Fundamentals of deep brain stimulation for Parkinson's disease in clinical practice: part 2.

The field of neuromodulation has evolved significantly over the past decade. Developments include novel indications and innovations of hardware, software, and stimulation techniques leading to an expansion in scope and role of these techniques as powerful therapeutic interventions. In this review, which is the second part of an effort to document and integrate the basic fundamentals and recent successful developments in the field, we will focus on classic paradigms for electrode placement as well as new exploratory targets, mechanisms of neuromodulation using this technique and new developments, including focused ultrasound driven ablative procedures.

O campo da neuromodulação evoluiu significativamente na última década. Esse progresso inclui novas indicações e inovações de hardware, software e técnicas de estimulação, levando a uma expansão das áreas clínicas cobertas e no papel dessas técnicas como intervenções terapêuticas eficazes. Nesta revisão, que é a segunda parte de um esforço para documentar e integrar os fundamentos básicos e os desenvolvimentos recentes e bem-sucedidos no campo, vamos nos concentrar em paradigmas clássicos para colocação de eletrodos, bem como em novos alvos exploratórios, mecanismos de neuromodulação usados por esta técnica e novos desenvolvimentos, incluindo procedimentos ablativos orientados por ultrassom focalizado.

Insertional effect following electrode implantation: an underreported but important phenomenon.

Deep brain stimulation has revolutionized the treatment of movement disorders and is gaining momentum in the treatment of several other neuropsychiatric disorders. In almost all applications of this therapy, the insertion of electrodes into the target has been shown to induce some degree of clinical improvement prior to stimulation onset. Disregarding this phenomenon, commonly referred to as 'insertional effect', can lead to biased results in clinical trials, as patients receiving sham stimulation may still experience some degree of symptom amelioration. Similar to the clinical scenario, an improvement in behavioural performance following electrode implantation has also been reported in preclinical models. From a neurohistopathologic perspective, the insertion of electrodes into the brain causes an initial trauma and inflammatory response, the activation of astrocytes, a focal release of gliotransmitters, the hyperexcitability of neurons in the vicinity of the implants, as well as neuroplastic and circuitry changes at a distance from the target. Taken together, it would appear that electrode insertion is not an inert process, but rather triggers a cascade of biological processes, and, as such, should be considered alongside the active delivery of stimulation as an active part of the deep brain stimulation therapy.

Current Progress in Magnetic Resonance-Guided Focused Ultrasound to Facilitate Drug Delivery across the Blood-Brain Barrier.

This review discusses the current progress in the clinical use of magnetic resonance-guided focused ultrasound (MRgFUS) and other ultrasound platforms to transiently permeabilize the blood-brain barrier (BBB) for drug delivery in neurological disorders and neuro-oncology. Safety trials in humans have followed on from extensive pre-clinical studies, demonstrating a reassuring safety profile and paving the way for numerous translational clinical trials in Alzheimer's disease, Parkinson's disease, and primary and metastatic brain tumors. Future directions include improving ultrasound delivery devices, exploring alternative delivery approaches such as nanodroplets, and expanding the application to other neurological conditions.

Fundamentals of deep brain stimulation for Parkinson's disease in clinical practice: part 1.

Deep brain stimulation (DBS) is recognized as an established therapy for Parkinson's disease (PD) and other movement disorders in the light of the developments seen over the past three decades. Long-term efficacy is established for PD with documented improvement in the cardinal motor symptoms of PD and levodopa-induced complications, such as motor fluctuations and dyskinesias. Timing of patient selection is crucial to obtain optimal benefits from DBS therapy, before PD complications become irreversible. The objective of this first part review is to examine the fundamental concepts of DBS for PD in clinical practice, discussing the historical aspects, patient selection, potential effects of DBS on motor and non-motor symptoms, and the practical management of patients after surgery.

