Cortex Epilepsy Research Articles

Predictors and outcome surgery for posterior cortex epilepsies

ObjectiveThe aim of this study is to identify the prognostic role of MRI and EEG in posterior cortex epilepsies (PCES) and to characterize their clinical features. Patient and MethodsWe retrospectively studied 54 consecutive patients (18 females, 36 males) from April 2011 to November 2015, who had undergone PCES surgery. Electro-clinical, pathological and surgical data were evaluated. Of the patients, 18 (33.3%) patients underwent a cortical resection (corticectomy), 10 (18.5%) lobectomy, 6 (11.1%) multilobar resection, 20 (30.1%) disconnection. ResultsThe postoperative follow-up duration was ≥1 year in all patients (12–44 months, mean = 25). Thirty-two patients (59.3%) became seizure free (ILAE 1) and 40 (74.1%) had a good (ILAE 1, 2, 3) outcome. The most common pathological finding was focal cortical dysplasia (in 34 patients). Univariate analysis showed that regional scalp interictal epilepsy discharges (IEDs) (P = 0.031), Regional EEG onset (P = 0.027), a MRI lesion (P = 0.001) and the number of seizures that were recorded by the epilepsy monitor unit (P = 0.016) were significantly associated with freedom from seizures. Multivariate analysis confirmed that MRI positive was statistically significant (HR = 4.284, CI = 1.198–15.315). ConclusionsSurgical treatment is effective for PCES, and MRI and EEG analyses are important in presurgical evaluation of PCES.

Disconnection Surgery for Intractable Epilepsy with a Structural Abnormality in the Medial Posterior Cortex

The lesionectomy is a general surgical procedure for treating focal epilepsy resulting from a structural abnormality, but a favorable outcome cannot be achieved in some patients, especially patients whose symptomatogenic zone is located in remote regions. Herein we propose the surgical disconnection of the seizure propagation pathway, which consists of short and long associating fibers linking the epileptogenic zone to the remote symptomatogenic zone, as an effective method of achieving favorable seizure outcomes in patients with posterior cortex epilepsy. Three patients with intractable epilepsy showing a structural abnormality in the medial posterior cortex participated in this study. Their habitual seizures were complex partial seizures stemming from remote symptomatogenic zones. Seizure propagation-related fibers were assumed by non-invasive examination and semiology. Cingulum and superior/inferior longitudinal fasciculus were considered to form main seizure propagation pathway. Based on the preoperative assumption and the intraoperative intracranial electroencephalogram findings, a lesionectomy and corticectomy were performed for 2 patients while a clusterectomy and corticectomy were performed for the remaining patient. The resection area was extended in the direction of the association fibers to disconnect the remote symptomatogenic zone completely from the epileptogenic zone. Engel class I was achieved in all the patients. The current study suggested that assuming the presence of association fibers was an important factor for achieving a favorable outcome in the surgical treatment of posterior cortex epilepsy. Though further study is required, disconnection surgery is recommended as a treatment option for cases in which the epileptogenic zone is located in an eloquent area.

Posterior Quadrant Disconnection: A Fiber Dissection Study.

Posterior quadrant disconnection can be highly effective in the surgical treatment of selected cases of refractory epilepsy. The technique aims to deafferent extensive areas of epileptogenic posterior cortex from the rest of the brain by isolating the temporoparietooccipital cortex. To describe this procedure and relevant white matter tracts with a specific emphasis on the extent of callosotomy in an anatomic study. Twenty hemispheres were dissected according to Klingler's fiber dissection technique illustrating the peri-insular (temporal stem, superior longitudinal fasciculus, corona radiata) and mesial disconnection (mesiotemporal cortex, cingulum, and corpus callosum). Extensive white matter tract disconnection is obtained after posterior quadrant disconnection. Callosal fibers connecting the anterior most part of the parietal cortex invariably ran through the isthmus of the corpus callosum and need to be disconnected, while frontal lobe connections including the corticospinal tract and the anterior two-thirds of the corpus callosum are spared during the procedure. Our findings suggest the involvement of both the splenium and the isthmus in interhemispheric propagation in posterior cortex epilepsies. Sectioning the total extent of the posterior one-third of the corpus callosum might therefore be necessary to achieve optimal outcomes in posterior quadrant epilepsy surgery.

