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1.
Transl Neurosci ; 10: 195-199, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31410303

RESUMO

Objective: To describe and assess the educational value of a functional neurosurgery clinical shadowing and research tutorial for pre-medical trainees. Design: Program participants observed functional neurosurgery procedures and conducted basic science and clinical research in neurosurgery fields. Former participants completed a brief online survey to evaluate their perspectives and experiences throughout the tutorial. Setting: Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA. Participants: 15 pre-medical and post-baccalaureate trainees participated in the tutorial. All former tutorial participants were emailed. Results: 11/15 former participants responded to the survey. Survey results suggest that the tutorial program increased participants' understanding of and interest in neurosurgery and related fields in neuroscience. Conclusions: The functional neurosurgery medical tutorial provides valuable clinical and research exposure in neurosurgery fields for pre-medical trainees. Our work is a preliminary step in addressing the crucial challenge of training the next generation of neurosurgeon-scientists by providing a pedagogical paradigm for development of formal experiences that integrate original scientific research with clinical neurosurgery exposure.

2.
Front Neurosci ; 13: 125, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30846925

RESUMO

Synchronous, rhythmic changes in the membrane polarization of neurons form oscillations in local field potentials. It is hypothesized that high-frequency brain oscillations reflect local cortical information processing, and low-frequency brain oscillations project information flow across larger cortical networks. This provides complex forms of information transmission due to interactions between oscillations at different frequency bands, which can be rendered with cross-frequency coupling (CFC) metrics. Phase-amplitude coupling (PAC) is one of the most common representations of the CFC. PAC reflects the coupling of the phase of oscillations in a specific frequency band to the amplitude of oscillations in another frequency band. In a normal brain, PAC accompanies multi-item working memory in the hippocampus, and changes in PAC have been associated with diseases such as schizophrenia, obsessive-compulsive disorder (OCD), Alzheimer disease (AD), epilepsy, and Parkinson's disease (PD). The purpose of this article is to explore CFC across the central nervous system and demonstrate its correlation to neurological disorders. Results from previously published studies are reviewed to explore the significant role of CFC in large neuronal network communication and its abnormal behavior in neurological disease. Specifically, the association of effective treatment in PD such as dopaminergic medication and deep brain stimulation with PAC changes is described. Lastly, CFC analysis of the electrocorticographic (ECoG) signals recorded from the motor cortex of a Parkinson's disease patient and the parahippocampal gyrus of an epilepsy patient are demonstrated. This information taken together illuminates possible roles of CFC in the nervous system and its potential as a therapeutic target in disease states. This will require new neural interface technologies such as phase-dependent stimulation triggered by PAC changes, for the accurate recording, monitoring, and modulation of the CFC signal.

3.
IEEE Trans Neural Syst Rehabil Eng ; 27(2): 293-303, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30624221

RESUMO

Brain-machine interface (BMI) researchers have traditionally focused on modeling endpoint reaching tasks to provide the control of neurally driven prosthetic arms. Most previous research has focused on achieving an endpoint control through a Cartesian-coordinate-centered approach. However, a joint-centered approach could potentially be used to intuitively control a wide range of limb movements. We systematically investigated the feasibility of discriminating between flexion and extension of different upper limb joints using electrocorticography(ECoG) recordings from sensorimotor cortex. Four subjects implanted with macro-ECoG (10-mm spacing), high-density ECoG (5-mm spacing), and/or micro-ECoG arrays (0.9-mm spacing and 4 mm × 4 mm coverage), performed randomly cued flexions or extensions of the fingers, wrist, or elbow contralateral to the implanted hemisphere. We trained a linear model to classify six movements using averaged high-gamma power (70-110 Hz) modulations at different latencies with respect to movement onset, and within a time interval restricted to flexion or extension at each joint. Offline decoding models for each subject classified these movements with accuracies of 62%-83%. Our results suggest that the widespread ECoG coverage of sensorimotor cortex could allow a whole limb BMI to sample native cortical representations in order to control flexion and extension at multiple joints.