Nas últimas três décadas, a estimulação cerebral profunda (ECP) se tornou um tratamento bem estabelecido para doença de Parkinson (DP) e outros transtornos do movimento. A eficácia a longo prazo na DP foi bem documentada para a melhora dos sintomas motores cardinais da DP e das complicações induzidas pelo uso do levodopa, como as flutuações motoras e as discinesias. O momento da seleção do paciente é crucial para se obter os benefícios ideais da ECP, antes que as complicações da DP se tornem irreversíveis. O objetivo desta primeira parte da revisão é examinar os conceitos fundamentais da ECP na prática clínica, discutindo os aspectos históricos, a seleção de pacientes, os potenciais efeitos da ECP nos sintomas motores e não motores da doença e o manejo prático dos pacientes após a cirurgia.

Treatment expectations and clinical outcomes following repetitive transcranial magnetic stimulation for treatment-resistant depression.

BACKGROUND: Patient expectations, including both positive (placebo) and negative (nocebo) effects, influence treatment outcomes, yet their impact on acute repetitive transcranial magnetic stimulation (rTMS) for treatment-resistant depression (TRD) is unclear. METHODS: In this single-center retrospective chart review, 208 TRD patients completed the Stanford Expectation of Treatment Scale (SETS) before starting open-label rTMS treatment. Patients were offered two excitatory rTMS protocols (deep TMS or intermittent theta-burst stimulation), which stimulated the left dorsolateral prefrontal cortex. A minimum of 20 once daily treatments were provided, delivered over 4-6 weeks. Primary outcomes were 1) remission, measured by a post-treatment score of <8 on the Hamilton Depression Rating Scale (HAMD-17), and 2) premature discontinuation. The change in HAMD-17 scores over time was used as a secondary outcome. Physicians were blinded to SETS scores. Logistic and linear regression, adjusting for covariates, assessed SETS and HAMD-17 relationships. RESULTS: Of 208 patients, 177 had baseline and covariate data available. The mean positivity bias score (positive expectancy minus negative expectancy subscale averages) was 0.48 ± 2.21, indicating the cohort was neutral regarding the expectations of their treatment on average. Higher positive expectancy scores were significantly associated with greater odds of remission (OR = 1.90, p = 0.003) and greater reduction in HAMD-17 scores (ß = 1.30, p = 0.005) at the end of acute treatment, after adjusting for covariates. Negative expectancy was not associated with decreased odds of remission (p = 0.2) or treatment discontinuation (p = 0.8). CONCLUSIONS: Higher pre-treatment positive expectations were associated with greater remission rates with open-label rTMS in a naturalistic cohort of patients with TRD.

A Pragmatic Review on Spinal Cord Stimulation Therapy for Parkinson's Disease Gait Related Disorders: Gaps and Controversies.

BACKGROUND: Parkinson's Disease (PD) is a progressive neurological disorder that results in potentially debilitating mobility deficits. Recently, spinal cord stimulation (SCS) has been proposed as a novel therapy for PD gait disorders. The highest levels of evidence remain limited for SCS. OBJECTIVES: In this systematic review and narrative synthesis, the literature was searched using combinations of key phrases indicating spinal cord stimulation and PD. METHODS: We included pre-clinical studies and all published clinical trials, case reports, conference abstracts as well as protocols for ongoing clinical trials. Additionally, we included trials of SCS applied to atypical parkinsonism. RESULTS: A total of 45 human studies and trials met the inclusion criteria. Based on the narrative synthesis, a number of knowledge gaps and future avenues of potential research were identified. This review demonstrated that evidence for SCS is currently not sufficient to recommend it as an evidence-based therapy for PD related gait disorders. There remain challenges and significant barriers to widespread implementation, including issues regarding patient selection, effective outcome selection, stimulation location and mode, and in programming parameter optimization. Results of early randomized controlled trials are currently pending. SCS is prone to placebo, lessebo and nocebo as well as blinding effects which may impact interpretation of outcomes, particularly when studies are underpowered. CONCLUSION: Therapies such as SCS may build on current evidence and be shown to improve specific gait features in PD. Early negative trials should be interpreted with caution, as more evidence will be required to develop effective methodologies in order to drive clinical outcomes.

