Radiosurgical Corpus Callosotomy for Intractable Epilepsy: Retrospective Long-Term Safety and Efficacy Assessment in 19 Patients an Review of the Literature.

BACKGROUND: Some patients suffering from intractable epileptic seizures, particularly drop attacks (DAs), are nonremediable by curative techniques. Palliative procedure carries a significant rate of surgical and neurological complications. OBJECTIVE: To propose evaluation of safety and efficacy of Gamma Knife corpus callosotomy (GK-CC) as an alternative to microsurgical corpus callosotomy. METHODS: This study included retrospective analysis of 19 patients who underwent GK-CC between 2005 and 2017. RESULTS: Of the 19 patients, 13 (68%) had improvement in seizure control and 6 had no significant improvement. Of the 13/19 (68%) with improvement in seizures, 3 (16%) became completely seizure-free, 2 (11%) became free of DA and generalized tonic-clonic but with residual other seizures, 3 (16%) became free of DA only, and 5 (26%) had >50% reduction in frequency of all seizure types. In the 6 (31%) patients with no appreciable improvement, there were residual untreated commissural fibers and incomplete callosotomy rather than failure of Gamma Knife to disconnect. Seven patients showed a transient mild complication (37% of patients, 33% of the procedures). No permanent complication or neurological consequence was observed during the clinical and radiological workup with a mean of 89 (42-181) months, except 1 patient who had no improvement of epilepsy and then aggravation of the pre-existing cognitive and walking difficulties (Lennox-Gastaut). The median time of improvement after GK-CC was 3 (1-6) months. CONCLUSION: Gamma Knife callosotomy is safe and accurate with comparable efficacy to open callosotomy in this cohort of patients with intractable epilepsy suffering from severe drop attacks.

Cost-effectiveness of invasive monitoring strategies in epilepsy surgery.

OBJECTIVE: Drug-resistant epilepsy occurs in up to 40% of patients with epilepsy who may be considered for epilepsy surgery. For drug-resistant focal epilepsy, up to 50% of patients require invasive monitoring prior to surgery. Of the most common invasive monitoring strategies (subdural electrodes [SDEs] and stereo-electroencephalography [sEEG]), the most cost-effective strategy is unknown despite substantial differences in morbidity profiles. METHODS: Using data collected from an internationally representative sample published in available systematic reviews and meta-analyses, this economic evaluation study employs a decision analysis model to simulate the risks and benefits of SDE and sEEG invasive monitoring strategies. In this model, patients faced differing risks of morbidity, mortality, resection, and seizure freedom depending on which invasive monitoring strategy they underwent. A range of cost values was obtained from a recently published single-center cost-utility analysis. The model considers a base case simulation of a characteristic patient with drug-resistant epilepsy using clinical parameters obtained from systematic reviews of invasive monitoring available in the literature. The main outcome measure was the probability of a positive outcome after invasive monitoring, which was defined as improvement in seizures without a complication. Cost-effectiveness was measured using an incremental cost-effectiveness ratio (ICER). RESULTS: Invasive monitoring with sEEG had an increased cost of $274 and increased probability of effectiveness of 0.02 compared with SDEs, yielding an ICER of $12,630 per positive outcome obtained. Sensitivity analyses varied parameters widely and revealed consistent model results across the range of clinical parameters reported in the literature. One-way sensitivity analyses revealed that invasive monitoring strategy costs were the most influential parameter for model outcome. CONCLUSIONS: In this analysis, based on available observational data and estimates of complication costs, invasive monitoring with either SDEs or sEEG was nearly equivalent in terms of cost-effectiveness.

Single-center cost comparison analysis of stereoelectroencephalography with subdural grid and strip implantation.

