Long-term seizure outcome following resective surgery at National Epilepsy Center in Shizuoka, Japan

Neuropathological spectrum of drug resistant epilepsy: 15-years-experience from a tertiary care centre

Neuropathology of drug resistant epilepsy (DRE) has direct bearing on the clinical outcome. Classification of the most common pathologies, hippocampal sclerosis (HS) and focal cortical dysplasia (FCD) have undergone several revisions and studies on the surgical pathology of DRE employing the updated ILAE classification are scarce. Here, we report the neuropathological spectrum of 482 surgically treated cases of DRE from a single institute using the latest ILAE classifications along with clinicoradiologic correlation. Majority of the cases (324, 67.2%) had temporal lobe epilepsy (TLE), with 158 (32.8%) having extratemporal seizure focus. Among TLE, HS was most common (n = 208, 64.2%), followed by neoplasms (42, 13%), FCD (26, 8%) and dual pathology (23, 7%). Less frequent were vascular malformations (cavernoma-3, arteriovenous malformation-1), mild malformation of cortical development (mMCD, 3), gliotic lesions (5), cysticercosis (2), double pathology (2) and polymicrogyria (1). Among extratemporal epilepsies, FCD was most common (46, 29.1%), followed by neoplasms (29, 18.3%), gliotic lesions (27, 17.1%), Rasmussen encephalitis (18, 11.4%), hypothalamic hamartoma (12, 7.6%), malformations of cortical development (10, 6.3%) and vascular malformations (6, 3.8%). Less frequent were double pathology (2, cysticercosis + FCD type IIb, DNET + FCD type IIb), mMCD (2), cysticercosis (1) and dual pathology (1). No underlying pathology was detected in 12 cases (2.5%). Radiopathological concordance was noted in 83%. In 36 cases (7.5%), histopathology detected an unsuspected second pathology that included FCD type III (n = 16) dual pathology (n = 18) and double pathology (n = 2). Further, in four MRI negative cases, histopathology was required for a conclusive diagnosis.

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.

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.

Long-term outcome of surgical treatment of patients with intractable epilepsy associated with schizencephaly

BACKGROUND

Schizencephaly is a developmental anomaly of the brain that is sometimes associated with intractable seizures. Patients that suffer from medically refractory seizures may be considered for surgical treatment.

METHOD

Five patients with intractable epilepsy associated with schizencephaly were studied. Evaluation methods included medical history assessment, neurological examination, magnetic resonance imaging (MRI) with three-dimensional (3D) surface rendering, positron emission tomography (PET), video-electroencephalogram (EEG) monitoring with surface electrodes and subdural grid electrodes, sodium amobarbital test, and neuropsychological assessments. Topectomy was performed close to the schizencephalic cleft in two patients, and at an area distant from the cleft in one under the guidance of electrocorticography (ECoG). Temporal lobectomy was performed in two patients.

RESULTS

MRI revealed unilateral schizencephaly in all five patients. Video-EEG monitoring recorded simple partial seizures in two patients and complex partial seizures in three patients. The epileptogenic zone was localized close to the schizencephalic cleft in two patients, distant to the cleft in one patient, and in the temporal lobe in two patients. Postoperatively, one of two patients with temporal lobectomy and one of three patients with topectomy were seizure-free at 1-year follow-up. Three patients experienced marked seizure reduction but were not seizure-free at 1 year; however, at the follow-up periods of 2.5 years and 6.5 years, two of these three patients were seizure free. One patient who underwent temporal lobectomy began to have very brief losses of consciousness lasting 1-3 s (3-4 times per year). Neurological complications included temporary upper monoparesis in one and hemiparesis in one.

CONCLUSIONS

The abnormal cortex lining schizencephalic clefts and cortical tissues near the cleft may be epileptogenic. Areas distant to the cleft may also be the source of seizures. Careful evaluation should be performed to define the epileptogenic zone in patients with intractable epilepsy associated with schizencephaly, and meticulous resection of the epileptogenic zone can lead to good seizure control.

Long-term outcomes of epilepsy surgery in Sweden: a national prospective and longitudinal study

Objective:

To investigate prospective, population-based long-term outcomes concerning seizures and antiepileptic drug (AED) treatment after resective epilepsy surgery in Sweden.

Methods:

Ten- and 5-year follow-ups were performed in 2005 to 2007 for 278/327 patients after resective epilepsy surgery from 1995 to 1997 and 2000 to 2002, respectively. All patients had been prospectively followed in the Swedish National Epilepsy Surgery Register. Ninety-three patients, who were presurgically evaluated but not operated, served as controls.

Results:

In the long term (mean 7.6 years), 62% of operated adults and 50% of operated children were seizure-free, compared to 14% of nonoperated adults (p < 0.001) and 38% of nonoperated children (not significant). Forty-one percent of operated adults and 44% of operated children had sustained seizure freedom since surgery, compared to none of the controls (p < 0.0005). Multivariate analysis identified ≥30 seizures/month at baseline and long epilepsy duration as negative predictors and positive MRI to be a positive predictor of long-term seizure-free outcome. Ten years after surgery, 86% of seizure-free children and 43% of seizure-free adults had stopped AEDs in the surgery groups compared to none of the controls (p < 0.0005).

Conclusions:

This population-based, prospective study shows good long-term seizure outcomes after resective epilepsy surgery. The majority of the patients who are seizure-free after 5 and 10 years have sustained seizure freedom since surgery. Many patients who gain seizure freedom can successfully discontinue AEDs, more often children than adults.