Functional surgery in pediatric drug-resistant posterior cortex epilepsy: Electro-clinical findings, cognitive and seizure outcome

PurposeEpilepsies originated from the occipital, parietal and/or the posterior edge of the temporal lobe are grouped together into posterior cortex epilepsy (PCE). Our objective was firstly to describe electro-clinical and imaging findings in the presurgical evaluation of children with PCE, and secondly to identify potential factors associated with surgical and cognitive outcomes. MethodFrom the total of patients referred to the Epilepsy Monitoring Unit of ‘Hospital Universitario Niño Jesús’ from 2003 to 2016, 55 had drug-resistant PCE. Different variables obtained from the multimodal presurgical work-up were analyzed among patients achieving seizure freedom after surgery (ILAE class 1) and patients with persistent seizures. Categorical variables were compared with Fisheŕs exact test and numeric variables with t-Student for independent samples, and multiple logistic regression were used to analyze predictive values. ResultsMedian duration of epilepsy until surgery was 5 years [3–10 years]. Fifty patients showed lesions in the MRI, and 62.5% had concordant MRI-PET corregistration. 37 (67%) patients were operated (lesionectomy in 21 subjects, tailored resection based on intracranial studies in 16), and 23 (62,2%) reached ILAE class 1, with a mean follow-up period of 3.51 [1–12] years. A lower number of basal seizures and antiepileptic drugs, a well-defined lesion on the MRI, an epileptogenic zone (EZ) restricted to the posterior quadrant and the normalization of postsurgical EEGs were associated with seizure freedom (p<0.05). Additionally, 65% of patients had a long-term improvement of cognitive performances. ConclusionsEpilepsy surgery should be considered in children with drug-resistant PCE, especially in those with a restricted EZ.

The Role of Thalamus Versus Cortex in Epilepsy: Evidence from Human Ictal Centromedian Recordings in Patients Assessed for Deep Brain Stimulation.

The onset of generalized seizures is a long debated subject in epilepsy. The relative roles of cortex and thalamus in initiating and maintaining the different seizure types are unclear. The purpose of the study is to estimate whether the cortex or the centromedian thalamic nucleus is leading in initiating and maintaining seizures in humans. We report human ictal recordings with simultaneous thalamic and cortical electrodes from three patients without anesthesia being assessed for deep brain stimulation (DBS). Patients 1 and 2 had idiopathic generalized epilepsy whereas patient 3 had frontal lobe epilepsy. Visual inspection was combined with nonlinear correlation analysis. In patient 1, seizure onset was bilateral cortical and the belated onset of leading thalamic discharges was associated with an increase in rhythmicity of discharges, both in thalamus and cortex. In patient 2, we observed bilateral independent interictal discharges restricted to the thalamus. However, ictal onset was diffuse, with discharges larger in the cortex even though they were led by the thalamus. In patient 3, seizure onset was largely restricted to frontal structures, with belated lagging thalamic involvement. In human generalized seizures, the thalamus may become involved early or late in the seizure but, once it becomes involved, it leads the cortex. In contrast, in human frontal seizures the thalamus gets involved late in the seizure and, once it becomes involved, it lags behind the cortex. In addition, the centromedian nucleus of the thalamus is capable of autonomous epileptogenesis as suggested by the presence of independent focal unilateral epileptiform discharges restricted to thalamic structures. The thalamus may also be responsible for maintaining the rhythmicity of ictal discharges.