Reduction of alpha-synuclein oligomers in preclinical models of Parkinson's disease by electrical stimulation in vitro and deep brain stimulation in vivo.

BACKGROUND: Deep brain stimulation (DBS) has been widely used to manage debilitating neurological symptoms in movement disorders such as Parkinson's disease (PD). Despite its well-established symptomatic benefits, our understanding of the mechanisms underlying DBS and its possible effect on the accumulation of pathological proteins in neurodegeneration remains limited. Accumulation and oligomerization of the protein alpha-synuclein (α-Syn) are implicated in the loss of dopaminergic neurons in the substantia nigra in PD, making α-Syn a potential therapeutic target for disease modification. OBJECTIVE: We examined the effects of high frequency electrical stimulation on α-Syn levels and oligomerization in cell and rodent models. METHODS: High frequency stimulation, mimicking DBS parameters used for PD, was combined with viral-mediated overexpression of α-Syn in cultured rat primary cortical neurons or in substantia nigra of rats. Bimolecular protein complementation with split fluorescent protein reporters was used to detect and quantify α-Syn oligomers. RESULTS: High frequency electrical stimulation reduced the expression of PD-associated mutant α-Syn and mitigated α-Syn oligomerization in cultured neurons. Furthermore, DBS in the substantia nigra, but not the subthalamic nucleus, decreased overall levels of α-Syn, including oligomer levels, in the substantia nigra. CONCLUSIONS: Taken together, our results demonstrate that direct high frequency stimulation can reduce accumulation and pathological forms of α-Syn in cultured neurons in vitro and in substantia nigra in vivo. Thus, DBS therapy could have a role beyond symptomatic treatment, with potential disease-modifying properties that can be exploited to target pathological proteins in neurodegenerative diseases.

Antidepressant class and concurrent rTMS outcomes in major depressive disorder: a systematic review and meta-analysis.

Background: Repetitive transcranial magnetic stimulation (rTMS) is frequently used as an adjunctive treatment with antidepressants for depression. We aimed to evaluate the clinical efficacy and safety of antidepressant classes when administered concurrently with rTMS for the management of major depressive disorder (MDD). Methods: In this systematic review and meta-analysis, MEDLINE, Embase, PsycINFO, and the Cochrane Library were searched from inception to April 12th 2024 for terms relating to medication, depression, and rTMS and appraised by 2 independent screeners. All randomized clinical trials that prospectively evaluated a specific antidepressant adjunctively with sham rTMS as a control in MDD were included. The study was registered with PROSPERO (CRD42023418435). The primary outcome measure assessed symptomatic improvement measured by formal depression scales. We used a random-effects model with pooled Standardized Mean Differences (SMDs) and log odds ratios (OR). All studies were assessed for their methodological quality and bias using the Cochrane Collaboration Risk of Bias tool version 2 (RoB2). Findings: 14 articles from 5376 identified studies were included in the systematic review and meta-analysis. There was only sufficient trial data to evaluate the effects of rTMS and combination therapy with selective serotonin reuptake inhibitors (SSRIs) and selective norepinephrine reuptake inhibitors (SNRIs). Across studies, 848 participants (mean [SD] age:41.1 [18.7] years for SSRIs, 51.8 [3.8] years for SNRIs) prospectively examined the efficacy of antidepressant medication with rTMS. Combining rTMS with SSRIs led to significantly lower depression scores, (SMD [CI] of -0.65 [-0.98, -0.31], p = 0.0002, I2 = 66.1%), higher response (OR = 0.97 [0.50, 1.44], p < 0.0001, I2 = 25.33%) and remission rates (OR = 1.04 [0.55, 1.52], p < 0.0001, I2 = 0.00%) than medication with sham rTMS. No additive benefit was found for SNRIs with rTMS (SMD of 0.10 [-0.14, 0.34], p = 0.42, I2 = 0.00%; OR = 0.12 [-0.39, 0.62], p = 0.64, I2 = 0.00%; OR = -0.31 [-0.90, 0.28], p = 0.86, I2 = 39.9%). The overall risk of bias for the included studies ranged from low to high, with 1 study having a high risk of bias. Interpretation: The combination of rTMS with SSRIs, but not SNRIs, significantly reduced depression severity, increasing response and remission rates. Some analyses demonstrated high heterogeneity, which was influenced by an SSRI trial with a high effect size. Overall, these results suggest that not all antidepressant combination therapies are alike, and SSRIs should be considered when initiating rTMS. Funding: Donald T. Stuss Young Investigator Research Innovation Award from the Sandra Black Centre for Brain Resilience & Recovery and the Harquail Centre for Neuromodulation through the Sunnybrook Foundation.