Assuntos
Eletrocorticografia/métodos , Articulações/fisiologia , Córtex Sensório-Motor/fisiologia , Extremidade Superior/fisiologia , Adolescente , Adulto , Interfaces Cérebro-Computador , Articulação do Cotovelo/fisiologia , Estudos de Viabilidade , Feminino , Dedos/fisiologia , Humanos , Modelos Lineares , Aprendizado de Máquina , Masculino , Estimulação Luminosa , Articulação do Punho/fisiologia , Adulto Jovem
4.
J Clin Neurosci ; 62: 80-82, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30655234

RESUMO

We performed a retrospective study to characterize the timing and prevalence of revision and removal surgeries after spinal cord stimulator (SCS) implantation in patients with chronic pain. In our analysis of 100 patients who had SCS implants, we found that 34% of patients underwent revision surgery and 53% of patients had their implant removed. Of the patients who required revision surgeries, the majority (56%) eventually opted for removal of their SCS system. The median time to the first revision surgery was 16 months post implantation and the median time to removal was 39 months post implantation. Our findings demonstrate that most SCS systems are removed within a few years post implantation, highlighting the clinical need for a more complete understanding of SCS technology in order to refine patient selection criteria.


Assuntos
Reoperação/estatística & dados numéricos , Estimulação da Medula Espinal , Adulto , Idoso , Dor Crônica/terapia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prevalência , Próteses e Implantes , Estudos Retrospectivos , Fatores de Tempo
5.
Cereb Cortex ; 29(11): 4551-4567, 2019 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-30590542

RESUMO

Rapid and flexible learning during behavioral choices is critical to our daily endeavors and constitutes a hallmark of dynamic reasoning. An important paradigm to examine flexible behavior involves learning new arbitrary associations mapping visual inputs to motor outputs. We conjectured that visuomotor rules are instantiated by translating visual signals into actions through dynamic interactions between visual, frontal and motor cortex. We evaluated the neural representation of such visuomotor rules by performing intracranial field potential recordings in epilepsy subjects during a rule-learning delayed match-to-behavior task. Learning new visuomotor mappings led to the emergence of specific responses associating visual signals with motor outputs in 3 anatomical clusters in frontal, anteroventral temporal and posterior parietal cortex. After learning, mapping selective signals during the delay period showed interactions with visual and motor signals. These observations provide initial steps towards elucidating the dynamic circuits underlying flexible behavior and how communication between subregions of frontal, temporal, and parietal cortex leads to rapid learning of task-relevant choices.

6.
Cereb Cortex ; 29(2): 777-787, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-29373641

RESUMO

Any given area in human cortex may receive input from multiple, functionally heterogeneous areas, potentially representing different processing threads. Alpha (8-13 Hz) and beta oscillations (13-20 Hz) have been hypothesized by other investigators to gate local cortical processing, but their influence on cortical responses to input from other cortical areas is unknown. To study this, we measured the effect of local oscillatory power and phase on cortical responses elicited by single-pulse electrical stimulation (SPES) at distant cortical sites, in awake human subjects implanted with intracranial electrodes for epilepsy surgery. In 4 out of 5 subjects, the amplitudes of corticocortical evoked potentials (CCEPs) elicited by distant SPES were reproducibly modulated by the power, but not the phase, of local oscillations in alpha and beta frequencies. Specifically, CCEP amplitudes were higher when average oscillatory power just before distant SPES (-110 to -10 ms) was high. This effect was observed in only a subset (0-33%) of sites with CCEPs and, like the CCEPs themselves, varied with stimulation at different distant sites. Our results suggest that although alpha and beta oscillations may gate local processing, they may also enhance the responsiveness of cortex to input from distant cortical sites.