S44 Non-invasive presurgical evaluation of insular cortex epilepsy

Introduction Considering the variability in seizure semiology, recognition of operculo-insular epilepsy (OIE) may be challenging and confirmation by non-invasive tests is warranted although few studies have assessed their value. Methods Surface EEG (n = 9), MRI (n = 48), 1H-MRS (n = 12), ictal SPECT (n = 18), interictal PET (n = 17) and MEG (n = 14) findings of OIE cases proven by the presence of an insular epileptogenic lesion or good surgical outcome were reviewed. Results (1) Scalp EEG: spikes were found over fronto, temporal and central leads, generally allowing adequate lateralization; ictal discharges were also generally lateralizing but more extent in distribution; auras lacked EEG changes. (2) MRI identified a neoplastic lesion in 27%, a malformation of cortical development in 21%, a vascular malformation in 19% and atrophy/gliosis from an acquired insult in 17%. (3) No significant differences in insular [NAA] or NAA/Cr ratios were found between the OIE group, the non-OIE group and healthy controls. (4) Ictal SPECT showed maximum hyperperfusion in the operculo-insular region in 65%; PET findings were localizing in 29%, lateralizing in another 18%, falsely localizing in 24% and with no hypometabolism in 29%. (5) Tight anterior and posterior operculo-insular clusters of dipoles were observed in 50% and 14%, respectively, while 29% had diffuse perisylvian dipoles. Focal resection in 6/7 patients with anterior or posterior operculo-insular clusters of dipoles resulted in seizure freedom, whereas both surgically treated patients with scattered perisylvian spike sources had an Engel II seizure outcome. Discussion Detection of an insular lesion on MRI greatly facilitates the diagnosis. Scalp EEG findings in fronto-central and/or temporal derivations generally allow lateralization of the seizure focus. Ictal SPECT has moderate sensitivity while PET findings were less localizing. Among newer techniques, MEG was found to be highly beneficial while MRS currently has limited value. Conclusion When OIE is clinically suspected, non-invasive tests (MRI, SPECT and especially MEG) may provide additional supporting information.

Invasive Investigation of Insular Cortex Epilepsy.

Invasive long-term EEG investigations of the insula have been performed since the mid-nineties in an expanding range of focal epilepsies suspected to involve the insular cortex. The various clinical forms of insular epilepsies were delineated during the last 2 decades, and include the following presentations: perisylvian epilepsy, temporal plus epilepsy, sleep hypermotor epilepsy, MRI-negative frontal and parietal lobe epilepsies, and insular lesions. In fact, a majority of complex stereoelectroencephalography procedures will include at least one electrode targeting the insula. Stereoelectroencephalography is currently the preferred method to investigate the insula, using orthogonal, oblique, or a combination of both trajectories, with no evidence of higher risk of intracranial bleeding than in other brain regions. Orthogonal trajectories allow to sample the overlaying opercula, while oblique trajectories offer a better sampling of the insular cortex. Intrainsular ictal EEG pattern are often characterized by a prolonged focal discharge restricted to one of the five insular gyri, militating for a dense enough sampling of the insular cortex in suspected insular epilepsies. Stereoelectroencephalography offers the potential to perform thermolesion of insular epileptogenic zones which, together with MRI-guided laser ablation, represent a possibly safer alternative treatment to open-skull surgical resection of the insula.

Proton MR Spectroscopy in Patients with Nonlesional Insular Cortex Epilepsy Confirmed by Invasive EEG Recordings

Recent studies suggest that a nonnegligible proportion of drug-resistant epilepsy surgery candidates have an epileptogenic zone that involves the insula. We aimed to examine the value of proton magnetic resonance spectroscopy (1 H-MRS) in identifying patients with insular cortex epilepsy. Patients with possible nonlesional drug-refractory insular epilepsy underwent a voxel-based 1 H-MRS study prior to an intracranial electroencephalographic (EEG) study. Patients were then divided into two groups based on invasive EEG findings: the insular group with evidence of insular seizures and the noninsular group with no evidence of insular seizures. Sixteen age-matched healthy controls were also scanned for normative data. Twenty-two epileptic patients were recruited, 12 with insular seizures and 10 with extra-insular seizures. Ipsilateral and contralateral insular N-acetyl-aspartate concentrations ([NAA]) and NAA/Cr ratios were found to be similar in both patient groups. No significant differences in [NAA] or NAA/Cr ratios were found between the insular group, noninsular group, and healthy controls. [NAA] and NAA/Cr asymmetry indices correctly lateralized the seizure focus in only 16.7% and 0% of patients, respectively. Our preliminary findings suggest that 1 H-MRS fares poorly in identifying patients with nonlesional insular epilepsy.

