Neurological morbidity of surgery for suprasylvian operculoinsular epilepsy.

OBJECTIVE: The objective of this study was to identify risk factors associated with surgery-related neurological morbidity in patients with drug-resistant epilepsy undergoing suprasylvian operculoinsular resections. As secondary outcomes, we also analyzed the risk factors for ischemic lesion (IL) of corona radiata and seizure recurrence. METHODS: A retrospective analysis was conducted on a cohort of patients who underwent suprasylvian operculoinsular resections for drug-resistant epilepsy. The association of several presurgical, surgical, and postsurgical factors with both primary (persistent neurological deficits) and secondary (structural abnormalities on postoperative magnetic resonance imaging [MRI] and seizure recurrence) postoperative outcomes was investigated with univariate and multivariate statistical analysis. RESULTS: The study included a total of 65 patients; 46.2% of patients exhibited postoperative neurological deficits, but only 12.3% experienced persistent deficits. On postoperative MRI, IL in the corona radiata and corticospinal tract Wallerian degeneration (CSTWd) were seen in 68% and 29% of cases, respectively. Only CSTWd was significantly associated with persistent neurological deficits (relative risk [RR] = 2.6). Combined operculoinsular resection (RR = 3.62) and surgery performed on the left hemisphere (RR = .37) were independently associated with IL in the corona radiata. Variables independently associated with CSTWd were the presence of malacic components in the IL (RR = 1.96), right central operculum resection (RR = 1.79), and increasing age at surgery (RR = 1.03). Sixty-two patients had a postoperative follow-up > 12 months (median = 56, interquartile range = 30.75-73.5), and 62.9% were in Engel class I at last outpatient control. The risk of seizure recurrence was reduced by selective opercular resection (RR = .25) and increased by the histological diagnosis of aspecific gliosis (RR = 1.39). SIGNIFICANCE: This study provides insights into the risk factors associated with surgery-related neurological morbidity, as well as further evidence on the postoperative occurrence of subcortical injury and seizure recurrence in epileptic patients undergoing suprasylvian operculoinsular resections. The findings highlighted in this study may be useful to better understand the processes supporting the increased surgical risk in the operculoinsular region.

Stereo-electroencephalography (SEEG)-Guided Surgery in Epilepsy With Cingulate Gyrus Involvement: Electrode Implantation Strategies and Postoperative Seizure Outcome.

SUMMARY: Surgical treatment of cingulate gyrus epilepsy is associated with good results on seizures despite its rarity and challenging aspects. Invasive EEG monitoring is often mandatory to assess the epileptogenic zone in these patients. To date, only small surgical series have been published, and a consensus about management of these complex cases did not emerge. The authors retrospectively analyzed a large surgical series of patients in whom at least part of the cingulate gyrus was confirmed as included in the epileptogenic zone by means of stereo-electroencephalography and was thus resected. One hundred twenty-seven patients were selected. Stereo-electroencephalography-guided implantation of intracerebral electrodes was performed in the right hemisphere in 62 patients (48.8%) and in the left hemisphere in 44 patients (34.7%), whereas 21 patients (16.5%) underwent bilateral implantations. The median number of implanted electrodes per patient was 13 (interquartile range 12-15). The median number of electrodes targeting the cingulate gyrus was 4 (interquartile range 3-5). The cingulate gyrus was explored bilaterally in 19 patients (15%). Complication rate was 0.8%. A favorable outcome (Engel class I) was obtained in 54.3% of patients, with a median follow-up of 60 months. The chance to obtain seizure freedom increased in cases in whom histologic diagnosis was type-IIb focal cortical dysplasia or tumor (mostly ganglioglioma or dysembryoplastic neuroepithelial tumor) and with male gender. Higher seizure frequency predicted better outcome with a trend toward significance. Our findings suggest that stereo-electroencephalography is a safe and effective methodology in achieving seizure freedom in complex cases of epilepsy with cingulate gyrus involvement.

