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1.
J Clin Monit Comput ; 33(2): 191-192, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30778916

RESUMO

The article Is the new ASNM intraoperative neuromonitoring supervision "guideline" a trustworthy guideline? A commentary, written by Stanley A. Skinner, Elif Ilgaz Aydinlar, Lawrence F. Borges, Bob S. Carter, Bradford L. Currier, Vedran Deletis, Charles Dong, John Paul Dormans, Gea Drost, Isabel Fernandez­Conejero, E. Matthew Hoffman, Robert N. Holdefer, Paulo Andre Teixeira Kimaid, Antoun Koht, Karl F. Kothbauer, David B. MacDonald, John J. McAuliffe III, David E. Morledge, Susan H. Morris, Jonathan Norton, Klaus Novak, Kyung Seok Park, Joseph H. Perra, Julian Prell, David M. Rippe, Francesco Sala, Daniel M. Schwartz, Martín J. Segura, Kathleen Seidel, Christoph Seubert, Mirela V. Simon, Francisco Soto, Jeffrey A. Strommen, Andrea Szelenyi, Armando Tello, Sedat Ulkatan, Javier Urriza and Marshall Wilkinson, was originally published electronically on the publisher's internet portal (currently SpringerLink) on 05 January 2019 without open access. With the author(s)' decision to opt for Open Choice the copyright of the article changed on 30 January 2019 to © The Author(s) 2019 and the article is forthwith distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, duplication, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made. The original article has been corrected.

2.
Ann Neurol ; 79(4): 636-45, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26841128

RESUMO

OBJECTIVE: Motor evoked potentials (MEPs) monitoring can promptly detect spinal cord ischemia (SCI) from aortic clamping during open thoracoabdominal aneurysm repair (OTAAR) with distal aortic perfusion (DAP) and thus help decrease the risk of immediate postoperative SCI (IP-SCI). However, neither stable MEPs during aortic clamp interval (ACI) nor absence of IP-SCI eliminate the possibility of delayed postoperative SCI (DP-SCI). We hypothesized that extension of MEPs monitoring beyond ACI can also help decrease the risk of DP-SCI. METHODS: We identified 150 consecutive patients at our institution between April 2005 and October 2014 who underwent OTAAR with DAP and MEPs monitoring and had no IP-SCI. Using logistic regression analysis, we studied the independent effect of extended MEPs monitoring on the risk of developing DP-SCI. We used a propensity score analysis to adjust for potential confounders, such as poorly controlled hypertension, previous aneurysm surgery, splenectomy, acute aortic dissection, aneurysm type, older age, and history of diabetes and smoking. RESULTS: From the 150 patients, 129 (86%) remained neurologically intact whereas 21 (14%) developed DP-SCI. Nineteen of these twenty-one patients (90%) had no extended monitoring. Fifty-seven of fifty-nine (97%) patients who benefited from extended monitoring had no DP-SCI (p = 0.003). Extended MEPs monitoring was independently associated with decreased risk of DP-SCI (odds ratio = 0.14; 95% confidence interval: 0.03, 0.65; p = 0.01). INTERPRETATION: MEPs detect the lowest systemic blood pressure that ensures appropriate spinal cord perfusion in the postoperative period. Thus, they inform the hemodynamic management of patients post-OTAAR, particularly in the absence of a reliable neurological exam.


Assuntos
Aneurisma da Aorta Torácica/cirurgia , Potencial Evocado Motor/fisiologia , Monitorização Neurofisiológica/métodos , Paraplegia/prevenção & controle , Complicações Pós-Operatórias/diagnóstico , Isquemia do Cordão Espinal/diagnóstico , Procedimentos Cirúrgicos Vasculares/efeitos adversos , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Paraplegia/etiologia , Complicações Pós-Operatórias/etiologia , Isquemia do Cordão Espinal/etiologia , Resultado do Tratamento
4.
J Clin Neurophysiol ; 41(2): 96-107, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38306217

