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.

Is the anatomical lesion always guilty?: A case report.

During a presurgical workup, when discordant structural and electroclinical localization is identified, further evaluation with invasive EEG is often necessary. We report a 44-year-old right-handed woman without significant risk factors for epilepsy who presented at 11 years of age with focal seizures manifest as jerking of the left side of her mouth and arm with frequent evolution to bilateral tonic-clonic seizures during sleep with a weekly frequency. During video-EEG monitoring, we observed interictal left fronto-central sharp waves and some independent sharp waves in the right fronto-central region. Habitual seizures were recorded and during the post-ictal state, the patient had left arm weakness for a few minutes. The ictal discharge on EEG was characterized by a bilateral fronto-central rhythmic slow activity more prevalent over the right hemisphere. MRI of the brain revealed a left precentral structural lesion. Considering the discordant structural and electroclinical information, we performed bilateral fronto-central stereo-EEG implantation and demonstrated clear right fronto-central seizure onset. Stereo-EEG-guided radiofrequency thermocoagulation was performed in the right fronto-central leads with subsequent seizure freedom for 9 months. The patient then underwent surgery (right fronto-central cortectomy), and histology revealed focal cortical dysplasia type Ia. The post-surgical outcome was Engel Ia. This case underscores the presence of a structural lesion is not sufficient to define the epileptogenic zone if not supported by clinical and EEG evidence. In such cases, an invasive investigation is typically required.

Association Between Semiology and Anatomo-functional Localization in Patients With Cingulate Epilepsy: A Cohort Study.

BACKGROUND AND OBJECTIVES: Cingulate epilepsy (CE) is a rare type of focal epilepsy that is challenging to diagnose because of the polymorphic semiology of the seizures, mimicking other types of epilepsy, and the limited utility of scalp EEG. METHODS: We selected consecutive patients with drug-resistant CE who were seizure-free after surgery, with seizure onset zone (SOZ) confirmed in the cingulate cortex (CC) by histology or stereo EEG. We analyzed subjective and objective ictal manifestations using video recordings and correlated semiology with anatomical CC subregion (anterior, anterior middle, posterior middle, and posterior) localization of SOZ. RESULTS: We analyzed 122 seizures in 57 patients. Seizures were globally characterized by complex behaviors, typically natural seeming and often accompanied by emotional components. All objective ictal variables considered (pronation of the body or arising from a lying/sitting position, tonic/dystonic posturing, hand movements, asymmetry, vocalizations, fluidity and repetitiveness of motor manifestations, awareness, and emotional and autonomic components) were differently distributed among CC subregions (p < 0.05). Along the rostro-caudal axis, fluidity and repetitiveness of movement, vocalizations, body pronation, and emotional components decreased anterior-posteriorly, whereas tonic/dystonic postures, signs of lateralization, and awareness increased. Vestibular and asymmetric somatosensory, somatosensory, and epigastric and enteroceptive/autonomic symptoms were distributed differently among CC subregions (p < 0.05). Along the rostro-caudal axis, vestibular, somatosensory, and somatosensory asymmetric symptoms increased anterior-posteriorly. DISCUSSION: CE is characterized by a spectrum of semiologic manifestations with a topographic distribution. CE semiology could indicate which cingulate sector is primarily involved.

SEEG re-exploration in a patient with complex frontal epilepsy with rapid perisylvian propagation and mixed "startle - reflex" seizures.

The SEEG International Course, organised in 2017, focused on the investigation and surgery of insulo-perisylvian epilepsies. We present one representative complex case that was discussed. The patient had seizures displaying startle/reflex components. He was MRI negative, while other non-invasive investigations offered only partially concordant data. Initial SEEG exploration resulted in an incomplete definition of the epileptogenic zone. A second SEEG followed, which led to a thorough assessment of the seizure onset zone and the epileptic network, localised to the lateral inferior premotor cortex, explaining the incongruent data obtained beforehand. This was the basis of a tailored resection with a favourable outcome. The patient has been seizure-free for five years without any motor nor cognitive deficits, but with pharmacodependence to one AED. The electroclinical reasoning is presented, accompanied by relevant commentaries and recommendations from the tutors [Published with video sequences].

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.

Clinical features of sleep-related hypermotor epilepsy in relation to the seizure-onset zone: A review of 135 surgically treated cases.

