Practice parameter: temporal lobe and localized neocortical resections for epilepsy: report of the Quality Standards Subcommittee of the American Academy of Neurology, in association with the American Epilepsy Society and the American Association of Neurological Surgeons

Subtypes of medial temporal lobe epilepsy: influence on temporal lobectomy outcomes?

Surgical resection of the hippocampus is the most successful treatment for medication-refractory medial temporal lobe epilepsy (MTLE) due to hippocampal sclerosis. Unfortunately, at least one of four operated patients continue to have disabling seizures after surgery, and there is no existing method to predict individual surgical outcome. Prior to surgery, patients who become seizure free appear identical to those who continue to have seizures after surgery. Interestingly, newly converging presurgical data from magnetic resonance imaging (MRI) and intracranial electroencephalography (EEG) suggest that the entorhinal and perirhinal cortices may play an important role in seizure generation. These areas are not consistently resected with surgery and it is possible that they continue to generate seizures after surgery in some patients. Therefore, subtypes of MTLE patients can be considered according to the degree of extrahippocampal damage and epileptogenicity of the medial temporal cortex. The identification of these subtypes has the potential to drastically improve surgical results via optimized presurgical planning. In this review, we discuss the current data that suggests neural network damage in MTLE, focusing on the medial temporal cortex. We explore how this evidence may be applied to presurgical planning and suggest approaches for future investigation.

Temporal lobe epilepsy surgery: what do patients want to know?

Patients with pharmacoresistant temporal lobe epilepsy (TLE) contemplating brain surgery must make a complex treatment decision involving trade-offs. Patient decision aids, containing information on the risks and benefits of treatment interventions, increase patient knowledge and facilitate shared decision making between patients and physicians. We conducted five focus groups to describe the information patients need to make informed decisions about TLE surgery. Twenty patients who had undergone TLE surgery described the information used in their decision-making process, and evaluated the potential for a patient decision aid to assist other patients who are considering surgery. Thematic analysis revealed information needs that were both experiential (i.e., learning about other patients' experiences through testimonials) and factual (i.e., individualized statistical information). Patients also made suggestions on how this information should be delivered to patients. These data will accelerate the development of a patient decision aid designed to assist TLE patients in their decision making about epilepsy surgery.

Response to first antiepileptic drug trial predicts health outcome in epilepsy

PURPOSE

Failure to respond to the initial antiepileptic drug (AED) is a predictor of increased risk of pharmacoresistant epilepsy. Whether response to the first AED also predicts adverse health outcomes is unknown.

METHODS

This longitudinal study compared rates of major adverse health outcomes (loss of driving privileges, unemployment, divorce/separation, injury, emergency room admission, hospitalization, and death) in 33 patients who failed the first AED (cases) and 30 patients who became seizure-free with the first AED (controls). Patient data were obtained by chart review and confirmed through a structured interview with each subject at 5-7 years after starting AED treatment. We also assessed between-group differences in quality of life, depression, and adverse AED effects by using standardized instruments completed by each subject at the end of follow-up.

KEY FINDINGS

The number of major adverse health outcomes was similarly high during the first year of AED treatment [mean ± standard deviation (SD) 2.64 ± 0.99 for cases and 2.50 ± 1.14 for controls], but thereafter decreased to a greater extent in controls than in cases (p < 0.001). Controls had a higher cumulative probability of experiencing ≥1 year free from major adverse health outcomes compared to cases (p = 0.002). Two cases died during the follow-up, both of sudden unexpected death. Cases had worse quality of life ratings than controls, whereas no significant between-group differences were found for measures of depression and adverse AED effects. In a post hoc analysis limited to cases, patients who became seizure-free with subsequent AED treatments showed for the first 4 years major adverse health outcome rates similar to those recorded in patients with persisting seizures. After 4 years, however, cases who achieved late seizure freedom tended to show a more favorable outcome.

SIGNIFICANCE

Patients with epilepsy failing the initial AED trial are at increased risk of experiencing adverse health outcomes, at least for the first 4 years after diagnosis. Incorporating these findings into clinical decision making may aid in reducing delays in surgical referrals for pharmacoresistant epilepsy.

Neurologists' and neurology residents' knowledge of issues related to pregnancy for women with epilepsy

We aimed to assess physician knowledge for 2009 guidelines established by the American Academy of Neurology and American Epilepsy Society regarding issues related to pregnancy for women with epilepsy. A questionnaire was developed and distributed to all neurologists and neurology residents practicing in a large Canadian health region serving a population of 1.4 million. Descriptive statistics were obtained and percentage of correct responses was calculated. Forty-five physicians completed the survey (response rate = 83.3%), with a median correct score of 50%. Residents were more likely (93.3%) to state that this information was important to their practice than staff physicians (40.0%). Overall knowledge of outcomes associated with specific AEDs was poor; less than half of the physicians correctly indicated which AEDs were associated with adverse outcomes for the majority of drug-related questions. We recommend multifaceted, interactive implementation strategies for increasing knowledge of guideline contents.

GABBR1 gene polymorphism(G1465A)isassociated with temporal lobe epilepsy

PURPOSE

γ-Aminobutyric acid B receptor 1(GABBR1) gene G1465A polymorphism has been considered as a potential risk factor for the development of temporal lobe epilepsy (TLE). However, the results were inconsistent. In this study, we performed a meta-analysis to assess the association between GABBR1 G1465A polymorphism and the risk of TLE.

