Summary
Objective
To examine the true incidence of hemorrhage related to stereo‐electroencephalography (SEEG) procedures. To analyze risk factors associated with the presence of different types of ...hemorrhage in SEEG procedures.
Methods
This was a retrospective, single‐center observational study examining every SEEG implantation performed at our center from 2009 to 2017. This consisted of 549 consecutive SEEG implantations using a variety of stereotactic and imaging techniques. A hemorrhage grading system was applied by a blinded neuroradiologist to every postimplant and postexplant computed tomography (CT) scan. Hemorrhages were classified as asymptomatic or symptomatic based on neurologic deficit seen on examination. Statistical analysis included multivariate regression using relevant preoperative variables to predict the presence of hemorrhage.
Results
One hundred five implantations (19.1%) had any type of hemorrhage seen on postimplant CT. Of these, 93 (16.9%) were asymptomatic and 12 (2.2%) were symptomatic, with 3 implantations (0.6%) resulting in either a permanent deficit (2, 0.4%) or death (1, 0.2%). Male sex, increased number of electrodes, and increasing age were associated with increased risk of postimplant hemorrhage on multivariate analysis. Increasing score in the grading system was related to a statistically significant increase in the likelihood of a symptomatic hemorrhage.
Significance
Detailed examination of every postimplant CT reveals that the total hemorrhage rate appears higher than previously reported. Most of these hemorrhages are small and asymptomatic. Our grading system may be useful to risk stratify these hemorrhages and awaits prospective validation.
Objective
Ultra‐high‐field 7‐Tesla (7T) magnetic resonance imaging (MRI) offers increased signal‐to‐noise and contrast‐to‐noise ratios, which may improve visualization of cortical malformations. We ...aim to assess the clinical value of in vivo structural 7T MRI and its post‐processing for the noninvasive identification of epileptic brain lesions in patients with pharmacoresistant epilepsy and nonlesional 3T MRI who are undergoing presurgical evaluation.
Methods
Sixty‐seven patients were included who had nonlesional 3T MRI by official radiology report. Epilepsy protocols were used for the 3T and 7T acquisitions. Post‐processing of the 7T T1‐weighted magnetization‐prepared two rapid acquisition gradient echoes sequence was performed using the morphometric analysis program (MAP) with comparison to a normal database consisting of 50 healthy controls. Review of 7T was performed by an experienced board‐certified neuroradiologist and at the multimodal patient management conference. The clinical significance of 7T findings was assessed based on intracranial electroencephalography (ICEEG) ictal onset, surgery, postoperative seizure outcomes, and histopathology.
Results
Unaided visual review of 7T detected previously unappreciated subtle lesions in 22% (15/67). When aided by 7T MAP, the total yield increased to 43% (29/67). The location of the 7T‐identified lesion was identical to or contained within the ICEEG ictal onset in 13 of 16 (81%). Complete resection of the 7T‐identified lesion was associated with seizure freedom (P = .03). Histopathology of the 7T‐identified lesions encountered mainly focal cortical dysplasia (FCD). 7T MAP yielded 25% more lesions (6/24) than 3T MAP, and showed improved conspicuity in 46% (11/24).
Significance
Our data suggest a major benefit of 7T with post‐processing for detecting subtle FCD lesions for patients with pharmacoresistant epilepsy and nonlesional 3T MRI.
Summary
Objective
Stereo‐electroencephalography (SEEG) is a procedure performed for patients with intractable epilepsy in order to anatomically define the epileptogenic zone (EZ) and the possible ...related functional cortical areas. By avoiding the need for large craniotomies and due to its intrinsic precision placement features, SEEG may be associated with fewer complications. Nevertheless, intracerebral electrodes have gained a reputation of excessive invasiveness, with a “relatively high morbidity” associated with their placement. A systematic literature review and meta‐analysis of SEEG complications has not been previously performed. The goal of this study is to quantitatively review the incidence of various surgical complications associated with SEEG electrode implantation in the literature and to provide a summary estimate. This will allow physicians to accurately counsel their patients about the potential complications related to this method of extraoperative invasive monitoring.