RESUMO

SUMMARY: Similar to adults, children undergoing brain surgery can significantly benefit from intraoperative neurophysiologic mapping and monitoring. Although young brains present the advantage of increased plasticity, during procedures in close proximity to eloquent regions, the risk of irreversible neurological compromise remains and can be lowered further by these techniques. More so, pathologies specific to the pediatric population, such as neurodevelopmental lesions, often result in medically refractory epilepsy. Thus, their successful surgical treatment also relies on accurate demarcation and resection of the epileptogenic zone, processes in which intraoperative electrocorticography is often employed. However, stemming from the development and maturation of the central and peripheral nervous systems as the child grows, intraoperative neurophysiologic testing in this population poses methodologic and interpretative challenges even to experienced clinical neurophysiologists. For example, it is difficult to perform awake craniotomies and language testing in the majority of pediatric patients. In addition, children may be more prone to intraoperative seizures and exhibit afterdischarges more frequently during functional mapping using electrical cortical stimulation because of high stimulation thresholds needed to depolarize immature cortex. Moreover, choice of anesthetic regimen and doses may be different in pediatric patients, as is the effect of these drugs on immature brain; these factors add additional complexity in terms of interpretation and analysis of neurophysiologic recordings. Below, we are describing the modalities commonly used during intraoperative neurophysiologic testing in pediatric brain surgery, with emphasis on age-specific clinical indications, methodology, and challenges.


Assuntos
Anestésicos , Neoplasias Encefálicas , Adulto , Humanos , Criança , Mapeamento Encefálico/métodos , Encéfalo/cirurgia , Eletrocorticografia , Craniotomia/métodos , Anestésicos/farmacologia , Neoplasias Encefálicas/cirurgia
5.
Clin Neurophysiol ; 162: 141-150, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38631074

RESUMO

OBJECTIVE: The laryngeal adductor reflex (LAR) is vital for airway protection and can be electrophysiologically obtained under intravenous general anesthesia (IGA). This makes the electrophysiologic LAR (eLAR) an important tool for monitoring of the vagus nerves and relevant brainstem circuitry during high-risk surgeries. We investigated the intra-class variability of normal and expected abnormal eLAR. METHODS: Repeated measures of contralateral R1 (cR1) were performed under IGA in 58 patients. Data on presence/absence of cR2 and potential confounders were also collected. Review of neuroimaging, pathology and clinical exam, allowed classification into normal and expected abnormal eLAR groups. Using univariate and multivariate analysis we studied the variability of cR1 parameters and their differences between the two groups. RESULTS: In both groups, cR1 latencies had coefficients of variation of <2%. In the abnormal group, cR1 had longer latencies, required higher activation currents and was more frequently desynchronized and unsustained; cR2 was more frequently absent. CONCLUSIONS: cR1 latencies show high analytical precision for measurements. Delayed onset, difficult to elicit, desynchronized and unsustained cR1, and absence of cR2 signal an abnormal eLAR. SIGNIFICANCE: Understanding the variability and behavior of normal and abnormal eLAR under IGA can aid in the interpretation of its changes during monitoring.


Assuntos
Reflexo , Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Idoso , Reflexo/fisiologia , Adulto , Músculos Laríngeos/fisiopatologia , Músculos Laríngeos/fisiologia , Eletromiografia/métodos
6.
Clin Neurophysiol ; 159: 13-23, 2024 03.
Artigo em Inglês | MEDLINE | ID: mdl-38241911

RESUMO

OBJECTIVE: Extraoperative electrical cortical stimulation (ECS) facilitates defining the seizure onset zone (SOZ) and eloquent cortex. The clinical relevance of stimulation-induced afterdischarges (ADs) is not well defined. METHODS: Fifty-five patients who underwent intracranial electroencephalogram evaluations with ECS were retrospectively identified. ADs were identified in these recordings and categorized by pattern, location, and association with stimulation-induced seizures. RESULTS: ADs were generated in 1774/9285 (19%) trials. Rhythmic spikes and irregular ADs within the stimulated bipolar contact pair were predictive of location within the SOZ compared to non-epileptogenic/non-irritative cortex (rhythmic spikes OR 2.24, p = 0.0098; irregular OR 1.39; p = 0.013). ADs immediately preceding stimulated seizures occurred at lower stimulation intensity thresholds compared to other stimulations (mean 2.94 ± 0.28 mA vs. 4.16 ± 0.05 mA respectively; p = 0.0068). CONCLUSIONS: Changes in AD properties can provide clinically relevant data in extraoperative stimulation mapping. SIGNIFICANCE: Although not exclusive to the SOZ, the generation of rhythmic spikes may suggest that a stimulation location is within the SOZ, while decreased stimulation intensity thresholds eliciting ADs may alert clinicians to a heightened probability of seizure generation with subsequent stimulation.


