions: ICD symptoms (including de novo symptoms) at 12 months follow-up were similar between PD patients undergoing DBS and patients treated with pharmacological therapy only. Monitoring for emergence of ICD symptoms is important in both surgically- and medication-only-treated PD patients.

Functional Movement Disorders and Deep Brain Stimulation: A Multi-Center Study.

Background: Functional movement disorders (FMD) are a commonly under-recognized diagnosis in patients with underlying neurodegenerative diseases. FMD have been observed in patients undergoing deep brain stimulation (DBS) for Parkinson's disease (PD) and other movement disorders. The prevalence of coexisting FMD among movement disorder-related DBS patients is unknown, and it may occur more often than previously recognized. Methods: We retrospectively assessed the relative prevalence and clinical characteristics of FMD occurring post-DBS, in PD and dystonia patients (FMD+, n = 29). We compared this cohort with age at surgery-, sex-, and diagnosis-matched subjects without FMD post-DBS (FMD-, n = 29). Results: Both the FMD prevalence (0.2%-2.1%) and the number of cases/DBS procedures/year varied across centers (0.15-3.65). A total of nine of 29 FMD+ cases reported worse outcomes following DBS. Although FMD+ and FMD- manifested similar features, FMD+ showed higher psychiatric comorbidity. Conclusions: DBS may be complicated by the development of FMD in a subset of patients, particularly those with pre-morbid psychiatric conditions.

The Human Tic Detector: An automatic approach to tic characterization using wearable sensors.

OBJECTIVE: Current rating scales for Tourette syndrome (TS) are limited by recollection bias or brief assessment periods. This proof-of-concept study aimed to develop a sensor-based paradigm to detect and classify tics. METHODS: We recorded both electromyogram and acceleration data from seventeen TS patients, either when voluntarily moving or experiencing tics and during the modified Rush Video Tic Rating Scale (mRVTRS). Spectral properties of voluntary and tic movements from the sensor that captured the dominant tic were calculated and used as features in a support vector machine (SVM) to detect and classify movements retrospectively. RESULTS: Across patients, the SVM had an accuracy, sensitivity, and specificity of 96.69 ± 4.84%, 98.24 ± 4.79%, and 96.03 ± 6.04%, respectively, when classifying movements in the test dataset. Furthermore, each patient's SVM was validated using data collected during the mRVTRS. Compared to the expert consensus, the tic detection accuracy was 85.63 ± 15.28% during the mRVTRS, while overall movement classification accuracy was 94.23 ± 5.97%. CONCLUSIONS: These results demonstrate that wearable sensors can capture physiological differences between tic and voluntary movements and are comparable to expert consensus. SIGNIFICANCE: Ultimately, wearables could individualize and improve care for people with TS, provide a robust and objective measure of tics, and allow data collection in real-world settings.

Optimal deep brain stimulation sites and networks for stimulation of the fornix in Alzheimer's disease.

Deep brain stimulation (DBS) to the fornix is an investigational treatment for patients with mild Alzheimer's Disease. Outcomes from randomized clinical trials have shown that cognitive function improved in some patients but deteriorated in others. This could be explained by variance in electrode placement leading to differential engagement of neural circuits. To investigate this, we performed a post-hoc analysis on a multi-center cohort of 46 patients with DBS to the fornix (NCT00658125, NCT01608061). Using normative structural and functional connectivity data, we found that stimulation of the circuit of Papez and stria terminalis robustly associated with cognitive improvement (R = 0.53, p < 0.001). On a local level, the optimal stimulation site resided at the direct interface between these structures (R = 0.48, p < 0.001). Finally, modulating specific distributed brain networks related to memory accounted for optimal outcomes (R = 0.48, p < 0.001). Findings were robust to multiple cross-validation designs and may define an optimal network target that could refine DBS surgery and programming.

Expanding sexual and gender minority research in movement disorders: More than awareness and acceptance.

Culturally competent and inclusive care is slowly becoming the standard throughout healthcare institutions. Awareness, acceptance, and inclusion of the sexual and gender minority (SGM) groups in medicine and neurology are progressing. Research in SGM health, although increasing, remains remarkably scant in parkinsonism and other movement disorders, a community whose patient population is on the rise. Most SGM health research in movement disorders only focuses on the symptoms associated with infection by the human immunodeficiency virus and the acquired immunodeficiency syndrome. Multiple clinical and epidemiological research questions remain unaddressed when considering the intersection of movement disorders and SGM health. In this article, we highlight gaps in the care of SGM individuals with movement disorders. First, the prevalence and phenomenology of movement disorders could be different, considering the different rates of risk factors and the use of gender-affirming hormones. Also, the effect of creating a safe environment in healthcare institutions to disclose sexual orientation and gender identity on seeking care, access to resources, and quality of services remains unknown. Moreover, many individuals with movement disorders would require services from multidisciplinary teams or long-term care facilities, which might not consider the needs of SGM patients in their models of care. Last, the effect of social isolation and self-perception (or misperceptions) in the SGM populations on the non-motor and motor symptoms of movement disorders and the treatment plans is not understood.