7.
J Comput Neurosci ; 45(3): 193-206, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30443813

RESUMO

Electrical stimulation of nerve fibers is used as a therapeutic tool to treat neurophysiological disorders. Despite efforts to model the effects of stimulation, its underlying mechanisms remain unclear. Current mechanistic models quantify the effects that the electrical field produces near the fiber but do not capture interactions between action potentials (APs) initiated by stimulus and APs initiated by underlying physiological activity. In this study, we aim to quantify the effects of stimulation frequency and fiber diameter on AP interactions involving collisions and loss of excitability. We constructed a mechanistic model of a myelinated nerve fiber receiving two inputs: the underlying physiological activity at the terminal end of the fiber, and an external stimulus applied to the middle of the fiber. We define conduction reliability as the percentage of physiological APs that make it to the somatic end of the nerve fiber. At low input frequencies, conduction reliability is greater than 95% and decreases with increasing frequency due to an increase in AP interactions. Conduction reliability is less sensitive to fiber diameter and only decreases slightly with increasing fiber diameter. Finally, both the number and type of AP interactions significantly vary with both input frequencies and fiber diameter. Modeling the interactions between APs initiated by stimulus and APs initiated by underlying physiological activity in a nerve fiber opens opportunities towards understanding mechanisms of electrical stimulation therapies.


Assuntos
Potenciais de Ação/fisiologia , Estimulação Elétrica , Modelos Neurológicos , Fibras Nervosas Mielinizadas/fisiologia , Condução Nervosa/fisiologia , Animais , Simulação por Computador , Humanos , Reprodutibilidade dos Testes
8.
Conf Proc IEEE Eng Med Biol Soc ; 2018: 3525-3528, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-30441139

RESUMO

Modern therapeutic interventions are increasingly favoring electrical stimulation to treat neurophysiological dis-orders. These therapies are associated with suboptimal efficacy since most neurostimulation devices operate in an open-loop manner $(i.e.$, stimulation settings like frequency, amplitude are preprogrammed). A closed-loop system can dynamically adjust stimulation parameters and may provide efficient therapies. Computational models used to design these systems vary in complexity which can adversely affect their real-time performance. In this study, we compare two models of varying degrees of complexity. We constructed two computational models of a myelinated nerve fiber (functional versus mechanistic) each receiving two inputs: the underlying physiological activity at one end of the fiber, and the external stimulus applied to the middle of the fiber. We then defined relay reliability as the percentage of physiological action potentials that make it to the other end of the nerve fiber. We applied the two inputs to the fiber at various frequencies and analyze reliability. We found that the functional model and the mechanistic model have similar reliability properties, but the functional model significantly decreases the computational complexity and simulation run time. This modeling effort is the first step towards understanding and designing closed loop, real-time neurostimulation devices.


Assuntos
Fibras Nervosas Mielinizadas , Potenciais de Ação , Animais , Estimulação Elétrica , Mamíferos , Modelos Neurológicos , Reprodutibilidade dos Testes
9.
Conf Proc IEEE Eng Med Biol Soc ; 2018: 3606-3609, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-30441157

RESUMO

Electrical stimulation of peripheral nerve fibers and dorsal column fibers is used to treat acute and chronic pain. Recent studies have shown that sensitized A-fibers maybe involved in the relay of pain information. These nerve fibers also carry sensory-induced action potentials (APs), such as proprioception, mechanoreception, etc. Electrical stimulation of these nerve fibers can result in interactions between sensory-induced APs and stimulation-induced APs. For example, the sensory-induced APs can collide with stimulus APs, and thus may never be relayed to the brain. In this study, we aimed to quantify the effects of stimulation frequency on these interactions. Specifically, we focused on the goal of stimulation to simultaneously (i) block noxious sensory signals while (ii) relaying innocuous sensory signals from the periphery to the brain via a myelinated nerve fiber. We defined a performance metric called the "selective relay $(SR)$ " measure. Specifically, we constructed a tractable model of a nerve fiber that receives two inputs: the underlying sensory activity at the bottom of the fiber (noxious or innocuous), and the external stimulus applied to the middle of the fiber. We then defined relay reliability, $R$, as the percentage of sensory APs that make it to the top of the fiber. $SR$ is then a product of relaying innocuous sensory information while blocking noxious pain stimuli, i.e., $SR=R_{\mathrm {s}\mathrm {e}\mathrm {n}}(1-R_{\mathrm {p}\mathrm {a}\mathrm {i}\mathrm {n}})$. We applied the two inputs to the fiber at various frequencies and analyzed relay reliability and then we studied selective relay assuming noxious and innocuous stimuli produce APs with distinct frequencies. We found that frequency stimulation between 50-100Hz effectively blocks relay of low-frequency pain signals, allowing mid-to-high frequency sensory signals to transmit to the brain.