Adverse Effects of Deep Brain Stimulation for Treatment-Resistant Depression: A Scoping Review.

Deep brain stimulation (DBS) is an emerging therapy for treatment-resistant depression (TRD). Although adverse effects have been reported in early-phase and a few randomized clinical trials, little is known about its overall safety profile, which has been assumed to be similar to that of DBS for movement disorders. The objective of this study was to pool existing safety data on DBS for TRD. Following PRISMA guidelines, PubMed was searched for English articles describing adverse outcomes after DBS for TRD. Studies were included if they reported at least 5 patients with a minimal follow-up of 6 months. After abstract (n = 607) and full-article review (n = 127), 28 articles reporting on 353 patients met criteria for final inclusion. Follow-up of the studies retrieved ranged from 12 to 96 months. Hemorrhages occurred in 0.8% of patients and infections in 10.2%. The rate of completed suicide was 2.5%. Development or worsening of depressive symptoms, anxiety, and mania occurred in 18.4%, 9.1%, and 5.1%, respectively. There were some differences between targets, but between-study heterogeneity precluded statistical comparisons. In conclusion, DBS for TRD is associated with surgical and psychiatric adverse events. Hemorrhage and infection occur at rates within an accepted range for other DBS applications. The risk of suicide after DBS for TRD is 2.5% but may not represent a significant deviation from the natural history of TRD. Finally, risks of worsening depression, anxiety, and the incidence of mania should be acknowledged when considering DBS for TRD.

Fundamentals of deep brain stimulation for Parkinson's disease in clinical practice: part 1 / Princípios da estimulação cerebral profunda na doença de Parkinson na prática clínica: parte 1

Abstract Deep brain stimulation (DBS) is recognized as an established therapy for Parkinson's disease (PD) and other movement disorders in the light of the developments seen over the past three decades. Long-term efficacy is established for PD with documented improvement in the cardinal motor symptoms of PD and levodopa-induced complications, such as motor fluctuations and dyskinesias. Timing of patient selection is crucial to obtain optimal benefits from DBS therapy, before PD complications become irreversible. The objective of this first part review is to examine the fundamental concepts of DBS for PD in clinical practice, discussing the historical aspects, patient selection, potential effects of DBS on motor and non-motor symptoms, and the practical management of patients after surgery.

Resumo Nas últimas três décadas, a estimulação cerebral profunda (ECP) se tornou um tratamento bem estabelecido para doença de Parkinson (DP) e outros transtornos do movimento. A eficácia a longo prazo na DP foi bem documentada para a melhora dos sintomas motores cardinais da DP e das complicações induzidas pelo uso do levodopa, como as flutuações motoras e as discinesias. O momento da seleção do paciente é crucial para se obter os benefícios ideais da ECP, antes que as complicações da DP se tornem irreversíveis. O objetivo desta primeira parte da revisão é examinar os conceitos fundamentais da ECP na prática clínica, discutindo os aspectos históricos, a seleção de pacientes, os potenciais efeitos da ECP nos sintomas motores e não motores da doença e o manejo prático dos pacientes após a cirurgia.

