Semiology of insular lobe seizures

World Neurosurgery, 2017

Stereo-electroencephalography (SEEG) is a safe procedure, including for insular implantations Introduction In some cases of drug-resistant focal epilepsy, phase 1 non-invasive pre-surgical investigation may be insufficient to clearly identify the ictal onset zone as well as the eloquent cortical areas. Such situations lead to propose phase 2 invasive investigation, including intracranial electroencephalography (EEG) recordings 1. Implantation subdural grid electrodes (SGE) is a very popular technique which has been considered as a reference technique 2. This technique is suitable for providing superficial hemispheric cortical recordings, however interhemispheric or temporo-mesial electrode placement can be difficult and can lead to adverse effects 3. Moreover, this invasive technique cannot record either the bottom of sulci or the insula and may lead to complications such as infections, intracranial hemorrhages, and elevation of intracranial pressure that are encountered in 1 to 4% of cases 4. Stereo-electroencephalography (SEEG) is another way to obtain intracranial EEG. This technique, that uses depth electrodes, developed in the second part of the XX th century in Western Europe, offers the possibility to accurately explore mesial structures, deep sulci and insula, and is becoming increasingly popular worldwide. A recent meta-analysis 5 provides strong data regarding the safety of SEEG based on a systematic review of all published complications 6-35 , However, there is a lack of published data related to the possible risk factors for complications. In drug-resistant patients in whom phase 2 investigation is necessary, implication of insula is a very frequent issue 36. Seizures spreading between frontal or temporo-mesial regions and the insula are a usual challenge and SEEG is the only way to investigate these structures with a high temporal resolution. Moreover insular seizures can have a clinical presentation very similar to frontal, parietal, or temporo-mesial seizures. Most of the SEEG investigations performed because of a possible temporal or frontal localization of the epileptogenic zone thus usually require the implantation of at least one electrode in the insula. This can lead to important therapeutic implications 37. Historically, these insular electrodes were considered as

The Canadian Journal of Neurological Sciences, 2000

Initially, epilepsy surgery was lesion-based, but the development of electrocorticography (ECoG) introduced an era of electrophysiologically-guided epilepsy surgery. Some investigators found cortical spike topography useful. They differentiated "primary" epileptiform abnormalities from those "conducted into relatively normal cortex from the primary epileptogenic area". 1 They also distinguished "persistence of preexisting epileptogenic abnormality not included in the excision" from "the appearance … of epileptiform abnormality in regions where, prior to the removal, this abnormality had been absent". 1 Others found ECoG less useful. Modern neuroimaging and extraoperative intracranial recording reemphasize lesions and direct attention to cortex involved in seizure onset. Consequently, the role and meaning of interictal ECoG spike topography in removal design remains controversial.

Journal of Neurosurgery, 2004

Object. The aim of this study was to investigate changes in electroencephalography (EEG) patterns obtained from added or repositioned electrodes after those initially implanted had failed to indicate the true local ictal onset zone. The authors focused on the following matters: rationale for adding or repositioning electrodes, topographic and frequency characteristics of ictal onset before and after adding or repositioning electrodes, the effect of the procedures, and the relationship between changes in intracranial EEG onset patterns and surgical outcomes. Methods. Of 183 patients with intracranial recordings, 18 experienced repositioning of existing or implanting of additional electrodes 7 or 10 days later. All patients underwent resection and were followed up for more than 1 year. In particular, the relationship between surgical outcome and distribution/frequency of intracranial seizure onset was analyzed. Results of noninvasive presurgical evaluations in patients who had undergo...

Epilepsia, 2010

Purpose: Different lines of evidence suggest that the insular cortex has many important functional roles. Direct electrical stimulation (ES) of the human insular cortex during surgical procedures for epilepsy, functional imaging techniques, and lesion studies also occasionally induces clinical responses. Methods: In this study, we evaluated 25 patients with drug-refractory focal epilepsy by stereotactically implanting at least one electrode into the insular cortex using an oblique approach (transfrontal or transparietal). One hundred twenty-eight insular sites (each situated between two contiguous contacts within the same electrode) were examined within the gyral substructures. We located each stimulation site by fusing preimplantation threedimensional (3D) magnetic resonance imaging (MRI) images with the postimplantation 3D computed tomography (CT) scans that revealed the electrode contacts.