METHODS

Biomedical literature databases including PubMed, ISI web of science and Embase were searched. The studies evaluating the association between GABBR1 G1465A polymorphism and TLE were included. Pooled odds ratio (OR) and 95%CI confidence interval (CI) were calculated using fixed- or random-effects model.

KEY FINDINGS

Seven studies (1011 cases and 2184 controls) met the inclusion criteria and were included in the meta-analysis. The overall result showed that the association between GABBR1 G1465A polymorphism was statistically significant (OR=5.381, 95%CI: 1.726, 16.776, P=0.004). Subgroup analysis showed that the effect estimate was higher in the studies with high quality score (OR=14.220, 95%CI: 6.933, 29.169, P=0.000) than that in the studies with low quality score (OR=1.158, 95%CI: 0.325, 4.123, P=0.821).

SIGNIFICANCE

The present meta-analysis suggests that GABBR1 G1465A polymorphism is associated with the risk of TLE. The role of GABBR1 G1465A polymorphism in the development of TLE merits further investigation.

Surgical management of intractable childhood epilepsy: curative and palliative procedures

Epilepsy surgery is increasingly used to treat intractable childhood-onset epilepsy although it remains an underused treatment option. Advances in technology allowing more accurate identification of the epileptogenic zone along with a better understanding of the benefits of both curative and palliative epilepsy surgery have resulted in an increase of potential candidates. This review covers factors contributing to medical intractability and then details the evaluation of potential surgical candidates. We discuss pre-, peri-, and postoperative variables that lead to curative procedures and highlight the role of palliative epilepsy surgery in cases in which seizure freedom is unlikely.

Determinants of quality of life after epilepsy surgery: systematic review and evidence summary

We systematically reviewed evidence-based determinants of health-related quality of life (QOL) in adults undergoing epilepsy surgery and assessed the effect of study methods. Medline, Embase, and the Cochrane library (1950-2008) were searched systematically. Two authors independently performed every step of the review. We obtained the proportion of studies reporting statistically significant positive or negative impact on QOL. Of 39 eligible studies, 32 assessed the impact of surgery on QOL and 29 (90.6%) found a significant positive effect. The most prevalent preoperative determinant was psychological function. Seizure freedom was the most prevalent postoperative determinant (80% of studies), followed by antiepileptic drug adverse events, employment status, and psychological function. Psychosocial (95%), physical (91%), and overall QOL (90%) domains improved most frequently, whereas role limitation (63%) and cognition (78%) improved least frequently. Methods, choice of instrument, and time of measurement influenced QOL outcomes and should be carefully chosen in future studies.

Double inversion recovery magnetic resonance imaging (MRI) in the preoperative evaluation of hippocampal sclerosis: correlation with volumetric measurement and proton magnetic resonance spectroscopy (¹H MRS)

OBJECTIVE

To determine whether the finding of hyperintense hippocampal signal intensity on double inversion recovery (DIR) magnetic resonance imaging is correlated with hippocampal volume loss and metabolic abnormalities in patients with mesial temporal lobe epilepsy (MTLE).

METHODS

This retrospective study had institutional review board approval, and informed consent was obtained. Thirteen patients with unilateral hippocampal sclerosis and 13 age-matched healthy control subjects were included. Quantitative assessment for hippocampus of the patients and the control subjects was determined, including DIR, 3-dimensional T1-weighted imaging and proton magnetic resonance spectroscopy. Hippocampal relative signal intensity on DIR images (RSIDIR), volumes, and N-acetylaspartate-to-choline and creatine/phosphocreatine ratios were measured during one magnetic resonance imaging session, and asymmetry indexes (AI) of bilateral hippocampi were calculated. Hippocampal RSIDIR and AIDIR were compared between the patients and the control subjects. The RSIDIR and AIDIR were further correlated with the quantitative MR measures and with the age at onset and duration of MTLE. Statistical analyses were performed with Student t test, 1-way analysis of variance, and Pearson correlation.

RESULTS

On DIR images, the hippocampi ipsilateral to the seizure focus demonstrated relatively extreme hyperintensity. The ipsilateral hippocampi showed significantly increased RSIDIR compared with contralateral hippocampi and the healthy subjects (F = 197.956, P < 0.001). The hippocampal AIDIR in the patients was also significantly higher than that in the control group (t = 24.896, P < 0.001). Significant Pearson correlations (2-tailed) were obtained between the RSIDIR and the volume of the ipsilateral hippocampi (r = -0.762, P < 0.01) and between the RSIDIR and duration of epilepsy (r = 0.557, P < 0.05). Moreover, there were significant correlations between the AIDIR and the AIvolume (r = 0.609, P < 0.05) and between the AIDIR and the duration of epilepsy (r = 0.610, P < 0.05). However, no significant correlations of hippocampal DIR measures with proton magnetic resonance spectroscopy were obtained.

CONCLUSIONS

Double inversion recovery imaging of the brain can yield complementary information about hippocampal pathology and efficiently lateralize the hippocampal sclerosis in patients with MTLE.

Ictal high-frequency oscillations in neocortical epilepsy: implications for seizure localization and surgical resection

PURPOSE

To investigate the characteristics of intracranial ictal high-frequency oscillations (HFOs).