Electrical stimulation for seizure induction during SEEG exploration: a useful predictor of postoperative seizure recurrence?

OBJECTIVE: Direct electrical stimulations of cerebral cortex are a traditional part of stereoelectroencephalography (SEEG) practice, but their value as a predictive factor for seizure outcome has never been carefully investigated. PATIENTS AND METHOD: We retrospectively analysed a cohort of 346 patients operated on for drug-resistant focal epilepsy after SEEG exploration. As potential predictors we included: aetiology, MRI data, age of onset, duration of epilepsy, age at surgery, topography of surgery and whether a seizure was induced by either low frequency electrical stimulation (LFS) or high frequency electrical stimulation. RESULTS: Of 346 patients, 63.6% had good outcome (no seizure recurrence, Engel I). Univariate analysis demonstrated significant correlation with favourable outcome (Engel I) for: aetiology, positive MRI and seizure induced by stimulation. At multivariate analysis, informative MRI, type II focal cortical dysplasia and tumour reduced the risk of seizure recurrence (SR) by 47%, 58% and 81%, respectively. Compared with the absence of induced seizures, the occurrence of ictal events after LFS significantly predicts a favourable outcome on seizures, with only 44% chance of disabling SR at last follow-up. CONCLUSION: Among the already known predictors outcome, seizure induction by LFS therefore represents a positive predictive factor for seizure outcome after surgery.

Trends in pediatric epilepsy surgery in Europe between 2008 and 2015: Country-, center-, and age-specific variation.

OBJECTIVE: To profile European trends in pediatric epilepsy surgery (<16 years of age) between 2008 and 2015. METHODS: We collected information on volumes and types of surgery, pathology, and seizure outcome from 20 recognized epilepsy surgery reference centers in 10 European countries. RESULTS: We analyzed retrospective aggregate data on 1859 operations. The proportion of surgeries significantly increased over time (P < .0001). Engel class I outcome was achieved in 69.3% of children, with no significant improvement between 2008 and 2015. The proportion of histopathological findings consistent with glial scars significantly increased between the ages of 7 and 16 years (P for trend = .0033), whereas that of the remaining pathologies did not vary across ages. A significant increase in unilobar extratemporal surgeries (P for trend = .0047) and a significant decrease in unilobar temporal surgeries (P for trend = .0030) were observed between 2008 and 2015. Conversely, the proportion of multilobar surgeries and unrevealing magnetic resonance imaging cases remained unchanged. Invasive investigations significantly increased, especially stereo-electroencephalography. We found different trends comparing centers starting their activity in the 1990s to those whose programs were developed in the past decade. Multivariate analysis revealed a significant variability of the proportion of the different pathologies and surgical approaches across countries, centers, and age groups between 2008 and 2015. SIGNIFICANCE: Between 2008 and 2015, we observed a significant increase in the volume of pediatric epilepsy surgeries, stability in the proportion of Engel class I outcomes, and a modest increment in complexity of the procedures.

Stereo-EEG ictal/interictal patterns and underlying pathologies.

PURPOSE: To define Stereo-EEG (SEEG) ictal and interictal patterns associated with different pathologies in a cohort of patients with drug-resistant focal epilepsy. METHODS: We retrospectively analyzed findings from 102 patient with epilepsy due to Polymicrogyria (PMG), Periventricular Nodular Heterotopia (PNH), Focal Cortical Dysplasia (FCD) type I, IIa, IIb and Hippocampal Sclerosis (HS). Ictal and interictal SEEG recordings were reviewed to describe Seizure Onset Zone (SEEG-SOZ) patterns and to define the Lesional and Irritative Zones. RESULTS: Five SEEG-SOZ patterns were identified: significant associations were found between low-voltage fast activity and PMG and between repetitive fast spikes bursts and FCD type IIa. A trend was found between fast activity and PNH, rhythmic sharp activity and FCD type I, repetitive fast spikes bursts and FCD type IIb, slow burst and HS. In 62 of the 102 patients, a complete surgical resection of the SEEG-SOZ was performed, and in 12 patients a partial resection was carried out to preserve eloquent areas. In 18 patients (15 with PNH) the SEEG-SOZ was thermo-coagulated. Seizure freedom was achieved in 58% of surgically treated patients and in 72% of those treated with thermocoagulation (mean ±â€¯SD follow-up 5.9 ±â€¯2.3 years). Seizure freedom after surgery was achieved in 84% of the patients with PMG, FCD I, IIa and IIb presenting with characteristic SEEG-SOZ patterns. With the exception of FCD type II, interictal activity was not sufficient to identify SEEG-SOZ boundaries. CONCLUSION: The study demonstrates that specific histopathologies correlate with particular neurophysiological patterns, reflecting lesion-specific seizure patterns in focal epilepsies.

