STN localization using local field potentials based on wavelet packet features and stacking ensemble learning.

BACKGROUND: DBS entails the insertion of an electrode into the patient brain, enabling Subthalamic nucleus (STN) stimulation. Accurate delineation of STN borders is a critical but time-consuming task, traditionally reliant on the neurosurgeon experience in deciphering the intricacies of microelectrode recording (MER). While clinical outcomes of MER have been satisfactory, they involve certain risks to patient safety. Recently, there has been a growing interest in exploring the potential of local field potentials (LFP) due to their correlation with the STN motor territory. METHOD: A novel STN detection system, integrating LFP and wavelet packet transform (WPT) with stacking ensemble learning, is developed. Initial steps involve the inclusion of soft thresholding to increase robustness to LFP variability. Subsequently, non-linear WPT features are extracted. Finally, a unique ensemble model, comprising a dual-layer structure, is developed for STN localization. We harnessed the capabilities of support vector machine, Decision tree and k-Nearest Neighbor in conjunction with long short-term memory (LSTM) network. LSTM is pivotal for assigning adequate weights to every base model. RESULTS: Results reveal that the proposed model achieved a remarkable accuracy and F1-score of 89.49% and 91.63%. COMPARISON WITH EXISTING METHODS: Ensemble model demonstrated superior performance when compared to standalone base models and existing meta techniques. CONCLUSION: This framework is envisioned to enhance the efficiency of DBS surgery and reduce the reliance on clinician experience for precise STN detection. This achievement is strategically significant to serve as an invaluable tool for refining the electrode trajectory, potentially replacing the current methodology based on MER.

Lead-free dual-frequency ultrasound implants for wireless, biphasic deep brain stimulation.

Ultrasound-driven bioelectronics could offer a wireless scheme with sustainable power supply; however, current ultrasound implantable systems present critical challenges in biocompatibility and harvesting performance related to lead/lead-free piezoelectric materials and devices. Here, we report a lead-free dual-frequency ultrasound implants for wireless, biphasic deep brain stimulation, which integrates two developed lead-free sandwich porous 1-3-type piezoelectric composite elements with enhanced harvesting performance in a flexible printed circuit board. The implant is ultrasonically powered through a portable external dual-frequency transducer and generates programmable biphasic stimulus pulses in clinically relevant frequencies. Furthermore, we demonstrate ultrasound-driven implants for long-term biosafety therapy in deep brain stimulation through an epileptic rodent model. With biocompatibility and improved electrical performance, the lead-free materials and devices presented here could provide a promising platform for developing implantable ultrasonic electronics in the future.

Edible electronics to treat the brain.

Ingestible electronic pills can be used for targeted noninvasive neuromodulation.

Designing next-generation subscalp devices for seizure monitoring: A systematic review and meta-analysis of established extracranial hardware.

Implantable brain recording and stimulation devices apply to a broad spectrum of conditions, such as epilepsy, movement disorders and depression. For long-term monitoring and neuromodulation in epilepsy patients, future extracranial subscalp implants may offer a promising, less-invasive alternative to intracranial neurotechnologies. To inform the design and assess the safety profile of such next-generation devices, we estimated extracranial complication rates of deep brain stimulation (DBS), cranial peripheral nerve stimulation (PNS), responsive neurostimulation (RNS) and existing subscalp EEG devices (sqEEG), as proxy for future implants. Pubmed was searched systematically for DBS, PNS, RNS and sqEEG studies from 2000 to February 2024 (48 publications, 7329 patients). We identified seven categories of extracranial adverse events: infection, non-infectious cutaneous complications, lead migration, lead fracture, hardware malfunction, pain and hemato-seroma. We used cohort sizes, demographics and industry funding as metrics to assess risks of bias. An inverse variance heterogeneity model was used for pooled and subgroup meta-analysis. The pooled incidence of extracranial complications reached 14.0%, with infections (4.6%, CI 95% [3.2 - 6.2]), surgical site pain (3.2%, [0.6 - 6.4]) and lead migration (2.6%, [1.0 - 4.4]) as leading causes. Subgroup analysis showed a particularly high incidence of persisting pain following PNS (12.0%, [6.8 - 17.9]) and sqEEG (23.9%, [12.7 - 37.2]) implantation. High rates of lead migration (12.4%, [6.4 - 19.3]) were also identified in the PNS subgroup. Complication analysis of DBS, PNS, RNS and sqEEG studies provides a significant opportunity to optimize the safety profile of future implantable subscalp devices for chronic EEG monitoring. Developing such promising technologies must address the risks of infection, surgical site pain, lead migration and skin erosion. A thin and robust design, coupled to a lead-anchoring system, shall enhance the durability and utility of next-generation subscalp implants for long-term EEG monitoring and neuromodulation.

