Surgical treatment of occipital lobe epilepsy

Endovascular treatment of dural arteriovenous fistulas involving the vein of Galen: a single-center cohort and meta-analysis

BACKGROUND

Dural arteriovenous fistulas (dAVFs) draining into the vein of Galen (VoG) are complex lesions that often necessitate treatment to minimize the risk of rupture and relieve symptoms. These lesions can be treated with open surgical resection, radiosurgery, or endovascular embolization. Unfortunately, endovascular treatment of dAVFs involving the VoG has not been robustly assessed across large patient cohorts. To meet this need, we performed a retrospective review of dAVFs involving the VoG at our center, and included these in a meta-analysis to identify the safety and efficacy of endovascular embolization, as well as describing current treatment trends for this disease.

METHODS

Consecutive patients with dAVFs involving the VoG treated at a single center were identified from a prospective database and retrospectively reviewed. A literature search was conducted with defined search criteria, and eligible studies were included alongside our cohort in a meta-analysis. Rates of complete dAVF treatment and clinical complications were pooled across studies with a random effects model and reported with a 95% CI.

RESULTS

Five dAVFs involving the VoG were treated endovascularly at our center during the study period. In this series, 80% of treatments led to complete occlusion of the fistula while no patients had clinical complications. Onyx was used for all treatments. In our meta-analysis, the overall rate of complete occlusion was 72.0% (95% CI 59.8% to 84.1%) and the overall rate of clinical complications was 10.0% (95% CI 4.7% to 15.3%).

CONCLUSIONS

Endovascular approaches for dAVFs involving the VoG are technically feasible, but carry a risk of clinical complications. Future work should identify optimal endovascular embolic agents.

Resection of bilateral occipital lobe lesions during a single operation as a treatment for bilateral occipital lobe epilepsy

BACKGROUND

Neurosurgical treatment of severe bilateral occipital lobe epilepsy usually involves two operations several mos apart.

AIM

To evaluate surgical resection of bilateral occipital lobe lesions during a single operation as a treatment for bilateral occipital lobe epilepsy.

METHODS

This retrospective case series included patients with drug-refractory bilateral occipital lobe epilepsy treated surgically between March 2006 and November 2015.

RESULTS

Preoperative evaluation included scalp video-electroencephalography (EEG), magnetic resonance imaging, and PET-CT. During surgery (bilateral occipital craniotomy), epileptic foci and important functional areas were identified by EEG (intracranial cortical electrodes) and cortical functional mapping, respectively. Patients were followed up for at least 5 years to evaluate treatment outcome (Engel grade) and visual function. The 20 patients (12 males) were aged 4-30 years (median age, 12 years). Time since onset was 3-20 years (median, 8 years), and episode frequency was 4-270/mo (median, 15/mo). Common manifestations were elementary visual hallucinations (65.0%), flashing lights (30.0%), blurred vision (20.0%) and visual field defects (20.0%). Most patients were free of disabling seizures (Engel grade I) postoperatively (18/20, 90.0%) and at 1 year (18/20, 90.0%), 3 years (17/20, 85.0%) and ≥ 5 years (17/20, 85.0%). No patients were classified Engel grade IV (no worthwhile improvement). After surgery, there was no change in visual function in 13/20 (65.0%), development of a new visual field defect in 3/20 (15.0%), and worsening of a preexisting defect in 4/20 (20.0%).

CONCLUSION

Resection of bilateral occipital lobe lesions during a single operation may be applicable in bilateral occipital lobe epilepsy.

Adult occipital lobe epilepsy: 12-years on

OBJECTIVE

Occipital lobe epilepsies (OLE) comprise 5-10% of focal epilepsies in surgical and paediatric series; with little data from adult medical cohorts. This longitudinal study examined OLE patients, to characterise prevalence, semiology, co-morbidity and prognosis in a neurology outpatient setting.

METHODS

24 adult OLE patients identified over 12 months from 1548 patients in a neurologist's service were followed over 12 years.

RESULTS

92% of these OLE patients had simple visual hallucinations, misdiagnosed in 40% of cases. 75% had co-morbid interictal migraine and 38% had visual field defects. Only 33% achieved long-term remission, and only 2 /10 (20%) of OLE patients with a structural aetiology were seizure-free. The two patients with migralepsy achieved remission.

CONCLUSION

Adult OLE accounted for 7.7% of focal epilepsies in this cohort, misdiagnosed or misclassified in 40%. Most patients had co-existing migraine. A minority had migralepsy characterised by a longer aura and good prognosis. Remission rates were lower than that of childhood OLE and general adult epilepsy populations, strengthening the argument for considering epilepsy surgery in drug-resistant OLE patients with a structural cause. Precision medicine will potentially refine diagnosis and management in those OLE patients without an identified cause but is predicated on accurate clinical phenotyping.

Surgical Outcome in Extratemporal Epilepsies Based on Multimodal Pre-Surgical Evaluation and Sequential Intraoperative Electrocorticography

Objective: to present the postsurgical outcome of extratemporal epilepsy (ExTLE) patients submitted to preoperative multimodal evaluation and intraoperative sequential electrocorticography (ECoG). Subjects and methods: thirty-four pharmaco-resistant patients with lesional and non-lesional ExTLE underwent comprehensive pre-surgical evaluation including multimodal neuroimaging such as ictal and interictal perfusion single photon emission computed tomography (SPECT) scans, subtraction of ictal and interictal SPECT co-registered with magnetic resonance imaging (SISCOM) and electroencephalography (EEG) source imaging (ESI) of ictal epileptic activity. Surgical procedures were tailored by sequential intraoperative ECoG, and absolute spike frequency (ASF) was calculated in the pre- and post-resection ECoG. Postoperative clinical outcome assessment for each patient was carried out one year after surgery using Engel scores. Results: frontal and occipital resection were the most common surgical techniques applied. In addition, surgical resection encroaching upon eloquent cortex was accomplished in 41% of the ExTLE patients. Pre-surgical magnetic resonance imaging (MRI) did not indicate a distinct lesion in 47% of the cases. In the latter number of subjects, SISCOM and ESI of ictal epileptic activity made it possible to estimate the epileptogenic zone. After one- year follow up, 55.8% of the patients was categorized as Engel class I–II. In this study, there was no difference in the clinical outcome between lesional and non lesional ExTLE patients. About 43.7% of patients without lesion were also seizure- free, p = 0.15 (Fischer exact test). Patients with satisfactory seizure outcome showed lower absolute spike frequency in the pre-resection intraoperative ECoG than those with unsatisfactory seizure outcome, (Mann– Whitney U test, p = 0.005). Conclusions: this study has shown that multimodal pre-surgical evaluation based, particularly, on data from SISCOM and ESI alongside sequential intraoperative ECoG, allow seizure control to be achieved in patients with pharmacoresistant ExTLE epilepsy.

Long-term outcomes of brainstem arteriovenous malformations after different management modalities: a single-centre experience

OBJECTIVE

The aims of this study are to clarify the long-term outcomes of brainstem arteriovenous malformations (AVMs) after different management modalities.

METHODS

The authors retrospectively reviewed 61 brainstem AVMs in their institution between 2011 and 2017. The rupture risk was represented by annualised haemorrhagic rate. Patients were divided into five groups: conservation, microsurgery, embolisation, stereotactic radiosurgery (SRS) and embolisation+SRS. Neurofunctional outcomes were evaluated by the modified Rankin Scale (mRS). Subgroup analysis was conducted between different management modalities to compare the long-term outcomes in rupture or unruptured cohorts.