Assuntos
Eletroencefalografia , Convulsões , Humanos , Estudos Retrospectivos , Estimulação Elétrica , Probabilidade , Convulsões/diagnóstico
7.
Epilepsia ; 53(4): e75-9, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22309192

RESUMO

Cortical dysplasias (CDs) are highly epileptogenic lesions with a good prognosis of seizure freedom, if totally resected. However, their accurate delineation and resection can be difficult, and depend on the extent of pathology and lesion location. Intraoperative neurophysiologic assessments are valuable in these situations. We present an illustrative case of intractable epilepsy where judicious use of intraoperative neurophysiologic-techniques guided resection of precentral CD, under general anesthesia and in the absence of preoperative electrophysiologic mapping data. Ictal onset was accurately delineated using electrocorticography (ECoG). Phase reversal of the median somatosensory-evoked potentials (MSSEPs) localized the central sulcus (CS). Motor evoked potentials (MEPs) triggered by high-frequency monopolar anodal electrical cortical stimulation at the primary motor cortex (PMC) threshold delineated the PMC. Using this technique, PMC and the corticospinal tract (CST) were continuously monitored during resection. No changes in MEPs from the preresection baseline were seen; no residual abnormal activity was present in the postresection ECoG. The patient emerged from surgery without deficits and has been seizure free during a 10-month follow-up. Staged multimodal intraoperative neurophysiology can be used successfully under general anesthesia to guide resection of epileptogenic lesions within the precentral gyrus, as an add-on or, in certain situations, as a viable alternative to preoperative electrophysiologic mapping.


Assuntos
Mapeamento Encefálico , Epilepsia/diagnóstico , Epilepsia/cirurgia , Potencial Evocado Motor/fisiologia , Giro do Cíngulo/patologia , Giro do Cíngulo/fisiopatologia , Monitorização Intraoperatória , Adulto , Eletroencefalografia , Eletromiografia , Feminino , Giro do Cíngulo/irrigação sanguínea , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Oxigênio/sangue , Tratos Piramidais/irrigação sanguínea , Tratos Piramidais/fisiopatologia
8.
Handb Clin Neurol ; 186: 11-38, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35772881

RESUMO

Electroencephalography (EEG) and electrocorticography (ECoG) are two important neurophysiologic techniques used in the operating room for monitoring and mapping electrical brain activity. In this chapter, we detail their principle, recording methodology, and address specifics of their interpretation in the intraoperative setting (e.g., effect of anesthetics), as well as their clinical applications in epilepsy and non-epilepsy surgeries. In addition, we address differences between scalp, surface, and deep cortical recordings that will help towards a more reliable interpretation of the significance of electrophysiologic parameters such as amplitude and morphology as well as in differentiation between abnormal and normal patterns of electrical brain activity. Electrical stimulation is used for intraoperative mapping of different cortical functions such as language, parietal, and motor. Stimulation paradigms used in clinical practice vary with regard to stimulation frequencies and probes being used. Parameters, such as the number of phases per pulse, pulse/phase duration, pulse frequency, organization, and polarity, define their characteristics, including their safety, propensity to trigger seizures, efficiency and reliability of stimulation, and the mapping thresholds. Specifically, in this chapter, we will address differences between monopolar and bipolar stimulation; anodal and cathodal polarity; monophasic and biphasic pulses; constant voltage, and constant current paradigms.


Assuntos
Mapeamento Encefálico , Eletrocorticografia , Mapeamento Encefálico/métodos , Estimulação Elétrica/métodos , Eletroencefalografia/métodos , Humanos , Reprodutibilidade dos Testes
9.
Handb Clin Neurol ; 186: 103-121, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35772880

RESUMO

Intraoperative neuromonitoring (IONM) complements modern presurgical investigations by providing information about the epileptic focus as well as real-time identification of critical functional tissue and assessment of ongoing neural integrity during resective epilepsy surgery. This chapter summarizes current IONM methods for mapping the epileptic focus and for mapping and monitoring functionally important structures with direct brain stimulation and evoked potentials. These techniques include electrocorticography, computerized high-frequency oscillation mapping, single-pulse electric stimulation, cortical and subcortical motor evoked potentials, somatosensory evoked potentials, visual evoked potentials, and cortico-cortical evoked potentials. They may help to maximize epileptic tissue resection while avoiding permanent postoperative neurologic deficits.