Definition of Implanted Neurological Device Abandonment: A Systematic Review and Consensus Statement.

Importance: Establishing a formal definition for neurological device abandonment has the potential to reduce or to prevent the occurrence of this abandonment. Objective: To perform a systematic review of the literature and develop an expert consensus definition for neurological device abandonment. Evidence Review: After a Royal Society Summit on Neural Interfaces (September 13-14, 2023), a systematic English language review using PubMed was undertaken to investigate extant definitions of neurological device abandonment. Articles were reviewed for relevance to neurological device abandonment in the setting of deep brain, vagal nerve, and spinal cord stimulation. This review was followed by the convening of an expert consensus group of physicians, scientists, ethicists, and stakeholders. The group summarized findings, added subject matter experience, and applied relevant ethics concepts to propose a current operational definition of neurological device abandonment. Data collection, study, and consensus development were done between September 13, 2023, and February 1, 2024. Findings: The PubMed search revealed 734 total articles, and after review, 7 articles were found to address neurological device abandonment. The expert consensus group addressed findings as germane to neurological device abandonment and added personal experience and additional relevant peer-reviewed articles, addressed stakeholders' respective responsibilities, and operationally defined abandonment in the context of implantable neurotechnological devices. The group further addressed whether clinical trial failure or shelving of devices would constitute or be associated with abandonment as defined. Referential to these domains and dimensions, the group proposed a standardized definition for abandonment of active implantable neurotechnological devices. Conclusions and Relevance: This study's consensus statement suggests that the definition for neurological device abandonment should entail failure to provide fundamental aspects of patient consent; fulfill reasonable responsibility for medical, technical, or financial support prior to the end of the device's labeled lifetime; and address any or all immediate needs that may result in safety concerns or device ineffectiveness and that the definition of abandonment associated with the failure of a research trial should be contingent on specific circumstances.

Neuromodulation for the treatment of Prader-Willi syndrome - A systematic review.

Prader-Willi syndrome (PWS) is a complex, genetic disorder characterized by multisystem involvement, including hyperphagia, maladaptive behaviors and endocrinological derangements. Recent developments in advanced neuroimaging have led to a growing understanding of PWS as a neural circuit disorder, as well as subsequent interests in the application of neuromodulatory therapies. Various non-invasive and invasive device-based neuromodulation methods, including vagus nerve stimulation (VNS), transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation (rTMS), and deep brain stimulation (DBS) have all been reported to be potentially promising treatments for addressing the major symptoms of PWS. In this systematic literature review, we summarize the recent literature that investigated these therapies, discuss the underlying circuits which may underpin symptom manifestations, and cover future directions of the field. Through our comprehensive search, there were a total of 47 patients who had undergone device-based neuromodulation therapy for PWS. Two articles described VNS, 4 tDCS, 1 rTMS and 2 DBS, targeting different symptoms of PWS, including aberrant behavior, hyperphagia and weight. Multi-center and multi-country efforts will be required to advance the field given the low prevalence of PWS. Finally, given the potentially vulnerable population, neuroethical considerations and dialogue should guide the field.

Do Antibiotic-Impregnated Envelopes Prevent Deep Brain Stimulation Implantable Pulse Generator Infections? A Prospective Cohort Study.