Methods
The systematic review was conducted following Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA). We conducted MEDLINE, Scopus, and Web of Science database searches with the search algorithm. We analyzed complication rates using a fixed‐effects model with inverse variance weighting. Calculations for the meta‐analysis and construction of forest plots were completed using an established spreadsheet. The principal summary measures were the effect summary value and 95% confidence intervals (CIs).
Results
The initial 1,901 retrieved citations were reviewed. After removing 787 duplicates, the titles and s of 1,114 publications were screened. At this stage, studies that did not mention the absence or presence of complications following SEEG or that did not fulfill the inclusion criteria in any manner were excluded. After excluding 1,057 citations, the full text was assessed in the resulting 57 articles for eligibility criteria. The most common complications were hemorrhagic (pooled prevalence 1.0%, 95% confidence interval CI 0.6–1.4%) or infectious (pooled prevalence 0.8%, 95% CI 0.3–1.2%). Five mortalities were identified (pooled prevalence 0.3%, 95% CI −0.1–0.6%). Overall, our analysis identified 121 surgical complications related to SEEG insertion and monitoring (pooled prevalence 1.3%, 95% CI 0.9–1.7%).
Significance
This review represents a comprehensive estimation of the actual incidence of complications related to SEEG. We report a rate substantially lower than the complication rates reported for other methods of extraoperative invasive monitoring. These data should alleviate the concerns of some regarding the safety of the “stereotactic” method, allowing a better decision process among the different methods of invasive monitoring and ameliorating the fear associated with the placement of depth electrodes.
The current standard model of language production involves a sensorimotor dorsal stream connecting areas in the temporo‐parietal junction with those in the inferior frontal gyrus and lateral premotor ...cortex. These regions have been linked to various aspects of word production such as phonological processing or articulatory programming, primarily through neuropsychological and functional imaging group studies. Most if not all the theoretical descriptions of this model imply that the same network should be identifiable across individual speakers. We tested this hypothesis by quantifying the variability of activation observed across individuals within each dorsal stream anatomical region. This estimate was based on electrical activity recorded directly from the cerebral cortex with millisecond accuracy in awake epileptic patients clinically implanted with intracerebral depth electrodes for pre‐surgical diagnosis. Each region's activity was quantified using two different metrics—intra‐cerebral evoked related potentials and high gamma activity—at the level of the group, the individual and the recording contact. The two metrics show simultaneous activation of parietal and frontal regions during a picture naming task, in line with models that posit interactive processing during word retrieval. They also reveal different levels of between‐patient variability across brain regions, except in core auditory and motor regions. The independence and non‐uniformity of cortical activity estimated through the two metrics push the current model towards sub‐second and sub‐region explorations focused on individualized language speech production. Several hypotheses are considered for this within‐region heterogeneity.
Standard models of language processing involve a dorsal stream connecting temporal, parietal and frontal regions, each linked to particular aspects of word production—for example, phonological processing or articulatory programming. Most theories imply that the same network should be identifiable across individuals. This hypothesis was tested by quantifying the variability of activation observed across speakers within each region. Two metrics of brain activity recorded intra‐cerebrally in awake epileptic patients revealed diverse levels of variability. Several hypotheses are considered for this within‐region heterogeneity.
In patients with drug‐resistant epilepsy (DRE) who are not candidates for resective surgery, various thalamic nuclei, including the anterior, centromedian, and pulvinar nuclei, have been extensively ...investigated as targets for neuromodulation. However, the therapeutic effects of different targets for thalamic neuromodulation on various types of epilepsy are not well understood. Here, we present a 32‐year‐old patient with multifocal bilateral temporoparieto‐occipital epilepsy and bilateral malformations of cortical development (MCDs) who underwent bilateral stereoelectroencephalographic (SEEG) recordings of the aforementioned three thalamic nuclei bilaterally. The change in the rate of interictal epileptiform discharges (IEDs) from baseline were compared in temporal, central, parietal, and occipital regions after direct electrical stimulation (DES) of each thalamic nucleus. A significant decrease in the rate of IEDs (33% from baseline) in the posterior quadrant regions was noted in the ipsilateral as well as contralateral hemisphere following DES of the pulvinar. A scoping review was also performed to better understand the current standpoint of pulvinar thalamic stimulation in the treatment of DRE. The therapeutic effect of neuromodulation can differ among thalamic nuclei targets and epileptogenic zones (EZs). In patients with multifocal EZs with extensive MCDs, personalized thalamic targeting could be achieved through DES with thalamic SEEG electrodes.