Assuntos
Encéfalo , Nervos Periféricos , Potenciais de Ação , Estimulação Elétrica , Reprodutibilidade dos Testes
10.
Med Phys ; 45(12): 5420-5436, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30339271

RESUMO

PURPOSE: Indirect-detection CMOS flat-panel detectors (FPDs) offer fine pixel pitch, fast readout, and low electronic noise in comparison to current a-Si:H FPDs. This work investigates the extent to which these potential advantages affect imaging performance in mobile C-arm fluoroscopy and cone-beam CT (CBCT). METHODS: FPDs based on CMOS (Xineos 3030HS, 0.151 mm pixel pitch) or a-Si:H (PaxScan 3030X, 0.194 mm pixel pitch) sensors were outfitted on equivalent mobile C-arms for fluoroscopy and CBCT. Technical assessment of 2D and 3D imaging performance included measurement of electronic noise, gain, lag, modulation transfer function (MTF), noise-power spectrum (NPS), detective quantum efficiency (DQE), and noise-equivalent quanta (NEQ) in fluoroscopy (with entrance air kerma ranging 5-800 nGy per frame) and cone-beam CT (with weighted CT dose index, CTDIw , ranging 0.08-1 mGy). Image quality was evaluated by clinicians in vascular, orthopaedic, and neurological surgery in realistic interventional scenarios with cadaver subjects emulating a variety of 2D and 3D imaging tasks. RESULTS: The CMOS FPD exhibited ~2-3× lower electronic noise and ~7× lower image lag than the a-Si:H FPD. The 2D (projection) DQE was superior for CMOS at ≤50 nGy per frame, especially at high spatial frequencies (~2% improvement at 0.5 mm-1 and ≥50% improvement at 2.3 mm-1 ) and was somewhat inferior at moderate-high doses (up to 18% lower DQE for CMOS at 0.5 mm-1 ). For smooth CBCT reconstructions (low-frequency imaging tasks), CMOS exhibited ~10%-20% higher NEQ (at 0.1-0.5 mm-1 ) at the lowest dose levels (CTDIw ≤0.1 mGy), while the a-Si:H system yielded slightly (~5%) improved NEQ (at 0.1-0.5 lp/mm) at higher dose levels (CTDIw ≥0.6 mGy). For sharp CBCT reconstructions (high-frequency imaging tasks), NEQ was ~32% higher above 1 mm-1 for the CMOS system at mid-high-dose levels and ≥75% higher at the lowest dose levels (CTDIw ≤0.1 mGy). Observer assessment of 2D and 3D cadaver images corroborated the objective metrics with respect to a variety of pertinent interventional imaging tasks. CONCLUSION: Measurements of image noise, spatial resolution, DQE, and NEQ indicate improved low-dose performance for the CMOS-based system, particularly at lower doses and higher spatial frequencies. Assessment in realistic imaging scenarios confirmed improved visibility of fine details in low-dose fluoroscopy and CBCT. The results quantitate the extent to which CMOS detectors improve mobile C-arm imaging performance, especially in 2D and 3D imaging scenarios involving high-resolution tasks and low-dose conditions.