Electrical stimulation of the posterior insular cortex induces opioid and cannabinoid-dependent antinociception and regulates glial cells in the spinal cord / A estimulação elétrica do córtex insular posterior induz antinocicepção opioide e canabinoide dependente e regula células da glia na medula espinal

ABSTRACT BACKGROUND AND OBJECTIVES: Half of neuropathic pain patients still end up failing clinical treatments. Electrical stimulation of the posterior insular cortex (ESI) modulates sensory and nociceptive circuits. This study evaluated the effects of a range of frequencies of ESI proposed to improve neuropathic pain. METHODS: Male Sprague Dawley rats, 280-340 g, submitted to the chronic constriction of the right sciatic nerve were tested for mechanical sensitivity using the paw pressure and von Frey flaments tests, and for thermal sensitivity using the hot plate test. The rats were submitted to ESI 10, 60 or 100 Hz (one, five or seven ESI, 15 min, 210 µs, 1V), applied to the posterior insular cortex, and were evaluated in the tests before and after ESI, or in follow-up of 48, 72 and 168h. The open field evaluated general activity after ESI 5. The involvment of opioid and cannabinoid testes were evaluated through treatment with naloxone and SR1416A - antagonist and inverse agonist/antagonist of the receptors, respectively, after ESI 5, while activation of astrocytes, marked by glial fibrillary acid protein (GFAP), and of microglia, marked by IBA-1 (glial marker), in the spinal cord evaluated by immunohistochemistry. RESULTS: Data demonstrate that 10, 60, and 100 Hz ESIs modulate mechanical and thermal sensitivity. ESI 5 increased immunoreactivity of GFAP in the spinal cord, without altering IBA-1 (glial marker). Naloxone and SR141716A reversed the antinociception of 60 Hz ESI 5. 60 Hz ESI 7 induced antinociception up to 72h. CONCLUSION: 60 Hz ESI induces opioid and cannabinoid-dependent antinociception and regulates glia. HIGHLIGHTS 60 Hz-delivered ESI was the best analgesic protocol for the insular stimulation. Data showed a prolonged analgesic effect up to 72h after repetitive ESI. ESI regulates glia activation in pain modulatory system.

RESUMO JUSTIFICATIVA E OBJETIVOS: Metade dos pacientes com dor neuropática são refratários aos tratamentos. A estimulação elétrica do córtex insular (EECI) posterior modula circuitos sensoriais e nociceptivos. Assim, este estudo avaliou os efeitos de uma faixa de frequências de EECI como tratamento em modelo animal de dor neuropática. MÉTODOS: Ratos machos, Sprague Dawley, 280-340 g, submetidos a cirurgia para indução de constrição crônica (ICC) do nervo isquiático direito, foram avaliados em relação à sensibilidade mecânica com a utilização do teste de pressão de pata e de flamentos de von Frey, e sensibilidade térmica usando o teste de placa quente. Os ratos foram submetidos a EECI de 10, 60 ou 100 Hz (uma, cinco ou sete EECI, 15 min, 210 µs, 1V), aplicada ao córtex insular posterior esquerdo, e avaliados nos testes antes e após EECI, ou em follow up de 48, 72 e 168 horas. Por meio do teste de campo aberto, avaliou-se a atividade geral após a EECI5. O envolvimento de receptores opioides e canabinoides foi avaliado por meio da administração de naloxona e SR141716A - antagonista e agonista/antagonista inverso dos receptores, respectivamente - após a EECI 5, enquanto a ativação de astrócitos - marcada por proteína ácida fibrilar glial (GFAP), e de micróglia - marcada por IBA-1 - na medula espinal foi avaliada por imuno-histoquímica. RESULTADOS: Os dados mostraram que EECI em 10, 60 e 100 Hz modulam a sensibilidade mecânica e térmica dos animais. A EECI 5 aumentou a imunorreatividade de GFAP na medula espinhal, sem alterar IBA-1 (marcador glial). Naloxona e SR141716A reverteram a antinocicepção produzida por EECI 5 de 60 Hz. EECI 7 de 60 Hz induziu antinocicepção por até 72 horas. CONCLUSÃO: A EECI 60 Hz produz antinocicepção dependente de opioides e canabinoides e regula a glia. DESTAQUES A EECI de 60 Hz foi o melhor protocolo analgésico para nossa estimulação insular. Os dados mostram um efeito analgésico prolongado de até 72h após repetidas EECI. A EECI regula a ativação da glia no sistema modulatório da dor.