METHODS

Among neocortical epilepsy patients who underwent intracranial monitoring and surgery, we studied patients with well-defined, unifocal seizure onsets characterized by discrete HFOs (≥70 Hz). Patients with multifocal or bilateral independent seizure onsets, electroencephalography (EEG) acquired at <1,000 Hz sampling rate, and nonresective surgery were excluded. Based on a prospectively defined protocol, we defined the seizure-onset zone (SOZ) presurgically to include only those channels with HFOs that showed subsequent sustained evolution (HFOs+ channels) but not the channels that lacked evolution (HFOs- channels). We then resected the SOZ as defined above, 1 cm of the surrounding cortex, and immediate spread area, modified by the presence of eloquent cortex in the vicinity. For purposes of this study, we also defined the SOZ based on the conventional frequency activity (CFA, <70 Hz) at seizure onset, although that information was not considered for preoperative determination of the surgical boundary. We investigated the temporal and spatial characteristics of the ictal HFOs post hoc by visual and spectral methods, and also compared them to the seizure onset defined by the CFA.

KEY FINDINGS

Of 14 consecutive neocortical epilepsy patients, six patients met the inclusion criteria. Magnetic resonance imaging (MRI) was normal or showed heterotopia. All had subdural electrodes, with additional intracerebral depth electrodes in some. Electrode coverage was extensive (median 94 channels), including limited contralateral coverage. Seizure onsets were lobar or multilobar. Resections were performed per protocol, except in two patients where complete resection of the SOZ could not be done due to overlap with speech area. Histology was abnormal in all patients. Postoperative outcome was class I/II (n = 5, 83%) or class III over a mean follow-up of 27 months. Post hoc analysis of 15 representative seizures showed that the ictal HFOs were widespread at seizure onset but evolved subsequently with different characteristics. In contrast to HFOs-, the HFOs+ were significantly higher in peak frequency (97.1 vs. 89.1 Hz, p = 0.001), more robust (nearly twofold higher peak power, p < 0.0001), and spatially restricted [mean 12.2 vs. 22.4 channels; odds ratio (OR) 0.51, 95% confidence interval (CI) 0.42-0.62; p < 0.0001]. The seizure onset defined by HFOs+ was earlier (by an average of 0.41 s), and occurred in a significantly different and smaller distribution (OR 0.27, 95% CI 0.21-0.34, p < 0.0001), than the seizure onset defined by the CFA. As intended, the HFOs+ channels were 10 times more likely to have been resected than the HFOs- channels (OR 9.7, 95% CI 5-17, p < 0.0001).

SIGNIFICANCE

Our study demonstrates the widespread occurrence of ictal HFOs at seizure onset, outlines a practical method to localize the SOZ based on their restricted pattern of evolution, and highlights the differences between the SOZs defined by HFOs and CFA. We show that smaller resections, restricted mainly to the HFOs channels with evolution, can lead to favorable seizure outcome. Our findings support the notion of widespread epileptic networks underlying neocortical epilepsy.

Long-term seizure and psychosocial outcomes of epilepsy surgery

Most results reported in studies focusing on long-term outcomes of epilepsy surgery resemble those reported in studies with shorter follow-up, indicating that many of the surgical results are enduring. In general, about 60% of patients with temporal epilepsy and 25% to 40% of those with extratemporal epilepsy achieve long-term seizure freedom after epilepsy surgery. Over a long term, about 20% of patients discontinue antiepileptic drugs, whereas 41% continue monotherapy and 31% use polytherapy. Evidence concerning the impact of epilepsy surgery on mortality is inconclusive, but some data support a reduction in the risk of death if patients become seizure-free. The information regarding long-term cognitive outcomes is limited but is similar to that derived from short-term studies. Decline in verbal memory occurs frequently after resections of the left temporal lobe; better memory outcomes are reported in seizure-free patients, and memory decline has been documented in patients with intractable epilepsy who do not undergo surgery. However, important confounders such as the effects of antiepileptic drugs, practice effects, and regression to the mean have not been adequately accounted for in these studies. All uncontrolled long-term studies report improved psychosocial outcomes with epilepsy surgery, including employment, education, driving status, satisfaction, and quality of life, but the results of the few existing controlled studies are less persuasive.

Epilepsy surgery in Argentina: long-term results in a comprehensive epilepsy centre

RATIONALE

Epilepsy surgery procedures started in Argentina more than 50 years ago. This is the first comprehensive and systematic survey of epilepsy surgery long-term outcome from our country.

METHODS

A descriptive cohort study was conducted between 1998 and 2008 for drug-resistant epilepsy surgery with a minimum of 12 months follow-up (n=110). In 84 cases (76.36%) resective surgery was performed, and outcome periodically assessed using the Engel score. Patients were stratified into groups: 12, 13-36, 37-60 and over than 60 months of follow-up. Video-EEG with and without intracranial electrode implants, intraoperative electrocorticograms, Wada tests, pathology reports, use of antiepileptic drugs (AEDs), and surgical complication rates were evaluated.

RESULTS

Surgical techniques included: 69 lobectomies (62.7%), 15 lesionectomies (13.6%), 6 callosotomies (5.4%), 6 multiple subpial transection (5.4%), 11 vagus nerve stimulations (10%), 3 hemispherectomies (2.7%). Male: female ratio: 1/1.44. Mean age at time of surgery: 26.2 years. Mean duration of epilepsy: 14 years. Age at seizure onset: 11.5 years. Mean follow-up: 46 months. Pathology findings: mesial temporal sclerosis 32 (35.1%); dual pathology 17 (18.7%); cortical dysplasia 15 (16.4%); non-specific inflammatory changes 11 (12.1%); tumors 7 (7.7%); other 6 (6.8%). Engel scores at 12 months follow-up: 72.6% (61) class I, 16.6% (14) class II and 15.5% (13) class III-IV; 13-36 months after surgery: 68.1% of cases were class I, 15.9% class II and 15.5% class III-IV. After 37-60 months, 74% class I, 14% class II, 14% class III-IV. Over 60 months (n=45) 78% class I, 13.5% class II and 8.1% class III-IV.