Assuntos
Tomografia Computadorizada de Feixe Cônico/instrumentação , Fluoroscopia/instrumentação , Metais/química , Óxidos/química , Semicondutores , Desenho de Equipamento , Humanos , Imagem Tridimensional , Razão Sinal-Ruído
11.
Yale J Biol Med ; 91(3): 323-331, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30258319

RESUMO

Failed back surgery syndrome (FBBS) is characterized by chronic pain that persists following spine surgery. In this review, we discuss the use of spinal cord stimulation (SCS) for FBBS treatment and how the clinical use of SCS may be influenced by private manufacturers. While SCS therapy can be promising for the appropriate patient, there remain knowledge gaps in understanding the full potential of SCS technology for delivering optimal therapeutic benefit. We caution that the use of SCS without a complete understanding of the technology may create exploitative situations that private manufacturers can capitalize on while subjecting patients to potentially unnecessary health and financial burdens.


Assuntos
Síndrome Pós-Laminectomia/cirurgia , Síndrome Pós-Laminectomia/terapia , Humanos , Neurocirurgia , Estimulação da Medula Espinal
12.
Netw Neurosci ; 2(2): 218-240, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30215034

RESUMO

Treatment of medically intractable focal epilepsy (MIFE) by surgical resection of the epileptogenic zone (EZ) is often effective provided the EZ can be reliably identified. Even with the use of invasive recordings, the clinical differentiation between the EZ and normal brain areas can be quite challenging, mainly in patients without MRI detectable lesions. Consequently, despite relatively large brain regions being removed, surgical success rates barely reach 60-65%. Such variable and unfavorable outcomes associated with high morbidity rates are often caused by imprecise and/or inaccurate EZ localization. We developed a localization algorithm that uses network-based data analytics to process invasive EEG recordings. This network algorithm analyzes the centrality signatures of every contact electrode within the recording network and characterizes contacts into susceptible EZ based on the centrality trends over time. The algorithm was tested in a retrospective study that included 42 patients from four epilepsy centers. Our algorithm had higher agreement with EZ regions identified by clinicians for patients with successful surgical outcomes and less agreement for patients with failed outcomes. These findings suggest that network analytics and a network systems perspective of epilepsy may be useful in assisting clinicians in more accurately localizing the EZ.

13.
Top Magn Reson Imaging ; 27(3): 171-177, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29870469

RESUMO

Intraoperative magnetic resonance imaging (iMRI) is increasingly implemented for image-guided procedures in functional neurosurgery. iMRI facilitates accurate electrode implantation for deep brain stimulation (DBS) and is currently an alternative method for DBS electrode targeting. The application of iMRI also allows for greater accuracy and precision in laser-induced thermal therapy (LITT). The expanding use of functional neurosurgical procedures makes safety and feasibility of iMRI important considerations, particularly in patients with comorbidities or complex medical histories. We review here the applications of iMRI and discuss its safety, feasibility, and limitations in functional neurosurgery.To motivate discussion of this topic, we also present a 52-year-old patient with an implanted cardioverter-defibrillator (ICD) who successfully underwent iMRI-guided DBS electrode implantation for advanced Parkinson disease (PD). Neither iMRI nor the passage of electrical current through the implanted DBS electrodes demonstrated detectable interference in ICD function. This case demonstrates that, even in complex clinical contexts, iMRI is a promising tool that merits further exploration for procedures requiring highly accurate and precise identification of target structures.


