Stereotactic Eeg

Due to heterogenous seizure semiology and poor contribution of scalp electroencephalography (EEG) signals, insular epilepsy requires use of the appropriate diagnostic tools for its diagnosis and characterization. The deep location of the insula also presents surgical challenges. The aim of this article is to review the current diagnostic and therapeutic tools and their contribution to the management of insular epilepsy. Magnetic resonance imaging (MRI), isotopic imaging, neurophysiological imaging, and genetic testing should be used and interpretated with caution...

OBJECTIVE: Stereotactic electroencephalography (sEEG) is an increasingly utilized method for identifying electrophysiological processes underlying sensorimotor, cognitive, and emotional behaviors. In this review, the authors outline current research using sEEG to investigate the neural activity underlying emotional and psychiatric behaviors. Understanding the current structure of intracranial research using sEEG will inform future studies of psychiatric disease and therapeutics for effective neuromodulation...

Callosotomy is widely used today as a treatment option for medically refractory epilepsy in patients with generalized or unknown-onset seizures. Other surgical indications include bilaterally distributed, most often synchronous, epileptiform discharges on EEG and some epilepsy syndromes, including Lennox-Gastaut syndrome and infantile spasms/West syndrome. Patients with drop attacks, mainly caused by epileptic spasms or atonic seizures, are most likely to benefit from this procedure. A more favorable seizure outcome was observed after a one-stage total callosal section in pediatric patients...

OBJECTIVE: Stereotactic-EEG (SEEG) and scalp EEG recordings can be modeled using mesoscale neural mass population models (NMM). However, the relationship between those mathematical models and the physics of the measurements is unclear. In addition, it is challenging to represent SEEG data by combining NMMs and volume conductor models due to the intermediate spatial scale represented by these measurements. APPROACH: We provide a framework combining the multi-compartmental modeling formalism and a detailed geometrical model to simulate the transmembrane currents that appear in layer 3, 5 and 6 pyramidal cells due to a synaptic input...

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Drug-resistant, nonlesional, extratemporal lobe focal epilepsy can be difficult to treat and may require a high degree of multidisciplinary teamwork to localize the seizure onset zone for resective surgery. Here, we describe a patient with longstanding drug-resistant, nonlesional, extratemporal focal epilepsy with a high seizure burden who became seizure-free after prolonged evaluation and eventual left frontal cortical resection. Prior evaluations included magnetoencephalography, invasive video-EEG monitoring, and implantation of a responsive neurostimulation (RNS) device for ongoing intracranial stimulation...

Insular epilepsy (IE) is an increasingly recognized cause of drug-resistant epilepsy amenable to surgery. However, concerns of suboptimal seizure control and permanent neurological morbidity hamper widespread adoption of surgery for IE. We performed a systematic review and individual participant data meta-analysis to determine the efficacy and safety profile of surgery for IE and identify predictors of outcomes. Of 2483 unique citations, 24 retrospective studies reporting on 312 participants were eligible for inclusion...

BACKGROUND: Humans perform object recognition using holistic processing, which is different from computers. Intermodulation responses in the steady-state visual evoked potential (SSVEP) of scalp electroencephalography (EEG) had recently been used as an objective label for holistic processing. NEW METHOD: Using stereotactic EEG (sEEG) to record SSVEP directly from inside of the brain, we decoded Chinese characters from non-characters with activation from multiple brain areas including occipital, parietal, temporal, and frontal cortices...

OBJECTIVE: Seizures are known to occur with diurnal and other rhythms. To gain insight into the neurophysiology of periodicity of seizures, we tested the hypothesis that intracranial high-frequency oscillations (HFOs) show diurnal rhythms and sleep-wake cycle variation. We further hypothesized that HFOs have different rhythms within and outside the seizure-onset zone (SOZ). METHODS: In drug-resistant epilepsy patients undergoing stereotactic-EEG (SEEG) monitoring to localize SOZ, we analyzed the number of 50-200 Hz HFOs/channel/minute (HFO density) through a 24-hour period...

Whole brain ionic and metabolic imaging has potential as a powerful tool for the characterization of brain diseases. We combined sodium MRI (23 Na MRI) and 1 H-MR Spectroscopic Imaging (1 H-MRSI), assessing changes within epileptogenic networks in comparison with electrophysiologically normal networks as defined by stereotactic EEG (SEEG) recordings analysis. We applied a multi-echo density adapted 3D projection reconstruction pulse sequence at 7 T (23 Na-MRI) and a 3D echo-planar spectroscopic imaging sequence at 3 T (1 H-MRSI) in 19 patients suffering from drug-resistant focal epilepsy who underwent presurgical SEEG...