RESULTS

All of 61 brainstem AVMs (12 unruptured and 49 ruptured) were followed up for an average of 4.5 years. The natural annualised rupture risk was 7.3%, and the natural annualised reruptured risk in the ruptured cohort was 8.9%. 13 cases were conservative managed and 48 cases underwent intervention (including 6 microsurgery, 12 embolisation, 21 SRS and 9 embolisation+SRS). In the selection of interventional indication, diffuse nidus were often suggested conservative management (p=0.004) and nidus involving the midbrain were more likely to be recommended for intervention (p=0.034). The risk of subsequent haemorrhage was significantly increased in partial occlusion compared with complete occlusion and conservative management (p<0.001, p=0.036, respectively). In the subgroup analysis, the follow-up mRS scores of different management modalities were similar whether in the rupture cohort (p=0.064) or the unruptured cohort (p=0.391), as well as the haemorrhage-free survival (p=0.145). In the adjusted Bonferroni correction analysis of the ruptured cohort, microsurgery and SRS could significantly improve the obliteration rate compared with conservation (p<0.001, p=0.001, respectively) and SRS may have positive effect on avoiding new-onset neurofunctional deficit compared with microsurgery and embolisation (p=0.003, p=0.003, respectively).

CONCLUSIONS

Intervention has similar neurofunctional outcomes as conservation in these brainstem AVM cohorts. If intervention is adopted, partial obliteration should be avoided because of the high subsequent rupture risk.

TRIAL REGISTRATION NUMBER

NCT04136860.

Evolution of patients with surgically treated drug-resistant occipital lobe epilepsy

Background

This study was to describe the evolution of patients who underwent surgical treatment of drug- resistant occipital lobe epilepsy (OLE) at our institution.

Methods

We performed a retrospective analysis of data collected from electronic and paper clinical records of 20 patients who were diagnosed of OLE and underwent epilepsy surgery at our institution between 1998 and 2018. We also contacted patients by telephone and asked them to fill out a questionnaire about quality of life in epilepsy (QOLIE-10). Assembled data were analyzed using descriptive statistics.

Results

The age at surgery ranged between 19 and 55 years. The period encompassing epilepsy onset and the date of surgery was variable. Semiology of seizures included visual symptoms in 75% of patients. In 90% of cases subdural grids, depth electrodes or a combination of both were used to plan the surgery. The most frequent neuroimaging and histopathological finding was cortical dysplasia (55%). The postoperative follow-up period was up to 15 years. The most common score on the Engel scale was I (70%). Visual deficits increased after surgery. Median score on QOLIE-10 questionnaire was 82.5 (interquartile range: 32.5).

Conclusion

Surgical treatment of drug-resistant OLE offers hopeful results to those patients who have run out of pharmacological options and leads to postoperative deficits that are deemed expectable and occasionally acceptable.

Awake perimetry testing for occipital epilepsy surgery

With the patient awake during surgery, the authors used a simple technique to determine which part of a patient's brain was essential for vision. This technique allows the surgeon to remove as much as the seizure-producing brain as possible by avoiding the areas that are critical for vision.

Surgery for epilepsy

BACKGROUND

This is an updated version of the original Cochrane review, published in 2015.Focal epilepsies are caused by a malfunction of nerve cells localised in one part of one cerebral hemisphere. In studies, estimates of the number of individuals with focal epilepsy who do not become seizure-free despite optimal drug therapy vary between at least 20% and up to 70%. If the epileptogenic zone can be located, surgical resection offers the chance of a cure with a corresponding increase in quality of life.

OBJECTIVES

The primary objective is to assess the overall outcome of epilepsy surgery according to evidence from randomised controlled trials.Secondary objectives are to assess the overall outcome of epilepsy surgery according to non-randomised evidence, and to identify the factors that correlate with remission of seizures postoperatively.

SEARCH METHODS

For the latest update, we searched the following databases on 11 March 2019: Cochrane Register of Studies (CRS Web), which includes the Cochrane Epilepsy Group Specialized Register and the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid, 1946 to March 08, 2019), ClinicalTrials.gov, and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP).

SELECTION CRITERIA

Eligible studies were randomised controlled trials (RCTs) that included at least 30 participants in a well-defined population (age, sex, seizure type/frequency, duration of epilepsy, aetiology, magnetic resonance imaging (MRI) diagnosis, surgical findings), with an MRI performed in at least 90% of cases and an expected duration of follow-up of at least one year, and reporting an outcome related to postoperative seizure control. Cohort studies or case series were included in the previous version of this review.

DATA COLLECTION AND ANALYSIS

Three groups of two review authors independently screened all references for eligibility, assessed study quality and risk of bias, and extracted data. Outcomes were proportions of participants achieving a good outcome according to the presence or absence of each prognostic factor of interest. We intended to combine data with risk ratios (RRs) and 95% confidence intervals (95% CIs).

MAIN RESULTS

We identified 182 studies with a total of 16,855 included participants investigating outcomes of surgery for epilepsy. Nine studies were RCTs (including two that randomised participants to surgery or medical treatment (99 participants included in the two trials received medical treatment)). Risk of bias in these RCTs was unclear or high. Most of the remaining 173 non-randomised studies followed a retrospective design. We assessed study quality using the Effective Public Health Practice Project (EPHPP) tool and determined that most studies provided moderate or weak evidence. For 29 studies reporting multivariate analyses, we used the Quality in Prognostic Studies (QUIPS) tool and determined that very few studies were at low risk of bias across domains.In terms of freedom from seizures, two RCTs found surgery (n = 97) to be superior to medical treatment (n = 99); four found no statistically significant differences between anterior temporal lobectomy (ATL) with or without corpus callosotomy (n = 60), between subtemporal or transsylvian approach to selective amygdalohippocampectomy (SAH) (n = 47); between ATL, SAH and parahippocampectomy (n = 43) or between 2.5 cm and 3.5 cm ATL resection (n = 207). One RCT found total hippocampectomy to be superior to partial hippocampectomy (n = 70) and one found ATL to be superior to stereotactic radiosurgery (n = 58); and another provided data to show that for Lennox-Gastaut syndrome, no significant differences in seizure outcomes were evident between those treated with resection of the epileptogenic zone and those treated with resection of the epileptogenic zone plus corpus callosotomy (n = 43). We judged evidence from the nine RCTs to be of moderate to very low quality due to lack of information reported about the randomised trial design and the restricted study populations.Of the 16,756 participants included in this review who underwent a surgical procedure, 10,696 (64%) achieved a good outcome from surgery; this ranged across studies from 13.5% to 92.5%. Overall, we found the quality of data in relation to recording of adverse events to be very poor.In total, 120 studies examined between one and eight prognostic factors in univariate analysis. We found the following prognostic factors to be associated with a better post-surgical seizure outcome: abnormal pre-operative MRI, no use of intracranial monitoring, complete surgical resection, presence of mesial temporal sclerosis, concordance of pre-operative MRI and electroencephalography, history of febrile seizures, absence of focal cortical dysplasia/malformation of cortical development, presence of tumour, right-sided resection, and presence of unilateral interictal spikes. We found no evidence that history of head injury, presence of encephalomalacia, presence of vascular malformation, and presence of postoperative discharges were prognostic factors of outcome.Twenty-nine studies reported multi-variable models of prognostic factors, and showed that the direction of association of factors with outcomes was generally the same as that found in univariate analyses.We observed variability in many of our analyses, likely due to small study sizes with unbalanced group sizes and variation in the definition of seizure outcome, the definition of prognostic factors, and the influence of the site of surgery AUTHORS' CONCLUSIONS: Study design issues and limited information presented in the included studies mean that our results provide limited evidence to aid patient selection for surgery and prediction of likely surgical outcomes. Future research should be of high quality, follow a prospective design, be appropriately powered, and focus on specific issues related to diagnostic tools, the site-specific surgical approach, and other issues such as extent of resection. Researchers should investigate prognostic factors related to the outcome of surgery via multi-variable statistical regression modelling, where variables are selected for modelling according to clinical relevance, and all numerical results of the prognostic models are fully reported. Journal editors should not accept papers for which study authors did not record adverse events from a medical intervention. Researchers have achieved improvements in cancer care over the past three to four decades by answering well-defined questions through the conduct of focused RCTs in a step-wise fashion. The same approach to surgery for epilepsy is required.