Assuntos
Epilepsia , Neurofisiologia , Mapeamento Encefálico/métodos , Epilepsia/cirurgia , Potencial Evocado Motor/fisiologia , Potenciais Somatossensoriais Evocados/fisiologia , Potenciais Evocados Visuais , Humanos , Procedimentos Neurocirúrgicos/métodos
10.
Handb Clin Neurol ; 186: 355-374, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35772895

RESUMO

Cerebral ischemia during carotid endarterectomy occurs via several mechanisms: inadequate collateral blood flow during carotid cross-clamping, thromboembolism due to carotid manipulation, and/or rethrombosis at the surgical site. Perioperative strokes increase not only the morbidity of endarterectomy but also its short- and long-term mortality. However, while several predictors of cerebral ischemia have been identified, precise individual risk is hard to assess. Since nonselective shunting during carotid cross-clamping is neither risk-free nor eliminates perioperative stroke, it is advisable to apply intraoperative monitoring techniques for detection and reversal of cerebral ischemia, which may occur at various stages of the procedure. This chapter addresses the methods available for monitoring, with an emphasis on neurophysiologic techniques, which are preferable given their direct assessment of how a decrease in cerebral blood flow impacts brain function. These include electroencephalography, somatosensory evoked potentials, and transcranial motor evoked potentials. Details regarding the methodology, advantages, disadvantages, and interpretation of these tests will be discussed within the anatomic, physiologic, surgical, and anesthetic contexts.


Assuntos
Isquemia Encefálica , Endarterectomia das Carótidas , Acidente Vascular Cerebral , Isquemia Encefálica/diagnóstico , Infarto Cerebral , Eletroencefalografia , Potenciais Somatossensoriais Evocados/fisiologia , Humanos , Monitorização Intraoperatória
11.
Handb Clin Neurol ; 186: 407-431, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35772899

RESUMO

Thoraco-abdominal aneurysm (TAA) repair carries a significant risk of spinal cord infarction. The latter results from irreversible changes in the spinal cord arterial network, e.g., sacrifice of the segmental arteries. Intra-operative neurophysiology with somatosensory and especially motor evoked potential (SEP and MEP respectively) monitoring, has emerged as an effective tool to assess the efficiency of the collateral blood flow, detect reversible spinal cord ischemia and guide the peri-operative multidisciplinary management to prevent postoperative paraplegia. The main roles of such monitoring include diagnosis of spinal cord vs peripheral limb ischemia, titration of mean arterial pressure during aortic clamping, the guidance of selective re-implantation of critical segmental arteries, and management of hemodynamics in the immediate postoperative period. In addition, manipulation of the aortic arch and proximal descending aorta, adds the risk of cerebral infarction from both low flow state and/or thromboembolic events. As such, EEG monitoring may be a useful add-on for either assessment of the efficiency of cerebral cooling as a neuroprotective method and/or for detection and treatment of reversible cerebral ischemia. This chapter presents the multimodality approach to open TAA monitoring as a versatile tool for the prevention of devastating postoperative neurologic deficits.


Assuntos
Aneurisma da Aorta Abdominal , Aneurisma da Aorta Torácica , Isquemia do Cordão Espinal , Aneurisma da Aorta Abdominal/cirurgia , Aneurisma da Aorta Torácica/diagnóstico , Aneurisma da Aorta Torácica/cirurgia , Potencial Evocado Motor/fisiologia , Humanos , Isquemia , Monitorização Intraoperatória/métodos , Medula Espinal/irrigação sanguínea , Isquemia do Cordão Espinal/prevenção & controle , Isquemia do Cordão Espinal/cirurgia
12.
Brain Sci ; 12(8)2022 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-36009088