CONCLUSION

Conducting a successful epilepsy surgery program in a developing country is challenging. These results should encourage specialists in these countries. Long-term outcome results comparable to centres in developed countries can be achieved.

A Novel Postoperative Seizure Classification for Long-term Mortality of Patients With Intractable Epilepsy: Comparison With the Engel System

BACKGROUND:

To explore the association of clinical seizure pattern with the long-term prognosis after epilepsy surgery is important for patient counseling and risk management.

OBJECTIVE:

To study the long-term mortality after surgery of intractable epilepsy patients with a novel classification of clinical patterns by long-term frequency and duration of seizure compared with the Engel classification.

METHODS:

We conducted a longitudinal cohort study by enrolling 280 patients with epilepsy who underwent anterior temporal lobectomy between 1987 and 2002. In addition to the Engel classification, we proposed a novel classification of clinical patterns pertaining to at least 1 year of follow-up of the frequency and duration of seizures after surgery (inactive, delayed, intermittent, and intensive groups). We followed the vital status of these members until 2007 to obtain a 15-year survival rate for each classification. The standardized mortality ratio and hazard ratios with proportional hazards regression model by the extent of severity were estimated.

RESULTS:

The overall 15-year survival rate for patients who underwent anterior temporal lobectomy was 95.1%. The standardized mortality ratio estimates (95% confidence interval) for our classification showed a gradient relationship from 0.6 (0.1-2.3), 2.5 (0.7-6.3), 7.6 (0.8-27.3), and 8.9 (3.2-19.3) for inactive, delayed, intermittent, and intensive groups, respectively (Trend test, P = .04), whereas the corresponding estimates were 0.8 (0.2-2.2), 5.9 (1.2-17.2), 6.7 (2.5-14.7), and 7.2 (0.8-25.9) for Engel I to IV, respectively, which showed a less increasing trend (Trend test, P = .82). Similar findings were noted for hazard ratios for the 2 classifications.

CONCLUSION:

The proposed novel classification with long-term observed frequency and duration of seizures after surgery is more informative for predicting long-term mortality than the Engel classification.

Identifying epilepsy surgery candidates in the outpatient clinic

Epilepsy is the most prevalent disabling neurological disorder across the life span, and is not controlled by medications in more than one-third of patients. Epilepsy surgery is an accepted treatment, with guidelines supporting utilization in patients with recurrent temporal lobe seizures after two or more trials of antiepileptic medications. Unfortunately, the average delay in presurgical evaluation of appropriate candidates is more than 20 years, and this delay has not improved in recent decades. This offers the international neurological community the opportunity to improve disability, mortality, and quality of life by more effective application of epilepsy surgery and earlier identification of potential candidates. Optimal use of MRI and video/EEG monitoring should allow cost-effective screening of persons with recurrent seizures prior to more detailed presurgical evaluation when indicated.

Apical temporal lobe resection; "tailored" hippocampus-sparing resection based on presurgical evaluation data

BACKGROUND

It is the aim of epilepsy surgery in patients with lesional epilepsy for the surgeon to not only remove the lesion itself, but also the epileptogenic zone. Here, we report our experience with a modified temporal resection technique confined to the apical temporal lobe, i.e., sparing the hippocampal formation in patients with epileptogenic lesions in the anterior part of the temporal lobe. This apical temporal lobe resection (aTLR) includes tailored lesionectomy, amygdalectomy, and resection of the mesial structures only in the apex of the temporal lobe. This paper presents our surgical technical details and the outcome of aTLR.

METHODS

Between 2001 and 2008, aTLR was performed in 61 patients. All patients underwent comprehensive presurgical evaluation including video-EEG monitoring, magnetic resonance imaging (MRI), and neuropsychological testing. All patients had a lesion in the apex of the temporal lobe and a normal hippocampus as seen in MRI, as well as intact memory functions in neuropsychological examination. There were 33 males (54.1%) and 28 females (45.9%). The mean age in years at epilepsy onset was 20.2 ± 13.4, the mean age at epilepsy surgery was 32.1 ± 11.9, the mean preoperative epilepsy duration was 11.8 ± 8.8 years and the mean duration of follow-up was 2.1 ± 1.3 years (range 0.5-6 years).

RESULTS

Fifty-four (88.5%) of 61 patients were in Engel Class 1 at 6 months, 38 (80.9%) of 47 at 2 years and nine (81.8%) of 11 at the 5 year follow-up. Histopathological examination showed tumors in 31 patients, FCD in ten patients, amygdala sclerosis in seven patients, cavernomas in six patients, unspecific reactions in eight patients, and gliosis in one patient. Surgical complications occurred in four patients: one had a permanent and three had transient complications which could be successfully treated. Fifty (82%) resections were considered to be complete resections as evaluated by serial postoperative MRI, seven patients (11.5%) had incomplete resection of the preoperative MRI lesion and in four patients (6.6%) it remained unclear. Fifteen patients (29.4%) were withdrawn from antiepileptic drugs for more than 2 years without relapse. Postoperative neuropsychological examination revealed worsening of memory performance in two patients (3.2%) and improved or no changes in the rest of the patients.