Hand posture as localizing sign in adult focal epileptic seizures.

OBJECTIVE: The aim of this study was to identify specific ictal hand postures (HPs) as localizing signs of the epileptogenic zone (EZ) in patients with frontal or temporal lobe epilepsy. METHODS: In this study, we retrospectively analyzed ictal semiology of 489 temporal lobe or frontal lobe seizures recorded over a 6-year period at the Seizure Disorder Center at University of California, Los Angeles in the USA (45 patients) or at the C. Munari Epilepsy Surgery Center at Niguarda Hospital in Milan, Italy (34 patients). Our criterion for EZ localization was at least 2 years of seizure freedom after surgery. We analyzed presence and latency of ictal HP. We then examined whether specific initial HPs are predictive for EZ localization. RESULTS: We found that ictal HPs were present in 72.5% of patients with frontal and 54.5% of patients with temporal lobe seizures. We divided HPs into 6 classes depending on the reciprocal position of the fingers ("fist," "cup," "politician's fist," "pincer," "extended hand," "pointing"). We found a striking correlation between EZ localization and ictal HP. In particular, fist and pointing HPs are strongly predictive of frontal lobe EZ; cup, politician's fist, and pincer are strongly predictive of temporal lobe EZ. INTERPRETATION: Our study offers simple ictal signs that appear to clarify differential diagnosis of temporal versus frontal lobe EZ localization. These results are meant to be used as a novel complementary tool during presurgical evaluation for epilepsy. At the same time, they give us important insight into the neurophysiology of hand movements. ANN NEUROL 2019;86:793-800.

Stereoelectroencephalography: retrospective analysis of 742 procedures in a single centre.

This retrospective description of a surgical series is aimed at reporting on indications, methodology, results on seizures, outcome predictors and complications from a 20-year stereoelectroencephalography (SEEG) activity performed at a single epilepsy surgery centre. Prospectively collected data from a consecutive series of 742 SEEG procedures carried out on 713 patients were reviewed and described. Long-term seizure outcome of SEEG-guided resections was defined as a binomial variable: absence (ILAE classes 1-2) or recurrence (ILAE classes 3-6) of disabling seizures. Predictors of seizure outcome were analysed by preliminary uni/bivariate analyses followed by multivariate logistic regression. Furthermore, results on seizures of these subjects were compared with those obtained in 1128 patients operated on after only non-invasive evaluation. Survival analyses were also carried out, limited to patients with a minimum follow-up of 10 years. Resective surgery has been indicated for 570 patients (79.9%). Two-hundred and seventy-nine of 470 patients operated on (59.4%) were free of disabling seizures at least 2 years after resective surgery. Negative magnetic resonance and post-surgical lesion remnant were significant risk factors for seizure recurrence, while type II focal cortical dysplasia, balloon cells, glioneuronal tumours, hippocampal sclerosis, older age at epilepsy onset and periventricular nodular heterotopy were significantly associated with seizure freedom. Twenty-five of 153 patients who underwent radio-frequency thermal coagulation (16.3%) were optimal responders. Thirteen of 742 (1.8%) procedures were complicated by unexpected events, including three (0.4%) major complications and one fatality (0.1%). In conclusion, SEEG is a safe and efficient methodology for invasive definition of the epileptogenic zone in the most challenging patients. Despite the progressive increase of MRI-negative cases, the proportion of seizure-free patients did not decrease throughout the years.