RESUMO

Objective: This pilot study aims to show the feasibility of noninvasive and real-time cerebral hemodynamic monitoring during carotid endarterectomy (CEA) via diffuse correlation spectroscopy (DCS) and near-infrared spectroscopy (NIRS). Methods: Cerebral blood flow index (CBFi) was measured unilaterally in seven patients and bilaterally in seventeen patients via DCS. In fourteen patients, hemoglobin oxygenation changes were measured bilaterally and simultaneously via NIRS. Cerebral autoregulation (CAR) and cerebrovascular resistance (CVR) were estimated using CBFi and arterial blood pressure data. Further, compensatory responses to the ipsilateral hemisphere were investigated at different contralateral stenosis levels. Results: Clamping of carotid arteries caused a sharp increase of CVR (~70%) and a marked decrease of ipsilateral CBFi (57%). From the initial drop, we observed partial recovery in CBFi, an increase of blood volume, and a reduction in CVR in the ipsilateral hemisphere. There were no significant changes in compensatory responses between different contralateral stenosis levels as CAR was intact in both hemispheres throughout the CEA phase. A comparison between hemispheric CBFi showed lower ipsilateral levels during the CEA and post-CEA phases (p < 0.001, 0.03). Conclusion: DCS alone or combined with NIRS is a useful monitoring technique for real-time assessment of cerebral hemodynamic changes and allows individualized strategies to improve cerebral perfusion during CEA by identifying different hemodynamic metrics.

13.
Clin Neurophysiol ; 136: 150-157, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35168029

RESUMO

OBJECTIVE: To investigate whether barques can be localized across the hippocampal longitudinal axis with sufficient specificity. METHODS: We identified 51 focal epilepsy patients implanted with a minimum of two electrodes - unilateral anterior and posterior - in either hippocampus. We used visual inspection of the intracranial electroencephalogram (iEEG) and 3D brain volume spectrum-based statistical parametric mapping (SPM) to localize barques. RESULTS: In 18/51 patients (35.29%), barques were identified in 22/70 (31.42%) hippocampi. In all hippocampi (100%), barques were present in the posterior hippocampus, while 9 (40.90%) showed concurrent non-independent barque activity anteriorly (P < 0.0001). Statistical parametric mapping confirmed the posterior barque localization, with significant differences in t-values (t(27) = 8.08, P < 0.0001) and z-scores (t(24) = 6.85, P < 0.0001) between anterior and posterior hippocampal barque activity. Posterior lateral extrahippocampal contacts demonstrated phase reversals of positive polarity during barque activity (P = 0.0092, compared to anterior extrahippocampal contacts). CONCLUSIONS: This study highlights the posterior hippocampal predominance of barques. Our findings are concordant with the posterior distribution of the scalp manifestation of barques as "14&6/sec positive spikes". The posterio-lateral hippocampal barque phase reversal can explain the positive polarity of scalp 14&6/sec spikes. SIGNIFICANCE: Understanding the properties of barques is critical for the iEEG interpretation in epilepsy surgery evaluations that include the hippocampus.


Assuntos
Epilepsias Parciais , Hipocampo , Eletrodos , Eletroencefalografia , Epilepsias Parciais/diagnóstico por imagem , Epilepsias Parciais/cirurgia , Hipocampo/diagnóstico por imagem , Hipocampo/cirurgia , Humanos , Imageamento por Ressonância Magnética , Couro Cabeludo
14.
J Vasc Surg ; 53(5): 1195-1201.e1, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21315544

RESUMO

OBJECTIVE: During a 24-year interval, we managed >90% of thoracoabdominal aortic aneurysm (TAA) repairs with a clamp-and-sew (clamp/sew) approach supplemented with protective adjuncts, including renal hypothermia and epidural cooling with aggressive intercostal reconstruction for spinal cord protection. A finite paraplegia rate led to operative modifications using distal aortic perfusion (DAP) through atriofemoral bypass to support cord collateral circulation and selective intercostal reconstruction based on motor evoked potential (MEP) monitoring. This study evaluated the effect of DAP/MEP on perioperative outcomes. METHODS: Consecutive patients undergoing repair of nonruptured Crawford extent I-III TAA using DAP/MEP were compared with propensity-matched patients treated with the clamp/sew technique. Outcomes included 30-day mortality and paraplegia. RESULTS: There were 52 patients in the DAP cohort vs 127 undergoing clamp/sew. The DAP and clamp/sew cohorts differed in age (62.6 vs 69.5 years, P = .0003), presence of Marfan disease (10% vs 2%, P = .01), and chronic dissection (37% vs 8%, P = .001). Operative mortality was low (DAP, 2%; clamp/sew, 5%; P = .38). Postoperative renal insufficiency, although doubled in clamp/sew (17%) vs DAP (8%; P = .10), was not significant. DAP patients had a significantly lower incidence of intercostal reconstruction than the clamp/sew group (10% vs 34%, P < .0001), yet there was no paraplegia in the DAP cohort vs 5% in clamp/sew (P = .11). The composite death/paraplegia rate was decreased with DAP at 1 of 52 (2%) vs clamp/sew at 11 of 127 (9%; P = .01). Paraparesis with complete recovery occurred in 5 of 52 (10%) of the DAP group. CONCLUSIONS: Elective TAA repair was accomplished with a low mortality in the DAP and clamp/sew cohorts. The use of MEP in the DAP cohort (despite a higher spinal cord ischemic risk due to the number of chronic dissection patients) decreased the need for intercostal reconstruction, with no paraplegia to date. DAP with MEP is the preferred operative strategy for extent I to III TAA repair.