Posterior cortex epilepsy surgery in childhood and adolescence: Predictors of long‐term seizure outcome

We aimed to investigate the long-term seizure outcome of children and adolescents who were undergoing epilepsy surgery in the parietooccipital cortex and determine their predictive factors. We retrospectively analyzed the data of 50 consecutive patients aged 11.1 (mean) ± 5.1 (standard deviation) years at surgery. All patients but one had a magnetic resonance imaging (MRI)-visible lesion. Resections were parietal in 40%, occipital in 32%, and parietooccipital in 28% cases; 24% patients additionally underwent a resection of the posterior border of the temporal lobe. Etiology included focal cortical dysplasia in 44%, benign tumors (dysembryoplastic neuroepithelial tumor, ganglioglioma, angiocentric glioma, and pilocystic astrocytoma) in 32%, peri- or postnatal ischemic lesions in 16%, and tuberous sclerosis in 8% cases. At last follow-up (mean 8 years, range 1.5-18 years), 60% patients remained seizure-free (Engel class I): 30% had discontinued and 20% had reduced antiepileptic drugs. Most seizure recurrences (71%) occurred within the first 6 months, and only three patients presented with seizures ≥2 years after surgery. Independent predictors of seizure recurrence included left-sided as well as parietal epileptogenic zones and resections. Longer epilepsy duration to surgery was identified as the only modifiable independent predictor of seizure recurrence. Our study demonstrates that posterior cortex epilepsy surgery is highly effective in terms of lasting seizure control and antiepileptic drug cessation in selected pediatric candidates. Most importantly, our data supports the early consideration of surgical intervention in children and adolescents with refractory posterior cortex epilepsy.

Simultaneous SEEG-MEG-EEG recordings Overcome the SEEG limited spatial sampling

During presurgical evaluation of pharmacoresistant partial epilepsies, stereoelectroencephalography (SEEG) records interictal and ictal activities directly but is inherently limited in spatial sampling. In contrast, scalp-EEG and MEG are less sensitive but provide a global view on brain activity. Therefore, recording simultaneously these three modalities should provide a better understanding of the underlying brain sources by taking advantage of the different sensitivities of the three recording techniques.We performed trimodal EEG-MEG-SEEG recordings in a 19-year-old woman with pharmacoresistant cryptogenic posterior cortex epilepsy. Sub-continuous and highly focal spikes that were not visible at the surface were marked on SEEG by an epileptologist. Surface signals, MEG and scalp-EEG, were then averaged locked on SEEG spikes. MEG sources were reconstructed based on a moving dipole approach (Brainstorm software). This analysis revealed source within the left occipital pole, located posteriorly to the SEEG leads presenting the maximal number of spikes, in a region not explored by SEEG. In summary, simultaneous recordings provide a new framework for obtaining a view on brain signals that is both local and global, thereby overcoming the inherent SEEG limited spatial sampling.

Epilepsy surgery in the posterior part of the brain.