OBJECTIVE: Use of invasive stereoelectroencephalography (SEEG) has gained traction recently. However, scant research has investigated the costs and resource utilization of SEEG compared with subdural grid (SDG)-based techniques in pediatric patients. Here, the authors have presented a retrospective analysis of charges associated with SEEG and SDG monitoring at a single institution. METHODS: The authors performed a retrospective case series analysis of pediatric patients with similar characteristics in terms of age, sex, seizure etiology, and epilepsy treatment strategy who underwent SEEG or SDG monitoring and subsequent craniotomy for resection of epileptogenic focus at St. Louis Children Hospital, St. Louis, Missouri, between 2013 and 2020. Financial data, including hospital charges, supplies, and professional fees (i.e., those related to anesthesia, neurology, neurosurgery, and critical care), were adjusted for inflation to 2020 US dollars. RESULTS: The authors identified 18 patients (9 underwent SEEG and 9 underwent SDG) with similar characteristics in terms of age (mean [range] 13.6 [1.9-21.8] years for SDG patients vs 11.9 [2.4-19.6] years for SEEG patients, p = 0.607), sex (4 females underwent SDG vs 6 females underwent SEEG, p = 0.637), and presence of lesion (5 patients with a lesion underwent SDG vs 8 underwent SEEG, p = 0.294). All patients underwent subsequent craniotomy for resection of epileptogenic focus. SEEG patients were more likely to have a history of status epilepticus (p = 0.029). Across 1 hospitalization for each SDG patient and 2 hospitalizations for each SEEG patient, SEEG patients had a significantly shorter mean operating room time (288 vs 356 minutes, p = 0.015), mean length of stay in the ICU (1.0 vs 2.1 days, p < 0.001), and tended to have a shorter overall length of stay in the hospital (8.4 vs 10.6 days, p = 0.086). Both groups underwent invasive monitoring for similar lengths of time (5.2 days for SEEG patients vs 6.4 days for SDG patients, p = 0.257). Time to treatment from the initial invasive monitoring evaluation was significantly longer in SEEG patients (64.6 vs 6.4 days, p < 0.001). Neither group underwent readmission within the first 30 days after hospital discharge. Seizure outcomes and complication rates were similar. After adjustment for inflation, the average total perioperative charges were $104,442 for SDG and $106,291 for SEEG (p = 0.800). CONCLUSIONS: Even though 2 hospitalizations were required for SEEG and 1 hospitalization was required for SDG monitoring, patients who underwent SEEG had a significantly shorter average length of stay in the ICU and operating room time. Surgical morbidity and outcomes were similar. Total perioperative charges for invasive monitoring and resection were approximately 2% higher for SEEG patients when corrected for inflation, but this difference was not statistically significant.

Multimodal assessment of motor pathways and intracortical connections in functional hemispherectomy.

PURPOSE: For selected children with medically intractable epilepsy, hemispherectomy can be an excellent treatment option and its efficacy in achieving seizure freedom or reduction in seizure frequency has been shown in several studies, but patients' selection could not be straightforward and often it is taken on subjective basis. We described a multimodal approach to assess patient eligible for hemispherectomy and possibly predicting post-surgical outcomes. METHODS: We describe pre- and post-surgical clinical features along with neuroradiological results by magnetic resonance imaging (MRI), functional magnetic resonance imaging (fMRI), MR-tractography (MRT), and neurophysiological study by single and paired pulses transcranial magnetic stimulation (TMS) in a child with cerebral palsy with epileptic encephalopathy, eligible for epilepsy surgery. RESULTS: Presurgical TMS evaluation showed a lateralization of motor function on the left motor cortex for both arms, and results were confirmed by MRI studies. Interestingly, after surgery, both epilepsy and motor performances improved and TMS showed enhancement of intracortical inhibition and facilitation activity. CONCLUSION: Functional hemispherectomy is an effective treatment for drug-resistant epilepsy, and multimodal presurgical assessment may be a useful approach to guide surgeons in selecting patients. Moreover, pre- and post-surgical evaluation of these patients may enhance our understanding of brain plasticity phenomena.

48-hour video-EEG monitoring for epilepsy presurgical evaluation is cost-effective and safe in resource-limited setting.