INTRODUCTION: Infection after deep brain stimulation (DBS) implanted pulse generator (IPG) replacement is uncommon but when it occurs can cause significant clinical morbidity, often resulting in partial or complete DBS system removal. An antibiotic absorbable envelope developed for cardiac implantable electronic devices (IEDs), which releases minocycline and rifampicin for a minimum of 7 days, was shown in the WRAP-IT study to reduce cardiac IED infections for high-risk cardiac patients. We aimed to assess whether placing an IPG in the same antibiotic envelope at the time of IPG replacement reduced the IPG infection rate. METHODS: Following institutional ethics approval (UnitingCare HREC), patients scheduled for IPG change due to impending battery depletion were prospectively randomised to receive IPG replacement with or without an antibiotic envelope. Patients with a past history of DBS system infection were excluded. Patients underwent surgery with standard aseptic neurosurgical technique [J Neurol Sci. 2017;383:135-41]. Subsequent infection requiring antibiotic therapy and/or IPG removal or revision was recorded. RESULTS: A total of 427 consecutive patients were randomised from 2018 to 2021 and followed for a minimum of 12 months. No patients were lost to follow-up. At the time of IPG replacement, 200 patients received antibiotic envelope (54 female, 146 male, mean age 72 years), and 227 did not (43 female, 184 male, mean age 71 years). The two groups were homogenous for risk factors of infection. The IPG replacement infection rate was 2.1% (9/427). There were six infections, which required antibiotic therapy and/or IPG removal, in the antibiotic envelope group (6/200) and three in the non-envelope group (3/227) (p = 0.66). CONCLUSION: This prospective randomised study did not find that an antibiotic envelope reduced the IPG infection rate in our 427 patients undergoing routine DBS IPG replacement. Further research to reduce IPG revisions and infections in a cost-effective manner is required.

Evaluation of 3D C-Arm Fluoroscopy versus Diagnostic CT for Deep Brain Stimulation Stereotactic Registration and Post-Operative Lead Localization.

INTRODUCTION: DBS efficacy depends on accuracy. CT-MRI fusion is established for both stereotactic registration and electrode placement verification. The desire to streamline DBS workflows, reduce operative time, and minimize patient transfers has increased interest in portable imaging modalities such as the Medtronic O-arm® and mobile CT. However, these remain expensive and bulky. 3D C-arm fluoroscopy (3DXT) units are a smaller and less costly alternative, albeit incompatible with traditional frame-based localization and without useful soft tissue resolution. We aimed to compare fusion of 3DXT and CT with pre-operative MRI to evaluate if 3DXT-MRI fusion alone is sufficient for accurate registration and reliable targeting verification. We further assess DBS targeting accuracy using a 3DXT workflow and compare radiation dosimetry between modalities. METHODS: Patients underwent robot-assisted DBS implantation using a workflow incorporating 3DXT which we describe. Two intra-operative 3DXT spins were performed for registration and accuracy verification followed by conventional CT post-operatively. Post-operative 3DXT and CT images were independently fused to the same pre-operative MRI sequence and co-ordinates generated for comparison. Registration accuracy was compared to 15 consecutive controls who underwent CT-based registration. Radial targeting accuracy was calculated and radiation dosimetry recorded. RESULTS: Data were obtained from 29 leads in 15 consecutive patients. 3DXT registration accuracy was significantly superior to CT with mean error 0.22 ± 0.03 mm (p < 0.0001). Mean Euclidean electrode tip position variation for CT to MRI versus 3DXT to MRI fusion was 0.62 ± 0.40 mm (range 0.0 mm-1.7 mm). In comparison, direct CT to 3DXT fusion showed electrode tip Euclidean variance of 0.23 ± 0.09 mm. Mean radial targeting accuracy assessed on 3DXT was 0.97 ± 0.54 mm versus 1.15 ± 0.55 mm on CT with differences insignificant (p = 0.30). Mean patient radiation doses were around 80% lower with 3DXT versus CT (p < 0.0001). DISCUSSION: Mobile 3D C-arm fluoroscopy can be safely incorporated into DBS workflows for both registration and lead verification. For registration, the limited field of view requires the use of frameless transient fiducials and is highly accurate. For lead position verification based on MRI co-registration, we estimate there is around a 0.4 mm discrepancy between lead position seen on 3DXT versus CT when corrected for brain shift. This is similar to that described in O-arm® or mobile CT series. For units where logistical or financial considerations preclude the acquisition of a cone beam CT or mobile CT scanner, our data support portable 3D C-arm fluoroscopy as an acceptable alternative with significantly lower radiation exposure.

