[Benefit of surgery in a case of negative motor focal epileptic seizures secondary to parietal cortical dysplasia]. / Beneficio de la cirugía en un caso de crisis epilépticas focales motoras negativas secundarias a displasia cortical parietal.

Focal atonic seizures are recognized rarely as ictal phenomena, they can correspond to both generalized epilepsy and focal epilepsy. The areas of the brain involved in the management of this type of seizure are: the negative motor area and the primary motor and primary somatosensory cortices, although the neurophysiology that generates them is still unclear. We present the case of a patient with focal atonic seizures in the left upper limb, refractory to drug treatment. Neuroimaging was performed, a parietal cortical lesion was diagnosed. A scalp Video EEG and then a Stereo EEG was performed, defining the epileptogenic area and its relationship with eloquent areas. Surgical resection of the lesion was performed, achieving complete seizure control.

Las crisis atónicas focales son poco reconocidas como fenómenos ictales, pueden corresponder tanto a una epilepsia generalizada como a una epilepsia focal. Las áreas del cerebro implicadas en la gestión de este tipo de crisis son: el área motora negativa y las cortezas motora primaria y somatosensitiva primaria, aunque aún la neurofisiología que las genera no está aclarada. Presentamos el caso de un paciente con crisis atónicas focales farmacorresistentes en miembro superior izquierdo. Se realizó resonancia de cerebro con diagnóstico de displasia cortical parietal, se monitoreó con video EEG de scalp y luego a video EEG con electrodos profundos. Se definieron el área epileptógena y su relación con áreas elocuentes, se realizó resección quirúrgica de la lesión, logrando el control completo de las crisis.

Magnetic resonance imaging findings and clinical characteristics in mild malformation of cortical development with oligodendroglial hyperplasia and epilepsy in a predominantly adult cohort.

OBJECTIVE: We aimed to better characterize the magnetic resonance imaging (MRI) findings of mild malformation of cortical development with oligodendroglial hyperplasia (MOGHE), a rare clinicopathological entity associated with pharmacoresistance recently described in patients with frontal lobe epilepsy. METHODS: We studied 12 patients who underwent epilepsy surgery and whose surgical specimens showed histopathological findings of MOGHE, characterized by preserved cortical lamination, blurred gray-white matter interface due to increased number of oligodendrocytes, and heterotopic neurons in the white matter. The age at MRI evaluation ranged from 11 to 58 years, except for one 4.5-year-old patient. RESULTS: Following a detailed MRI analysis using an in-house protocol, we found abnormalities in all cases. The lesion was circumscribed in the frontal lobe in six (50%) and in the temporal lobe in three (25%) patients. In the remaining three patients (25%), the lesion was multilobar (frontotemporal and temporoparieto-occipital). Cortical thickening was mild in all patients, except in the 4.5-year-old patient, who had pronounced cortical thickening and white matter blurring. We also identified cortical/subcortical hyperintense T2/fluid-attenuated inversion recovery signal associated with gray/white matter blurring in all but one patient. When present, cleft cortical dimple, and deep sulci aided in localizing the lesion. Overall, the MRI findings were like those in focal cortical dysplasia (FCD) Type IIa. Surgical outcome was excellent in five patients (Engel Class I in 25% and II in 17%). The remaining seven patients (58%) had worthwhile seizure reduction (Engle Class III). Incomplete lesion resection was significantly associated with worse outcomes. SIGNIFICANCE: MRI findings associated with MOGHE are similar to those described in FCD Type IIa. Although more frequent in the frontal lobe, MOGHE also occurred in the temporal lobe or involved multiple lobes. Multilobar or extensive MOGHE MRI lesions are associated with less favorable surgical outcomes. Because this is a rare condition, multicenter studies are necessary to characterize MOGHE further.

Visual analysis of automated segmentation in the diagnosis of focal cortical dysplasias with magnetic resonance imaging.

Focal cortical dysplasias (FCDs) are a frequent cause of epilepsy. It has been reported that up to 40% of them cannot be visualized with conventional magnetic resonance imaging (MRI). The main objective of this work was to evaluate by means of a retrospective descriptive observational study whether the automated brain segmentation is useful for detecting FCD. One hundred and fifty-five patients, who underwent surgery between the years 2009 and 2016, were reviewed. Twenty patients with FCD confirmed by histology and a preoperative segmentation study, with ages ranging from 3 to 43 years (14 men), were analyzed. Three expert neuroradiologists visually analyzed conventional and advanced MRI with automated segmentation. They were classified into positive and negative concerning visualization of FCD by consensus. Of the 20 patients evaluated with conventional MRI, 12 were positive for FCD. Of the negative studies for FCD with conventional MRI, 2 (25%) were positive when they were analyzed with automated segmentation. In 13 of the 20 patients (with positive segmentation for FCD), cortical thickening was observed in 5 (38.5%), while pseudothickening was observed in the rest of patients (8, 61.5%) in the anatomical region of the brain corresponding to the dysplasia. This work demonstrated that automated brain segmentation helps to increase detection of FCDs that are unable to be visualized in conventional MRI images.