Spontaneous subarachnoid hemorrhage as the primary manifestation of carotid cavernous fistulas: case report

We report the case of a 19-year old male patient initially admitted to our service after a motor vehicle accident with a normal neurologic evaluation and a CT scan that revealed no abnormalities. Nineteen months later, he was readmitted after a subtle headache episode, followed by a brief loss of consciousness. He was submitted to a complete evaluation, which revealed no abnormalities (even in the neurologic and ophthalmologic exams). A CT was performed revealing a diffuse subarachnoid hemorrhage. Contrast enhancement displayed a right paraselar lesion, which was first interpreted as a giant aneurysm. The patient underwent a cerebral angiography which showed a right carotid-cavernous fistula with retrograde venous drainage through the superior and inferior petrosal sinuses. Filling of various cortical vessels was observed. The patient was treated with endovascular technique and a control angiographic study assured the complete closure of the fistula. He had an excellent clinical recovery, being discharged in good conditions

Intraventricular pressure monitoring in patients with thalamic and ganglionic hemorrhages

In the present study, we have evaluated the use of intraventricular pressure catheters in thalamic and ganglionic hemorrhages. Ten patients admitted in our Emergency Department in Glasgow Coma Scale (GCS) equal or below 13 enrolled the study (at least one point should have been lost in the eye opening score to exclude purely aphasic patients that were fully alert). After a complete clinical and neurological evaluation, computed tomography scans were obtained and the volume of the hematomas, as well as presence or absence of hydrocephalus, were considered. Intraventricular pressure catheters connected in parallel to external derivation systems were implanted and patients were thereafter sent to the ICU. Patients that presented mass effect lesions with sustained increased ICP levels or clinical and neurological deterioration were submitted in addition, to the surgical evacuation of the hematomas. Clinical evolution, complications and the rehabilitation of the patients were recorded. Clinical outcome was assessed with the Glasgow Outcome Score. In all but three patients the initial intracranial pressure levels were bellow 20 mmHg (mean for all patients was 14.1 ± 6.5 mmHg). Notwithstanding, these three patients were extremely difficult to treat. For this group of patients mortality was 100 percent. Among the patients that presented ICP levels bellow 20 mmHg, 04 developed hydrocephalus and 03 did not display ventricular dilation. As expected, the major benefits concerning the intraventricular pressure catheters connected in parallel with external derivation systems were observed in the group of patients that presented ICP levels bellow 20 mmHg and had hydrocephalus. Mild non-statistically significant correlations for all the three groups were achieved either when the initial GCS and ICP levels (r=-0.28, p=0.43) or when ICP levels and the volumes of the hematomas were compared (r=0.38, p=0.28). In addition, no significant correlations were observed concerning the final outcome of the patients and the variables previously evaluated

Tratamento cirurgico funcional da dor / Functional surgery for pain

Varios sao os procedimentos cirurgicos funcionais destinados ao tratamento da dor resultante de afeccoes musculo-esqueleticas. A descompressao de estruturas nervosas tronculares ou radiculares angustiadas em decorrencia...

Braquiterapia nos tumores cerebrais: revisäo / Brachytherapy in brain tumors: a review

A braquiterapia vem assumindo posiçäo de importância no tratamento adjuvante dos tumores cerebrais. A implantaçäo de isótopos radioativos através de estereotaxia tem mostrado resultados animadores no manejo de tumores malignos primários e secundários, bem como em tumores benignos inoperáveis. O propósito deste trabalho é realizar uma revisäo dos conceitos fundamentais, resultados obtidos e novas perspectivas realcionadas à braquiterapia encefálica

Cervicalgias / Cervicalgias

A cervicalgia pode ser decorrente de condicoes sistemicas, ou de anormalidades viscerais, musculo-esqueleticas ou neurologicas envolvendo a regiao cervical. Muitas vezes, entretanto, os exames laboratoriais,...