INTRODUCTION: Video-EEG monitoring is one of the key investigations in epilepsy pre-surgical evaluation but limited by cost. This study aimed to determine the efficacy and safety of a 48-hour (3-day) video EEG monitoring, with rapid pre-monitoring antiepileptic drugs withdrawal. MATERIAL AND METHODS: This is a retrospective study of epilepsy cases with VEM performed in University Malaya Medical Center (UMMC), Kuala Lumpur, from January 2012 till August 2016. RESULTS: A total of 137 cases were included. The mean age was 34.5 years old (range 15-62) and 76 (55.8 %) were male. On the first 24 -h of recording (D1), 81 cases (59.1 %) had seizure occurrence, and 109 (79.6 %) by day 2 (D2). One-hundred and nine VEMs (79.6 %) were diagnostic, in guiding surgical decision or further investigations. Of these, 21 had less than 2 seizures recorded in the first 48 h but were considered as diagnostic because of concordant interictal ± ictal activities, or a diagnosis such as psychogenic non-epileptic seizure was made. Twenty-eight patients had extension of VEM for another 24-48 h, and 11 developed seizures during the extension period. Extra-temporal lobe epilepsy and seizure frequency were significant predictors for diagnostic 48 -h VEM. Three patients developed complications, including status epilepticus required anaesthetic agents (1), seizure clusters (2) with postictal psychosis or dysphasia, and all recovered subsequently. CONCLUSIONS: 48-h video EEG monitoring is cost-effective in resource limited setting.

Standard Free Versus Osteoplastic Craniotomy: Assessment of Complication Rates During Intracranial Electroencephalogram Electrode Placement for Seizure Localization.

OBJECTIVE: Patients with medically intractable epilepsy often undergo sequential surgeries and are therefore exposed to an elevated risk for infection, resulting in unanticipated returns to the operating room. The goal of our study was to determine whether use of an osteoplastic bone flap technique would reduce the infection rate in these patients. METHODS: A single-institution, retrospective chart review of patients with medically intractable epilepsy for grid placement was performed. Univariate analyses and linear regression were used to assess primary outcomes, including infection and hematomas requiring surgical evacuation. Secondary outcomes included duration of treatment and other, unanticipated surgeries. RESULTS: A total of 199 patients were identified, 56 (28%) with osteoplastic flaps. Standard free flaps were associated with an increased rate of infection at the craniotomy site (n = 24, 17%, vs. 0, 0%, P = 0.003), whereas osteoplastic flaps were associated with more returns to operating room for hematoma evacuation (n = 5, 9% vs. 3.2%, P = 0.024). Overall, the rate of return to operating room for unanticipated surgeries was similar, but infectious complications prolonged the duration of treatment (median: 17 days vs. 2 days, χ2 = 13.97, P < 0.001). CONCLUSIONS: Osteoplastic bone flaps markedly decreased the risk of craniotomy infections compared with free flaps in patients undergoing sequential surgeries. This decrease is offset, however, by an increase in intracranial hematoma requiring return to the operating room. Infection appeared to be a more significant complication as it was associated with increased duration of treatment. The osteoplastic technique is especially appealing in those patients likely to undergo multiple surgeries in short succession.

Indications and expectations for neuropsychological assessment in epilepsy surgery in children and adults.

In our first paper in this series (Epilepsia 2015; 56(5): 674-681), we published recommendations for the indications and expectations for neuropsychological assessment in routine epilepsy care. This partner paper provides a comprehensive overview of the more specialist role of neuropsychological assessment in the pre and postoperative evaluation of epilepsy surgery patients. The paper is in two parts. The first part presents the framework for the mandatory role of neuropsychologists in the presurgical evaluation of epilepsy surgery candidates. A preoperative neuropsychological assessment should be comprised of standardised measures of cognitive function in addition to wider measures of behavioural and psychosocial function. The results from the presurgical assessment are used to: (1) establish a baseline against which change can be measured following surgery; (2) provide a collaborative contribution to seizure characterization, lateralization and localization; (3) provide evidence-based predictions of cognitive risk associated with the proposed surgery; and (4) provide the evidence base for comprehensive preoperative counselling, including exploration of patient expectations of surgical treatment. The second part examines the critical role of the neuropsychologist in the evaluation of postoperative outcomes. Neuropsychological changes following surgery are dynamic and a comprehensive, long-term assessment of these changes following surgery should form an integral part of the postoperative follow-up. The special considerations with respect to pre and postoperative assessment when working with paediatric populations and those with an intellectual disability are also discussed. The paper provides a summary checklist for neuropsychological involvement throughout the epilepsy surgery process, based on the recommendations discussed.