Malformations of cortical development: New surgical advances.

Epilepsy related to malformations of cortical development is frequently drug resistant or requires heavy medication, therefore surgery is key in their management. The role of stereotactic surgery has recently changed the diagnosis and treatment of focal cortical dysplasias (FCD), hypothalamic hamartomas (HH) and periventricular nodular heterotopias (PNH). In HH, radiosurgery using Gammaknife® leads to 60 % of seizure control and is associated with excellent neuropsychological results without significant endocrine function impairment. The seizure control rate is even higher (more than 80 %) with monopolar multiple stereotactic thermocoagulations and Laser interstitial Thermal Therapy (LiTT). While the first technique is associated with a 2 % complications rate (but with excellent neuropsychological outcomes), the latest has up to 22 % side effects in some series. All three of these techniques have encouraging results, but controlled studies are still lacking to provide evidence-based new therapeutic algorithms. With regard to the PNH, surgical management has long been limited by the depth of the lesions and their close anatomical relations with the functional brain connectome. Stereotactic approaches required to perform a SEEG, to locate the part of the PNH responsible for the seizure onset, are later followed by a stereotactic lesioning procedure, therefore doubling the bleeding risk. That is why SEEG-guided radiofrequency-thermocoagulation (SEEG guided-RF-TC), which makes it possible to perform these two steps in a single procedure, was considered as a promising option. A recent meta-analysis confirmed this intuition and reported 38 % of seizure-free patients and 81 % of responders with only 0.3 % of complications, making this approach the first treatment line, followed by LiTT. Among the multiple advances in the FCD identification by non-invasive investigations, a new modality of per-operative diagnostic procedure, the three-dimensional electrocorticography may lead to simplify the preoperative investigation and enhance the accuracy of FCD delineation. Evidence is nevertheless still insufficient to validate this promising concept. Conventional surgical resection has also been concerned by significant conceptual advances during the past few years, in particular with the development of the hodotopic approach, initially in oncologic surgery. Associated with a better understanding of neuroplasticity in epilepsy and the setting up of functional mapping during SEEG or during awake surgery, the possibility of surgical resections grew up. A short-term perspective in this field, when surgical resection remains impossible, would be to target crucial nodes of the epileptic network, distinct from the core functional connectome.

Clinical Application of an Open-Source 3D Volume Rendering Software to Neurosurgical Approaches.

BACKGROUND: Preoperative recognition of the anatomic individualities of each patient can help to achieve more precise and less invasive approaches. It also may help to anticipate potential complications and intraoperative difficulties. Here we describe the use, accuracy, and precision of a free tool for planning microsurgical approaches using 3-dimensional (3D) reconstructions from magnetic resonance imaging (MRI). METHODS: We used the 3D volume rendering tool of a free open-source software program for 3D reconstruction of images of surgical sites obtained by MRI volumetric acquisition. We recorded anatomic reference points, such as the sulcus and gyrus, and vascularization patterns for intraoperative localization of lesions. Lesion locations were confirmed during surgery by intraoperative ultrasound and/or electrocorticography and later by postoperative MRI. RESULTS: Between August 2015 and September 2016, a total of 23 surgeries were performed using this technique for 9 low-grade gliomas, 7 high-grade gliomas, 4 cortical dysplasias, and 3 arteriovenous malformations. The technique helped delineate lesions with an overall accuracy of 2.6 ± 1.0 mm. 3D reconstructions were successfully performed in all patients, and images showed sulcus, gyrus, and venous patterns corresponding to the intraoperative images. All lesion areas were confirmed both intraoperatively and at the postoperative evaluation. CONCLUSIONS: With the technique described herein, it was possible to successfully perform 3D reconstruction of the cortical surface. This reconstruction tool may serve as an adjunct to neuronavigation systems or may be used alone when such a system is unavailable.

Developmental tumors and adjacent cortical dysplasia: single or dual pathology?