Posterior cortex epilepsy surgery is rarely performed and is associated with a high number of surgical failures, partly because accurate localization of the epileptogenic zone in the posterior part of the brain is extremely difficult. We present the characteristics as well as the surgical outcome and its determinants of a cohort of 208 consecutive patients (adults/children: 125/83) operated on for drug-resistant posterior cortex epilepsy at the "Claudio Munari" Epilepsy Surgery Centre, Milan between May 1996 and May 2013 (mean postsurgical follow-up: 9.6years). In addition, we highlight the differences in anatomoelectroclinical features and outcome between (i) patients who necessitated an invasive preoperative evaluation and those who proceeded directly to surgery and (ii) adults and children. Mean age at epilepsy onset was 6.8years (91.4% with onset before 14years of age). A high seizure frequency was reported by 51% of subjects, interictal and ictal EEG features were localizing in 16% and 28% of cases, and 86% of patients had a positive, judged as more or less informative, MRI. Invasive presurgical evaluation by stereoelectroencephalography was performed in 54% of patients; explorations may schematically be grouped in three main implantation patterns. Globally, 70% of subjects achieved seizure freedom, and further, 10% achieved Engel class II, with the patients operated on in childhood achieving significantly better postsurgical results in terms of seizure freedom and drug discontinuation. Duration of epilepsy represented the most consistent predictor of surgical outcome, with early surgery being correlated with higher chances of surgical success. Therefore, we recommend an early surgical referral in cases of pharmacoresistant posterior cortex seizures. Furthermore, we suggest that surgical failure might be predicted very early, namely within the first 6 postoperative months. We conclude that surgical management of posterior cortex epilepsy may attain excellent results.

Magnetoencephalographic signatures of insular epileptic spikes based on functional connectivity.

Failure to recognize insular cortex seizures has recently been identified as a cause of epilepsy surgeries targeting the temporal, parietal, or frontal lobe. Such failures are partly due to the fact that current noninvasive localization techniques fare poorly in recognizing insular epileptic foci. Our group recently demonstrated that magnetoencephalography (MEG) is sensitive to epileptiform spikes generated by the insula. In this study, we assessed the potential of distributed source imaging and functional connectivity analyses to distinguish insular networks underlying the generation of spikes. Nineteen patients with operculo-insular epilepsy were investigated. Each patient underwent MEG as well as T1-weighted magnetic resonance imaging (MRI) as part of their standard presurgical evaluation. Cortical sources of MEG spikes were reconstructed with the maximum entropy on the mean algorithm, and their time courses served to analyze source functional connectivity. The results indicate that the anterior and posterior subregions of the insula have specific patterns of functional connectivity mainly involving frontal and parietal regions, respectively. In addition, while their connectivity patterns are qualitatively similar during rest and during spikes, couplings within these networks are much stronger during spikes. These results show that MEG can establish functional connectivity-based signatures that could help in the diagnosis of different subtypes of insular cortex epilepsy. Hum Brain Mapp 37:3250-3261, 2016. © 2016 Wiley Periodicals, Inc.

Multimodal investigation of epileptic networks: The case of insular cortex epilepsy.

The insula is a deep cortical structure sharing extensive synaptic connections with a variety of brain regions, including several frontal, temporal, and parietal structures. The identification of the insular connectivity network is obviously valuable for understanding a number of cognitive processes, but also for understanding epilepsy since insular seizures involve a number of remote brain regions. Ultimately, knowledge of the structure and causal relationships within the epileptic networks associated with insular cortex epilepsy can offer deeper insights into this relatively neglected type of epilepsy enabling the refining of the clinical approach in managing patients affected by it. In the present chapter, we first review the multimodal noninvasive tests performed during the presurgical evaluation of epileptic patients with drug refractory focal epilepsy, with particular emphasis on their value for the detection of insular cortex epilepsy. Second, we review the emerging multimodal investigation techniques in the field of epilepsy, that aim to (1) enhance the detection of insular cortex epilepsy and (2) unveil the architecture and causal relationships within epileptic networks. We summarize the results of these approaches with emphasis on the specific case of insular cortex epilepsy.

Widespread inter-ictal excitability changes in patients with temporal lobe epilepsy: A TMS/MEG study