Assuntos
Estimulação Encefálica Profunda/métodos , Terapia a Laser/métodos , Imagem por Ressonância Magnética Intervencionista/métodos , Procedimentos Neurocirúrgicos/métodos , Doença de Parkinson/diagnóstico por imagem , Doença de Parkinson/terapia , Encéfalo/diagnóstico por imagem , Encéfalo/cirurgia , Eletrodos Implantados , Humanos , Masculino , Pessoa de Meia-Idade
14.
J Alzheimers Dis ; 64(2): 597-606, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29914028

RESUMO

BACKGROUND: Given recent challenges in developing new treatments for Alzheimer dementia (AD), it is vital to explore alternate treatment targets, such as neuromodulation for circuit dysfunction. We previously reported an exploratory Phase IIb double-blind trial of deep brain stimulation targeting the fornix (DBS-f) in mild AD (the ADvance trial). We reported safety but no clinical benefits of DBS-f versus the delayed-on (sham) treatment in 42 participants after one year. However, secondary post hoc analyses of the one-year data suggested a possible DBS-f benefit for participants≥65 years. OBJECTIVE: To examine the long-term safety and clinical effects of sustained and delayed-on DBS-f treatment of mild AD after two years. METHODS: 42 participants underwent implantation of DBS-f electrodes, with half randomized to active DBS-f stimulation (early on) for two years and half to delayed-on (sham) stimulation after 1 year to provide 1 year of active DBS-f stimulation (delayed on). We evaluated safety and clinical outcomes over the two years of the trial. RESULTS: DBS-f had a favorable safety profile with similar rates of adverse events across both trial phases (years 1 and 2) and between treatment arms. There were no differences between treatment arms on any primary clinical outcomes. However, post-hoc age group analyses suggested a possible benefit among older (>65) participants. CONCLUSION: DBS-f was safe. Additional study of mechanisms of action and methods for titrating stimulation parameters will be needed to determine if DBS has potential as an AD treatment. Future efficacy studies should focus on patients over age 65.


Assuntos
Doença de Alzheimer/terapia , Estimulação Encefálica Profunda/métodos , Fórnice/fisiologia , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Estudos Longitudinais , Masculino , Testes Neuropsicológicos , Escalas de Graduação Psiquiátrica
15.
JAMA Neurol ; 75(3): 353-359, 2018 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-29340590

RESUMO

Importance: Collective evidence has strongly suggested that deep brain stimulation (DBS) is a promising therapy for Tourette syndrome. Objective: To assess the efficacy and safety of DBS in a multinational cohort of patients with Tourette syndrome. Design, Setting, and Participants: The prospective International Deep Brain Stimulation Database and Registry included 185 patients with medically refractory Tourette syndrome who underwent DBS implantation from January 1, 2012, to December 31, 2016, at 31 institutions in 10 countries worldwide. Exposures: Patients with medically refractory symptoms received DBS implantation in the centromedian thalamic region (93 of 163 [57.1%]), the anterior globus pallidus internus (41 of 163 [25.2%]), the posterior globus pallidus internus (25 of 163 [15.3%]), and the anterior limb of the internal capsule (4 of 163 [2.5%]). Main Outcomes and Measures: Scores on the Yale Global Tic Severity Scale and adverse events. Results: The International Deep Brain Stimulation Database and Registry enrolled 185 patients (of 171 with available data, 37 females and 134 males; mean [SD] age at surgery, 29.1 [10.8] years [range, 13-58 years]). Symptoms of obsessive-compulsive disorder were present in 97 of 151 patients (64.2%) and 32 of 148 (21.6%) had a history of self-injurious behavior. The mean (SD) total Yale Global Tic Severity Scale score improved from 75.01 (18.36) at baseline to 41.19 (20.00) at 1 year after DBS implantation (P < .001). The mean (SD) motor tic subscore improved from 21.00 (3.72) at baseline to 12.91 (5.78) after 1 year (P < .001), and the mean (SD) phonic tic subscore improved from 16.82 (6.56) at baseline to 9.63 (6.99) at 1 year (P < .001). The overall adverse event rate was 35.4% (56 of 158 patients), with intracranial hemorrhage occurring in 2 patients (1.3%), infection in 4 patients with 5 events (3.2%), and lead explantation in 1 patient (0.6%). The most common stimulation-induced adverse effects were dysarthria (10 [6.3%]) and paresthesia (13 [8.2%]). Conclusions and Relevance: Deep brain stimulation was associated with symptomatic improvement in patients with Tourette syndrome but also with important adverse events. A publicly available website on outcomes of DBS in patients with Tourette syndrome has been provided.