CONCLUSIONS

Apical temporal resection sparing the mesial temporal structures is an effective procedure with good long-term seizure outcome in patients with refractory epilepsy due to lesions confined to the apex of the temporal lobe.

From the American Epilepsy Society 2009 Annual Course. Non-substrate-directed epilepsy and surgery: PRO and CON

The surgical treatment of epilepsy is the most efficacious therapeutic modality for patients with a medically refractory partial seizure disorder. Epilepsy surgery has been demonstrated to be both effective and well tolerated in individuals with medial temporal lobe epilepsy associated with mesial temporal sclerosis. The identification of an MRI pathological substrate may be useful in identifying the epileptogenic zone and the appropriate operative strategy, and is predictive of the long-term seizure outcome. Patients with a non-substrate-directed partial epilepsy often require a more rigorous presurgical evaluation because of issues regarding the lateralization and localization of the epileptic brain tissue. The surgical outcome may be most disappointing in individuals with localization-related epilepsy of extratemporal origin associated with a normal MRI study. The present discussion focuses on the selection of patients with extratemporal non-substrate-directed epilepsy for a presurgical evaluation. The important factors associated with an improved quality of life subsequent to epilepsy surgery include seizure remission and avoidance of operation-induced adverse effects.

Efficacy of vagus nerve stimulation for refractory epilepsy among patient subgroups: a re-analysis using the Engel classification

Optimal candidates for VNS as a treatment for refractory epilepsy have not been identified. In this retrospective two-center study, we used the Engel classification for evaluating seizure outcome, and tried to identify predictive factors for outcome by means of subgroup analysis. The medical records of patients who have been treated with VNS for at least one year at Dartmouth-Hitchcock Medical Center and Ghent University Hospital were evaluated. Seizure frequency outcome was assessed using the Engel classification for the study population as a whole, and for patient subgroups with regard to mental functioning, seizure type, predisposing factors for developing epilepsy, age at time of VNS implantation and epilepsy duration. 189 patients (102M/87F) were included in the study (mean FU: 41 months). 6% had a class I outcome (seizure-free), 13% a class II outcome (almost seizure-free), 49% a class III outcome (worthwhile improvement) and 32% had a class IV outcome (no improvement). When patients were divided into specific subgroups, a statistically significant better outcome was found patients with normal mental functioning (p=0.029). In our series, results for VNS are clearly inferior to resective surgery, but comparable to other treatment modalities for refractory epilepsy. With combined class I and II outcomes around 20%, and another 50% of patients having worthwhile improvement, VNS is a viable alternative when resective surgery is not feasible.

Robustness of implantable algorithms to detect epileptiform activity in the presence of broad-spectrum background noise

Detection of epileptiform activity is of interest for responsive stimulation and diagnostic or monitoring devices in epilepsy; some implantable systems use low-computational-complexity algorithms such as line length trending and half-wave detection. Broadband noise was added to recorded electrocorticographic signals in order to model the potential impact of factors such as electrode-tissue interface properties and distance from the epileptic focus on these detection tools. Simulation demonstrated that half-wave and line length tools can yield consistent results in the presence of moderate amounts of noise.

Design considerations for a multicenter randomized controlled trial of early surgery for mesial temporal lobe epilepsy

PURPOSE

To describe the trial design for the multicenter Early Randomized Surgical Epilepsy Trial (ERSET). Patients with pharmacoresistant epilepsy are generally referred for surgical treatment an average of two decades after onset of seizures, often too late to avoid irreversible disability. ERSET was designed to assess the safety and efficacy of early surgical intervention compared to continued pharmacotherapy.

METHODS

ERSET is a randomized controlled, parallel group clinical trial with blinded outcome adjudication. Participants are patients with mesial temporal lobe epilepsy (MTLE) older than the age of 12 who have had pharmacoresistant seizures for not >2 years and are determined by detailed evaluation to be surgical candidates prior to randomization. The primary outcome measure is seizure freedom in the second year of a 2-year follow-up period. Health-related quality of life (HRQOL), neurocognitive function, ancillary outcomes, and adverse events were also measured.

RESULTS

Significant methodologic problems addressed by the study design included the following: recruitment of participants early in the course of epilepsy; establishment of operational definitions for "pharmacoresistant" and "early"; and standardization of diagnostic testing, medical treatment, and surgical interventions across multiple centers.

DISCUSSION

Rigorous trial designs to assess surgical interventions in epilepsy are necessary to provide evidence to guide treatment. This article is the first of a series; trial results will be reported in subsequent publications.

Diverse perspectives on developments in epilepsy surgery

The objective of this article is to review the dramatic changes that have occurred in the field of epilepsy surgery since the founding of Epilepsy Action in 1950. We have chosen to consider these advances from the biomedical perspective (the physician and basic scientist), and the behavioral perspective (the psychologist and the patient). Both these viewpoints are equally important in understanding the evolution of epilepsy surgery over the past 60 years, but may not always be well synchronized.