OBJECTIVE: We aimed to clarify the pathophysiology of epilepsy involving seizures with apparently generalized onset, progressing to focal ictal rhythm through stereotactic EEG (SEEG) implantation, recording, stimulation and high-frequency oscillation (HFO) analysis. METHODS: We identified two patients with seizures with bilateral electrographic onset evolving to focal ictal rhythm, who underwent SEEG implantation. Patients had pre-surgical epilepsy work-up, including prolonged video scalp EEG, brain MRI, PET, ictal/interictal SPECT, MEG, and EEG-fMRI prior to SEEG implantation...

Recent studies have shown it is possible to decode and synthesize speech directly using brain activity recorded from implanted electrodes. While this activity has been extensively examined using electrocorticographic (ECoG) recordings from cortical surface grey matter, stereotactic electroen-cephalography (sEEG) provides comparatively broader coverage and access to deeper brain structures including both grey and white matter. The present study examines the relative and joint contributions of grey and white matter electrodes for speech activity detection in a brain-computer interface...

Mania is characterized by affective and cognitive alterations, with heightened external and self-awareness that are opposite to the alteration of awareness during epileptic seizures. Electrical stimulations carried out routinely during stereotactic intracerebral EEG (SEEG) recordings for presurgical evaluation of epilepsy may represent a unique opportunity to study the pathophysiology of such complex emotional-behavioral phenomenon, particularly difficult to reproduce in experimental setting. We investigated SEEG signals-based functional connectivity between different brain regions involved in emotions and in consciousness processing during a manic state induced by electrical stimulation in a patient with drug-resistant focal epilepsy...

OBJECTIVE: To clinically validate the connectivity-based magnetoencephalography (MEG) analyses to identify seizure onset zone (SOZ) with comparing to equivalent current dipole (ECD). METHODS: The ECD cluster was quantitatively analyzed by calculating the centroid of the cluster and maximum distance (the largest distance between all dipoles). The "primary hub" was determined by the highest eigencentrality. The distribution of nodes in the top 5% of eigenvector centrality values was quantified by generating the convex hull between each node...

BACKGROUND: For patients with difficult-to-lateralize temporal lobe epilepsy, the use of chronic recordings as a diagnostic tool to inform subsequent surgical therapy is an emerging paradigm that has been reported in adults but not in children. OBSERVATIONS: The authors reported the case of a 15-year-old girl with pharmacoresistant temporal lobe epilepsy who was found to have bitemporal epilepsy during a stereoelectroencephalography (sEEG) admission. She underwent placement of a responsive neurostimulator system with bilateral hippocampal depth electrodes...

INTRODUCTION: Drug-resistant focal epilepsy presents a significant morbidity burden globally, and epilepsy surgery has been shown to be an effective treatment modality. Therefore, accurate identification of the epileptogenic zone for surgery is crucial, and in those with unclear noninvasive data, stereoencephalography is required. AREAS COVERED: This review covers the history and current practices in the field of intracranial EEG, particularly analyzing how stereotactic image-guidance, robot-assisted navigation, and improved imaging techniques have increased the accuracy, scope, and use of SEEG globally...

OBJECTIVE: Although stereotactic EEG (sEEG) has become a widely used intracranial EEG technique, the significance of subclinical seizures (SCS) recorded on sEEG is unclear and studies examining this finding on sEEG are limited. We investigated (1) the prevalence of SCS in patients undergoing sEEG and clinical factors associated with their presence, (2) how often the subclinical seizure onset zone (SOZ) colocalizes with clinical SOZ, (3) the association of SCS and surgical outcomes, and (4) the influence of resection of the subclinical SOZ on surgical outcome...

Insular epilepsy is a great mimicker and can be mistaken for seizures originating from other areas of the brain or as nonepileptic spells. The semiology of insular epilepsy can include, but is not limited to, auditory illusions, paresthesias, gastric rising, laryngeal constriction, and hyperkinetic movements. These arise from both the functions of the insula itself and its extensive connections with other regions of the brain. Noninvasive workup can be negative or nonlocalizing because of the insula's location deep within the lateral sulcus...

CONTEXT: Parietal lobe epilepsy (PLE) accounts for approximately 5% of all focal epilepsies worldwide,1 and few PLE patients have undergone epilepsy surgery in the past. With the introduction of functional neuroimaging methods, such as interictal fluorodeoxyglucose-positron emission tomography (FDG-PET), stereotactic electroencephalograms (SEEGs), and high-resolution magnetic resonance imaging (MRI), more patients with intractable neocortical epilepsy have been considered for surgical treatment...

Magnetoencephalography (MEG) is a noninvasive diagnostic modality that directly measures neuronal signaling by recording the magnetic field created from dendritic, intracellular, electrical currents of the neuron at the surface of the head. In clinical practice, MEG is used in the epilepsy presurgical evaluation and most commonly is an "interictal" study that can provide source localization of spike-wave discharges. However, seizures may be recorded during MEG ("ictal MEG") and mapping of these discharges may provide more accurate localization of the seizure onset zone...