Assuntos
Estimulação Encefálica Profunda/métodos , Sistema de Registros , Síndrome de Tourette/terapia , Resultado do Tratamento , Adolescente , Adulto , Estudos de Coortes , Bases de Dados Factuais/estatística & dados numéricos , Feminino , Globo Pálido/fisiologia , Humanos , Cooperação Internacional , Masculino , Pessoa de Meia-Idade , Índice de Gravidade de Doença , Método Simples-Cego , Tálamo/fisiologia , Adulto Jovem
16.
Oper Neurosurg (Hagerstown) ; 15(1): 39-45, 2018 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-29029236

RESUMO

BACKGROUND: Neuromodulation devices have the potential to transform modern day treatments for patients with medicine-resistant neurological disease. For instance, the NeuroPace System (NeuroPace Inc, Mountain View, California) is a Food and Drug Administration (FDA)-approved device developed for closed-loop direct brain neurostimulation in the setting of drug-resistant focal epilepsy. However, current methods require placement either above or below the skull in nonanatomic locations. This type of positioning has several drawbacks including visible deformities and scalp pressure from underneath leading to eventual wound healing difficulties, micromotion of hardware with infection, and extrusion leading to premature explantation. OBJECTIVE: To introduce complete integration of a neuromodulation device within a customized cranial implant for biocompatibility optimization and prevention of visible deformity. METHODS: We report a patient with drug-resistant focal epilepsy despite previous seizure surgery and maximized medical therapy. Preoperative imaging demonstrated severe resorption of previous bone flap causing deformity and risk for injury. She underwent successful responsive neurostimulation device implantation via complete integration within a clear customized cranial implant. RESULTS: The patient has recovered well without complication and has been followed closely for 180 d. Device interrogation with electrocorticographic data transmission has been successfully performed through the clear implant material for the first time with no evidence of any wireless transmission interference. CONCLUSION: Cranial contour irregularities, implant site infection, and bone flap resorption/osteomyelitis are adverse events associated with implantable neurotechnology. This method represents a novel strategy to incorporate all future neuromodulation devices within the confines of a low-profile, computer-designed cranial implant and the newfound potential to eliminate contour irregularities, improve outcomes, and optimize patient satisfaction.


Assuntos
Encéfalo/cirurgia , Estimulação Encefálica Profunda , Epilepsia Resistente a Medicamentos/cirurgia , Epilepsias Parciais/cirurgia , Neuroestimuladores Implantáveis , Feminino , Humanos , Pessoa de Meia-Idade , Resultado do Tratamento
17.
J Neurol Neurosurg Psychiatry ; 89(7): 777-787, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29242310

RESUMO

Based on the success of deep brain stimulation (DBS) for treating movement disorders, there is growing interest in using DBS to treat schizophrenia (SZ). We review the unmet needs of patients with SZ and the scientific rationale behind the DBS targets proposed in the literature in order to guide future development of DBS to treat this vulnerable patient population. SZ remains a devastating disorder despite treatment. Relapse, untreated psychosis, intolerable side effects and the lack of effective treatment for negative and cognitive symptoms contribute to poor outcome. Novel therapeutic interventions are needed to treat SZ and DBS is emerging as a potential intervention. Convergent genetic, pharmacological and neuroimaging evidence implicating neuropathology associated with psychosis is consistent with SZ being a circuit disorder amenable to striatal modulation with DBS. Many of the DBS targets proposed in the literature may modulate striatal dysregulation. Additional targets are considered for treating tardive dyskinesia and negative and cognitive symptoms. A need is identified for the concurrent development of neurophysiological biomarkers relevant to SZ pathology in order to inform DBS targeting. Finally, we discuss the current clinical trials of DBS for SZ, and their ethical considerations. We conclude that patients with severe symptoms despite treatment must have the capacity to consent for a DBS clinical trial in which risks can be estimated, but benefit is not known. In addition, psychiatric populations should have access to the potential benefits of neurosurgical advances.