Design of CMOS Analog Front-End Local-Field Potential Chopper Amplifier With Stimulation Artifact Tolerance for Real-Time Closed-Loop Deep Brain Stimulation SoC Applications.

A CMOS analog front-end (AFE) local-field potential (LFP) chopper amplifier with stimulation artifact tolerance, improved right-leg driven (RLD) circuit, and improved auxiliary path is proposed. In the proposed CMOS AFE LFP chopper amplifier, common-mode artifact voltage (CMAV) and differential-mode artifact voltage (DMAV) removal using the analog template removal method are proposed to achieve good signal linearity during stimulation. An improved auxiliary path is employed to boost the input impedance and allow the negative stimulation artifact voltage passing through. The common-mode noise is suppressed by the improved RLD circuit. The chip is implemented in 0.18- µm CMOS technology and the total chip area is 5.46-mm2. With the improved auxiliary path, the measured input impedance is larger than 133 M[Formula: see text] in the signal bandwidth and reaches 8.2 G[Formula: see text] at DC. With the improved RLD circuit, the measured CMRR is 131 - 144 dB in the signal bandwidth. Under 60-µs pulse width and 130-Hz constant current stimulation (CCS) with ±1-V CMAV and ±50-mV DMAV, the measured THD at the SC Amp output of fabricated AFE LFP chopper amplifier is 1.28%. The measurement results of In vitro agar tests have shown that with ±1.6-mA CCS pulses injecting to agar, the measured THD is 1.69%. Experimental results of both electrical and agar tests have verified that the proposed AFE LFP chopper amplifier has good stimulation artifact tolerance. The proposed CMOS AFE LFP chopper amplifier with analog template removal method is suitable for real-time closed-loop deep drain stimulation (DBS) SoC applications.

Estimulação cerebral profunda para o tratamento da distonia primária generalizada e distonia cervical / Deep brain stimulation for the treatment of primary generalized dystonia and cervical dystonia