Red flags in epilepsy surgery: Identifying the patients who pay a high cognitive price for an unsuccessful surgical outcome.

Preoperative estimates of cognitive and seizure outcome must be as accurate as possible if the candidate is to make an informed decision about epilepsy surgery. Significant declines in memory function are reported in approximately 30% of temporal lobe surgery patients. The percentage varies according to the ways in which a postoperative deterioration is defined but since the majority of outcome studies do not take into account the patient's capacity to deteriorate if they are functioning at or close to the floor of a memory test prior to surgery, the published percentages may be an underrepresentation of the true extent of memory decline following epilepsy surgery. We examined the cognitive 'cost' of epilepsy surgery in a consecutive series of 474 patients who underwent elective surgery for medically intractable epilepsy. All patients underwent a presurgical assessment prior to and 1year after the surgery. Reliable change indices were used to identify significant postoperative memory decline. Postoperative outcome was dichotomized using the ILAE 2008 classification. All patients in class one were classified as seizure-free (67.5% of the sample). Excluding patients already functioning at or below the 2nd percentile on standardized memory tests, 37.8% experienced a significant postoperative decline in memory function. Twelve percent experienced the 'double hit' of significant postoperative memory decline and ongoing seizures following surgery. Patients with pathologies other than hippocampal sclerosis and with signs of limited cognitive reserve, both in terms of memory function and overall intellectual ability were most likely to suffer a double hit. Our results indicate that caution should be exercised when operating on these patients and preoperative counseling should be tailored to reflect the likely risk/benefit ratio of a temporal lobe resection for medically intractable epilepsy in this group.

A reappraisal of mortality after epilepsy surgery.

OBJECTIVE: To assess whether epilepsy surgery is associated with a reduction in mortality rate and if postoperative seizure frequency and severity affect mortality. METHODS: A total of 1,110 patients were evaluated (1,006 surgically and 104 nonsurgically treated) for a total follow-up of 8,126.62 person-years from 1986 to 2013. Deaths were ascertained through database and Social Security Death Index query. Patients were grouped by surgery type and seizure status; standardized mortality ratio and deaths per 1,000 person-years were calculated. Survival analysis and Cox proportional hazard regression were performed. RESULTS: Eighty-nine deaths were observed. Surgically treated patients had a lower mortality rate (8.6 per 1,000 person-years [95% confidence interval (CI) 6.58-11.15]) than nonsurgically treated patients (25.3 per 1,000 person-years [14.50-41.17]; p < 0.001). Seizure-free patients had a lower mortality rate (5.2 per 1,000 person-years [95% CI 2.67-9.02]) than non-seizure-free patients (10.4 per 1,000 person-years [95% CI 7.67-13.89] p = 0.03). More frequent postoperative tonic-clonic seizures (>2 per year) were associated with increased mortality (p = 0.006) whereas complex partial seizure frequency was not related to death rate. Mortality was similar in temporal and extratemporal epilepsy patients (p = 0.7). CONCLUSIONS: Brain surgery is associated with a reduction in mortality rate in drug-resistant epilepsy, both when seizures are abolished and when it results in significant palliation of tonic-clonic seizure frequency. These observations provide further rationale for earlier consideration of epilepsy surgery.

Interictal epileptiform discharge effects on neuropsychological assessment and epilepsy surgical planning.

Both animal research and human research suggest that interictal epileptiform discharges (IEDs) may affect cognition, although the significance of such findings remains controversial. We review a wide range of literature with bearing on this topic and present relevant epilepsy surgery cases, which suggest that the effects of IEDs may be substantial and informative for surgical planning. In the first case, we present a patient with epilepsy with left anterior temporal lobe (TL) seizure onset who experienced frequent IEDs during preoperative neuropsychological assessment. Cognitive results strongly lateralized to the left TL. Because the patient failed performance validity tests and appeared amnestic for verbal materials inconsistent with his work history, selected neuropsychological tests were repeated 6 weeks later. Scores improved one to two standard deviations over the initial evaluation and because of this improvement, were only mildly suggestive of left TL impairment. The second case involves another patient with documented left TL epilepsy who experienced epileptiform activity while undergoing neurocognitive testing and simultaneous ambulatory EEG recording. This patient's verbal memory performance was impaired during the period that IEDs were present but near normal when such activity was absent. Overall, although the presence of IEDs may be helpful in confirming laterality of seizure onset, frequent IEDs might disrupt focal cognitive functions and distort accurate measurement of neuropsychological ability, interfering with accurate characterization of surgical risks and benefits. Such transient effects on daily performance may also contribute to significant functional compromise. We include a discussion of the manner in which IED effects during presurgical assessment can hinder individual patient presurgical planning as well as distort outcome research (e.g., IEDs occurring during presurgical assessment may lead to an underestimation of postoperative neuropsychological decline).