OBJECTIVES: Sleep-related hypermotor epilepsy (SHE), formerly nocturnal frontal lobe epilepsy, is characterized by abrupt and typically sleep-related seizures with motor patterns of variable complexity and duration. They seizures arise more frequently in the frontal lobe than in the extrafrontal regions but identifying the seizure onset-zone (SOZ) may be challenging. In this study, we aimed to describe the clinical features of both frontal and extrafrontal SHE, focusing on ictal semiologic patterns in order to increase diagnostic accuracy. METHODS: We retrospectively analyzed the clinical features of patients with drug-resistant SHE seen in our center for epilepsy surgery. Patients were divided into frontal and extrafrontal SHE (temporal, operculoinsular, and posterior SHE). We classified seizure semiology according to four semiology patterns (SPs): elementary motor signs (SP1), unnatural hypermotor movements (SP2), integrated hypermotor movements (SP3), and gestural behaviors with high emotional content (SP4). Early nonmotor manifestations were also assessed. RESULTS: Our case series consisted of 91 frontal SHE and 44 extrafrontal SHE cases. Frontal and extrafrontal SHE shared many features such as young age at onset, high seizure-frequency rate, high rate of scalp electroencephalography (EEG) and magnetic resonance imaging (MRI) abnormalities, similar histopathologic substrates, and good postsurgical outcome. Within the frontal lobe, SPs were organized in a posteroanterior gradient (SP1-4) with respect to the SOZ. In temporal SHE, SP1 was rare and SP3-4 frequent, whereas in operculoinsular and posterior SHE, SP4 was absent. Nonmotor manifestations were frequent (70%) and some could provide valuable localizing information. SIGNIFICANCE: Our study shows that the presence of certain SP and nonmotor manifestations may provide helpful information to localize seizure onset in patients with SHE.

Experience-based SEEG planning: from retrospective data to automated electrode trajectories suggestions.

StereoElectroEncephaloGraphy (SEEG) is a minimally invasive technique that consists of the insertion of multiple intracranial electrodes to precisely identify the epileptogenic focus. The planning of electrode trajectories is a cumbersome and time-consuming task. Current approaches to support the planning focus on electrode trajectory optimisation based on geometrical constraints but are not helpful to produce an initial electrode set to begin with the planning procedure. In this work, the authors propose a methodology that analyses retrospective planning data and builds a set of average trajectories, representing the practice of a clinical centre, which can be mapped to a new patient to initialise planning procedure. They collected and analysed the data from 75 anonymised patients, obtaining 30 exploratory patterns and 61 mean trajectories in an average brain space. A preliminary validation on a test set showed that they were able to correctly map 90% of those trajectories and, after optimisation, they have comparable or better values than manual trajectories in terms of distance from vessels and insertion angle. Finally, by detecting and analysing similar plans, they were able to identify eight planning strategies, which represent the main tailored sets of trajectories that neurosurgeons used to deal with the different patient cases.

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.

A new tool for touch-free patient registration for robot-assisted intracranial surgery: application accuracy from a phantom study and a retrospective surgical series.

OBJECTIVE The purpose of this study was to compare the accuracy of Neurolocate frameless registration system and frame-based registration for robotic stereoelectroencephalography (SEEG). METHODS The authors performed a 40-trajectory phantom laboratory study and a 127-trajectory retrospective analysis of a surgical series. The laboratory study was aimed at testing the noninferiority of the Neurolocate system. The analysis of the surgical series compared Neurolocate-based SEEG implantations with a frame-based historical control group. RESULTS The mean localization errors (LE) ± standard deviations (SD) for Neurolocate-based and frame-based trajectories were 0.67 ± 0.29 mm and 0.76 ± 0.34 mm, respectively, in the phantom study (p = 0.35). The median entry point LE was 0.59 mm (interquartile range [IQR] 0.25-0.88 mm) for Neurolocate-registration-based trajectories and 0.78 mm (IQR 0.49-1.08 mm) for frame-registration-based trajectories (p = 0.00002) in the clinical study. The median target point LE was 1.49 mm (IQR 1.06-2.4 mm) for Neurolocate-registration-based trajectories and 1.77 mm (IQR 1.25-2.5 mm) for frame-registration-based trajectories in the clinical study. All the surgical procedures were successful and uneventful. CONCLUSIONS The results of the phantom study demonstrate the noninferiority of Neurolocate frameless registration. The results of the retrospective surgical series analysis suggest that Neurolocate-based procedures can be more accurate than the frame-based ones. The safety profile of Neurolocate-based registration should be similar to that of frame-based registration. The Neurolocate system is comfortable, noninvasive, easy to use, and potentially faster than other registration devices.

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.

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.

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.

Surgical treatment of polymicrogyria-related epilepsy.