Epilepsy surgery: recommendations for India

The following article recommends guidelines for epilepsy surgery for India. This article reviews the indications, the various surgical options available and the outcome of surgery for drug resistant epilepsy based on current evidence. Epilepsy surgery is a well-established option for patients who have been diagnosed to have drug resistant epilepsy (DRE) (on at least two appropriate, adequate anti-epileptic drugs (AEDs) (either in monotherapy or in combination) with continuing seizures), where the presurgical work-up has shown concordance of structural imaging (magnetic resonance imaging) and electrical mapping data (electroencephalography (EEG), video EEG). There may be a requirement of functional imaging techniques in a certain number of DRE like positron emission tomography (PET), single photon emission tomography, (SPECT)). Invasive monitoring should be restricted to a few when all noninvasive investigations are inconclusive, there is a dual pathology or there is a discordance of noninvasive data. The types of surgery could be curative (resective surgeries: amygdalo hippocampectomy, lesionectomy and multilobar resections; functional surgeries: hemispherotomy) and palliative (multiple subpial transaction, corpus callosotomy, vagal nerve stimulation). Epilepsy surgery in indicated cases has a success range from 50 to 86% in achieving seizure freedom as compared with <5% success rate with AEDs only in persons with DRE. Centers performing surgery should be categorized into Level I and Level II.

Referral pattern for epilepsy surgery after evidence-based recommendations: a retrospective study

BACKGROUND

Class I evidence for surgical effectiveness in refractory temporal lobe epilepsy (TLE) in 2001 led to an American Academy of Neurology practice parameter in 2003 recommending "referral to a surgical epilepsy center on failing appropriate trials of first-line antiepileptic drugs." We examined whether this led to a change in referral patterns to our epilepsy center.

METHODS

We compared referral data for patients with TLE at our center for 1995 to 1998 (group 1, n = 83) and 2005 to 2008 (group 2, n = 102) to determine whether these recommendations resulted in a change in referral patterns for surgical evaluation. Patients with brain tumors, previous epilepsy surgery evaluations, or brain surgery (including epilepsy surgery) were excluded.

RESULTS

We did not find a difference between the groups in the duration from the diagnosis of habitual seizures to referral (17.1 +/- 10.0 vs 18.6 +/- 12.6 years, p = 0.39) or the age at the time of evaluation (34.1 +/- 10.3 vs 37.0 +/- 11.8 years, p = 0.08). However, there was a difference in the distributions of age at evaluation (p = 0.03) and the duration of pharmacotherapy (p = 0.03) between the groups, with a greater proportion of patients in group 2 with drug-resistant epilepsy both earlier and later in their treatment course. Nonepileptic seizures were referred significantly earlier than TLE in either group or when combined.

CONCLUSIONS

Our analysis does not identify a significantly earlier referral for epilepsy surgery evaluation as recommended in the practice parameter, but suggests a hopeful trend in this direction.

Prescribing pattern of anti-epileptic drugs in an Italian setting of elderly outpatients: a population-based study during 2004-07

AIMS

The aims of the study were to assess the trend of older and newer anti-epileptic drugs (AEDs) in the elderly population and to analyze the effects of a health-policy intervention with regard to AED use in general practice in a setting in Southern Italy.

METHODS

Data were extracted from the 'Caserta-1' Local-Health-Unit Arianna database in the years 2004-07. Patients aged over 65 years, receiving at least one AED prescription and registered in the lists of 88 general practitioners, were selected. The use of older and newer AEDs was calculated as 1 year prevalence and incidence of use and defined daily dose (DDD) per 1000 inhabitants day(-1) . Sub-analyses by gender, age and indication of use were performed.

RESULTS

Most of AED users were treated because of neuropathic pain (64.8%). However, the main indication of use for older AEDs (57.8%) was epilepsy, whereas newer AEDs (79.5%) were used for neuropathic pain. Prevalence and incidence of newer AED use increased until 2006, followed by a reduction in 2007. Newer AEDs, particularly gabapentin and pregabalin, were used in the treatment of more patients than older AEDs. However phenobarbital, accounting for more than 50% of total AED volume, was the most prescribed medication during the entire study period.

CONCLUSIONS

An increasing use of AEDs has been observed during 2004-07, mostly due to the prescription of newer compounds for neuropathic pain. The fall in the use of newer AEDs during 2007 coincides with revised re-imbursement criteria for gabapentin and pregabalin. The large use of phenobarbital in the elderly should be considered in the light of a risk of adverse drug reactions.

Comparison between Initial and Recent Surgical Outcome of 15-Year Series of Surgically Remediable Epilepsy

OBJECTIVE

The aim of this study is to compare the surgical outcome of the initial and recent surgical cases, during our 15-years experience, in terms of the surgical strategies and the prognostic factors for surgically remediable epilepsy.

METHODS

We retrospectively reviewed and compared the surgical outcomes between the initial 256 (Group I) and recent 139 (Group II) patients according to the time period of operation for a total of 518 consecutive epilepsy surgeries at our institution since 1992. The patients of the middle intermediate period, which were subjected to changed surgical strategies, were excluded.

RESULTS

The surgical outcome data from the initial and recent groups showed a much improved outcome for patients who underwent temporal lobe epilepsy (TLE) surgery over time. The number of patients with a good outcome (Engel class I-II) was much increased from 87.7% (178 TLE cases of Group I) to 94.8% (79 TLE cases of Group II) and this was statistically significant (p = 0.0324) on univariate analysis. Other remarkable changes were the decreased performance of intracranial invasive studies from 43.5% in Group I to 30.9% in Group II due to the advanced neuroimaging tools. The strip/grid ratio was reduced from 131/32 in Group I to 17/25 in Group II, because of a markedly reduced mesial TLE surgery and an increased extratemporal epilepsy surgery.

CONCLUSION

Our results show that surgical outcome of epilepsy surgery has improved over time and it has shown to be efficient to control medically intractable epilepsy. Appropriate patient selection, comprehensive preoperative assessments and more extensive resection are associated with good postoperative outcomes.