The Severity of Gliosis in Hippocampal Sclerosis Correlates with Pre-Operative Seizure Burden and Outcome After Temporal Lobectomy.

Astrogliosis and microgliosis in hippocampal sclerosis (HS) are widespread and are postulated to contribute to the pro-excitatory neuropathological environment. This study aimed to establish if seizure burden at the time of surgery or post-surgical outcome were correlated with the extent of gliosis in HS. As a secondary aim, we wanted to determine if the degree of gliosis could be predicted by pre-operative neuroimaging.Children and adults who underwent epilepsy surgery for HS between 2002 and 2011 were recruited (n = 43), and age-matched autopsy controls obtained (n = 15). Temporal lobe specimens were examined by DAB immunohistochemistry for astrocytes (glial fibrillary acidic protein (GFAP)) and microglia (CD68). Cell counting for GFAP and CD68 was performed and quantitative densitometry undertaken for GFAP. Seizure variables and outcome (Engel) were determined through medical record and patient review. Seizure frequency in the 6 months prior to surgery was measured to reflect the acute seizure burden. Duration of seizures, age at onset and age at operation were regarded to reflect chronic seizure burden. Focal, lobar and generalized atrophy on pre-operative MRI were independently correlated with the degree of cortical gliosis in the surgical specimen.In HS, both acute and chronic seizure burden were positively correlated with the degree of gliosis. An increase in reactive astrocyte number in CA3 was the strongest predictor of poor post-operative seizure outcome at 1 and 3 years post-operatively in this cohort. Changes in lower cortical astrocyte and upper cortical microglial number also correlated with post-operative outcome at 1 year. Post-surgical seizure outcome (1, 3 and 5 years) did not otherwise correlate with GFAP immunoreactivity (GFAP-IR) or CD68 immunoreactivity (CD68-IR). Increased microglial activation was detected in patients with pre-operative bilateral convulsive seizures, compared to those without convulsive seizures. Furthermore, focal, lobar and generalized atrophy on pre-operative neuroimaging were independently correlated with the degree of cortical gliosis in the surgical specimen.

Costs and Clinical Outcomes of Epilepsy Surgery in Children With Drug-Resistant Epilepsy.

PURPOSE: Approximately 20% of children with epilepsy are drug-resistant, incurring considerable costs. Epilepsy surgery has been shown to be an effective intervention in this population. This study provides an initial look at the costs associated with surgical management of children with drug-resistant epilepsy as compared with medical management alone. PROCEDURES: In a retrospective cohort study of children with drug-resistant epilepsy referred for possible surgical intervention, we compared direct costs of those treated surgically versus those offered surgery but managed medically instead. We also assessed the difference in seizure frequency between the two groups. FINDINGS: There were 94 total patients, 78 (83%) in the surgical group and 16 (17%) in the medical group. The median (25th-75th percentile) cost of the epilepsy surgery hospitalization was $118,400 ($101,900-$143,800). Total median annual follow-up costs, not including the cost of surgical hospitalization, were not significantly different between the two groups at 1- or 2-year follow-up. However, the surgical patients who were seizure-free at 1-year follow-up, and those that remained seizure-free at 2-year follow-up, had significantly lower costs compared with the medical group ($8000 versus $16,200, P = 0.04 and $4300 versus $7600, P = 0.05, respectively). The surgical group had significantly fewer seizures compared with the medical group at 1-year follow-up. CONCLUSIONS: Although epilepsy surgery is expensive and the overall costs of surgical and medical management are similar in the first 2 years, patients who achieved seizure freedom after surgery had lower costs compared with those treated medically.