Response to Telemedicine Visits From Patients With Parkinsonism During the COVID-19 Pandemic on Postvisit Surveys.

Parkinson's disease and parkinsonism are common chronic neurodegenerative disorders that tend to affect older adults and cause physical and sometimes cognitive limitations. Given that these limitations could impact successful telemedicine use, we aimed to investigate the experiences of patients with parkinsonism using telemedicine during the COVID-19 pandemic. A 19-item survey was emailed to patients with parkinsonism following telemedicine visits at a single US tertiary care parkinsonism specialty clinic. Seventy-four individuals responded, out of 270 invitations sent. Almost two-thirds (61.6%) of the respondents were comfortable with using technology in general, and almost all were very satisfied with their telemedicine experience. The most commonly reported benefits included cost and travel savings, ease of access to a specialist, and time savings. Issues with technology and previsit instructions were the most commonly identified challenges (28%). Urgent implementation, due to the pandemic, of telemedicine care for patients with parkinsonism was feasible and well received. The challenges most commonly reported by patients could be potentially alleviated by better education and support.

The 5 Pillars in Tourette Syndrome Deep Brain Stimulation Patient Selection: Present and Future.

The selection of patients with Tourette syndrome (TS) for deep brain stimulation (DBS) surgery rests on 5 fundamental pillars. However, the operationalization of the multidisciplinary screening process to evaluate these pillars remains highly diverse, especially across sites. High tic severity and tic-related impact on quality of life (first 2 pillars) require confirmation from objective, validated measures, but malignant features of TS should per se suffice to fulfill this pillar. Failure of behavioral and pharmacologic therapies (third pillar) should be assessed taking into account refractoriness through objective and subjective measures supporting lack of efficacy of all interventions of proven efficacy, as well as true lack of tolerability, adherence, or access. Educational interventions and use of remote delivery formats (for behavioral therapies) play a role in preventing misjudgment of treatment failure. Stability of comorbid psychiatric disorders for 6 months (fourth pillar) is needed to confirm the predominant impact of tics on quality of life, to prevent pseudo-refractoriness, and to maximize the future DBS response. The 18-year age limit (fifth pillar) is currently under reappraisal, considering the potential impact of severe tics in adolescence and the predictive effect of tic severity in childhood on tic severity when transitioning into adulthood. Future advances should aim at a consensus-based definition of failure of specific, noninvasive treatment strategies for tics and of the minimum clinical observation period before considering DBS treatment, the stability of behavioral comorbidities, and the use of a prospective international registry data to identify predictors of positive response to DBS, especially in younger patients.

Evolution of Globus Pallidus Targeting for Parkinson's and Dystonia Deep Brain Stimulation: A 15-Year Experience.

Objective: The aim of this study is to evaluate the evolution of GPi DBS targeting. Methods: This retrospective, single-center study included patients implanted with GPi DBS leads for dystonia or PD during the years 2004 to 2018 at the University of Florida Fixel Institute for Neurological Diseases. Each patient underwent a high-resolution targeting study on the day prior to the surgery, which was fused with a high resolution CT scan that was acquired on the day of the procedure. Intraoperative target location was selected using a digitized 3D Schaltenbrand-Bailey atlas. All patients underwent a high-resolution head CT scan without contrast approximately one month after lead implantation and accurate measurement of neuroanatomical lead position was acquired after fusion of pre-operative and post-operative image studies. Results: We analyzed 253 PD patients with 352 leads and 80 dystonia patients with 141 leads. During 15 years of follow-up, lead locations in the PD group migrated more laterally (ß = 0.09, p < 0.0001), posteriorly [slope (ß) = 0.04, p < 0.05], and dorsally (ß = 0.07, p < 0.001), whereas leads in the dystonia group did not significantly change position aside from a trend in the dorsal direction (ß = 0.06, p = 0.053). Conclusion: The evolving target likely results from multiple factors including improvements in targeting techniques and clinical feedback intraoperatively and post-operatively. Our demonstrates the potential importance of a systematic post-operative DBS lead measurement protocol to ensure quality control and to inform and optimize DBS programming.