Electroencephalographic features of temporal lobe epilepsy

Electroencephalography (EEG) is an important tool for diagnosing, lateralizing and localizing temporal lobe seizures. In this paper, we review the EEG characteristics of temporal lobe epilepsy (TLE). Several "non-standard" electrodes may be needed to further evaluate the EEG localization, Ictal EEG recording is a major component of preoperative protocols for surgical consideration. Various ictal rhythms have been described including background attenuation, start-stop-start phenomenon, irregular 2-5 Hz lateralized activity, and 5-10 Hz sinusoidal waves or repetitive epileptiform discharges. The postictal EEG can also provide valuable lateralizing information. Postictal delta can be lateralized in 60% of patients with TLE and is concordant with the side of seizure onset in most patients. When patients are being considered for resective surgery, invasive EEG recordings may be needed. Accurate localization of the seizure onset in these patients is required for successful surgical management.

The Art of Managing Conversions between Antiepileptic Drugs: Maximizing Patient Tolerability and Quality of Life

Conversion between anti-epilectic drugs (AEDs) is frequently necessary in epilepsy care, exposing patients to a risk of incurring adverse effects and reduced quality of life. Little practical guidance is available to practitioners to guide conversions between AED monotherapies, or in adding a new adjunctive AED into a polytherapy regimen. This article reviews the impact of adverse effects of AEDs on quality of life in epilepsy patients, then reviews several important patient-related factors such as age, gender, medical and psychiatric co-morbidities, and co-medications that must be considered when selecting AEDs and ensuring tolerable and safe AED conversions. Practical strategies for transitional polytherapy AED conversion are then considered in different commonly encountered clinical scenarios in newly diagnosed and refractory epilepsy care, including inadequate seizure control, intolerable adverse effects, or idiosyncratic safety hazards. Successful conversion between AEDs requires regular monitoring for patient-reported adverse effects and appropriately reactive adjustment of AED therapy to maximize patient quality of life.

Microseizures and the spatiotemporal scales of human partial epilepsy

Focal seizures appear to start abruptly and unpredictably when recorded from volumes of brain probed by clinical intracranial electroencephalograms. To investigate the spatiotemporal scale of focal epilepsy, wide-bandwidth electrophysiological recordings were obtained using clinical macro- and research microelectrodes in patients with epilepsy and control subjects with intractable facial pain. Seizure-like events not detectable on clinical macroelectrodes were observed on isolated microelectrodes. These 'microseizures' were sparsely distributed, more frequent in brain regions that generated seizures, and sporadically evolved into large-scale clinical seizures. Rare microseizures observed in control patients suggest that this phenomenon is ubiquitous, but their density distinguishes normal from epileptic brain. Epileptogenesis may involve the creation of these topographically fractured microdomains and ictogenesis (seizure generation), the dynamics of their interaction and spread.

Epilepsy and cognition

It is well known that neuropsychological impairment can be associated with chronic epilepsy. This review suggests that a broad lifespan perspective of cognition in epilepsy should include consideration of: a) neurobiological factors that antedate the first seizure and influence cognition, b) epilepsy-related factors that influence brain growth and cognitive development after epilepsy is diagnosed and treated, c) clinical epilepsy and other risk factors associated with poor cognitive prognosis in the context of chronic pharmacoresistant epilepsy, and d) the modifiable and non-modifiable risk factors that influence cognitive aging in the general population.

Natural Products in Epilepsy-the Present Situation and Perspectives for the Future

More efficacious and better tolerated treatments for epilepsy are clearly needed. Complementary and alternative medicine (CAM) has a long history of use in certain parts of the world and has gained increasing interest over the last decades in Western countries. In countries with a Western-based type of medical system, people with epilepsy (PWE) take natural products or engage in other forms of CAM mainly to enhance general health, but also to prevent seizures or to alleviate symptoms of comorbidities or side effects of antiepileptic medications. In other countries, well developed medical systems, such as traditional Chinese Medicine and Ayurveda, are often the basis for treating PWE. Based on anecdotal reports of efficacy in PWE, natural products from these and other traditions are increasingly being studied in animal models of epilepsy, and candidates for further clinical development have been identified. It is likely, therefore, that natural products will be further evaluated for safety, tolerability and efficacy in PWE with drug-resistant seizures.

Association between temporal lobe P-glycoprotein expression and seizure recurrence after surgery for pharmacoresistant temporal lobe epilepsy

Surgery is recommended for pharmacoresistant temporal lobe epilepsy (TLE), but seizures recur in approximately one third of patients postsurgery. P-glycoprotein is an efflux multidrug transporter that is overexpressed in a range of epileptogenic pathologies. We hypothesized that increased expression of P-glycoprotein in the epileptogenic temporal lobe might be a marker for recurrence of pharmacoresistant seizures postsurgery. We performed immunohistochemistry on temporal lobe tissues resected from 69 patients who underwent anterior temporal lobectomy for pharmacoresistant TLE with histopathological proven hippocampal sclerosis. P-glycoprotein expression was rated by three pathologists independently. Patients with seizure recurrence (n=22) had greater number of positively stained capillaries (p=0.001) and higher P-glycoprotein immunoreactive score in capillaries (p=0.002) in the white matter of resected temporal lobe. The differences remained significant in multivariate analysis (p=0.002 and 0.006, respectively). The results suggest that P-glycoprotein expression in temporal lobe may be associated with seizure recurrence after surgery for pharmacoresistant TLE.