Assuntos
Aneurisma da Aorta Torácica/cirurgia , Monitorização Intraoperatória , Perfusão , Isquemia do Cordão Espinal/prevenção & controle , Procedimentos Cirúrgicos Vasculares , Idoso , Aneurisma da Aorta Torácica/mortalidade , Aneurisma da Aorta Torácica/fisiopatologia , Boston , Distribuição de Qui-Quadrado , Circulação Colateral , Constrição , Potencial Evocado Motor , Feminino , Humanos , Estimativa de Kaplan-Meier , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Monitorização Intraoperatória/métodos , Paraparesia/etiologia , Paraparesia/prevenção & controle , Paraplegia/etiologia , Paraplegia/prevenção & controle , Insuficiência Renal/etiologia , Insuficiência Renal/prevenção & controle , Medição de Risco , Fatores de Risco , Isquemia do Cordão Espinal/etiologia , Isquemia do Cordão Espinal/fisiopatologia , Técnicas de Sutura , Fatores de Tempo , Resultado do Tratamento , Procedimentos Cirúrgicos Vasculares/efeitos adversos , Procedimentos Cirúrgicos Vasculares/mortalidade
15.
Clin Neurophysiol ; 132(12): 3002-3009, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34715425

RESUMO

OBJECTIVE: To assess whether hippocampal spindles and barques are markers of epileptogenicity. METHODS: Focal epilepsy patients that underwent stereo-electroencephalography implantation with at least one electrode in their hippocampus were selected (n = 75). The occurrence of spindles and barques in the hippocampus was evaluated in each patient. We created pairs of pathologic and pathology-free groups according to two sets of criteria: 1. Non-invasive diagnostic criteria (patients grouped according to focal epilepsy classification). 2. Intracranial neurophysiological criteria (patient's hippocampi grouped according to their seizure onset involvement). RESULTS: Hippocampal spindles and barques appear equally often in both pathologic and pathology-free groups, both for non-invasive (Pspindles = 0.73; Pbarques = 0.46) and intracranial criteria (Pspindles = 0.08; Pbarques = 0.26). In Engel Class I patients, spindles occurred with similar incidence both within the non-invasive (P = 0.67) and the intracranial criteria group (P = 0.20). Barques were significantly more frequent in extra-temporal lobe epilepsy defined by either non-invasive (P = 0.01) or intracranial (P = 0.01) criteria. CONCLUSIONS: Both spindles and barques are normal entities of the hippocampal intracranial electroencephalogram. The presence of barques may also signify lack of epileptogenic properties in the hippocampus. SIGNIFICANCE: Understanding that hippocampal spindles and barques do not reflect epileptogenicity is critical for correct interpretation of epilepsy surgery evaluations and appropriate surgical treatment selection.