OBJECTIVE: The role of resective surgery in the treatment of polymicrogyria (PMG)-related focal epilepsy is uncertain. Our aim was to retrospectively evaluate the seizure outcome in a consecutive series of patients with PMG-related epilepsy who received, or did not receive, surgical treatment, and to outline the clinical characteristics of patients who underwent surgery. METHODS: We evaluated 64 patients with epilepsy associated with magnetic resonance imaging (MRI)-documented PMG. After presurgical evaluation, 32 patients were excluded from surgical treatment and 32 were offered surgery, which was declined by 8 patients. Seizure outcome was assessed in the 40 nonsurgical and 24 surgical patients. RESULTS: Of 40 nonsurgical patients, 8 (20%) were seizure-free after a mean follow-up of 91.7 ± (standard deviation) 59.5 months. None of the eight patients who declined surgical treatment was seizure-free (mean follow-up: 74.3 ± 60.6 months). These seizure outcomes differ significantly (p = 0.000005 and p = 0.0003, respectively) from that of the 24 surgical patients, 18 of whom (66.7%) were Engel's class I postoperatively (mean follow-up: 66.5 ± 54.0 months). Of the eight patients excluded from surgery for seizure control at first visit, two had seizure recurrence at last contact. At last contact, antiepileptic drugs (AEDs) had been withdrawn in 6 of 24 surgical and in one of 40 nonsurgical cases (p = 0.0092). SIGNIFICANCE: The present study indicates that, at least in a subset of adequately selected patients with PMG-related epilepsy, surgery may provide excellent seizure outcomes. Furthermore, it suggests that surgery is superior to AEDs for achieving seizure freedom in these cases.

Risk factors for postoperative depression: A retrospective analysis of 248 subjects operated on for drug-resistant epilepsy.

The aim of this retrospective case series analysis was to identify the predictors of postoperative depression (PostOp-D) in a sample of 248 subjects with focal drug-resistant focal epilepsy. The presence or absence of PostOp-D during a 12-month follow-up period was the outcome variable. Demographic, neurologic, psychiatric characteristics, and antiepileptic therapy were the explanatory variables. After preliminary bivariate analysis, a multivariate logistic regression model was fitted to identify variables associated with PostOp-D. Sixty-seven patients (27%) experienced PostOp-D. At multivariate analysis, lifetime depression, age at surgery, and levetiracetam (LEV) are positive predictors of PostOp-D; carbamazepine (CBZ) and anxiety disorders are protective factors. LEV increases the risk for PostOp-D by about half; the relative risk (RR) is 1.48. Conversely, CBZ decreases the risk for PostOp-D by about half (RR 0.59). Our results suggest that careful psychiatric evaluation and follow-up should be recommended for subjects at risk. It is advisable to treat patients with depression before surgery. Antiepileptic drugs should be selected carefully when patients present with not modifiable risk factors, such as positive personal history for depression.

Stereoelectroencephalography-guided radiofrequency thermocoagulation in the epileptogenic zone: a retrospective study on 89 cases.

OBJECT: Radiofrequency thermocoagulation (RF-TC) of presumed epileptogenic lesions and/or structures has gained new popularity as a treatment option for drug-resistant focal epilepsy, mainly in patients with mesial temporal lobe epilepsy. The role of this minimally invasive procedure in more complex cases of drug-resistant epilepsy, which may require intracranial electroencephalographic evaluation, has not been fully assessed. This retrospective study reports on a case series of patients with particularly complex focal epilepsy who underwent stereoelectroencephalography (SEEG) evaluation with stereotactically implanted multicontact intracerebral electrodes for the detailed identification of the epileptogenic zone (EZ) and who received RF-TC in their supposed EZ (according to SEEG findings). METHODS: Eighty-nine patients (49 male and 40 female; age range 2-49 years) who underwent SEEG evaluation and subsequent RF-TC of the presumed EZ at the authors' institution between January 2008 and December 2013 were selected. Brain MRI revealed structural abnormalities in 43 cases and no lesions in 46 cases. After SEEG, 67 patients were judged suitable for resective surgery (Group 1), whereas surgery was excluded for 22 patients (Group 2). Thermocoagulation was performed in each of these patients by using the previously implanted multicontact recording electrodes and delivering RF-generated currents to adjacent electrode contacts. RESULTS: The mean number of TC sites per patient was 10.6 ± 7.2 (range 1-33). Sustained seizure freedom occurred after TC in 16 patients (18.0%) (13 in Group 1 and 3 in Group 2). A sustained worthwhile improvement was reported by 9 additional patients (10.1%) (3 in Group 1 and 6 in Group 2). As a whole, 25 patients (28.1%) exhibited a persistent significant improvement in their seizures. More favorable results were observed in patients with nodular heterotopy (p = 0.0001389), those with a lesion found on MRI (not significant), and those with hippocampal sclerosis (not significant). Other variables significantly correlated to seizure freedom were the patient's age (p = 0.02885) and number of intralesional TC sites (p = 0.0271). The patients in Group 1 who did not benefit at all (21 patients) or who experienced only a transient benefit (30 patients) from TC underwent microsurgical resection of their EZ. Thermocoagulation was followed by severe permanent neurological deficits in 2 patients (an unexpected complex neuropsychological syndrome in one patient and an expected and anticipated permanent motor deficit in the other). CONCLUSIONS: This study provides evidence that SEEG-guided TC in the EZ may be a treatment option for particularly complex drug-resistant focal epilepsy that requires invasive evaluation. A small subset of patients who achieve seizure freedom or worthwhile improvement may avoid open surgery or take advantage of an otherwise unexpected treatment if resection is not an option. Patients with epileptogenic nodular heterotopy are probably ideal candidates for this treatment.