Extent of neocortical resection and surgical outcome of epilepsy: intracranial EEG analysis

PURPOSE

Intracranial electroencephalography (EEG) monitoring is an important process in the presurgical evaluation for epilepsy surgery. The objective of this study was to identify the ideal resection margin in neocortical epilepsy guided by subdural electrodes. For this purpose, we investigated the relationship between the extent of resection guided by subdural electrodes and the outcome of epilepsy surgery.

METHODS

Intracranial EEG studies were analyzed in 177 consecutive patients who had undergone resective epilepsy surgery. We reviewed various intracranial EEG findings and resection extent. We analyzed the relationships between the surgical outcomes and intracranial EEG factors: the frequency, morphology, and distribution of ictal-onset discharges, the propagation speed, and the time lag between clinical and intracranial ictal onset. We also investigated whether the extent of resection, including the area showing ictal rhythm and various interictal abnormalities--such as frequent interictal spikes, pathologic delta waves, and paroxysmal fast activity--influenced the surgical outcome.

RESULTS

Seventy-five patients (42%) were seizure free. A seizure-free outcome was significantly associated with a resection that included the area showing ictal spreading rhythm during the first 3 s or included all the electrodes showing pathologic delta waves or frequent interictal spikes. However, subgroup analysis revealed that the extent of resection did not affect the surgical outcome in lateral temporal lobe epilepsy.

CONCLUSIONS

The extent of resection is closely associated with surgical outcome, especially in extratemporal lobe epilepsy. Resection that includes the area with total pathologic delta waves and frequent interictal spikes predicts a good surgical outcome.

Localization of seizure onset area from intracranial non-seizure EEG by exploiting locally enhanced synchrony

For as many as 30% of epilepsy patients, seizures are poorly controlled with medication alone. For some of these patients surgery may be an option: the brain region responsible for seizure onset may be removed surgically. However, this requires accurate delineation of the seizure onset region. Currently, the key to making this determination is seizure EEG. Therefore, EEG recordings must continue until enough seizures are obtained to determine the onset region; this may take about 5 days to several weeks. In some cases these recordings must be done using invasive electrodes, a procedure that includes substantial risk, discomfort and cost. In this paper, techniques are developed that use periods of intracranial non-seizure ("rest") EEG to localize epileptogenic networks. Analysis of intracranial EEG (recorded by surface and/or depth electrodes) of 6 epileptic patients shows that certain EEG channels and hence cortical regions are consistently more synchronous ("hypersynchronous") compared to others. It is shown that hypersynchrony seems to strongly correlate with the seizure onset zone; this phenomenon may in the long term allow to determine the seizure onset area(s) from non-seizure EEG, which in turn would enable shorter hospitalizations or even avoidance of semi-chronic implantations all-together.

Surgical outcomes in lesional and non-lesional epilepsy: a systematic review and meta-analysis

PURPOSES

To provide evidence-based quantitative summary estimates of seizure outcomes in patients with non-lesional and lesional epilepsy treated with surgery, and to assess the consistency of results among published studies.

METHODS

An exhaustive literature search identified articles published since 1995, describing outcomes according to lesional status in patients of any age who underwent resective epilepsy surgery. Two reviewers independently assessed study eligibility and extracted the data. Disagreements were resolved through discussion. Random effects meta-analyses were used after assessing the dataset for heterogeneity.

RESULTS

Forty articles fulfilled eligibility criteria and described outcomes in 697 patients with non-lesional epilepsy and 2860 patients with lesional epilepsy. Overall, the odds of being seizure-free after surgery were 2.5 times higher in patients with lesions on MRI or histopathology (OR 2.5, 95%CI 2.1, 3.0, p<0.001). In patients with temporal lobe epilepsy surgery the odds were 2.7 times higher in those with lesions (OR 2.7, 95%CI 2.1, 3.5, p<0.001). In patients with extratemporal epilepsy surgery the odds were 2.9 higher in those with lesions (OR 2.9, 95%CI 1.6, 5.1, p<0.001). Outcomes were similar in children, adults, and studies that used MRI or histopathology to identify lesions.

DISCUSSION

Overall, the odds of seizure freedom after surgery are two to three times higher in the presence of a lesion on histopathology or MRI. The results are clinically and statistically significant, consistent across various subgroups, and quite homogeneous across studies.

Electrophysiological and auditory behavioral evaluation of individuals with left temporal lobe epilepsy

The purpose of this study was to determine the repercussions of left temporal lobe epilepsy (TLE) for subjects with left mesial temporal sclerosis (LMTS) in relation to the behavioral test-Dichotic Digits Test (DDT), event-related potential (P300), and to compare the two temporal lobes in terms of P300 latency and amplitude. We studied 12 subjects with LMTS and 12 control subjects without LMTS. Relationships between P300 latency and P300 amplitude at sites C3A1,C3A2,C4A1, and C4A2, together with DDT results, were studied in inter-and intra-group analyses. On the DDT, subjects with LMTS performed poorly in comparison to controls. This difference was statistically significant for both ears. The P300 was absent in 6 individuals with LMTS. Regarding P300 latency and amplitude, as a group, LMTS subjects presented trend toward greater P300 latency and lower P300 amplitude at all positions in relation to controls, difference being statistically significant for C3A1 and C4A2. However, it was not possible to determine laterality effect of P300 between affected and unaffected hemispheres.