Assuntos
Ondas Encefálicas/fisiologia , Epilepsias Parciais/fisiopatologia , Epilepsia do Lobo Temporal/fisiopatologia , Hipocampo/fisiopatologia , Adulto , Eletrocorticografia , Epilepsias Parciais/cirurgia , Epilepsia do Lobo Temporal/cirurgia , Feminino , Hipocampo/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
16.
Clin Neurophysiol ; 132(7): 1416-1432, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34023624

RESUMO

OBJECTIVE: Neuromonitoring of primary motor regions allows preservation of motor strength and is frequently employed during cranial procedures. Less is known about protection of sensory function and ability to modulate movements, both of which rely on integrity of thalamocortical afferents (TCA) to fronto-parietal regions. We describe our experience with TCA monitoring and their cortical relays during brain tumor surgery. METHODOLOGY: To study its feasibility and usefulness, continuous somatosensory evoked potentials (SSEP) recording via a subdural electrode was attempted in 32 consecutive patients. RESULTS: Median and posterior tibial SSEP were successfully monitored in 31 and 17 patients respectively. SSEP improved lesion localization and prevented unnecessary cortical stimulation in 9 and 16 cases respectively. A threshold of ≥30% SSEP amplitude decrease influenced management in 10 patients while a decrement of ≥50 % had a sensitivity of 0.89 and specificity of 1 in detecting worsening of sensory function. Simultaneous motor evoked potentials (MEP) and SSEP monitoring were performed in 10 cases, 9 of which showed short-lived fluctuations of the former. CONCLUSION: Direct cortical SSEP monitoring is feasible, informs management and predicts outcome. SIGNIFICANCE: Early intervention prevents sensory deficit. Concomitant MEP fluctuations may reflect modulation of motor activity by TCA.


Assuntos
Neoplasias Encefálicas/cirurgia , Craniotomia/métodos , Potenciais Somatossensoriais Evocados/fisiologia , Monitorização Neurofisiológica Intraoperatória/métodos , Córtex Motor/fisiologia , Tálamo/fisiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias Encefálicas/fisiopatologia , Eletrocorticografia/métodos , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos
17.
Oper Neurosurg (Hagerstown) ; 20(2): 219-225, 2021 01 13.
Artigo em Inglês | MEDLINE | ID: mdl-33269396

RESUMO

BACKGROUND: Subcortical mapping of the corticospinal tract has been extensively used during craniotomies under general anesthesia to achieve maximal resection while avoiding postoperative motor deficits. To our knowledge, similar methods to map the thalamocortical tract (TCT) have not yet been developed. OBJECTIVE: To describe a neurophysiologic technique for TCT identification in 2 patients who underwent resection of frontoparietal lesions. METHODS: The central sulcus (CS) was identified using the somatosensory evoked potentials (SSEP) phase reversal technique. Furthermore, monitoring of the cortical postcentral N20 and precentral P22 potentials was performed during resection. Subcortical electrical stimulation in the resection cavity was done using the multipulse train (case #1) and Penfield (case #2) techniques. RESULTS: Subcortical stimulation within the postcentral gyrus (case #1) and in depth of the CS (case #2), resulted in a sudden drop in amplitudes in N20 (case #1) and P22 (case #2), respectively. In both patients, the potentials promptly recovered once the stimulation was stopped. These results led to redirection of the surgical plane with avoidance of damage of thalamocortical input to the primary somatosensory (case #1) and motor regions (case #2). At the end of the resection, there were no significant changes in the median SSEP. Both patients had no new long-term postoperative sensory or motor deficit. CONCLUSION: This method allows identification of TCT in craniotomies under general anesthesia. Such input is essential not only for preservation of sensory function but also for feedback modulation of motor activity.


Assuntos
Potencial Evocado Motor , Monitorização Intraoperatória , Mapeamento Encefálico , Craniotomia , Potenciais Somatossensoriais Evocados , Humanos
18.
Clin Neurophysiol ; 132(11): 2916-2931, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34419344

RESUMO

OBJECTIVE: Interictal discharges (IIDs) and high frequency oscillations (HFOs) are established neurophysiologic biomarkers of epilepsy, while microseizures are less well studied. We used custom poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) microelectrodes to better understand these markers' microscale spatial dynamics. METHODS: Electrodes with spatial resolution down to 50 µm were used to record intraoperatively in 30 subjects. IIDs' degree of spread and spatiotemporal paths were generated by peak-tracking followed by clustering. Repeating HFO patterns were delineated by clustering similar time windows. Multi-unit activity (MUA) was analyzed in relation to IID and HFO timing. RESULTS: We detected IIDs encompassing the entire array in 93% of subjects, while localized IIDs, observed across < 50% of channels, were seen in 53%. IIDs traveled along specific paths. HFOs appeared in small, repeated spatiotemporal patterns. Finally, we identified microseizure events that spanned 50-100 µm. HFOs covaried with MUA, but not with IIDs. CONCLUSIONS: Overall, these data suggest that irritable cortex micro-domains may form part of an underlying pathologic architecture which could contribute to the seizure network. SIGNIFICANCE: These results, supporting the possibility that epileptogenic cortex comprises a mosaic of irritable domains, suggests that microscale approaches might be an important perspective in devising novel seizure control therapies.