Transcranial magnetic stimulation (TMS) has been used to elucidate the altered balance between excitatory and inhibitory circuits in the motor cortex in epilepsy; however, TMS could not well assess excitability changes beyond the motor cortex. This study aimed to address the spatial profile of cortical excitability changes in patients with temporal lobe epilepsy (TLE) by using TMS and magnetoencephalography (MEG). Eighteen patients with TLE and 18 healthy control subjects were recruited. Resting motor threshold (RMT) and intracortical inhibition (ICI) were measured to reflect motor cortical excitability by using TMS. A whole-head MEG was applied to record auditory and somatosensory evoked responses to paired-pulse stimuli. A paired-pulse inhibition (PPI) ratio, defined as the amplitude ratio between responses to the second and the first stimuli, was used to assess the auditory and somatosensory cortical excitability. A high PPI ratio suggests an increase in cortical excitability, while a low ratio indicates a decrease in excitability. Compared to control subjects, TLE patients exhibited increased RMT in motor cortex and higher PPI ratios for auditory P50m and somatosensory P35m responses. Notably, patients with a lower seizure frequency tended to exhibit a higher RMT or a lower P35m PPI ratio. Present data suggest that the cortical excitability alteration in focal epilepsy is widely distributed beyond the epileptic focus and the profiles of excitability change correlate with clinical severity in terms of seizure frequency. Combined MEG and TMS studies provide new insight into the inter-ictal cortical excitability profiles in patients with epilepsy.

Insular Cortex and Insular Epilepsy

Insular cortex epilepsy is an under-recognized, localization-related syndrome. The presence of this condition could account for the surgery treatment failure seen in a portion of patients with temporal epilepsy, as well as a portion of those with frontal and parietal lobe epilepsy. Most cases of intractable temporal epilepsy are associated with insular cortex involvement. In this review, we will discuss the associations of insular cortex with other nervous cortex systems anatomically and functionally in order to correctly understand the insular lobe; the relationship between insular epilepsy and temporal epilepsy, the independence of insular epilepsy, and differences of insular epilepsy between the independent epileptogenesis and epileptic system as well as the concept of epileptic foci-complex were also discussed based on the current literature and our clinical experience in the treatment of epilepsy.

Magnetic source imaging in posterior cortex epilepsies.

Posterior cortex epilepsies (PCE) are characterized by less satisfying postoperative results than temporal lobe epilepsies and are thus challenging for non-invasive presurgical investigations. The objective of this study was to evaluate the performance of magnetic source imaging (MSI) in PCE, validating the results by the SEEG (stereoelectroencephalography) definition of irritative and epileptogenic zones (IZ and EZ). Fourteen PCE surgery candidates were investigated using MSI and SEEG. LCMV (Linearly Constrained Minimum Variance) and MUSIC algorithms were used. IZ was quantified using a semi-automatic detection of interictal spikes. EZ was quantified using the epileptogenicity index (EI) method that accounts for both the propensity of a brain area to generate rapid discharges and the time for this area to get involved in the seizure. EI values range from 0 (no epileptogenicity) to 1 (maximal epileptogenicity). Levels of concordance between MSI and IZ, MSI and EZ were determined as follows: A=localized on MSI and SEEG for the site of value 1 (IZ and EZ quantification), B=localized on MSI and SEEG for a part of the IZ or a structure involved in the EZ (without the maximal value 1), C=localized on MSI and not SEEG, D=localized on SEEG and not MSI, E=localized on MSI and SEEG, discordant for site. Five PCE cases were characterized by focal IZ, nine by distributed IZ between several distant brain areas. MSI allowed to determinate IZ in 4/5 focal IZ cases. In case of distributed IZ, levels of concordance were A (2 cases), B (4 cases) and D (3 cases). In most distributed cases, MSI allowed to localize only a part of the IZ. Medial temporal involvement in the IZ was frequent (9/12 cases) and not evidenced by MSI. The brain area that demonstrated the maximal value of EI was shown by MSI in four out of five (80%) focal IZ cases, in two out of nine (22%) distributed cases. MSI results depend on IZ characteristics. A distributed IZ organization presents difficulties for MSI and highlights the need for further methodological approaches.