Assuntos
Estimulação Encefálica Profunda/métodos , Esquizofrenia/terapia , Humanos
18.
Conf Proc IEEE Eng Med Biol Soc ; 2017: 1110-1113, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-29060069

RESUMO

Transcranial direct current stimulation (tDCS) is an emerging method, used for non-invasively stimulating the brain in normal healthy subjects and in patients with neurological disorders. However, the pattern of the spatial distribution of the current intensity induced by tDCS is poorly understood. In this study, we directly measured the spatial characteristics of the current intensity induced by tDCS using an intracranial strip electrode array implanted over the motor cortex in patients with Parkinson's disease undergoing deep brain stimulation lead placement surgery. We used a bilateral stimulation configuration for the tDCS electrode placement and measured the amount of electric current passing through the contacts along the implanted strip electrode contacts. Our results showed significant changes of the current flow induced by the tDCS in some of the contacts during stimulation with respect to baseline activities. These results may provide vital information regarding the biophysical effects of tDCS stimulation and might be potentially useful for developing more effective stimulation strategies.


Assuntos
Espaço Subdural , Eletrodos Implantados , Humanos , Córtex Motor , Estimulação Transcraniana por Corrente Contínua , Estimulação Magnética Transcraniana
19.
Conf Proc IEEE Eng Med Biol Soc ; 2017: 3868-3871, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-29060742

RESUMO

Electrical neurostimulation is increasingly used over neuropharmacology to treat various diseases. Despite efforts to model the effects of electrical stimulation, its underlying mechanisms remain unclear. This is because current mechanistic models just quantify the effects that the electrical field produces near the fiber and do not capture interactions between stimulus-initiated action potentials (APs) and underlying physiological activity initiated APs. In this study, we aim to quantify and compare these interactions. We construct two computational models of a nerve fiber of varying degrees of complexity (probabilistic versus mechanistic) each receiving two inputs: the underlying physiological activity at one end of the fiber, and the external stimulus applied to the middle of the fiber. We then define reliability, R, as the percentage of physiological APs that make it to the other end of the nerve fiber. We apply the two inputs to the fiber at various frequencies and analyze reliability. We find that the probabilistic model captures relay properties for low input frequencies (<; 10 Hz) but then differs from the mechanistic model if either input has a larger frequency. This is because the probabilistic model only accounts for only (i) inter signal loss of excitability and (ii) collisions between stimulus-initiated action potentials (APs) and underlying physiological activity initiated APs. This first step towards modeling the interactions in a nerve fiber opens up opportunities towards understanding mechanisms of electrical stimulation therapies.


Assuntos
Estimulação Elétrica , Potenciais de Ação , Animais , Terapia por Estimulação Elétrica , Fibras Nervosas , Probabilidade , Reprodutibilidade dos Testes
20.
Conf Proc IEEE Eng Med Biol Soc ; 2017: 3918-3921, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-29060754

RESUMO

The use of motion tracking devices in healthcare is under investigation. Although many motion tracking applications have been proposed to monitor the progress of rehabilitation, using such technology to quantify the progression or improvement of therapies for movement disorders is still scarce. In this study, we introduce a touch-free reaching task which uses a motion sensing device. Our motion tracking system combines a motion tracking device and visual feedback to implement a movement task for the evaluation of the state of motor functions impairment symptoms in Parkinson's disease and other movement disorders.


Assuntos
Doença de Parkinson , Retroalimentação Sensorial , Humanos , Movimento (Física) , Movimento , Tato
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