INTRODUÇÃO: A distonia é um distúrbio neurológico caracterizado por contrações musculares involuntárias, responsáveis por posturas e movimentos anormais. Sua expressão clínica é determinada pela gravidade e distribuição dos músculos envolvidos, desde variações focais e segmentares mais leves, a casos mais graves de manifestação generalizada. No Brasil, no âmbito do Sistema Único de Saúde (SUS), há um Protocolo Clínico e Diretrizes Terapêuticas sobre o cuidado de Distonia e Espasmo Hemifacial que preconiza a utilização da Toxina Botulínica Tipo A (TBA). A estimulação cerebral profunda (Deep Brain Stimulation - DBS) é um procedimento cirúrgico utilizado no tratamento de várias doenças neurológicas, normalmente em casos refratários à terapia usual. A DBS consiste na implantação de um dispositivo médico para fornecer estimulação elétrica a regiões específicas do cérebro. Tendo em vista que existem produtos de saúde aprovados pela Anvisa para realização da DBS e que o procedimento já está disponível no SUS para determinadas condições, o presente relatório foi desenvolvido com o objetivo de compreender a viabilidade de ampliação de uso desse procedimento no SUS para o tratamento de distonia primária generalizada e distonia cervical. PERGUNTA DE PESQUISA: O uso da DBS é eficaz, seguro e custo-efetivo para o tratamento de distonia primária generalizada e distonia cervical em pacientes adultos e pediátricos refratários ao tratamento convencional? EVIDÊNCIAS CLÍNICAS: Foi realizada uma revisão sistemática a partir de buscas nas bases de dados MEDLINE (via Pubmed), EMBASE, Cochrane Library, LILACS, IBECS, BRISA (via BVS), considerando o tratamento de distonia primária generalizada e distonia cervical com o procedimento de estimulação cerebral profunda. Foram estabelecidos critérios de elegibilidade abrangentes devido à escassez de estudos disponíveis na literatura científica. Os estudos foram avaliados quanto ao risco de viés com a ferramenta Cochrane Risk of Bias Tool ­ ROB 2.0 para Ensaio Clínico Randomizado (ECR) e a ferramenta Risk of Bias in Non-Randomised Studies of Interventions (ROBINS-I) para os estudos observacionais. A qualidade geral da evidência foi avaliada utilizando a abordagem GRADE (Grading of Recommendatons Assessment, Development and Evaluaton). Para distonia primária generalizada, foram incluídos 17 estudos que envolveram 350 pacientes, entre crianças e adultos. Entre os estudos identificados um era ensaio clínico randomizado (ECR) que comparou DBS e sham; os demais estudos eram ensaios clínicos não randomizados (n=4) ou observacionais (estudos de coorte (n=10) e séries de casos (n=2). O ECR analisado incluiu tanto crianças quanto adultos e avaliou no total 40 pacientes. Os resultados apresentados foram positivos na redução do comprometimento motor (redução de 39,3%) e da incapacidade (redução de 37,5%) em pacientes que realizaram a DBS, avaliados pela escala Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS). é importante destacar a consistência em relação aos resultados sempre mostrarem benefício e a magnitude do efeito, que é relevante clinicamente. Os estudos observacionais incluídos também sugerem resultados positivos com o uso da DBS, com qualidade geral da evidência variando de baixa a muito baixa devido ao risco de viés grave ou crítico, principalmente pela presença de potenciais fatores de confundimento e/ou problemas relacionados ao cegamento (ausência de descrição ou relato inadequado). Para distonia cervical, foram incluídos 13 estudos que envolveram 300 pacientes, a maioria dos estudos incluindo apenas adultos. Entre os estudos identificados um era ECR comparando a DBS com procedimento sham; os demais estudos clínicos eram não randomizados (n=2) ou observacionais (estudos de coorte (n=9) e caso-controle (n=1). O ECR avaliou 62 pacientes adultos e os resultados, avaliados pela escala Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS), indicam que a DBS reduz o comprometimento motor (redução média de 5,1 pontos), incapacidade (redução média de 5,6 pontos) e dor (redução média de 4,4 pontos) em pacientes com distonia cervical refratária ao tratamento farmacológico quando comparado com a estimulação simulada. Novamente é importante ressaltar que os resultados foram clinicamente relevantes e observou-se consistência entre os achados no ECR e nos demais estudos. Os estudos observacionais