Cranial neurosurgical 30-day readmissions by clinical indication.

OBJECT: Postsurgical readmissions are common and vary by procedure. They are significant drivers of increased expenditures in the health care system. Reducing readmissions is a national priority that has summoned significant effort and resources. Before the impact of quality improvement efforts can be measured, baseline procedure-related 30-day all-cause readmission rates are needed. The objects of this study were to determine population-level, 30-day, all-cause readmission rates for cranial neurosurgery and identify factors associated with readmission. METHODS: The authors identified patient discharge records for cranial neurosurgery and their 30-day all-cause readmissions using the Agency for Healthcare Research and Quality (AHRQ) State Inpatient Databases for California, Florida, and New York. Patients were categorized into 4 groups representing procedure indication based on ICD-9-CM diagnosis codes. Logistic regression models were developed to identify patient characteristics associated with readmissions. The main outcome measure was unplanned inpatient admission within 30 days of discharge. RESULTS: A total of 43,356 patients underwent cranial neurosurgery for neoplasm (44.23%), seizure (2.80%), vascular conditions (26.04%), and trauma (26.93%). Inpatient mortality was highest for vascular admissions (19.30%) and lowest for neoplasm admissions (1.87%; p < 0.001). Thirty-day readmissions were 17.27% for the neoplasm group, 13.89% for the seizure group, 23.89% for the vascular group, and 19.82% for the trauma group (p < 0.001). Significant predictors of 30-day readmission for neoplasm were Medicaid payer (OR 1.33, 95% CI 1.15-1.54) and fluid/electrolyte disorder (OR 1.44, 95% CI 1.29-1.62); for seizure, male sex (OR 1.74, 95% CI 1.17-2.60) and index admission through the emergency department (OR 2.22, 95% CI 1.45-3.43); for vascular, Medicare payer (OR 1.21, 95% CI 1.05-1.39) and renal failure (OR 1.52, 95% CI 1.29-1.80); and for trauma, congestive heart failure (OR 1.44, 95% CI 1.16-1.80) and coagulopathy (OR 1.51, 95% CI 1.25-1.84). Many readmissions had primary diagnoses identified by the AHRQ as potentially preventable. CONCLUSIONS: The frequency of 30-day readmission rates for patients undergoing cranial neurosurgery varied by diagnosis between 14% and 24%. Important patient characteristics and comorbidities that were associated with an increased readmission risk were identified. Some hospital-level characteristics appeared to be associated with a decreased readmission risk. These baseline readmission rates can be used to inform future efforts in quality improvement and readmission reduction.

The statistics of a practical seizure warning system.

Statistical methods for evaluating seizure prediction algorithms are controversial and a primary barrier to realizing clinical applications. Experts agree that these algorithms must, at a minimum, perform better than chance, but the proper method for comparing to chance is in debate. We derive a statistical framework for this comparison, the expected performance of a chance predictor according to a predefined scoring rule, which is in turn used as the control in a hypothesis test. We verify the expected performance of chance prediction using Monte Carlo simulations that generate random, simulated seizure warnings of variable duration. We propose a new test metric, the difference between algorithm and chance sensitivities given a constraint on proportion of time spent in warning, and use a simple spectral power-based measure to demonstrate the utility of the metric in four patients undergoing intracranial EEG monitoring during evaluation for epilepsy surgery. The methods are broadly applicable to other scoring rules. We present them as an advance in the statistical evaluation of a practical seizure advisory system.

A systematic review of the effectiveness and cost-effectiveness of neuroimaging assessments used to visualise the seizure focus in people with refractory epilepsy being considered for surgery.