Tailored multilobar disconnective epilepsy surgery in the posterior quadrant.

OBJECTIVE: Surgical treatment of drug-resistant epilepsy originating from the posterior quadrant (PQ) of the brain often requires large multilobar resections, and disconnective techniques have been advocated to limit the risks associated with extensive tissue removal. Few previous studies have described a tailored temporoparietooccipital (TPO) disconnective approach; only small series with short postoperative follow-ups have been reported. The aim of the present study was to present a tailored approach to multilobar PQ disconnections (MPQDs) for epilepsy and to provide details about selection of patients, presurgical investigations, surgical technique, treatment safety profile, and seizure and cognitive outcome in a large, single-center series of patients with a long-term follow-up. METHODS: In this retrospective longitudinal study, the authors searched their prospectively collected database for patients who underwent MPQD for drug-resistant epilepsy in the period of 2005-2017. Tailored MPQDs were a posteriori grouped as follows: type I (classic full TPO disconnection), type II (partial TPO disconnection), type III (full temporooccipital [TO] disconnection), and type IV (partial TO disconnection), according to the disconnection plane in the occipitoparietal area. A bivariate statistical analysis was carried out to identify possible predictors of seizure outcome (Engel class I vs classes II-IV) among several presurgical, surgical, and postsurgical variables. Preoperative and postoperative cognitive profiles were also collected and evaluated. RESULTS: Forty-two consecutive patients (29 males, 24 children) met the inclusion criteria. According to the presurgical evaluation (including stereo-electroencephalography in 13 cases), 12 (28.6%), 24 (57.1%), 2 (4.8%), and 4 (9.5%) patients received a type I, II, III, or IV MPQD, respectively. After a mean follow-up of 80.6 months, 76.2% patients were in Engel class I at last contact; at 6 months and 2 and 5 years postoperatively, Engel class I was recorded in 80.9%, 74.5%, and 73.5% of cases, respectively. Factors significantly associated with seizure freedom were the occipital pattern of seizure semiology and the absence of bilateral interictal epileptiform abnormalities at the EEG (p = 0.02). Severe complications occurred in 4.8% of the patients. The available neuropsychological data revealed postsurgical improvement in verbal domains, whereas nonunivocal outcomes were recorded in the other functions. CONCLUSIONS: The presented data indicate that the use of careful anatomo-electro-clinical criteria in the presurgical evaluation allows for customizing the extent of surgical disconnections in PQ epilepsies, with excellent results on seizures and an acceptable safety profile.

Surgery in patients with childhood-onset epilepsy: analysis of complications and predictive risk factors for a severely complicated course.

OBJECT: To compare the occurrence of surgery-related complications in patients with childhood-onset focal epilepsy operated on in the paediatric or in the adult age. To investigate risk factors for surgery-related complications in the whole cohort, with special attention to age at surgery and severe morbidity. METHODS: A cohort of 1282 patients operated on for childhood-onset focal epilepsy was retrospectively analysed. Occurrence of surgery-related complications, including a severely complicated course (SCC: surgical complication requiring reoperation and/or permanent neurological deficit and/or death), was compared between patients operated on in the paediatric age (<16 year-old; 452 cases) and, respectively, in adulthood (≥16 year-old; 830 cases). The whole cohort of patients was also evaluated for risk factors for a SCC. RESULTS: At last contact (median follow-up 98 months), 74.5% of patients were in Engel's class I (78.0% of children and 73.0% of adults). One hundred patients (7.8%) presented a SCC (6.4% for children and 8.6% for adult patients). Postoperative intracranial haemorrhages occurred more frequently in adult cases. At multivariate analysis, increasing age at operation, multilobar surgery, resections in the rolandic/perirolandic and in insulo-opercular regions were independent risk factors for a SCC. CONCLUSIONS: Surgery for childhood-onset focal epilepsy provides excellent results on seizures and an acceptable safety profile at any age. Nevertheless, our results suggest that increasing age at surgery is associated with an increase in odds of developing severe surgery-related complications. These findings support the recommendation that children with drug-resistant, symptomatic (or presumed symptomatic) focal epilepsy should be referred for a surgical evaluation as early as possible after seizure onset.