incluídos também relatam resultados positivos com o uso da DBS. AVALIAÇÃO ECONÔMICA: A razão de custo-efetividade incremental da ampliação de uso da DBS foi de R$ 4.378,58 por QALY na distonia generalizada e de R$46.119,11 por QALY na distonia cervical, com a maior parte dos resultados demonstrando superioridade clínica da tecnologia avaliada na análise de sensibilidade. Pela análise de sensibilidade probabilística, 95% dos valores de RCEI estão abaixo de R$7.000 para a distonia generalizada e abaixo de R$1.000.000,00 para a cervical. ANÁLISE DE IMPACTO ORÇAMENTÁRIO: Estima-se que 945 pessoas possuem distonia generalizada e 10.698 distonias cervical no Brasil e que 482 pacientes sejam passíveis de serem tratados com DBS em 2022. Considerando a participação de mercado do procedimento, 72 pacientes fariam a DBS em 2022, 124 em 2023, 131 em 2024, 98 em 2025 e 55 em 2026. Isso corresponde, em uma ampliação de uso progressiva, um impacto orçamentário de, aproximadamente, R$7.710.181,32 em 5 anos. MONITORAMENTO DO HORIZONTE TECNOLÓGICO: No Monitoramento do Horizonte Tecnológico foram encontradas 2 novas tecnologias com registros ANVISA e FDA (Percept PC Brain Sense e Vercise Genus). Em relação aos depósitos e patentes concedidas foi possível evidenciar 1 documento patentário, com depósito em 2021, referente a métodos e sistemas para estimulação cerebral profunda focalizada não invasiva. CONSIDERAÇÕES FINAIS: As evidências disponíveis para a comparação entre DBS e estimulação simulada para os tipos de distonia avaliadas foram baseadas apenas em dois ECRs. Os resultados dos ECRs mostraram resultados favoráveis à intervenção. Os estudos observacionais identificados, ainda que apresentem limitações metodológicas, também apoiam os resultados dos ECRs avaliados. Como o cuidado da distonia em casos refratários ao tratamento usual carece de alternativas terapêuticas é possível que os pacientes com distonia já façam uso desse procedimento por meio dos CIDs do grupo R (R250, R251, R252, R253 e R258), para os quais o procedimento já está disponível no SUS. RECOMENDAÇÃO PRELIMINAR: os membros presentes no Plenário da Conitec, em sua 110ª Reunião Ordinária, realizada no dia 06 de julho de 2022, deliberaram que a matéria fosse disponibilizada em consulta pública com recomendação preliminar favorável à ampliação de uso da estimulação cerebral profunda para o tratamento da distonia. Para essa recomendação, a Conitec considerou que as evidências acerca da eficácia e segurança do procedimento são escassas, mas provém de ensaios clínicos randomizados com resultados clinicamente relevantes, o quadro clínico que exige seu uso seria para aqueles pacientes refratários a todos os demais tratamentos. CONSULTA PÚBLICA: Todos os participantes da CP nº 50/2022, que realizaram contribuições frente ao tema avaliado, realizada entre os dias 01/08/2022 e 22/08/2022, concordaram com recomendação preliminar da Conitec favorável à ampliação de uso da estimulação cerebral profunda para o tratamento da distonia primária generalizada e distonia cervical. Foram recebidas 23 contribuições, sendo 13 através do formulário técnico-científico e 10 através do formulário de experiência ou opinião. De forma geral, as contribuições ressaltaram os benefícios clínicos do procedimento, principalmente destacando melhora da qualidade de vida. Também comentaram a respeito do alto custo e dificuldade de acesso ao procedimento. RECOMENDAÇÃO FINAL DA CONITEC: Pelo exposto, o Plenário da Conitec, em sua 112ª Reunião Ordinária, realizada no dia 31 de agosto de 2022, deliberou por unanimidade recomendar a ampliação de uso da estimulação cerebral profunda para o tratamento da distonia primária generalizada e distonia cervical em pacientes refratários a terapia convencional. Os membros da Conitec consideraram os benefícios proporcionados pelo procedimento e a necessidade de uso para aqueles pacientes refratários aos demais tratamentos. A consulta pública não trouxe elementos para mudança da recomendação preliminar. Por fim, foi assinado o Registro de Deliberação nº 767/2022. DECISÃO: de ampliar o uso, no âmbito do Sistema Único de Saúde - SUS, da estimulação cerebral profunda para o tratamento de distonias, conforme protocolo estabelecido pelo Ministério da Saúde, conforme a Portaria nº 108, publicada no Diário Oficial da União nº 192, seção 1, página 61, em 7 de outubro de 2022.