Seizure Outcomes in Occipital Lobe and Posterior Quadrant Epilepsy Surgery: A Systematic Review and Meta-Analysis

BACKGROUND

Occipital lobe epilepsy (OLE) is an uncommon but debilitating focal epilepsy syndrome with seizures often refractory to medical management. While surgical resection has proven a viable treatment, previous studies examining postoperative seizure freedom rates are limited by small sample size and patient heterogeneity, thus exhibiting significant variability in their results.

OBJECTIVE

To review the medical literature on OLE so as to investigate rates and predictors of both seizure freedom and visual outcomes following surgery.

METHODS

We reviewed manuscripts exploring surgical resection for drug-resistant OLE published between January 1990 and June 2015 on PubMed. Seizure freedom rates were analyzed and potential predictors were evaluated with separate meta-analyses. Postoperative visual outcomes were also examined.

RESULTS

We identified 27 case series comprising 584 patients with greater than 1 yr of follow-up. Postoperative seizure freedom (Engel class I outcome) was observed in 65% of patients, and was significantly predicted by age less than 18 yr (odds ratio [OR] 1.54, 95% confidence interval [CI] 1.13-2.18), focal lesion on pathological analysis (OR 2.08, 95% CI 1.58-2.89), and abnormal preoperative magnetic resonance imaging (OR 3.24, 95% 2.03-6.55). Of these patients, 175 also had visual outcomes reported with 57% demonstrating some degree of visual decline following surgery. We did not find any relationship between postoperative visual and seizure outcomes.

CONCLUSION

Surgical resection for OLE is associated with favorable outcomes with nearly two-thirds of patients achieving postoperative seizure freedom. However, patients must be counseled regarding the risk of visual decline following surgery.

Relationship between cortical resection and visual function after occipital lobe epilepsy surgery

OBJECTIVE In this study, the authors investigated long-term clinical and visual outcomes of patients after occipital lobe epilepsy (OLE) surgery and analyzed the relationship between visual cortical resection and visual function after OLE surgery. METHODS A total of 42 consecutive patients who were diagnosed with OLE and underwent occipital lobe resection between June 1995 and November 2013 were included. Clinical, radiological, and histopathological data were reviewed retrospectively. Seizure outcomes were categorized according to the Engel classification. Visual function after surgery was assessed using the National Eye Institute Visual Functioning Questionnaire 25. The relationship between the resected area of the visual cortex and visual function was demonstrated by multivariate linear regression models. RESULTS After a mean follow-up period of 102.2 months, 27 (64.3%) patients were seizure free, and 6 (14.3%) patients had an Engel Class II outcome. Nineteen (57.6%) of 33 patients had a normal visual field or quadrantanopia after surgery (normal and quadrantanopia groups). Patients in the normal and quadrantanopia groups had better vision-related quality of life than those in the hemianopsia group. The resection of lateral occipital areas 1 and 2 of the occipital lobe was significantly associated with difficulties in general vision, peripheral vision, and vision-specific roles. In addition, the resection of intraparietal sulcus 3 or 4 was significantly associated with decreased social functioning. CONCLUSIONS The authors found a favorable seizure control rate (Engel Class I or II) of 78.6%, and 57.6% of the subjects had good visual function (normal vision or quadrantanopia) after OLE surgery. Lateral occipital cortical resection had a significant effect on visual function despite preservation of the visual field.

Effectiveness of Preradiosurgical Embolization with NBCA for Arteriovenous Malformations - Retrospective Outcome Analysis in a Japanese Registry of 73 Patients (J-REAL study)

Purpose

Recent reports have posed doubts about the effect of preradiosurgical embolization in brain arteriovenous malformation (AVM) because it makes the planning of stereotactic radiosurgery (SRS) difficult and has the risk of recanalization out of the target. We investigated whether the performance and quality of embolization may influence the success of SRS based on a retrospective case cohort study.

Materials and Methods

Seventy-three patients who underwent embolization followed by SRS between 2003 and 2012 in eight institutes with neurointerventionists were considered. They were divided into the following two groups at 3 years of follow up after the final SRS: “successful occlusion group” (S group), with radiologically complete occlusion of AVM; and “non-successful occlusion group” (N group) with persistent remnant nidus or abnormal vascular networks. Patient background, AVM profile, embolization performance grade and complications were compared in each group. The quality of embolization was evaluated with the new grading system: embolization performance grade (E grade), specializing the achievement of nidus embolization. E grade A was defined as sufficient nidus embolization with more than half of the total number of feeders achieving nidus penetration. E grade B was defined as less than half achievement of nidus embolization, and E grade C was defines as failure to perform nidus embolization.

Results

Forty-three patients were included in the S group, and 29 patients were included in the N group. The size and Spetzler-Martin grade of AVM and the rate of diffuse type was higher in the N group without statistical significance. The embolization performance level according to E grade indicated a significantly higher rate of successful embolization with more than 50% of nidus penetration in the S group (P<0.001). This difference was also confirmed in the subanalysis for limited cases, excluding smaller AVMs with complete occlusion with SRS alone (P=0.001).

Conclusion

The cause of the unsuccessful result of post-embolization SRS might be the large, diffuse angioarchitecture, but proper embolization with a high rate of nidus penetration to avoid recanalization is more important. Effective embolization is essential to contribute to and promote the effect of radiosurgery.

Onyx embolization prior to stereotactic radiosurgery for brain arteriovenous malformations: a single-center treatment algorithm

BACKGROUND

Embolization before stereotactic radiosurgery (SRS) for brain arteriovenous malformations (BAVMs) is controversial.

OBJECTIVE

To compare clinical and radiographic outcomes in patients undergoing pre-SRS embolization with ethylene copolymer (Onyx) with outcomes in patients undergoing SRS alone.

METHODS

Seventy consecutive patients with BAVMs who underwent SRS were retrospectively reviewed. Univariate and multivariate analyses were performed to assess the factors associated with radiographic obliteration and complication.

RESULTS

Forty-one (59%) patients presented without BAVM rupture and 29 (41%) patients presented with rupture. Pre-SRS embolization was used in 20 patients (28.6%; 7 unruptured and 13 ruptured). Twenty-five of 70 (36%) patients sustained a complication from treatment, including 6 (9%) patients with a post-SRS latency period hemorrhage. Ten (14%) patients had persistent neurological deficits after treatment. Functional outcome (as modified Rankin Scale), complication rate, and radiographic obliteration at last follow-up were not significantly different between embolized and non-embolized groups in both unruptured and ruptured BAVMs. For unruptured BAVMs, 3- and 5-year rates of radiographic obliteration were 23% and 73% for non-embolized patients and 20% and 60% for embolized patients, respectively. For ruptured BAVMs, 3- and 5-year rates of radiographic obliteration were 45% and 72% for non-embolized patients and 53% and 82% for embolized patients, respectively.

CONCLUSION

Pre-SRS embolization with Onyx was not associated with worse clinical or radiographic outcomes than SRS treatment without embolization. Pre-SRS embolization has a low complication rate and can safely be used to target high-risk BAVM features in carefully selected patients destined for SRS.

Improvement of visual field defects after focal resection for occipital lobe epilepsy: case report

Improvement of visual field defects after surgical treatment for occipital lobe epilepsy is rare. Here, the authors report on a 24-year-old man with a 15-year history of refractory epilepsy that developed after he had undergone an occipital craniotomy to remove a cerebellar astrocytoma at the age of 4. His seizures started with an elementary visual aura, followed by secondary generalized tonic-clonic convulsion. Perimetry revealed left-sided incomplete hemianopia, and MRI showed an old contusion in the right occipital lobe. After evaluation with ictal video-electroencephalography, electrocorticography, and mapping of the visual cortex with subdural electrodes, the patient underwent resection of the scarred tissue, including the epileptic focus at the occipital lobe. After surgery, he became seizure free and his visual field defect improved gradually. In addition, postoperative ¹²³I-iomazenil (IMZ) SPECT showed partly normalized IMZ uptake in the visual cortex. This case is a practical example suggesting that neurological deficits attributable to the functional deficit zone can be remedied by successful focal resection.

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.

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.