Corpus callosum atrophy and post-surgical seizures in temporal lobe epilepsy associated with hippocampal sclerosis.

OBJECTIVE: Our aim in this retrospective study was to explore whether corpus callosum atrophy could predict the post-surgical seizure control in patients with temporal lobe epilepsy associated with Hippocampal Sclerosis (HS). METHODS: We used the Corpus Callosum Index (CCI) obtained from best mid-sagittal T2/FLAIR or T1-weighted MRI at two time-points, more than one year apart. CCI has been mainly used in Multiple Sclerosis (MS), but not in epilepsy, so we tested the validity of our results performing a proof of concept cohort, incorporating MS patients with and without epilepsy. Then, we explored this measurement in a well-characterized and long-term cohort of patients with temporal lobe epilepsy associated with HS. RESULTS: In the proof of concept cohort (MS without epilepsy n:40, and MS with epilepsy, n:15), we found a larger CCI atrophy rate in MS patients with poor epilepsy control vs. MS without epilepsy (p:0.01). Then, in HS patients (n:74), annualized CCI atrophy rate was correlated with the long-term Engel scale (Rho:0.31, p:0.007). In patients with post-surgical seizure recurrence, a larger CCI atrophy rate was found one year before any seizure relapse. Univariate analysis showed an increased risk of seizure recurrence in males, higher pre-surgical seizure frequency, necessity of invasive EEG monitoring, and higher CCI atrophy rate. Two of these variables were independent predictors in the multivariate analysis, male gender (HR:4.87, p:0.002) and CCI atrophy rate (HR:1.21, p:0.001). CONCLUSION: We demonstrated that atrophy of the corpus callosum, using the CCI, is related with poor seizure control in two different neurological disorders presenting with epilepsy, which might suggest that corpus callosum atrophy obtained in early post-surgical follow-up, could be a biomarker for predicting recurrences and guiding treatment plans.

Histopathological Findings in Brain Tissue Obtained during Epilepsy Surgery.

BACKGROUND: Detailed neuropathological information on the structural brain lesions underlying seizures is valuable for understanding drug-resistant focal epilepsy. METHODS: We report the diagnoses made on the basis of resected brain specimens from 9523 patients who underwent epilepsy surgery for drug-resistant seizures in 36 centers from 12 European countries over 25 years. Histopathological diagnoses were determined through examination of the specimens in local hospitals (41%) or at the German Neuropathology Reference Center for Epilepsy Surgery (59%). RESULTS: The onset of seizures occurred before 18 years of age in 75.9% of patients overall, and 72.5% of the patients underwent surgery as adults. The mean duration of epilepsy before surgical resection was 20.1 years among adults and 5.3 years among children. The temporal lobe was involved in 71.9% of operations. There were 36 histopathological diagnoses in seven major disease categories. The most common categories were hippocampal sclerosis, found in 36.4% of the patients (88.7% of cases were in adults), tumors (mainly ganglioglioma) in 23.6%, and malformations of cortical development in 19.8% (focal cortical dysplasia was the most common type, 52.7% of cases of which were in children). No histopathological diagnosis could be established for 7.7% of the patients. CONCLUSIONS: In patients with drug-resistant focal epilepsy requiring surgery, hippocampal sclerosis was the most common histopathological diagnosis among adults, and focal cortical dysplasia was the most common diagnosis among children. Tumors were the second most common lesion in both groups. (Funded by the European Union and others.).

Increasing volume and complexity of pediatric epilepsy surgery with stable seizure outcome between 2008 and 2014: A nationwide multicenter study.