Developmental tumors often lead to refractory partial seizures and constitute a well-defined, surgically remediable epilepsy syndrome. Dysplastic features are often associated with these tumors, and their significance carries both practical and conceptual relevance. If associated focal cortical dysplasia (FCD) relates to the extent of the epileptogenic tissue, then presurgical evaluation and surgical strategies should target both the tumor and the surrounding dyslaminated cortex. Furthermore, the association has been included in the recently revised classification of FCD and the epileptogenicity of this associated dysplastic tissue is crucial to validate such revision. In addition to the possibility of representing dual pathology, the association of developmental tumors and adjacent dysplasia may instead represent a single developmental lesion with distinct parts distributed along a histopathologic continuum. Moreover, the possibility that this adjacent dyslamination is of minor epileptogenic relevance should also be entertained. Surgical data show that complete resection of the solid tumors and immediately adjacent tissue harboring satellites may disrupt epileptogenic networks and lead to high rates of seizure freedom, challenging the epileptogenic relevance of more extensive adjacent dyslaminated cortex. Whether the latter is a primary or secondary abnormality and whether dyslaminated cortex in the context of a second lesion may produce seizures after complete resection of the main lesion is still to be proven.

Type II focal cortical dysplasia: electroclinical study and surgical outcome in 31 pediatric patients.

OBJECTIVE: The aim of this study was to analyze the electroclinical features and surgical outcome of 31 pediatric patients with focal cortical dysplasia (FCD) type II. MATERIAL AND METHODS: We conducted a retrospective, descriptive study of 31 patients with FCD type II followed between 1998 and 2011. We included patients with FCD type II confirmed by histopathological examination with abnormal magnetic resonance imaging and at least 1 year of follow-up. RESULTS: All patients had severe focal epilepsy; in infancy, four of them had also had epileptic spasms, associated with hypsarrhythmia in three. Focal status epilepticus occurred in five patients (16 %) and epilepsia partialis continua in one (3.2 %). Seizures occurred during sleep in 20 (64.5 %) and in clusters in 19 (61.3 %) patients. Neurological examination showed a mild motor deficit in seven (22.8 %) patients. Interictal abnormalities were characterized by rhythmic spikes and polyspike discharges, increasing during sleep in 13 (41.9 %) patients. Average time of follow-up after surgery was 4.7 years with a median time of 4 years and a range from 1 to 9 years. Engel classification class I was found in 20 (67.7 %) and class II in 3 cases (9.6 %). There were no significant changes after an average time of follow-up of 4.7 years. CONCLUSION: Our results confirm that surgery is the best treatment option for pediatric patients with refractory focal epilepsy due to type II FCD. A statistically significant correlation was found between a good prognosis and age at epilepsy onset older than 2 years.

Bilateral perisylvian ulegyria: an under-recognized, surgically remediable epileptic syndrome.

PURPOSE: Interest in the association of epilepsy and pseudobulbar palsy was rekindled since the identification through magnetic resonance imaging (MRI) of bilateral perisylvian polymicrogyria (PMG). Seizures are often intractable, but resective epilepsy surgery has not been recommended. However, a similar clinical picture can be encountered in patients with bilateral perisylvian destructive lesions, which fit the description of ulegyria (ULG). We report a series of patients with epilepsy and pseudobulbar palsy due to bilateral perisylvian ULG (BP-ULG), show that hippocampal sclerosis (HS) is often associated and highlight the fact that in this entity, unlike in malformative bilateral perisylvian PMG, seizures may be surgically treated. METHODS: The motor, cognitive, epileptologic, and imaging features of 12 patients with perisylvian ULG followed at three institutions are described. For patients with refractory seizures, we detail extracranial and intracranial electrographic recordings, surgical strategies, histopathologic analyses of the resected tissue, and outcome of surgical treatment. Descriptive statistics were used for quantitative and categorical variables. Student's t-test was used to compare means, and a p < 0.05 was considered significant. KEY FINDINGS: Pseudobulbar palsy and mental retardation were present in all patients with symmetrical BP-ULG. Five had refractory seizures. There was no relationship between the severity of the pseudobulbar palsy or of the mental retardation and the degree of seizure control with medication. The five patients in whom seizures were refractory to medication had significantly earlier age of onset and longer duration of epilepsy (p < 0.05). Dual pathology with associated unilateral HS was present in four. One patient with dual pathology had a temporolimbic electroclinical picture and had an anterior temporal lobectomy (ATL) based upon noninvasive evaluation. The other four had ictal semiology suggesting involvement of both temporolimbic and perisylvian cortex. Intracranial electroencephalography (EEG) showed concomitant seizure onset in the anterior temporal region and in the ipsilateral ULG in three of the four with dual pathology and in the ulegyric cortex in the one without HS. Resection guided by a combination of semiology, MRI, and extra and intracranial EEG led to complete seizure control in two and almost complete seizure control (Engel class II) in two other patients. The only surgical failure was an isolated ATL in a patient with dual pathology, and concomitant seizure onset in both lesions according to semiology and intracranial EEG. SIGNIFICANCE: Our findings suggest that BP-ULG mimics the clinical features of bilateral perisylvian PMG. In patients with refractory seizures, recognition of this entity should lead to consideration of resective surgery despite the bilateral ULG.