We determined the incidence of post‐traumatic epilepsy after severe traumatic brain injury. Of 392 patients surviving to discharge, cumulative incidence of post‐traumatic epilepsy was 25% at 5 years ...and 32% at 15 years, an increase compared with historical reports. Among patients with one late seizure (>7 days post‐trauma), the risk of seizure recurrence was 62% after 1 year and 82% at 10 years. Competing hazards regression identified age, decompressive hemicraniectomy, and intracranial infection as independent predictors of post‐traumatic epilepsy. Patients with severe traumatic brain injury and a single late post‐traumatic seizure will likely require long‐term antiseizure medicines. ANN NEUROL 2022;92:663–669
Objective
In the presurgical workup of magnetic resonance imaging (MRI)‐negative (MRI− or “nonlesional”) pharmacoresistant focal epilepsy (PFE) patients, discovering a previously undetected lesion ...can drastically change the evaluation and likely improve surgical outcome. Our study utilizes a voxel‐based MRI postprocessing technique, implemented in a morphometric analysis program (MAP), to facilitate detection of subtle abnormalities in a consecutive cohort of MRI− surgical candidates.
Methods
Included in this retrospective study was a consecutive cohort of 150 MRI− surgical patients. MAP was performed on T1‐weighted MRI, with comparison to a scanner‐specific normal database. Review and analysis of MAP were performed blinded to patients' clinical information. The pertinence of MAP+ areas was confirmed by surgical outcome and pathology.
Results
MAP showed a 43% positive rate, sensitivity of 0.9, and specificity of 0.67. Overall, patients with the MAP+ region completely resected had the best seizure outcomes, followed by the MAP− patients, and patients who had no/partial resection of the MAP+ region had the worst outcome (p < 0.001). Subgroup analysis revealed that visually identified subtle findings are more likely correct if also MAP+. False‐positive rate in 52 normal controls was 2%. Surgical pathology of the resected MAP+ areas contained mainly non–balloon‐cell focal cortical dysplasia (FCD). Multiple MAP+ regions were present in 7% of patients.
Interpretation
MAP can be a practical and valuable tool to: (1) guide the search for subtle MRI abnormalities and (2) confirm visually identified questionable abnormalities in patients with PFE due to suspected FCD. A MAP+ region, when concordant with the patient's electroclinical presentation, should provide a legitimate target for surgical exploration. Ann Neurol 2015;77:1060–1075
Summary
Purpose: Stereo‐electroencephalography (SEEG) enables precise recordings from deep cortical structures, multiple noncontiguous lobes, as well as bilateral explorations while avoiding large ...craniotomies. Despite a long reported successful record, its application in the United States has not been widely adopted. We report on our initial experience with the SEEG methodology in the extraoperative mapping of refractory focal epilepsy in patients who were not considered optimal surgical candidates for other methods of invasive monitoring. We focused on the applied surgical technique and its utility and efficacy in this subgroup of patients.
Methods: Between March 2009 and May 2011, 100 patients with the diagnosis of medically refractory focal epilepsy who were not considered optimal candidates for subdural grids and strips placement underwent SEEG implantation at Cleveland Clinic Epilepsy Center. Demographics, noninvasive clinical data, number and location of implanted electrodes, electrophysiologic localization of the epileptic zone, complications, and short‐term seizure outcome after resection were prospectively collected and analyzed.
Key Findings: Mean age was 32 years (range 5–68 years); 54 were male and 46 female. The mean follow‐up after resection was 15 months. In total, 1,310 electrodes were implanted. Analyses of the SEEG recordings resulted in the electrographic localization of the epileptogenic focus in 96 patients. In the group of 75 patients who underwent resection, only 53 had at least 12 months follow‐up. From this group, 33 patients (62.3%) were seizure‐free at the end of the follow‐up period. The presence of abnormal pathologic finding was strongly associated with postoperative seizure control (p = 0.005). The risk of hemorrhagic complications per electrode was 0.2%.