Occipital and occipital "plus" epilepsies: A study of involved epileptogenic networks through SEEG quantification

Compared with temporal or frontal lobe epilepsies, the occipital lobe epilepsies (OLE) remain poorly characterized. In this study, we aimed at classifying the ictal networks involving OLE and investigated clinical features of the OLE network subtypes. We studied 194 seizures from 29 consecutive patients presenting with OLE and investigated by stereoelectroencephalography (SEEG). Epileptogenicity of occipital and extraoccipital regions was quantified according to the 'epileptogenicity index' (EI) method. We found that 79% of patients showed widespread epileptogenic zone organization, involving parietal or temporal regions in addition to the occipital lobe. Two main groups of epileptogenic zone organization within occipital lobe seizures were identified: a pure occipital group and an occipital "plus" group, the latter including two further subgroups, occipitotemporal and occipitoparietal. In 29% of patients, the epileptogenic zone was found to have a bilateral organization. The most epileptogenic structure was the fusiform gyrus (mean EI: 0.53). Surgery was proposed in 18/29 patients, leading to seizure freedom in 55% (Engel Class I). Results suggest that, in patient candidates for surgery, the majority of cases are characterized by complex organization of the EZ, corresponding to the occipital plus group.

A second chance--reoperation in patients with failed surgery for intractable epilepsy: long-term outcome, neuropsychology and complications

OBJECT

Resective surgery is a safe and effective treatment of drug-resistant epilepsy. If surgery has failed reoperation after careful re-evaluation may be a reasonable option. This study was to summarise the risks and benefits of reoperation in patients with epilepsy.

METHODS

This is a retrospective single centre study comprising clinical data, long-term seizure outcome, neuropsychological outcome and postoperative complications of patients, who had undergone a second resective epilepsy surgery from 1989 to 2009.

RESULTS

A total of 66 patients with median follow-up of 10.3 years were included into the study. Fifty-one patients (77%) had surgery for temporal lobe epilepsy, the remaining 15 cases for extra-temporal lobe epilepsies. The most frequent histological findings were tumours (n=33, 50%), followed by dysplasia, gliosis (n=11, each) and hippocampus sclerosis (n=9). The main reasons for seizure recurrence were incomplete resection (59.1%) of the putative epileptogenic lesion. After reoperation 46 patients (69.7%) were completely seizure-free International League Against Epilepsy 1 (ILAE 1) at the last available follow-up. The neuropsychological evaluation demonstrated that repeated losses in the same cognitive domain, that is, successive changes from better to worse performance categories, were rare and that those losses after first surgery were followed by improvement rather than decline. However, reoperations lead to an increased rate of permanent neurological deficits (9%), overall surgical complications (9%) and visual field deficits (67%).

CONCLUSIONS

Reoperation after failed resective epilepsy surgery led to approximately 70% long-time seizure freedom and reasonable neuropsychological outcome. There is an increased risk of permanent postoperative neurological deficits, which should be taken into consideration when counselling for reoperation.

Volume-staged radiosurgery for large arteriovenous malformations: an evolving paradigm

OBJECT

Large arteriovenous malformations (AVMs) remain difficult to treat, and ideal treatment parameters for volume-staged stereotactic radiosurgery (VS-SRS) are still unknown. The object of this study was to compare VS-SRS treatment outcomes for AVMs larger than 10 ml during 2 eras; Era 1 was 1992-March 2004, and Era 2 was May 2004–2008. In Era 2 the authors prospectively decreased the AVM treatment volume, increased the radiation dose per stage, and shortened the interval between stages.

METHODS

All cases of VS-SRS treatment for AVM performed at a single institution were retrospectively reviewed.

RESULTS

Of 69 patients intended for VS-SRS, 63 completed all stages. The median patient age at the first stage of VS-SRS was 34 years (range 9–68 years). The median modified radiosurgery-based AVM score (mRBAS), total AVM volume, and volume per stage in Era 1 versus Era 2 were 3.6 versus 2.7, 27.3 ml versus 18.9 ml, and 15.0 ml versus 6.8 ml, respectively. The median radiation dose per stage was 15.5 Gy in Era 1 and 17.0 Gy in Era 2, and the median clinical follow-up period in living patients was 8.6 years in Era 1 and 4.8 years in Era 2. All outcomes were measured from the first stage of VS-SRS. Near or complete obliteration was more common in Era 2 (log-rank test, p = 0.0003), with 3- and 5-year probabilities of 5% and 21%, respectively, in Era 1 compared with 24% and 68% in Era 2. Radiosurgical dose, AVM volume per stage, total AVM volume, era, compact nidus, Spetzler-Martin grade, and mRBAS were significantly associated with near or complete obliteration on univariate analysis. Dose was a strong predictor of response (Cox proportional hazards, p < 0.001, HR 6.99), with 3- and 5-year probabilities of near or complete obliteration of 5% and 16%, respectively, at a dose < 17 Gy versus 23% and 74% at a dose ≥ 17 Gy. Dose per stage, compact nidus, and total AVM volume remained significant predictors of near or complete obliteration on multivariate analysis. Seventeen patients (25%) had salvage surgery, SRS, and/or embolization. Allowing for salvage therapy, the probability of cure was more common in Era 2 (log-rank test, p = 0.0007) with 5-year probabilities of 0% in Era 1 versus 41% in Era 2. The strong trend toward improved cure in Era 2 persisted on multivariate analysis even when considering mRBAS (Cox proportional hazards, p = 0.055, HR 4.01, 95% CI 0.97–16.59). The complication rate was 29% in Era 1 compared with 13% in Era 2 (Cox proportional hazards, not significant).

CONCLUSIONS

VS-SRS is an option to obliterate or downsize large AVMs. Decreasing the AVM treatment volume per stage to ≤ 8 ml with this technique allowed a higher dose per fraction and decreased time to response, as well as improved rates of near obliteration and cure without increasing complications. Reducing the volume of these very large lesions can facilitate a surgical approach for cure.

A comparison of occipital and temporal lobe epilepsies

PURPOSE

Differentiating between occipital lobe epilepsy (OLE) and temporal lobe epilepsy (TLE) is often challenging. This retrospective case-control study compares OLE to TLE and explores markers that suggest the diagnosis of OLE.

METHODS

We queried the Jefferson Epilepsy Center surgery database for patients who underwent a resection that involved the occipital lobe. For each patient with OLE, three sequential case-control patients with TLE were matched. Demographic characteristics, symptoms, electrophysiological findings, imaging findings, and surgical outcome were compared.

RESULTS

Nineteen patients with OLE and 57 patients with TLE were included in the study. Visual symptoms were unique to patients with OLE (8/19) and were not reported by patients with TLE (P < 0.0001). Occipital interictal spikes (IIS) were found only in one-third of the patients with OLE (6/19) and in no patients with TLE (P < 0.0001). IIS in the posterior temporal lobe were found in five of 19 patients with OLE vs one of 57 patients with TLE (P = 0.003). IIS involved more than one lobe of the brain in most patients with OLE (11/19) but only in nine of 57 the TLE group. (P = 0.0003) Multilobar resection was needed in most patients with OLE (15/19), typically including the temporal lobe, but in only one of the patients with TLE (P < 0.0001).

CONCLUSION

Occipital lobe epilepsy is difficult to identify and may masquerade as temporal lobe epilepsy. Visual symptoms and occipital findings in the EEG suggest the diagnosis of OLE, but absence of these features, does not exclude the diagnosis. When posterior temporal EEG findings or multilobar involvement occurs, the diagnosis of OLE should be considered.

The role of microsurgical resection and radiosurgery for cerebral arteriovenous malformations

Cerebral arteriovenous malformations (AVMs) present unique challenges to cerebrovascular specialists. Management of these lesions begins with assessing their natural history. Intervention with the goal of complete obliteration requires some component of microsurgical techniques or radiosurgery. Clinicians must weigh observation and acceptance of the natural history of these lesions versus intervention on a case-by-case basis. Microsurgical resection and radiosurgery are both well-validated tools used in selectively treating cerebral AVMs. This manuscript offers a general review of the management of cerebral AVMs with multimodality treatment recommendations.