Surgical and postmortem pathology studies: contribution for the investigation of temporal lobe epilepsy / Patologia cirúrgica e post mortem: contribuição para a investigação da epilepsia do lobo temporal

Pathology studies in epilepsy patients bring useful information for comprehending the physiopathology of various forms of epilepsy, as well as aspects related to response to treatment and long-term prognosis. These studies are usually restricted to surgical specimens obtained from patients with refractory focal epilepsies. Therefore, most of them pertain to temporal lobe epilepsy (TLE) with mesial temporal sclerosis (MTS) and malformations of cortical development (MCD), thus providing information of a selected group of patients and restricted regions of the brain. Postmortem whole brain studies are rarely performed in epilepsy patients, however they may provide extensive information on brain pathology, allowing the analysis of areas beyond the putative epileptogenic zone. In this article, we reviewed pathology studies performed in epilepsy patients with emphasis on neuropathological findings in TLE with MTS and MCD. Furthermore, we reviewed data from postmortem studies and discussed the importance of performing these studies in epilepsy populations.

Estudos de patologia em pacientes com epilepsia trazem informações úteis para compreender a fisiopatologia de várias formas de epilepsia, bem como aspectos relacionados ao tratamento e ao prognóstico a longo prazo. Esses estudos são usualmente restritos a espécimes cirúrgicos obtidos de pacientes com epilepsias focais refratárias. Portanto, a maioria diz respeito à epilepsia do lobo temporal (ELT) com esclerose mesial temporal (EMT) e às malformações do desenvolvimento cortical (MDC). Desse modo, fornecem informações sobre um grupo selecionado de pacientes e sobre regiões restritas do cérebro. Raramente são realizados estudos post mortem do cérebro inteiro em pacientes com epilepsia; entretanto, eles podem prover informações relevantes sobre patologia cerebral, permitindo a análise de áreas além da zona epileptogênica putativa. Neste artigo, foram revisados estudos de patologia feitos em pacientes com epilepsia, com ênfase nos achados neuropatológicos em ELT com EMT e MDC. Foram revisados, ainda, dados de estudos post mortem e discutiu-se a importância da realização desses estudos em populações de pessoas com epilepsia.

Surgical and postmortem pathology studies: contribution for the investigation of temporal lobe epilepsy.

Pathology studies in epilepsy patients bring useful information for comprehending the physiopathology of various forms of epilepsy, as well as aspects related to response to treatment and long-term prognosis. These studies are usually restricted to surgical specimens obtained from patients with refractory focal epilepsies. Therefore, most of them pertain to temporal lobe epilepsy (TLE) with mesial temporal sclerosis (MTS) and malformations of cortical development (MCD), thus providing information of a selected group of patients and restricted regions of the brain. Postmortem whole brain studies are rarely performed in epilepsy patients, however they may provide extensive information on brain pathology, allowing the analysis of areas beyond the putative epileptogenic zone. In this article, we reviewed pathology studies performed in epilepsy patients with emphasis on neuropathological findings in TLE with MTS and MCD. Furthermore, we reviewed data from postmortem studies and discussed the importance of performing these studies in epilepsy populations.

Microscopic mild focal cortical dysplasia in temporal lobe dual pathology: an electrocorticography study.

BACKGROUND: Associations between electrophysiological and histological findings might provide an insight into the epileptogenicity of mild focal cortical dysplasia (FCD) in patients with temporal lobe epilepsy (TLE) and a dual pathology. SUBJECTS AND METHODS: A total of 22 patients with pharmacoresistant TLE were included in the study, 16 of them with histologically confirmed hippocampal sclerosis (HS) associated with neocortical temporal mild Palmini Type-I FCD subtypes and 6 with HS. Intraoperative electrocorticography (ECoG) recordings were analysed for epileptiform discharge frequency and morphology. Associations between histological, and electrocorticography pattern findings in these patients were analysed. Electroclinical outcomes in these patients were also evaluated. RESULTS: Neocortical areas with mild Palmini Type-I FCD showed a significantly higher spike frequency (SF) recorded in the inferior temporal gyrus than those neocortical areas in patients with HS. There was a tendency to higher spike frequency and lower amplitude in neocortical areas with histopathologic subtype IB FCD in relation with IA during intraoperative ECoG. Post-SF excision and amplitude were significantly lower during neocortical post-excision intraoperative ECoG than during neocortical pre-excision recording. There was no difference found in the clinical outcome between patients with and without FCD. CONCLUSIONS: Intraoperative electrocorticographic interictal spike frequency recorded in the neocortical inferior temporal gyrus may help to characterize the histopathologic subtypes of mild Palmini Type-I FCD in patients with temporal lobe epilepsy (TLE) and a dual pathology. Our data support the epileptogenicity of neocortical mild FCD in TLE and assessments of ECoG patterns are relevant to determine the extent of the resection in these patients which can influence the electroclinical outcome.