Classification of evidence:

This study provides Class III evidence that more patients are seizure-free and have stopped AED treatment in the long term after resective epilepsy surgery than nonoperated epilepsy patients.

A population-based study of long-term outcome of epilepsy in childhood with a focal or hemispheric lesion on neuroimaging

PURPOSE

To evaluate long-term seizure outcome in children with epilepsy and a focal or hemispheric neuroimaging abnormality.

METHODS

All children (<18 years and residing in Olmsted County, Minnesota) with new-onset epilepsy diagnosed between 1980 and 2004 and a single focal lesion on neuroimaging were identified by review of the Rochester Epidemiologic Project database. Outcomes were divided into three categories: (1) seizure freedom for 1 or more years at last follow-up, (2) ongoing seizures but not medically intractable epilepsy, and (3) medically intractable epilepsy or undergoing epilepsy surgery. We also evaluated the proportion who achieved seizure control without surgical intervention and whether lesion type predicted intractability.

KEY FINDINGS

Of the 359 children with newly diagnosed epilepsy, 37 (10%) had a focal or hemispheric lesion on neuroimaging. Median age of diagnosis was 89 months (25th percentile 26 months, 75th percentile 142 months) and at follow-up was 137 months (25th percentile 95 months, 75th percentile 211 months). Eighty-three percent of children with malformations of cortical development, 67% with mesial temporal sclerosis, 33% with encephalomalacia, and 50% with vascular malformations had intractable epilepsy at follow-up or underwent resective surgery for medically intractable epilepsy. Among the different etiologies, presence of encephalomalacia predicted the lowest likelihood of medical intractability or undergoing surgery (p < 0.01). At final follow-up, 24 (65%) of our entire cohort was seizure free. Following surgery, seizure freedom was achieved in 80% with mesial temporal sclerosis, 67% with encephalomalacia, 67% with vascular malformation, and 50% with malformations of cortical development. There was no statistically significant difference between the different etiologies on neuroimaging and seizure freedom after surgery. Twelve children (32%) achieved seizure freedom with medical management alone.

SIGNIFICANCE

Focal lesions on neuroimaging confer a high risk of medical intractability among children with new-onset epilepsy. However, 32% of this cohort achieved seizure remission with medical management alone, including 58% with encephalomalacia and 33% with mesial temporal sclerosis.

Neuropathological findings in intractable epilepsy: 435 Chinese cases

The number of patients with intractable epilepsy undergoing surgical management in China is increasing rapidly. We retrospectively reviewed 435 consecutive cases of intractable epilepsy receiving surgical resection from 2005 to 2008 in our hospital, looking specifically at the neuropathological findings. The three most common causes of intractable epilepsy were focal cortical dysplasia (FCD; 52.9%), scar lesions (22.8%) and brain tumors (11.7%). Hippocampal sclerosis was identified in 74 cases (17.0%), although most of these were accompanied by dual pathology with FCD (especially Palmini type IB), scar lesions or tumors. Among FCD cases, Palmini type I lesions are the most frequently observed abnormality, with a preferred location in the temporal lobe (60.1%) and often accompanied by dual pathology. In contrast, Palmini type II FCD lesions occurred predominantly in the frontal regions and with a lower age of onset. Most tumors were mixed neuronal-glial tumors, mainly ganglioglioma (19 cases) and dysembryoplastic neuroepithelial tumor (10 cases), with a trend toward a temporal location and usually accompanied by cortical dysplasia in the peritumor area. Our data on the neuropathology of intractable epilepsy in China show that glioneuronal lesions are the most prominent cause of intractable epilepsy, and this is consistent with reports from other countries.

Long-term seizures and quality of life after epilepsy surgery compared with matched controls

OBJECTIVE

We compared long-term seizure outcome and health-related quality of life (HRQoL) of patients who underwent epilepsy surgery and matched medically treated nonsurgical controls with intractable epilepsy.

METHODS

Medically treated controls were identified for patients operated on for epilepsy between January 1, 1949 and December 31, 1992. We used a matched cohort design, matching for age, sex, and seizure type. The analysis was based on 70 complete matching pairs. HRQoL was assessed with the Quality of Life in Epilepsy Inventory 89 questionnaire an average of 15 years after surgery.

RESULTS

Among surgery patients, 48% were seizure-free during the previous year compared with 19% of the controls (P = 0.0004). Fewer surgery patients used antiepileptic drugs (70%) than controls (93%). The odds of being seizure-free were higher for surgery patients in total and in subgroups divided according to length of follow-up. The mean HRQoL for surgery patients was higher in five of the 17 Quality of Life in Epilepsy Inventory 89 dimensions and worse in none. Among patients with more than 7 years of follow-up, HRQoL was better in three dimensions and worse in none. Among patients with 7 years of follow-up or less, HRQoL was better in two dimensions and worse in the language dimension of the Quality of Life in Epilepsy Inventory 89.

CONCLUSION

After an average of more than 15 years of follow-up, epilepsy surgery patients had fewer seizures, used less antiepileptic medication, and had better HRQoL in several dimensions of the Quality of Life in Epilepsy Inventory 89 instrument than matched medically treated controls with refractory epilepsy, although possibly at a slight disadvantage in the language dimension among those with 7 years of follow-up or less.