Surgery for epilepsy

BACKGROUND

Focal epilepsies are caused by a malfunction of nerve cells localised in one part of one cerebral hemisphere. In studies, estimates of the number of individuals with focal epilepsy who do not become seizure-free despite optimal drug therapy vary according to the age of the participants and which focal epilepsies are included, but have been reported as at least 20% and in some studies up to 70%. If the epileptogenic zone can be located surgical resection offers the chance of a cure with a corresponding increase in quality of life.

OBJECTIVES

The primary objective is to assess the overall outcome of epilepsy surgery according to evidence from randomised controlled trials.The secondary objectives are to assess the overall outcome of epilepsy surgery according to non-randomised evidence and to identify the factors that correlate to remission of seizures postoperatively.

SEARCH METHODS

We searched the Cochrane Epilepsy Group Specialised Register (June 2013), the Cochrane Central Register of Controlled Trials (CENTRAL 2013, Issue 6), MEDLINE (Ovid) (2001 to 4 July 2013), ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) for relevant trials up to 4 July 2013.

SELECTION CRITERIA

Eligible studies were randomised controlled trials (RCTs), cohort studies or case series, with either a prospective and/or retrospective design, including at least 30 participants, a well-defined population (age, sex, seizure type/frequency, duration of epilepsy, aetiology, magnetic resonance imaging (MRI) diagnosis, surgical findings), an MRI performed in at least 90% of cases and an expected duration of follow-up of at least one year, and reporting an outcome relating to postoperative seizure control.

DATA COLLECTION AND ANALYSIS

Three groups of two review authors independently screened all references for eligibility, assessed study quality and risk of bias, and extracted data. Outcomes were proportion of participants achieving a good outcome according to the presence or absence of each prognostic factor of interest. We intended to combine data with risk ratios (RR) and 95% confidence intervals.

MAIN RESULTS

We identified 177 studies (16,253 participants) investigating the outcome of surgery for epilepsy. Four studies were RCTs (including one that randomised participants to surgery or medical treatment). The risk of bias in the RCTs was unclear or high, limiting our confidence in the evidence that addressed the primary review objective. Most of the remaining 173 non-randomised studies had a retrospective design; they were of variable size, were conducted in a range of countries, recruited a wide demographic range of participants, used a wide range of surgical techniques and used different scales used to measure outcomes. We performed quality assessment using the Effective Public Health Practice Project (EPHPP) tool and determined that most studies provided moderate or weak evidence. For 29 studies reporting multivariate analyses we used the Quality in Prognostic Studies (QUIPS) tool and determined that very few studies were at low risk of bias across the domains.In terms of freedom from seizures, one RCT found surgery to be superior to medical treatment, two RCTs found no statistically significant difference between anterior temporal lobectomy (ATL) with or without corpus callosotomy or between 2.5 cm or 3.5 cm ATL resection, and one RCT found total hippocampectomy to be superior to partial hippocampectomy. We judged the evidence from the four RCTs to be of moderate to very low quality due to the lack of information reported about the randomised trial design and the restricted study populations.Of the 16,253 participants included in this review, 10,518 (65%) achieved a good outcome from surgery; this ranged across studies from 13.5% to 92.5%. Overall, we found the quality of data in relation to the recording of adverse events to be very poor.In total, 118 studies examined between one and eight prognostic factors in univariate analysis. We found the following prognostic factors to be associated with a better post-surgical seizure outcome: an abnormal pre-operative MRI, no use of intracranial monitoring, complete surgical resection, presence of mesial temporal sclerosis, concordance of pre-operative MRI and electroencephalography (EEG), history of febrile seizures, absence of focal cortical dysplasia/malformation of cortical development, presence of tumour, right-sided resection and presence of unilateral interictal spikes. We found no evidence that history of head injury, presence of encephalomalacia, presence of vascular malformation or presence of postoperative discharges were prognostic factors of outcome. We observed variability between studies for many of our analyses, likely due to the small study sizes with unbalanced group sizes, variation in the definition of seizure outcome, definition of the prognostic factor and the influence of the site of surgery, all of which we observed to be related to postoperative seizure outcome. Twenty-nine studies reported multivariable models of prognostic factors and the direction of association of factors with outcome was generally the same as found in the univariate analyses. However, due to the different multivariable analysis approaches and selective reporting of results, meaningful comparison of multivariate analysis with univariate meta-analysis is difficult.

AUTHORS' CONCLUSIONS

The study design issues and limited information presented in the included studies mean that our results provide limited evidence to aid patient selection for surgery and prediction of likely surgical outcome. Future research should be of high quality, have a prospective design, be appropriately powered and focus on specific issues related to diagnostic tools, the site-specific surgical approach and other issues such as the extent of resection. Prognostic factors related to the outcome of surgery should be investigated via multivariable statistical regression modelling, where variables are selected for modelling according to clinical relevance and all numerical results of the prognostic models are fully reported. Protocols should include pre- and postoperative measures of speech and language function, cognition and social functioning along with a mental state assessment. Journal editors should not accept papers where adverse events from a medical intervention are not recorded. Improvements in the development of cancer care over the past three to four decades have been achieved by answering well-defined questions through the conduct of focused RCTs in a step-wise fashion. The same approach to surgery for epilepsy is required.

Volume-staged versus dose-staged radiosurgery outcomes for large intracranial arteriovenous malformations

OBJECT

The aim in this paper was to compare the outcomes of dose-staged and volume-staged stereotactic radio-surgery (SRS) in the treatment of large (> 10 cm(3)) arteriovenous malformations (AVMs).

METHODS

A systematic literature review was performed using PubMed. Studies written in the English language with at least 5 patients harboring large (> 10 cm(3)) AVMs treated with dose- or volume-staged SRS that reported post-treatment outcomes data were selected for review. Demographic information, radiosurgical treatment parameters, and post-SRS outcomes and complications were analyzed for each of these studies.

RESULTS

The mean complete obliteration rates for the dose- and volume-staged groups were 22.8% and 47.5%, respectively. Complete obliteration was demonstrated in 30 of 161 (18.6%) and 59 of 120 (49.2%) patients in the dose- and volume-staged groups, respectively. The mean rates of symptomatic radiation-induced changes were 13.5% and 13.6% in dose- and volume-staged groups, respectively. The mean rates of cumulative post-SRS latency period hemorrhage were 12.3% and 17.8% in the dose- and volume-staged groups, respectively. The mean rates of post-SRS mortality were 3.2% and 4.6% in dose- and volume-staged groups, respectively.

CONCLUSIONS

Volume-staged SRS affords higher obliteration rates and similar complication rates compared with dose-staged SRS. Thus, volume-staged SRS may be a superior approach for large AVMs that are not amenable to single-session SRS. Staged radiosurgery should be considered as an efficacious component of multimodality AVM management.

Stereotactic radiosurgery with and without embolization for intracranial arteriovenous malformations: a systematic review and meta-analysis

OBJECT

The effectiveness and risk of stereotactic radiosurgery (SRS) in the management of partially embolized intracranial arteriovenous malformations (AVMs) remain controversial. The aim of this analysis was to assess current evidence regarding the efficiency and safety of SRS for AVM patients with and without prior embolization.

METHODS

To compare SRS in patients with and without embolization, the authors conducted a meta-analysis of studies by searching the literature via PubMed and EMBASE for the period between January 2000 and December 2013, complemented by a hand search. Primary outcome was the rate of AVM obliteration on a 3-year follow-up angiogram. Secondary outcome was the rate of hemorrhage at 3 years after SRS. Tertiary outcome was permanent neurological deficits related to radiation-induced changes.

RESULTS

Ten studies eligible for analysis included 1988 patients: 593 had undergone embolization followed by SRS and 1395 had undergone SRS alone. The AVM obliteration rate was significantly lower in patients who had undergone embolization followed by SRS than in those who had undergone SRS alone (41.0% vs 59%, OR 0.46, 95% CI 0.37-0.56, p < 0.00001). However, the rates of hemorrhage (7.3% vs 5.6%, OR 1.17, 95% CI 0.74-1.83, p = 0.50) and permanent neurological deficits related to radiation-induced changes (3.3% vs 3.4%, OR 1.41, 95% CI 0.64-3.11, p = 0.39) were not significantly different between the two groups.