De novo status epilepticus possibly related to battery depletion of anterior thalamic brain stimulator.

Anterior thalamic deep brain stimulation is an effective therapeutic option for patients with drug-refractory focal epilepsy who are poor surgical candidates. Although the precise mechanism of action of thalamic neurostimulation is unknown, studies demonstrating increased efficacy over time have raised the possibility that therapeutic benefits are mediated by stimulation-related long-term neuroplastic changes. Adverse effects related to hardware malfunction have been previously described, and most commonly include local infection, sensory disturbances, and migration of leads. However, the withdrawal effect of sudden deep brain stimulation malfunction on seizure control is unclear. We present the case of a 21-year-old patient with intractable focal epilepsy who developed status epilepticus concurrently with unexpected deep brain stimulator battery failure, 21 months post implantation. This case demonstrates an unfamiliar possible adverse effect of anterior thalamic stimulation withdrawal and emphasizes the importance of stimulator hardware assessment in patients presenting with seizure worsening.

High Frequency of Low-Virulent Microorganisms Detected by Sonication of Implanted Pulse Generators: So What?

INTRODUCTION: Deep brain stimulation (DBS) has become a well-established treatment modality for a variety of conditions over the last decades. Multiple surgeries are an essential part in the postoperative course of DBS patients if nonrechargeable implanted pulse generators (IPGs) are applied. So far, the rate of subclinical infections in this field is unknown. In this prospective cohort study, we used sonication to evaluate possible microbial colonization of IPGs from replacement surgery. METHODS: All consecutive patients undergoing IPG replacement between May 1, 2019 and November 15, 2020 were evaluated. The removed hardware was investigated using sonication to detect biofilm-associated bacteria. Demographic and clinical data were analyzed. RESULTS: A total of 71 patients with a mean (±SD) of 64.5 ± 15.3 years were evaluated. In 23 of these (i.e., 32.4%) patients, a positive sonication culture was found. In total, 25 microorganisms were detected. The most common isolated microorganisms were Cutibacterium acnes (formerly known as Propionibacterium acnes) (68%) and coagulase-negative Staphylococci (28%). Within the follow-up period (5.2 ± 4.3 months), none of the patients developed a clinical manifest infection. DISCUSSIONS/CONCLUSIONS: Bacterial colonization of IPGs without clinical signs of infection is common but does not lead to manifest infection. Further larger studies are warranted to clarify the impact of low-virulent pathogens in clinically asymptomatic patients.

Selección de objetivos para la estimulación cerebral profunda en la esquizofrenia resistente al tratamiento / Target Selection For Deep Brain Stimulation In Treatment Resistant Schizophrenia

Tras co-liderar el primer ensayo clínico sobre la estimulación cerebralprofunda en esquizofrenia resistente al tratamiento, investigadoresde FIDMAG, junto con investigadores del Hospital de la SantaCreu i Sant Pau revisan la literatura hasta la fecha sobre las basesneurobiológicas de la esquizofrenia y las localizaciones previamentepropuestas y empleadas en estimulación cerebral profunda (ECP).Esta revisión aporta información clave para la colocación de loselectrodos en futuros ensayos clínicos, destacando estructuras comoel núcleo accumbens o el córtex cingulado anterior, como potencialmenteprometedoras para su empleo en la ECP. Y destacando lanecesidad de continuar con la investigación para dilucidar las basesneurobiológicas de la esquizofrenia que permitirán avanzar en lostratamientos de la esquizofrenia. (AU)

After co-leading the first clinical trial on deep brain stimulationin treatment-resistant schizophrenia, FIDMAG researchers, togetherwith researchers from the Hospital de la Santa Creu i Sant Pau reviewthe literature to date on the neurobiological basis of schizophreniaand the locations previously proposed and used in deep brain stimulation(DBS). This review provides key information for the placementof electrodes in future clinical trials, highlighting structuressuch as the nucleus accumbens or the anterior cingulate cortex aspotentially promising for use in DBS. And highlighting the need forcontinued research to elucidate the neurobiological basis of schizophreniathat will advance treatments for schizophrenia. (AU)

Comparison of methodologies for modeling directional deep brain stimulation electrodes.

Deep brain stimulation (DBS) is an established clinical therapy, and directional DBS electrode designs are now commonly used in clinical practice. Directional DBS leads have the ability to increase the therapeutic window of stimulation, but they also increase the complexity of clinical programming. Therefore, computational models of DBS have become available in clinical software tools that are designed to assist in the identification of therapeutic settings. However, the details of how the DBS model is implemented can influence the predictions of the software. The goal of this study was to compare different methods for representing directional DBS electrodes within finite element volume conductor (VC) models. We evaluated 15 different DBS VC model variants and quantified how their differences influenced estimates on the spatial extent of axonal activation from DBS. Each DBS VC model included the same representation of the brain and head, but the details of the current source and electrode contact were different for each model variant. The more complex VC models explicitly represented the DBS electrode contacts, while the more simple VC models used boundary condition approximations. The more complex VC models required 2-3 times longer to mesh, build, and solve for the DBS voltage distribution than the more simple VC models. Differences in individual axonal activation thresholds across the VC model variants were substantial (-24% to +47%). However, when comparing total activation of an axon population, or estimates of an activation volume, the differences between model variants decreased (-7% to +8%). Nonetheless, the technical details of how the electrode contact and current source are represented in the DBS VC model can directly affect estimates of the voltage distribution and electric field in the brain tissue.

Comparison of robotic and manual implantation of intracerebral electrodes: a single-centre, single-blinded, randomised controlled trial.