Assuntos
Mapeamento Encefálico/métodos , Encéfalo/fisiopatologia , Eletroencefalografia/métodos , Epilepsia/fisiopatologia , Monitorização Neurofisiológica Intraoperatória/métodos , Microeletrodos , Adulto , Encéfalo/cirurgia , Eletroencefalografia/instrumentação , Epilepsia/diagnóstico , Epilepsia/cirurgia , Feminino , Humanos , Monitorização Neurofisiológica Intraoperatória/instrumentação , Masculino , Pessoa de Meia-Idade , Adulto Jovem
19.
J Clin Neurosci ; 74: 225-231, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31973921

RESUMO

OBJECT: Spinal cord surgeries carry a high risk for significant neurological impairments. The initial techniques for spinal cord mapping emerged as an aid to identify the dorsal columns and helped select a safe myelotomy site in intramedullary tumor resection. Advancements in motor mapping of the cord have also been made recently, but exclusively with tumor surgery. We hereby present our experiences with dynamic mapping of the corticospinal tract (CST) in other types of spinal cord procedures that carry an increased risk of postoperative motor deficit, and thus could directly benefit from this technique. CASE REPORTS: Two patients with intractable unilateral lower extremity pain due to metastatic disease of the sacrum and a thoraco-lumbar chordoma, respectively underwent thoracic cordotomy to interrupt the nociceptive pathways. A third patient with progressive leg weakness underwent cord untethering and surgical repair of a large thoracic myelomeningocele. In all three cases, multimodality intraoperative neurophysiologic testing included somatosensory and motor evoked potentials monitoring as well as dynamic mapping of the CST. CONCLUSION: CST mapping allowed safe advancement of the cordotomy probe and exploration of the meningocele sac with untethering of the anterior-lateral aspect of the cord respectively, resulting in postoperative preservation or improvement of motor strength from the pre-operative baseline. Stimulus thresholds varied likely with the distance between the stimulating probe and the CST as well as with the baseline motor strength in the mapped myotomes.


Assuntos
Cordotomia , Meningomielocele/cirurgia , Procedimentos Neurocirúrgicos/métodos , Tratos Piramidais/anatomia & histologia , Tratos Piramidais/fisiopatologia , Idoso , Potencial Evocado Motor/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Monitorização Intraoperatória/métodos , Tratos Piramidais/cirurgia , Raízes Nervosas Espinhais/anatomia & histologia , Raízes Nervosas Espinhais/fisiopatologia
20.
Epilepsia ; 50(1): 147-54, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19125835

RESUMO

The purpose of this study was to characterize the epileptogenicity of tubers and surrounding cortex in patients with tuberous sclerosis complex (TSC). Three pediatric patients with TSC and intractable epilepsy underwent surgical resection of tubers associated with epileptogenic foci. In all patients, presurgical imaging revealed a prominent tuber that correlated on electroencephalography (EEG) with frequent interictal epileptiform discharges and electrographic seizures. Intracranial electrocorticography (ECoG) was performed using subdural grids placed over the tuber and surrounding cortex and depth electrodes positioned directly within the tuber. In all three patients, the depth electrode within the tuber was electrographically silent, whereas the surrounding cortical tissue showed significant epileptiform activity. The tuber and the electrically active adjacent cortex were resected. The patients experienced a drastic reduction in seizure frequency postsurgery. Epileptogenicity of cortical tubers may derive not from the lesion itself, but rather from the perturbation or abnormal development of the surrounding cortex.


Assuntos
Eletroencefalografia , Epilepsia/diagnóstico , Epilepsia/etiologia , Esclerose Tuberosa/complicações , Esclerose Tuberosa/diagnóstico , Adolescente , Pré-Escolar , Epilepsia/fisiopatologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Esclerose Tuberosa/patologia
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