CONCLUSIONS

Embolization before SRS significantly decreases the AVM obliteration rate. However, there is no significant difference in the risk of hemorrhage and permanent neurological deficits after SRS alone and following embolization. Further validation by well-designed prospective or randomized cohort studies is still needed.

The Classical Pathways of Occipital Lobe Epileptic Propagation Revised in the Light of White Matter Dissection

The clinical evidences of variable epileptic propagation in occipital lobe epilepsy (OLE) have been demonstrated by several studies. However the exact localization of the epileptic focus sometimes represents a problem because of the rapid propagation to frontal, parietal, or temporal regions. Each white matter pathway close to the supposed initial focus can lead the propagation towards a specific direction, explaining the variable semiology of these rare epilepsy syndromes. Some new insights in occipital white matter anatomy are herein described by means of white matter dissection and compared to the classical epileptic patterns, mostly based on the central position of the primary visual cortex. The dissections showed a complex white matter architecture composed by vertical and longitudinal bundles, which are closely interconnected and segregated and are able to support specific high order functions with parallel bidirectional propagation of the electric signal. The same sublobar lesions may hyperactivate different white matter bundles reemphasizing the importance of the ictal semiology as a specific clinical demonstration of the subcortical networks recruited. Merging semiology, white matter anatomy, and electrophysiology may lead us to a better understanding of these complex syndromes and tailored therapeutic options based on individual white matter connectivity.

Stereotactic radiosurgery for arteriovenous malformations after Onyx embolization: a case-control study

OBJECT

Onyx, an ethylene-vinyl alcohol copolymer mixed in a dimethyl sulfoxide solvent, is currently one of the most widely used liquid materials for embolization of intracranial arteriovenous malformations (AVMs). The goal of this study was to define the risks and benefits of stereotactic radiosurgery (SRS) for patients who have previously undergone partial AVM embolization with Onyx.

METHODS

Among a consecutive series of 199 patients who underwent SRS between January 2007 and December 2012 at the University of Virginia, 25 patients had Onyx embolization prior to SRS (the embolization group). To analyze the obliteration rates and complications, 50 patients who underwent SRS without prior embolization (the no-embolization group) were matched by propensity score method. The matched variables included age, sex, nidus volume before SRS, margin dose, Spetzler-Martin grade, Virginia Radiosurgery AVM Scale score, and median imaging follow-up period.

RESULTS

After Onyx embolization, 18 AVMs were reduced in size. Total obliteration was achieved in 6 cases (24%) at a median of 27.5 months after SRS. In the no-embolization group, total obliteration was achieved in 20 patients (40%) at a median of 22.4 months after SRS. Kaplan-Meier analysis demonstrated obliteration rates of 17.7% and 34.1% in the embolization group at 2 and 4 years, respectively. In the no-embolization group, the corresponding obliteration rates were 27.0% and 55.9%. The between-groups difference in obliteration rates after SRS did not achieve statistical significance. The difference in complications, including adverse radiation effects, hemorrhage episodes, seizure control, and patient mortality also did not reach statistical significance.

CONCLUSIONS

Onyx embolization can effectively reduce the size of many AVMs. This case-control study did not show any statistically significant difference in the rates of embolization or complications after SRS in patients who had previously undergone Onyx embolization and those who had not.

Intractable occipital lobe epilepsy: clinical characteristics, surgical treatment, and a systematic review of the literature

PURPOSE

We reported our experience in the surgical treatment of a relatively large cohort of patients with occipital lobe epilepsy (OLE). We also carried out a systematic review of the literature on OLE.

METHODS

Thirty-five consecutive patients who underwent occipital resection for epilepsy were included. Diagnoses were made following presurgical evaluations, including magnetic resonance imaging (MRI), fluorodeoxyglucose-positron emission tomography (FDG-PET), scalp video-electroencephalogram (EEG) monitoring, and intracranial EEG monitoring. At last follow-up, seizure outcome was classified using the Engel classification scheme.

RESULTS

Twenty-five of 35 patients experienced/had experienced ≥1 type of aura before the seizure. Invasive recordings were used to define the epileptogenic area in 30 of 35 patients (85.7 %). All patients underwent occipital lesionectomies or topectomies. Histopathology revealed: cortical dysplasias, gliosis, dysembryoplastic neuroepithelial tumor, ganglioglioma, and tuberous sclerosis. After a mean follow-up of 44 months, 25 patients (71.4 %) were seizure free (Engel class I), 3 (8.6 %) rarely had seizures (Engel class II), 5 (14.3 %) improved more than 75 % (Engel class III), and 2 (5.7 %) had no significant improvement (Engel class IV). Preoperatively, 12 of 33 patients (36.4 %) had visual field deficits. Postoperatively, 25 patients (75.8 %) had new or aggravated visual field deficits.

CONCLUSIONS

The management of OLE has been aided greatly by the availability of high-resolution diagnosis. Postoperative visual field deficits occur in a significant proportion of patients. Comprehensive intracranial EEG coverage of all occipital surfaces helps to define the epileptogenic area and preserve visual function, especially in cases of focal cortical dysplasia undetectable by MRI.

Staged-volume radiosurgery for large arteriovenous malformations: a review

Stereotactic radiosurgery is an effective management strategy for properly selected patients with arteriovenous malformations (AVMs). However, the risk of postradiosurgical radiation-related injury is higher in patients with large AVMs. Multistaged volumetric management of large AVMs was undertaken to limit the radiation exposure to the surrounding normal brain. This strategy offers a promising method for obtaining high AVM obliteration rates with minimal normal tissue damage. The use of embolization as an adjunctive method in the treatment of large AVMs remains controversial. Unfortunately, staged-volume radiosurgery (SVR) has a number of potential pitfalls that affect the outcome. The aim of this article is to highlight the role of SVR in the treatment of large AVMs, to discuss the outcome comparing it to other treatment modalities, and to discuss the potential improvement that could be introduced to this method of treatment.

Mirror focus in a patient with intractable occipital lobe epilepsy

Mirror focus is one of the evidence of progression in epilepsy, and also has practical points for curative resective epilepsy surgery. The mirror foci are related to the kindling phenomena that occur through interhemispheric callosal or commissural connections. A mirror focus means the secondary epileptogenic foci develop in the contralateral hemispheric homotopic area. Thus mirror foci are mostly reported in patients with temporal or frontal lobe epilepsy, but not in occipital lobe epilepsy. We have observed occipital lobe epilepsy with mirror focus. Before epilepsy surgery, the subject's seizure onset zone was observed in the left occipital area by ictal studies. Her seizures abated for 10 months after the resection of left occipital epileptogenic focus, but recurred then. The recurred seizures were originated from the right occipital area which was in the homotopic contralateral area. This case can be an evidence that occipital lobe epilepsy may have mirror foci, even though each occipital lobe has any direct interhemispheric callosal connections between them.

Evolution of cranial epilepsy surgery complication rates: a 32-year systematic review and meta-analysis

Object

Surgical interventions for medically refractory epilepsy are effective in selected patients, but they are underutilized. There remains a lack of pooled data on complication rates and their changes over a period of multiple decades. The authors performed a systematic review and meta-analysis of reported complications from intracranial epilepsy surgery from 1980 to 2012.

Methods

A literature search was performed to find articles published between 1980 and 2012 that contained at least 2 patients. Patients were divided into 3 groups depending on the procedure they underwent: A) temporal lobectomy with or without amygdalohippocampectomy, B) extratemporal lobar or multilobar resections, or C) invasive electrode placement. Articles were divided into 2 time periods, 1980–1995 and 1996–2012.