OBJECTIVE: The objective of the study was to assess common practice in pediatric epilepsy surgery in Italy between 2008 and 2014. METHODS: A survey was conducted among nine Italian epilepsy surgery centers to collect information on presurgical and postsurgical evaluation protocols, volumes and types of surgical interventions, and etiologies and seizure outcomes in pediatric epilepsy surgery between 2008 and 2014. RESULTS: Retrospective data on 527 surgical procedures were collected. The most frequent surgical approaches were temporal lobe resections and disconnections (133, 25.2%) and extratemporal lesionectomies (128, 24.3%); the most frequent etiologies were FCD II (107, 20.3%) and glioneuronal tumors (105, 19.9%). Volumes of surgeries increased over time independently from the age at surgery and the epilepsy surgery center. Engel class I was achieved in 73.6% of patients (range: 54.8 to 91.7%), with no significant changes between 2008 and 2014. Univariate analyses showed a decrease in the proportion of temporal resections and tumors and an increase in the proportion of FCDII, while multivariate analyses revealed an increase in the proportion of extratemporal surgeries over time. A higher proportion of temporal surgeries and tumors and a lower proportion of extratemporal and multilobar surgeries and of FCD were observed in low (<50surgeries/year) versus high-volume centers. There was a high variability across centers concerning pre- and postsurgical evaluation protocols, depending on local expertise and facilities. SIGNIFICANCE: This survey reveals an increase in volume and complexity of pediatric epilepsy surgery in Italy between 2008 and 2014, associated with a stable seizure outcome.

Epilepsy surgery of "low grade epilepsy associated neuroepithelial tumors": A retrospective nationwide Italian study.

OBJECTIVE: To analyze the attitude and results of Italian epilepsy surgery centers in the surgical management of "low grade epilepsy associated neuroepithelial tumors" (LEATs). METHODS: We conducted a retrospective study enrolling 339 consecutive patients with LEATs who underwent surgery between January 2009 and June 2015 at eight Italian epilepsy surgery centers. We compared demographic, clinical, pathologic, and surgical features of patients with favorable (Engel class I) and unfavorable (Engel class II, III, and IV) seizure outcome. In addition, we compared patients with tumor-associated focal cortical dysplasia (FCD) and patients with solitary tumors to identify factors correlated with FCD diagnosis. RESULTS: Fifty-five (98.2%) of 56 patients with medically controlled epilepsy were seizure-free after surgery, compared to 249 (88.0%) of 283 patients with refractory epilepsy. At multivariate analysis, three variables independently predict unfavorable seizure outcome in the drug-resistant group. Age at surgery is largely the most significant (p = 0.001), with an odds ratio (OR) of 1.04. This means that the probability of seizure recurrence grows by 4% for every waited year. The resection site is also significant (p = 0.039), with a relative risk (RR) of 1.99 for extratemporal tumors. Finally, the completeness of tumor resection has a trend toward significance (p = 0.092), with an RR of 1.82 for incomplete resection. Among pediatric patients, a longer duration of epilepsy was significantly associated with preoperative neuropsychological deficits (p < 0.001). A statistically significant association was observed between FCD diagnosis and the following variables: tailored surgery (p < 0.001), temporal resection (p = 0.001), and surgical center (p = 0.012). SIGNIFICANCE: Our nationwide LEATs study gives important insights on factors predicting seizure outcome in refractory epilepsy and determining variability in FCD detection. Timely surgery, regardless of pharmacoresistance and oriented to optimize epileptologic, neuropsychological, and oncologic outcomes should be warranted.

Correlating Interictal Spikes with Sigma and Delta Dynamics during Non-Rapid-Eye-Movement-Sleep.