Epilepsia, 2000

The Canadian Journal of Neurological Sciences, 2000

Scalp EEG telemetry is an electrophysiologic technique that involves continuous recording of EEG and patient behavior (image and sound) over prolonged periods. In the context of epilepsy surgery, this investigation is used to assist in defining the ictal and interictal epileptogenic cortical areas by obtaining EEG signals with synchronized assessment of the patient's behavior during recorded seizures. In optimum circumstances for surgical intervention there will be a congruence of the EEG with clinical, radiological, and neuropsychological data. This review will focus on the use of scalp EEG in the evaluation of candidates for temporal lobe epilepsy surgery. SOME TECHNICAL CONSIDERATIONS The International Standard ten-twenty electrode system continues to be the most widely accepted method of measurement and application of EEG scalp electrodes. 1 Other systems describing additional electrode positions have been proposed. 2 A variety of additional "nonstandard" electrodes have been described to more completely evaluate the EEG ABSTRACT: Electroencephalography (EEG) with standard scalp and additional noninvasive electrodes plays a major role in the selection of patients for temporal lobe epilepsy surgery. Recent studies have provided data supporting the value of interictal and postictal EEG in assessing the site of ictal onset. Scalp ictal rhythms are morphologically complex but at least one pattern (a five cycles/second rhythm maximum at the sphenoidal or anterior temporal electrode) occurs in >50% of patients and has a high predictive value and interobserver reliability for temporal lobe originating seizures. Thorough interictal and ictal scalp EEG evaluation, in conjunction with modern neuroimaging, is sufficient for proceeding to surgery without invasive recordings in some patients. Further studies are required to define the scalp ictal characteristics of mesial vs. lateral temporal lobe epilepsy. RÉSUMÉ: L'ÉEG de surface dans la chirurgie de l'épilepsie temporale. L'électroencéphalographie (ÉEG) enregistré au moyen d'électrodes standard de surface et d'électrodes non effractives additionnelles a un rôle majeur dans la sélection des patients pour la chirurgie de l'épilepsie temporale. Des études récentes supportent la valeur de l'ÉEG interictal et postictal dans l'évaluation du site de déclenchement de la crise. Les rythmes de l'enregistrement de surface de la crise ont une morphologie complexe, mais au moins un patron (un rythme de 5 cycles/seconde enregistré par l'électrode sphénoïdale ou temporale antérieure) qu'on retrouve chez plus de 50% des patients, a une valeur prédictive et une fiabilité inter-observateur élevées dans les crises originant dans le lobe temporal. L'évaluation minutieuse par l'ÉEG de surface interictal et ictal, conjointement avec la neuroimagerie moderne sont suffisantes pour procéder à la chirurgie sans enregistrement invasif chez certains patients. D'autres études sont nécessaires pour définir les caractéristiques de l'épilepsie temporale mésiale par rapport à l'épilepsie temporale latérale, à l'enregistrement ictal de surface.

Seizure, 1996

Seizure, 2003

Intraoperative electrocorticography (ECoG) has been traditionally used in the surgical management of medically refractory partial epilepsies to identify the location and limits of the epileptogenic area, to guide the extent of resection, and to assess its completeness. Although in clinical use for many years, the basic questions regarding indications and limitations of this method has remained unanswered. ECoG plays a major role in tailored temporal lobectomies, whereas, it serves no practical purpose in standard resection of medial temporal lobe epilepsy (TLE) with magnetic resonance imaging (MRI) evidence of mesial temporal sclerosis (MTS). Residual hippocampal spikes, unaltered by resection, correlate with a greater proportion of seizure recurrence. Intraoperative hippocampal ECoG can allow sparing of functionally important hippocampus, thus minimising postoperative memory decline. ECoG eminently aids removal of developmental malformations of brain, and most importantly, the excision of highly epileptogenic cortical dysplasias (CDs) for deciding the extent of resection for best seizure control. The ECoG can be a valuable tool during multiple subpial transections (MST).

Operative Neurosurgery, 2008

Objective: This study investigates the feasibility, safety, and usefulness of depth electrodes stereotactically implanted within the insular cortex. Methods: Thirty patients with suspected insular involvement during epileptic seizure underwent presurgical stereotactic electroencephalographic recordings using 10 to 16 depth electrodes per patient. Among these, one or two electrodes were implanted via an oblique approach to widely sample the insular cortex. Results: Thirty-five insular electrodes were implanted in the 30 patients without morbidity. A total of 226 recording contacts (mean, 7.5 contacts/patient) explored the insular cortex. Stereotactic electroencephalographic recordings of seizures allowed the differentiation into groups: Group 1, 10 patients with no insular involvement; Group 2, 15 patients with secondary insular involvement; and Group 3, five patients with an initial insular involvement. In temporal epilepsy (n = 17), the insula was never involved at the seizure onse...

– Pre-operative assessment and surgical management of patients with non-lesional extratemporal epilepsy remain challenging due to a lack of precise localisation of the epileptic zone. In most cases, inva-sive recording with depth or subdural electrodes is required. Here, we describe the case of 6.5-year-old girl who underwent comprehensive non-invasive phase I video-EEG investigation for drug-resistant epilepsy, including electric source and nuclear imaging. Left operculo-insular epilepsy was diagnosed. Post-operatively, she developed aphasia which resolved within one year, corroborating the notion of enhanced language plasticity in children. The patient remained seizure-free for more than three years.