OBJECTIVE: To review the effectiveness and/or accuracy, cost-effectiveness, and predictive value of neuroimaging of the cerebral cortex to visualise the seizure focus in people with refractory epilepsy being considered for surgery. DATA SOURCES: Electronic databases, Internet searches, hand searching and consultation with experts. METHODS: A systematic review was undertaken according to published guidelines. Results of diagnostic accuracy studies were analysed according to the imaging test evaluated. For each study the proportion of patients who were correctly localised, not localised, partially localised or incorrectly localised by the index test was calculated. Due to the heterogeneity present between studies, statistical pooling was not performed. Instead, a narrative synthesis of results is presented. For studies using multivariate analysis to look at the association of neuroimaging findings and outcome following surgery, all factors considered in the analyses were presented. Studies were grouped according to the neuroimaging technique investigated and the findings discussed with reference to possible sources of heterogeneity between studies. RESULTS: No randomised controlled trials (RCTs) were identified, with the majority of studies evaluating the diagnostic accuracy of various imaging techniques in the localisation of epileptic seizure foci. There was significant heterogeneity (p<0.05) between studies for at least one of the localisation categories (correctly localised, not localised, partially localised and incorrectly localised) for all imaging techniques. Possible explanations for this heterogeneity include differing study designs, index test characteristics, reference standards and population characteristics. Test performance was more promising in studies restricted to patients with temporal lobe epilepsy. Ictal single photon emission computed tomography (SPECT) generally had more correctly localising (70--100%) and fewer non-localising (0--7%) scans than other techniques evaluated in patients with temporal lobe epilepsy. Results for computed tomography and interictal SPECT suggest that these tests are relatively poor at localising the seizure focus. Volumeric magnetic resonance imaging (MRI) and position emission tomography (PET) appear promising, and subtraction ictal single photon emission computed tomography co-registered to magnetic resonance imaging (SISCOM) and magnetic resonance spectrosopy (MRS) less promising than ictal SPECT, but these technologies have been assessed in fewer studies. T2 relaxometry was reported in only one small study with inconclusive results. Seventeen studies (33 evaluations) provided sufficient data on the association of a localised scan with outcome following surgery to calculate a relative risk. The majority of evaluations (24/33) suggested that patients with a correctly or partially localised scan had a better outcome following surgery than those with an incorrectly localised or non-localised scan. However, this association was statistically significant in only three studies, two evaluating routine MRI [(relative risk (RR) 2.74, 95% confidence interval (CI): 1.32 to 5.67; RR 1.28, 95% CI: 1.00 to 1.63] and the other SISCOM (RR 2.12, 95% CI: 1.01, 4.44). Nine studies used multivariate analysis to investigate the association of MRI (7 studies), MRS and volumetric MRI (1 study), PET (3 studies), SPECT (1 study) and SISCOM (3 studies) with the outcome following surgery. There was a trend for localisation of abnormalities to be associated with a beneficial outcome. CONCLUSIONS: Due to the limitations of the included studies, the results of this review do little to inform clinical practice, with insufficient evidence regarding effectiveness and cost-effectiveness of imaging techniques in the work-up for epilepsy surgery. Given the inadequacy of existing data, there is a pressing need for studies investigating the utility of imaging techniques in the work up for epilepsy surgery. The most reliable method to achieve this is the RCT, which could examine the single tests or combinations of tests on patient outcome. The authors suggest that it is important that clinicians, patient groups, policy makers and healthcare/research funders meet and debate the most appropriate way to investigate these technologies.

Epilepsy surgery: patient-perceived long-term costs and benefits.

PURPOSE: The goal of this study was to assess the patient-perceived costs and benefits associated with the longer-term outcomes of epilepsy surgery in patients who underwent anterior temporal lobectomy or selective amygdalohippocampectomy. METHODS: Surgery patients who were assessed in 1997 were reassessed in 2003. Demographic, clinical, and psychosocial details were collected using a validated self-completion questionnaire. Data were collected from 67 patients who had undergone surgery. RESULTS: Forty-five percent were seizure-free. There were significant differences (P<0.001) between the seizure-free (SF) and continuous seizure (CS) groups with respect to anxiety, depression, impact of epilepsy, self-esteem, mastery, stigma, affect balance, self-reported health, and quality of life. More SF patients were also employed and driving (P<0.001). Despite these differences there were no differences for regret over surgery but there were differences for satisfaction and success ratings. CONCLUSIONS: Patients who were not SF, in the longer term, had little regret undergoing surgery but were less likely to be satisfied and had a poorer psychosocial profile.