Interictal spikes (IS) are one of the major hallmarks of epilepsy. Understanding the factors promoting or suppressing IS would increase our comprehension of epilepsy and possibly open new avenues for therapy. Sleep strongly influences epileptic activity, and the modulatory effects of the different sleep stages on IS have been studied for decades. However, several aspects are still disputed, in particular the role of sleep spindles and slow waves in the activation of IS during Non-REM sleep. Here, we correlate the rate of IS with quantitative measures derived from stereo-EEG during one Non-REM cycle in 10 patients suffering from drug-resistant epilepsy due to type 2 focal cortical dysplasia. We show that the IS rate (ISR) is positively correlated with sigma power (a surrogate for sleep-spindle density) but negatively correlated with delta power (surrogate for slow wave activity). In addition, we present two new indices for quantifying the spatial and temporal instability of sleep. We found that both instability indices are correlated with a high ISR. The main contribution of this study is to confirm the suppressive effect of stable deep sleep on IS. This result might influence future guidelines for therapy of patients suffering from epilepsy and sleep disorders.

Epilepsy surgery in patients older than 50 years: Effectiveness, safety, and predictors of outcome.

PURPOSE: Surgery is an effective treatment for drug resistant focal epilepsy. Predictors of seizure outcome have been extensively addressed in the general population but similar data on older patients are still lacking. The aim of this study is to evaluate effectiveness and safety of surgery for patients over 50 years and to investigate variables associated to seizure outcome. METHODS: We performed a single center retrospective study including 50 patients over 50 years treated surgically for drug resistant focal epilepsy between 1997 and 2014. We analyzed the rate of success of seizure control, the association of several clinical variables with seizure outcome and the rate of surgery-related complications. We also investigated the impact of surgery on the patients' cognitive performances and mood profile. RESULTS: At last follow-up 78% of our patients were seizure-free, similar to patients younger than 50 years operated on in the same period (p=1). The rate of surgery-related complications was 10%, higher compared to younger patients (p<0.0001). Pre-surgical daily seizure frequency (p=0.0040) and the histological diagnosis of LEAT (p=0.0233) were associated to a poorer seizure outcome. No significant differences were evidenced between pre- and postoperative neuropsychological profiles. A slight, not statistically significant improvement of the mood profile was observed postoperatively. CONCLUSION: Our results suggest that surgery is an effective treatment option also for older epileptic patients, although it is burdened by a higher surgical risk as compared to younger patients. The availability of predictors of outcome also for these patients may be helpful for pre-surgical counseling.

Stereo-EEG-guided radiofrequency thermocoagulations.

The rationale and the surgical technique of stereo-electroencephalography (SEEG)-guided radiofrequency thermocoagulation (RF-TC) in the epileptogenic zone (EZ) of patients with difficult-to-treat focal epilepsy are described in this article. The application of the technique in pediatric patients is also detailed. Stereotactic ablative procedures by RF-TC have been employed in the treatment of epilepsy since the middle of the last century. This treatment option has gained new popularity in recent decades, mainly because of the availability of modern imaging techniques, which allow accurate targeting of intracerebral epileptogenic structures. SEEG is a powerful tool for identifying the EZ in the most challenging cases of focal epilepsy by recording electrical activity with tailored stereotactic implantation of multilead intracerebral electrodes. The same recording electrodes may be used to place thermocoagulative lesions in the EZ, following the indications provided by intracerebral monitoring. The technical details of SEEG implantation and of SEEG-guided RF-TC are described herein, with special attention to the employment of the procedure in pediatric cases. SEEG-guided RF-TC offers a potential therapeutic option based on robust electroclinical evidence with acceptable risks and costs. The procedure may be performed in patients who, according to SEEG recording, are not eligible for resective surgery, and it may be an alternative to resective surgery in a small subset of operable patients.

Mesial Extratemporal Lobe Epilepsy: Clinical Features and Surgical Strategies.