Results

Sixty-one articles with a total of 5623 patients met the study's eligibility criteria. Based on the 2 time periods, neurological deficits decreased dramatically from 41.8% to 5.2% in Group A and from 30.2% to 19.5% in Group B. Persistent neurological deficits in these 2 groups decreased from 9.7% to 0.8% and from 9.0% to 3.2%, respectively. Wound infections/meningitis decreased from 2.5% to 1.1% in Group A and from 5.3% to 1.9% in Group B. Persistent neurological deficits were uncommon in Group C, although wound infections/meningitis and hemorrhage/hematoma increased over time from 2.3% to 4.3% and from 1.9% to 4.2%, respectively. These complication rates are additive in patients undergoing implantation followed by resection.

Conclusions

Complication rates have decreased dramatically over the last 30 years, particularly for temporal lobectomy, but they remain an unavoidable consequence of epilepsy surgery. Permanent neurological deficits are rare following epilepsy surgery compared with the long-term risks of intractable epilepsy.

Combined treatment of brain AVMs with use of Onyx embolization followed by radiosurgery

BACKGROUND AND PURPOSE

The treatment of cerebral AVMs is complex, reliant on interventions such as embolization, surgery, and radiosurgery, or a combination of these modalities. To date, treatment with the embolic agent Onyx, followed by radiosurgery, has not been evaluated. The goal of this study was to evaluate the safety and efficacy of this combination in a homogeneous, monocentric series.

MATERIALS AND METHODS

From April 2003 to June 2008, a total of 20 patients (11 women and 9 men; age range, 10-55 years) were treated for AVMs with Onyx embolization followed by radiosurgery. AVM sizes were <3 cm in 7 patients and ≥3 cm in 13 patients. Modalities and complications of the procedure were analyzed as well as the long-term clinical and anatomic outcomes (2-5 years after treatment).

RESULTS

Of 17 patients evaluated by DSA after radiosurgery, 10 (58.8%) were observed to have complete occlusion of the AVM nidus. Complete occlusion was observed in 5 (71.4%) of 7 Spetzler-Martin grade I-II AVMs and in 5 (50.0%) of 10 Spetzler-Martin grade III-IV AVMs. Complete occlusion was observed in 4 (80.0%) of 5 AVMs of <3 cm and 6 (50.0%) of 12 AVMs of >3 cm. One of 20 patients had significant worsening of clinical status (mRS ≥2) at long-term follow-up.

CONCLUSIONS

In this preliminary series, the safety and efficacy of combined treatment by Onyx embolization followed by radiosurgery are quite satisfactory, with a low rate of clinical complications (5.0%) and a 58.8% rate of complete obliteration of the AVM.

Epilepsy surgery of the cingulate gyrus and the frontomesial cortex

BACKGROUND

Epilepsy surgery involving the cingulate gyrus has been mostly presented as case reports, and larger series with long-term follow-up are not published yet.

OBJECTIVE

To report our experience with focal epilepsy arising from the cingulate gyrus and surrounding structures and its surgical treatment.

METHODS

Twenty-two patients (mean age, 36; range, 12-63) with a mean seizure history of 23 years (range, 2-52) were retrospectively analyzed. We report presurgical diagnostics, surgical strategy, and postoperative follow-up concerning functional morbidity and seizures (mean follow-up, 86 months; range, 25-174).

RESULTS

Nineteen patients showed potential epileptogenic lesions on preoperative magnetic resonance imaging (MRI). All patients had noninvasive presurgical workup; 15 (68%) underwent invasive Video-electroencephalogram (EEG)-Monitoring. In 12 patients we performed extended lesionectomy according to MRI; an extension with regard to EEG results was done in 6 patients. In 4 patients, the resection was incomplete because of the involvement of eloquent areas according to functional mapping results. Eight pure cingulate resections (36%, 3 in the posterior cingulate gyrus) and 14 extended supracingular frontal resections were performed. Nine patients experienced temporary postoperative supplementary motor area syndrome after resection in the superior frontal gyrus. Two patients retained a persistent mild hand or leg paresis, respectively. Postoperatively, 62% of patients were seizure-free (International League Against Epilepsy [ILAE] 1), and 76% had a satisfactory seizure outcome (ILAE 1-3).

CONCLUSION

Epilepsy surgery for lesions involving the cingulate gyrus represents a small fraction of all epilepsy surgery cases, with good seizure outcome and low rates of postoperative permanent deficits. In case of extended supracingular resection, supplementary motor area syndrome should be considered.

Prediction of neuropsychological outcome after resection of temporal and extratemporal seizure foci

Resection of seizure foci is an effective treatment for the control of medically intractable epilepsy. However, cognitive morbidity can occur as a result of surgical intervention. This morbidity is dependent on several factors, including location and extent of resection, disease characteristics, patient demographic characteristics, and functional status of the tissue to be resected. In this review article, the authors provide a summary of the neurocognitive outcomes of epilepsy surgery with an emphasis on presurgical predictors of postsurgical cognitive decline.

Long-term outcome of extratemporal resection in posttraumatic epilepsy

Object

Posttraumatic epilepsy (PTE) is a common cause of medically intractable epilepsy. While much of PTE is extratemporal, little is known about factors associated with good outcomes in extratemporal resections in medically intractable PTE. The authors investigated and characterized the long-term outcome and patient factors associated with outcome in this population.

Methods

A single-institution retrospective query of all epilepsy surgeries at Regional Epilepsy Center at the University of Washington was performed for a 17-year time span with search terms indicative of trauma or brain injury. The query was limited to adult patients who underwent an extratemporal resection (with or without temporal lobectomy), in whom no other cause of epilepsy could be identified, and for whom minimum 1-year follow-up data were available. Surgical outcomes (in terms of seizure reduction) and clinical data were analyzed and compared.

Results

Twenty-one patients met inclusion and exclusion criteria. In long-term follow-up 6 patients (28%) were seizure-free and an additional 6 (28%) had a good outcome of 2 or fewer seizures per year. Another 5 patients (24%) experienced a reduction in seizures, while only 4 (19%) did not attain significant benefit. The presence of focal encephalomalacia on imaging was associated with good or excellent outcomes in 83%. In 8 patients with the combination of encephalomalacia and invasive intracranial EEG, 5 (62.5%) were found to be seizure free. Normal MRI examinations preoperatively were associated with worse outcomes, particularly when combined with multifocal or poorly localized EEG findings. Two patients suffered complications but none were life threatening or disabling.

Conclusions

Many patients with extratemporal PTE can achieve good to excellent seizure control with epilepsy surgery. The risks of complications are acceptably low. Patients with focal encephalomalacia on MRI generally do well. Excellent outcomes can be achieved when extratemporal resection is guided by intracranial EEG electrodes defining the extent of resection.

Posterior resection for childhood lesional epilepsy: neuropsychological evolution

The aim of this study was to provide information on the neuropsychological evolution of children with symptomatic epilepsy who have undergone surgical resection of posterior (occipitoparietal) lesions. Twelve children with epilepsy with parietal and/or occipital lesions were enrolled in the study and followed after surgical resection: full clinical and epileptic examinations were performed before and after surgery, as was a neuropsychological study of both general and specific cognitive abilities. Epilepsy evolution was generally good (Engel classification IA in nine cases) with persistent selective neurological impairments (eye field defects, sensory unilateral spatial neglect) in some cases, consistent with the lesion site. Neuropsychological defects before surgery in the absence of refractory epilepsy were minimal with a normal global cognitive competence; yet, the relatively low performance scores with some impairment of specific cognitive skills were strictly correlated with defects in visual perceptive skills in both right- and left-sided lesions. Surgery seems to have improved performance abilities, whereas other abnormal specific skills did not change with the exception of working memory that in some cases was defective before surgery and normalized after lesion removal. Our study in this particular cohort of children with epileptogenic occipitoparietal lesions thus confirmed a trend toward a benign epileptic and neurodevelopmental outcome after surgical resection of the lesion.

Liquid embolization material reduces the delivered radiation dose: clinical myth or reality?

BACKGROUND AND PURPOSE

To be radiopaque, BAVM embolization products must contain high-atomic-number materials, which may also attenuate photon beams delivered with radiosurgery. This "shielding effect" has been invoked to explain why radiation therapy may be less effective for previously embolized BAVMs. To evaluate the impact of embolization material on radiation dose, we measured and compared the dose delivered to the center of an AVM model, before and following embolization with various materials in a LINAC.