Significance: In patients who are not considered to be ideal candidates for subdural grids and strips implantation, the SEEG methodology is a safe, useful and reliable alternative option for invasive monitoring in patients with refractory focal epilepsy, providing an additional mean for seizure localization and control in a “difficult to localize” subgroup of patients.
Every fourth patient submitted to epilepsy surgery suffers from a brain tumor. Microscopically, these neoplasms present with a wide-ranging spectrum of glial or glio-neuronal tumor subtypes. ...Gangliogliomas (GG) and dysembryoplastic neuroepithelial tumors (DNTs) are the most frequently recognized entities accounting for 65 % of 1,551 tumors collected at the European Epilepsy Brain Bank (
n
= 5,842 epilepsy surgery samples). These tumors often present with early seizure onset at a mean age of 16.5 years, with 77 % of neoplasms affecting the temporal lobe. Relapse and malignant progression are rare events in this particular group of brain tumors. Surgical resection should be regarded, therefore, also as important treatment strategy to prevent epilepsy progression as well as seizure- and medication-related comorbidities. The characteristic clinical presentation and broad histopathological spectrum of these highly epileptogenic brain tumors will herein be classified as “long-term epilepsy associated tumors—LEATs”. LEATs differ from most other brain tumors by early onset of spontaneous seizures, and conceptually are regarded as developmental tumors to explain their pleomorphic microscopic appearance and frequent association with Focal Cortical Dysplasia Type IIIb. However, the broad neuropathologic spectrum and lack of reliable histopathological signatures make these tumors difficult to classify using the WHO system of brain tumors. As another consequence from poor agreement in published LEAT series, molecular diagnostic data remain ambiguous. Availability of surgical tissue specimens from patients which have been well characterized during their presurgical evaluation should open the possibility to systematically address the origin and epileptogenicity of LEATs, and will be further discussed herein. As a conclusion, the authors propose a novel A–B–C terminology of epileptogenic brain tumors (“epileptomas”) which hopefully promote the discussion between neuropathologists, neurooncologists and epileptologists. It must be our future mission to achieve international consensus for the clinico-pathological classification of LEATs that would also involve World Health Organization (WHO) and the International League against Epilepsy (ILAE).
Objective
Posttraumatic epilepsy (PTE) develops in as many as one third of severe traumatic brain injury (TBI) patients, often years after injury. Analysis of early electroencephalographic (EEG) ...features, by both standardized visual interpretation (viEEG) and quantitative EEG (qEEG) analysis, may aid early identification of patients at high risk for PTE.
Methods
We performed a case–control study using a prospective database of severe TBI patients treated at a single center from 2011 to 2018. We identified patients who survived 2 years postinjury and matched patients with PTE to those without using age and admission Glasgow Coma Scale score. A neuropsychologist recorded outcomes at 1 year using the Expanded Glasgow Outcomes Scale (GOSE). All patients underwent continuous EEG for 3–5 days. A board‐certified epileptologist, blinded to outcomes, described viEEG features using standardized descriptions. We extracted 14 qEEG features from an early 5‐min epoch, described them using qualitative statistics, then developed two multivariable models to predict long‐term risk of PTE (random forest and logistic regression).
Results
We identified 27 patients with and 35 without PTE. GOSE scores were similar at 1 year (p = .93). The median time to onset of PTE was 7.2 months posttrauma (interquartile range = 2.2–22.2 months). None of the viEEG features was different between the groups. On qEEG, the PTE cohort had higher spectral power in the delta frequencies, more power variance in the delta and theta frequencies, and higher peak envelope (all p < .01). Using random forest, combining qEEG and clinical features produced an area under the curve of .76. Using logistic regression, increases in the delta:theta power ratio (odds ratio OR = 1.3, p < .01) and peak envelope (OR = 1.1, p < .01) predicted risk for PTE.
Significance
In a cohort of severe TBI patients, acute phase EEG features may predict PTE. Predictive models, as applied to this study, may help identify patients at high risk for PTE, assist early clinical management, and guide patient selection for clinical trials.
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