There has been a significant rise in robotic trajectory guidance devices that have been utilised for stereotactic neurosurgical procedures. These devices have significant costs and associated learning curves. Previous studies reporting devices usage have not undertaken prospective parallel-group comparisons before their introduction, so the comparative differences are unknown. We study the difference in stereoelectroencephalography electrode implantation time between a robotic trajectory guidance device (iSYS1) and manual frameless implantation (PAD) in patients with drug-refractory focal epilepsy through a single-blinded randomised control parallel-group investigation of SEEG electrode implantation, concordant with CONSORT statement. Thirty-two patients (18 male) completed the trial. The iSYS1 returned significantly shorter median operative time for intracranial bolt insertion, 6.36 min (95% CI 5.72-7.07) versus 9.06 min (95% CI 8.16-10.06), p = 0.0001. The PAD group had a better median target point accuracy 1.58 mm (95% CI 1.38-1.82) versus 1.16 mm (95% CI 1.01-1.33), p = 0.004. The mean electrode implantation angle error was 2.13° for the iSYS1 group and 1.71° for the PAD groups (p = 0.023). There was no statistically significant difference for any other outcome. Health policy and hospital commissioners should consider these differences in the context of the opportunity cost of introducing robotic devices.Trial registration: ISRCTN17209025 ( https://doi.org/10.1186/ISRCTN17209025 ).

Pedunculopontine tegmental Nucleus-evoked prepulse inhibition of the blink reflex in Parkinson's disease.

OBJECTIVE: To investigate the effects on the blink reflex (BR) of single stimuli applied to the pedunculopontine tegmental nucleus (PPTg). METHODS: The BR was evoked by stimulating the supraorbital nerve (SON) in fifteen patients suffering from idiopathic Parkinson's disease (PD) who had electrodes monolaterally or bilaterally implanted in the PPTg for deep brain stimulation (DBS). Single stimuli were delivered to the PPTg through externalized electrode connection wires 3-4 days following PPTg implantation. RESULTS: PPTg stimuli increased the latency and reduced duration, amplitude and area of the R2 component of the BR in comparison to the response recorded in the absence of PPTg stimulation. These effects were independent of the side of SON stimulation and were stable for interstimulus interval (ISI) between PPTg prepulse and SON stimulus from 0 to 110 ms. The PPTg-induced prepulse inhibition of the BR was bilaterally present in the brainstem. The R1 component was unaffected. CONCLUSIONS: The prepulse inhibition of the R2 component may be modulated by the PPTg. SIGNIFICANCE: These findings suggest that abnormalities of BR occurring in PD may be ascribed to a reduction of basal ganglia-mediated inhibition of brainstem excitability.

Deep brain stimulation: Challenges at the tissue-electrode interface and current solutions.

Deep brain stimulation (DBS) is used to treat the motor symptoms of Parkinson's disease patients by stimulating the subthalamic nucleus. However, optimization of DBS is still needed since the performance of the neural electrodes is limited by the body's response to the implant. This review discusses the issues with DBS, such as placement of electrodes, foreign body response, and electrode degradation. The current solutions to these technical issues include modifications to electrode material, coatings, and geometry.

Intracranial brain stimulation modulates fMRI-based network switching.

The extent to which functional MRI (fMRI) reflects direct neuronal changes remains unknown. Using 160 simultaneous electrical stimulation (es-fMRI) and intracranial brain stimulation recordings acquired in 26 individuals with epilepsy (with varying electrode locations), we tested whether brain networks dynamically change during intracranial brain stimulation, aiming to establish whether switching between brain networks is reduced after intracranial brain stimulation. As the brain spontaneously switches between a repertoire of intrinsic functional network configurations and the rate of switching is likely increased in epilepsy, we hypothesised that intracranial stimulation would reduce the brain's switching rate, thus potentially normalising aberrant brain network dynamics. To test this hypothesis, we quantified the rate that brain regions changed networks over time in response to brain stimulation, using network switching applied to multilayer modularity analysis of time-resolved es-fMRI connectivity. Network switching and synchrony was decreased after the first brain stimulation, followed by a more consistent pattern of network switching over time. This change was commonly observed in cortical networks and adjacent to the electrode targets. Our results suggest that neuronal perturbation is likely to modulate large-scale brain networks, and multilayer network modelling may be used to inform the clinical efficacy of brain stimulation in epilepsy.