MATERIALS AND METHODS

Two in vitro AVM models were constructed by drilling interconnected tubular perforations in plastic water phantoms to simulate nidal vessels. Phantoms were designed to allow the positioning of a radiation detector at their center. One model was embolized with Onyx 18 and a second model, with a combination of Indermil, Lipiodol, tungsten powder, and Onyx 18. The radiation delivered was compared between embolized and nonembolized controls following irradiation with a standard 250-cGy dose.

RESULTS

The mean dose of radiation delivered to the model embolized with Onyx alone was 244 ± 5 cGy before and 246 ± 5 cGy following embolization. The mean dose of radiation delivered to the model embolized with various agents was 242 ± 5 cGy before, and 254 ± 5 cGy after embolization.

CONCLUSIONS

Embolic material did not reduce the radiation dose delivered by a LINAC to the center of our experimental BAVM models. The shielding effect may be compensated by scattered and reflected radiation.

Linac stereotactic radiosurgery for the treatment of small arteriovenous malformations: lower doses can be equally effective

OBJECTIVE

The purpose of this study was to examine the efficacy and toxicity of treating small arteriovenous malformations (AVMs) (≤3 cm in diameter) with a median marginal applied dose of 14 Gy.

METHODS

Two hundred and thirteen patients diagnosed with AVMs were treated between January 1991 and December 2005. Seventy-three percent of the patients had hemorrhaged prior to treatment, 13% had had previous surgery and 19.2% had had previous embolization. The median follow-up duration was 48.1 months.

RESULTS

The Kaplan-Meier analysis estimated that the 36-month obliteration rate was 65.5% for patients undergoing their first stereotactic radiosurgery (SRS) and 68.3% for those undergoing repeated SRS. The Kaplan-Meier analysis estimated the 60-month AVMs obliteration rate for the entire cohort to be 82.4%. The median time to AVM obliteration was 40 ± 2.8 months. We found a statistically significant relationship between the time of obliteration and the following factors: site of the AVMs (sites other than brainstem), a higher prescribed dose and a positive history of previous hemorrhage. Thirteen patients (7.6%) experienced toxicities.

CONCLUSIONS

SRS was an effective and safe treatment for AVMs ≤3 cm in diameter, with acceptable toxicity.

Effect of liquid embolic agents on Gamma Knife surgery dosimetry for arteriovenous malformations

Object

The effectiveness of Gamma Knife stereotactic surgery to obliterate brain arteriovenous malformations (AVMs) may be diminished by the preoperative adjunctive use of endovascular liquid embolic agents. The purpose of the present investigation was to determine if commercially available liquid embolic agents reduce the radiation dose to the target because of attenuation of the 60Co beam.

Methods

The apparent linear attenuation coefficients for 120- to 140-keV radiographs in embolized regions were retrieved from CT scans for several patients with AVMs who had undergone embolization procedures with liquid embolic agents to reduce nidal volumes. Based on these coefficients and a virtual model of Gamma Knife surgery (GKS) with basic ray tracing, the authors obtained the path lengths and densities of the embolized regions. The attenuation of 60Co beams was then calculated for various sizes and positions of embolized AVM regions and for the number of beams used for treatment. Published experiments for several high-atomic-number materials were used to estimate the effective 60Co beam attenuation coefficients for the N-butyl cyanoacrylate (NBCA, suspended in ethiodized oil) and ethylene vinyl alcohol copolymer (EVOH, with suspended micronized tantalum powder, Onyx) used in the AVM embolizations. Dose reductions during GKS were calculated for a theoretical model based on the CT-documented apparent linear attenuation coefficients and for the 60Co energy attenuation coefficient. Dose measurements were obtained in a phantom study with EVOH for comparison with the estimates generated from the two attenuation coefficients.

Results

Based on CT (keV) apparent attenuation coefficients, the authors' theoretical model predicted that the cumulative effect of either of the embolic agents decreased the number of kilovoltage photons in an embolized nidus by −8% to −15% because of the increased atomic number and density of NBCA and Onyx. However, in using the effective attenuation coefficient for the 60Co energies as is used in GKS, the authors' theoretical model yielded only a 0.2% dose reduction per beam and a < 0.01%–0.2% dose reduction in total. These theoretical results were validated by measurements in a head phantom containing Onyx.

Conclusions

Dose reduction due to attenuation of the 60Co beam by the AVM embolization material was negligible for both NBCA and EVOH because of the high-energy 60Co beam.

Planning extent of resection in epilepsy: limited versus large resections

Aggressive versus limited resection is an often-debated topic in epilepsy surgery. There are two inherent questions within this debate: (1) Can a more limited resection yield seizure freedom rates similar to those afforded by wider/more aggressive resection, with lower rates of neurological complications? (2) Does wider/more aggressive resection increase seizure freedom rates, with tolerable neurological complications rates? Further, if more limited resection has a lower seizure freedom rate, but fewer complications, is quality of life better or worse than that following a wider/more aggressive resection that increases seizure freedom rate but yields a higher complication rate? Here, we review the literature to address these questions. Because most studies are retrospective observational studies, with limited statistical power to draw strong conclusions, there is a need for more randomized prospective multicenter clinical trials incorporating advances in technique for identifying the seizure onset zone (e.g., subtractive ictal SPECT) and tissue at risk (e.g., diffusion tensor imaging) to inform this discussion.

Intractable occipital lobe epilepsy: clinical characteristics and surgical treatment

Intractable occipital lobe epilepsy remains a surgical challenge. Clinical characteristics of 14 patients were analyzed. Twelve patients had surgery, seven patients had visual auras (50%) and only eight patients (57%) had posterior scalp EEG changes. Ictal single-proton emission computed tomography (SPECT) incorrectly localized in 7 of 10 patients. Six patients (50%) had Engel's class I outcome. Patients with inferior occipital seizure onset appeared to fare better (three of four class I) than patients with lateral or medial occipital seizure onset (three of eight class I). Patients who had all three occipital surfaces covered with electrodes had a better outcome (four of five class I) than patients who had limited electroencephalography (EEG) coverage (two of seven class I). Magnetic resonance imaging (MRI) lesions did not guarantee a seizure free outcome. In conclusion, visual auras, scalp EEG, and imaging findings are not reliable for correct identification of occipital onset. Occipital seizure onset can be easily missed in nonlesional epilepsy. Comprehensive intracranial EEG coverage of all three occipital surfaces leads to better outcomes.

Epilepsy and brain tumors

PURPOSE OF REVIEW

To present an overview of the recent findings in pathophysiology and management of epileptic seizures in patients with brain tumors.

RECENT FINDINGS

Low-grade gliomas are the most epileptogenic brain tumors. Regarding pathophysiology, the role of peritumoral changes [hypoxia and acidosis, blood-brain barrier (BBB) disruption, increase or decrease of neurotransmitters and receptors] are of increasing importance. Tumor-associated epilepsy and tumor growth could have some common molecular pathways. Total/subtotal surgical resection (with or without epilepsy surgery) allows a seizure control in a high percentage of patients. Radiotherapy and chemotherapy as well have a role. New antiepileptic drugs are promising, both in terms of efficacy and tolerability. The resistance to antiepileptic drugs is still a major problem: new insights into pathogenesis are needed to develop strategies to manipulate the pharmakoresistance.

SUMMARY

Epileptic seizures in brain tumors have been definitely recognized as one of the major problems in patients with brain tumors, and need specific and multidisciplinary approaches.

Occipital ganglioglioma in an older adult

Gangliogliomas are rare benign tumors of the central nervous system that typically involve the temporal lobe in younger patients. We present a 63-year-old man with an unusual occipital ganglioma with new seizures resolving after resection. A search of the literature revealed only three reports of occipital ganglioma in adults over 30 years old. Therefore, ganglioglioma of the occipital lobe in older patients is rare, but is a diagnostic consideration.