Cerebral Angiography for Multimodal Surgical Planning in Epilepsy Surgery: Description of a New Three-Dimensional Technique and Literature Review.

OBJECTIVE: Cerebrovascular imaging is critical for safe and accurate planning of Stereo-ElectroEncephaloGraphy (SEEG) electrode trajectory. We developed a new technique for Cone Beam Computed Tomography (CBCT) Three-Dimensional Digital Subtraction Angiography (3D DSA). METHODS: The workflow core is the acquisition of computed tomography datasets without (bone mask) and with selective injection of contrast medium in the main brain-feeding arteries, followed by dataset registration and subtraction. The images were acquired with the O-armTM 1000 System (Medtronic). Images were postprocessed with FSL software package. We retrospectively analyzed 191 3D DSA procedures and qualitatively analyzed the quality of each 3D DSA dataset. RESULTS: The quality of 3D DSA was good in 150 procedures, sufficient in 37, and poor in 4. 3D rendering of the vascular tree was helpful for both SEEG implantation and resective surgery planning. Angiography complications occurred in only one procedure that was aborted due to a major allergic reaction to contrast medium. No other complications directly related to 3D DSA occurred. Minor intracerebral hemorrhage occurred in 2/191 patients after SEEG implantation, with no permanent sequelae. CONCLUSIONS: CBCT 3D DSA is a safe diagnostic procedure for SEEG electrode trajectory planning and for 3D reconstructions of the vascular tree in multimodal scenes for resections. The high fidelity and geometric accuracy contribute to the safety of electrode implantation.

Drug-resistant parietal epilepsy: polymorphic ictal semiology does not preclude good post-surgical outcome.

We investigated the anatomo-electro-clinical features and clinical outcome of surgical resections strictly confined to the parietal lobe in 40 consecutive patients who received surgery for pharmacoresistant seizures. The population was subcategorized into a paediatric (11 subjects; mean age at surgery: 7.2+/-3.7 years) and an adult group (29 patients; mean age at surgery: 30+/-10.8 years). The paediatric group more frequently exhibited personal antecedents, neurological impairment, high seizure frequency, and dysplastic lesions. Nonetheless, compared with adults, children had better outcome and more frequently reached definitive drug discontinuation after surgery. After a mean follow-up of 9.4 years (range: 3.1-16.7), 30 subjects (75%) were classified as Engel Class I. The presence of multiple types of aura in the same patient, as well as a high incidence of secondary generalization, represented a characteristic feature of parietal seizures and did not correlate negatively with surgical outcome. A total resection of the epileptogenic zone and a localizing/regional interictal EEG were statistically significant predictive factors of outcome. Intracerebral investigation, performed in 55% of cases, contributed to complete tailored resections of the epileptogenic area and determination of prognosis. Frequent subjective manifestations of parietal lobe seizures, such as vertiginous, cephalic and visual-moving sensations, underscore their potential misdiagnosis as non-epileptic events.

Validation of FreeSurfer-estimated brain cortical thickness: comparison with histologic measurements.

FreeSurfer software package automatically estimates the cerebral cortical thickness. Its use is widely accepted, albeit this tool was validated against histologic measurements in only two post-mortem isolated brain MR scans. Indeed, a comparison between histologic measurements and FreeSurfer estimation from in vivo data was never performed. At the "Claudio Munari" Center for Epilepsy and Parkinson Surgery we have included FreeSurfer in our presurgical workflow since 2008, mainly because the automatic reconstruction of the brain surface is useful for carefully planning the surgical resection. We therefore compared cortical thickness values obtained by the automatic software pipeline with manual histologic measurements performed on 27 histologic specimens resected from the corresponding brain regions of the same epileptic subjects. This method-comparison study, including Passing-Bablok regression and Bland-Altman plot analysis, showed a good agreement between FreeSurfer estimation and histologic measurements of cortical thickness. The mean cortical thickness values (±Standard Deviation) obtained with FreeSurfer and histologic measurements were 3.65 mm ± 0.44 and 3.72 mm ± 0.36, respectively (P value = 0.32). Our findings strengthen previous reports on cortical thickness changes as biomarkers of different neurological conditions.