Gamma Knife Radiosurgery of Paracentral Epilepsy

Background: In pharmacoresistant focal epilepsies involving the central region, risk of motor deficit generally contraindicates cortical resection. Gamma knife radiosurgery (GK) is an established treatment for mesial temporal epilepsy and epilepsy associated with hypothalamic hamartoma. Objectives: To explore the safety profile and efficacy of GK in motor cortex epilepsies. Methods: Four patients (18-31 years) with intractable focal sensorimotor epilepsy seizures arising from the paracentral lobule, demonstrated by stereoelectroencephalography, in whom conventional surgery was contraindicated because of motor deficit risk underwent GK. A marginal dose of 24 Gy was delivered to a focal zone involving the paracentral lobule. Results Volume of treatment ranged from 1.6 to 3.18 cm³ (median: 2.34). No motor deficit or other adverse effect occurred. Follow-up was available for at least 3 years (range: 36-78 months; median: 49). No complication of GK, including motor deficit, occurred. Two patients achieved an Engel class 1B outcome and 2 were unchanged. Both of the patients who improved had gradual disappearance of objective motor ictal semiology (6-12 months after GK), preceding reduced seizure frequency (12-18 months onwards). Cerebral MRI showed no change. Conclusions: GK is a potentially useful treatment for focal paracentral epilepsies where conventional surgery would carry an unacceptable risk of motor deficit.

Paediatric epilepsy surgery in the posterior cortex: a study of 62 cases.

Past surgical series have emphasized the diagnostic complexity of posterior cortex epilepsy. Available data are sparse, especially in children, and most published series report a high number of surgical failures and post-operative neurological deficits. In this article, we present a paediatric cohort of 62 children who underwent surgery for drug resistant posterior cortex epilepsy before the age of 16 years with a mean post-operative follow-up of 6.94 years (range: 2-16). Mean age at epilepsy onset was 3.2 years and 28 children (45%) had onset before 1 year of age. The mean age at surgery was 7.9 years (range: 1-16). Daily seizures were present in 63% of children. MRI was positive in 58 cases (93.5%) and invasive stereo-EEG was judged mandatory in 24/62 (39%) of patients. Surgery was confined to the parietal lobe in 11 children, the occipital lobe in 8, the occipito-parietal region in four, the occipito-temporal region in 18, and involved both the temporal and parietal lobes in the remaining 21. Following surgery, 53 subjects (85.5%) remained seizure-free and among those who underwent a SEEG procedure, 75% achieved seizure freedom. Focal cortical dysplasia was the most frequent histopathological diagnosis (50%), followed by tumoural (24%) and gliotic lesions (14.5%). An older age at epilepsy onset, the presence of a rather restricted epileptogenic area, and a complete resection of the epileptogenic zone were predictive of a favourable surgical outcome. These results demonstrate that a good surgical outcome is possible in children with drug resistant posterior cortex epilepsy. Accurate analysis of the chronology of ictal semiology and electrophysiological features, viewed in the context of the complete electroclinical pattern, provides a topographical orientation for posterior cortex epilepsy and, together with the presence of a lesion detectable on imaging, may improve the rate of surgical success of posterior cortex epilepsy at paediatric age.

GAMMA KNIFE RADIOSURGICAL TREATMENT OF MOTOR CORTEX EPILEPSY

In pharmacoresistant focal epilepsies involving primary motor cortex, risk of motor deficit generally contraindicates cortical resection. Gamma knife radiosurgery (GK) is an established treatment for certain focal epilepsies, notably mesial...

Intraoperative Motor Cortex Functional Localization Based on ECoG Detecting Techniques

It is a big problem how to finish intraoperative functional localization precisely, rapidly and no-invasively during neurosurgery operations. Previous researchs shown that the SCP (slow cortical potential) is a specific ECoG (electrocorticography) rhythm in the cortical motor areas. A real limb movement induced ERP(event-related potential) of SCP in the motor cortex. In this study, based on ERP of SCP phenomenon, wavelet analysis and SVM (support vector machine) were used to extract and classify the ERP of SCP feature, an algorithms for classification of the ERP in the motor regions utilizing experimental data was designed and verified. Then the results of classification were used to mapping the boundary curve of motor cortex functional areas. Results demonstrated that the accuracy of localization detection was 93.75% , the degree of accuracy was less than 5 mm, with an operation time of 2 minutes, avoiding the problems of cerebral cortex injury and epilepsy onset. The cerebral motor cortex functional localization based on SCP in ECoG detecting technique is accurate, safe and rapid.