Background: Extratemporal lobe epilepsy surgery remains a diagnostic and therapeutic challenge. Scalp electroencephalography (EEG) correlates, clinical semiology, and imaging findings are often ambiguous or difficult to interpret, necessitating the need for invasive recordings. This is particularly true for those extratemporal lobe epilepsy cases in which seizures develop from the midline. Objective: The aim of this study was to examine the clinical features and surgical strategies in mesial extratemporal lobe epilepsy. Methods: A retrospective study reviewing clinical and surgical characteristics was conducted in 30 patients who underwent epilepsy surgery in mesial extratemporal areas at our institution between 1991 and 2011. Results: Although the location of the epileptogenic zone was associated with specific seizure types, semiology proved to be heterogeneous. Although scalp EEG was of good lateralizing value, it was poor for localizing the epileptogenic zone, necessitating a frequent need for invasive electroencephalographic recordings. Conclusion: Surgical resections in mesial extratemporal regions were found to be safe and resulted in satisfactory seizure outcomes.

SUrface-PRojected FLuid-Attenuation-Inversion-Recovery Analysis: A Novel Tool for Advanced Imaging of Epilepsy.

OBJECTIVE: The objective of this pilot retrospective study is to describe the SUrface-PRojected FLuid-Attenuation-Inversion-Recovery (SUPR-FLAIR) analysis, a novel method mainly aimed at revealing cortical areas with subtle signal hyperintensity. METHODS: Images from 101 healthy controls and 10 patients suffering from drug-resistant partial epilepsy were retrospectively postprocessed. The brain surface was reconstructed from a 3-dimensional (3D) T1-weighted fast field echo (T1W-FFE) magnetic resonance imaging (MRI) scan. A turbo spin echo fluid attenuated inversion recovery axial scan was registered to the 3D T1W-FFE scan, and its intensity values were normalized. The cortical intensity signal was projected onto the brain surface, and surface-based analysis was performed, comparing each patient against the 101 controls. The localizations of the first positive lower P value cluster (PLPC) peak and the resection zone (RZ) were compared. We studied 5 patients with focal cortical dysplasia (3 of them with negative MRI) and 5 with hippocampal sclerosis. RESULTS: SUPR-FLAIR analysis localized the first PLPC peak in the RZ in all cases. Because all patients have been seizure free since surgery, it can be assumed that the epileptogenic zone (EZ) was included in the RZ. Therefore, SUPR-FLAIR analysis correctly aligned with the EZ, with 100% sensitivity. CONCLUSIONS: SUPR-FLAIR analysis is a noninvasive technique that could be helpful for the definition of the EZ, especially when MRI is negative. Its use could reduce the indications for invasive electroencephalography or could provide essential data to refine the strategy of intracerebral electrode implantation in the most challenging cases.

Implantation of Stereoelectroencephalography Electrodes: A Systematic Review.

BACKGROUND: Stereoelectroencephalography (SEEG) was developed by Talairach and Bancaud in Paris in the late 1950s. Subsequently, the Talairach methodology was adopted at a number of additional centers in Europe and Canada. Technical aspects remained essentially unchanged for the following 30 years. Only in the last two decades, because of advancements in image-guided surgery systems, robotics, and computer-aided planning, use of SEEG has become more widespread, and reports describing these new developments have been published. OBJECTIVES: This systematic review was designed to assess published reports of SEEG surgical techniques and safety profile. DATA SOURCES: An electronic search was performed of Medline, Embase, and Scopus databases. In addition, the content pages of several standard epilepsy surgery textbooks were searched. Full-text English studies describing SEEG surgical technique or pertinent epidemiological data were included. Conference abstracts, reviews, posters, editorials, comments, and letters were excluded. RESULTS: Three hundred fifty-nine of 2,903 potentially eligible studies published by 32 centers were reviewed. Thirty-one of these primarily discussed the surgical technique. Thirty-five major complications (including 4 fatalities) were reported among 4,000 patients (0.8%) implanted with 33,000 electrodes. LIMITATIONS: The number of SEEG patients is likely to be underestimated because only a few groups have exhaustively reported their experience. Moreover, it is possible that a number of teams performing SEEG have not published studies on the topic. CONCLUSIONS: Rigorous SEEG, thanks to its basic principles and updated technologies, is a safe and accurate method to define the epileptogenic zone by means of stereotactically implanted intracerebral electrodes.

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.