Reduction of AEDs in postsurgical patients who attain remission

Beyond seizure freedom: Reduction in anti-seizure medication after epilepsy surgery

INTRODUCTION

Patients considering therapeutic epilepsy surgery often seek to decrease the number of anti-seizure medications (ASMs) they need. Predicting such reductions remains challenging. Although predictors of seizure freedom after epilepsy surgery are well-established, long-term outcomes remain modest and factors associated with ASM reduction, even in the absence of seizure freedom, may improve surgical planning to align with patient goals.

METHODS

We studied a large multi-institutional cohort of patients who underwent epilepsy surgery between 2001 and 2022, with a minimum of two years follow-up. Preoperative features, including duration of epilepsy, epilepsy etiology, non-invasive investigation data, and total number of ASMs prescribed immediately prior to surgery were extracted for each patient. Primary endpoints included likelihood of ASM reduction and ASM freedom at multiple post-operative time points up to 15 years and stratified by seizure control.

RESULTS

A total of 250 patients were followed for a median of 6.0 (range 2, 22) years after intracranial EEG (iEEG) surgery. Significant ASM reduction was only observed in those who underwent subsequent resection, whereas those undergoing neuromodulation saw their ASM usage maintained. Engel I outcomes were the strongest driver of ASM reduction. In patients with persistent seizures, patients with lateralized seizure onset zones (SOZs) also achieved sustained ASM reduction over time. Similarly, an increased number of preoperative ASMs also corresponded to a higher likelihood of ASM reduction across all follow-up periods. Other preoperative factors, including seizure etiology, did not independently influence ASM reduction.

CONCLUSIONS

Even patients with persistent seizures after epilepsy surgery can observe meaningful ASM reduction during long-term follow-up. ASM reduction may be a relevant secondary outcome measure for epilepsy surgery.

Characterization of anti-seizure medication reduction and discontinuation rates following epilepsy surgery

OBJECTIVE

Many patients pursue epilepsy surgery with the hope of reducing or stopping anti-seizure medications (ASMs), in addition to reducing their seizure frequency and severity. While ASM decrease is primarily driven by surgical outcomes and patient preferences, preoperative estimates of meaningful ASM reduction or discontinuation are uncertain, especially when accounting for the various forking paths possible following intracranial EEG (iEEG), including resection, neuromodulation, or even the absence of further surgery. Here, we characterize in detail the ASM reduction in a large cohort of patients who underwent iEEG, facilitating proactive, early counseling for a complicated cohort considering surgical treatment.

METHODS

We identified a multi-institutional cohort of patients who underwent iEEG between 2001 and 2022, with a minimum of two years follow-up. The total number of ASMs prescribed immediately prior to surgery, choice of investigation modality, and subsequent surgical treatment were extracted for each patient. Primary endpoints included decreases in ASM counts from preoperative baseline to various follow-up intervals.

RESULTS

A total of 284 patients were followed for a median of 6.0 (range 2,22) years after iEEG surgery. Patients undergoing resection saw an average reduction of ∼ 0.5 ASMs. Patients undergoing neuromodulation saw no decrease and trended towards requiring increased ASM usage during long-term follow-up. Only patients undergoing resection were likely to completely discontinue all ASMs, with an increasing probability over time approaching ∼ 10 %. Up to half of resection patients saw ASM decreases, which was largely stable during long-term follow-up, whereas only a quarter of neuromodulation patients saw a reduction, though their ASM reduction decreased over time.

CONCLUSIONS

With the increasing use of stereotactic EEG and non-curative neuromodulation procedures, realistic estimates of ASM reduction and discontinuation should be considered preoperatively. Almost half of patients undergoing resective surgery can expect to reduce their ASMs, though only a tenth can expect to discontinue ASMs completely. If reduction is not seen early, it likely does not occur later during long-term follow-up. Less than a third of patients undergoing neuromodulation can expect ASM reduction, and instead most may require increased usage during long-term follow-up.

Do we have to continue antiseizure medications post surgery in long-term epilepsy associated tumors (LEATs)?

OBJECTIVE

To identify the rate of successful antiseizure medication (ASM) withdrawal after resective surgery in patients with long-term epilepsy-associated tumors (LEATs).

METHODS

A retrospective analysis (from our prospectively archived data) on the post-operative ASM profile of 123 consecutive patients who completed a minimum of 2 years after resection of LEATs for ASM-resistant epilepsy. A comparison between recurred and non-recurred groups in terms of seizure recurrence was used to identify the potential predictors of seizure recurrence whose attributes were further analyzed using univariate and multiple logistic regression analysis. Kaplan-Meier survival curves were used to study the probability of ASM freedom following surgery.

RESULTS

We attempted ASM withdrawal in 102 (82.9 %) patients. Forty-eight (47.1 %) had seizure recurrence while reducing ASM, of which 22 (21.6 %) continued to have seizures even after ASM optimisation. On univariate analysis, presence of pre-operative secondary generalized seizure(s) was the only factor associated with seizure recurrence. At a mean follow-up of 6.1 years, 72 (58.5 %) patients were seizure-free and aura-free at terminal follow-up (53 patients were off any ASM). The cumulative probability of achieving complete ASM-free status was 29 % at fourth year, 42 % at sixth year, 55 % at eighth year, and 59 % at 10th year after surgery.

CONCLUSIONS

Following resective surgery for LEATs, ASM(s) could be successfully discontinued in half of the patients. About one-third of the patients may have recurrent seizures on follow-up. Presence of secondary generalized seizure(s) prior to surgery predicts seizure recurrence, whereas MRI defined completeness of resection will not. This information will help in rationalising decisions on ASM management post-resection.

Early antiseizure medication withdrawal and risk of seizure recurrence in children after epilepsy surgery: A retrospective study

OBJECTIVE

The timing of antiseizure medication (ASM) withdrawal in children after epilepsy surgery remains controversial and lacks recognized standards. Given the various negative effects of ASM on development in children, this study aimed to evaluate the safety and feasibility of early ASM withdrawal after epileptic resection surgery.

METHODS

We retrospectively assessed the seizure outcomes and ASM profiles of children who had undergone epileptic resection surgery between August 2015 and August 2020 and attempted ASM reduction in the early postoperative phase. Tapering the dose of ASM was attempted when children were seizure-free with no interictal epileptiform discharges (IEDs) on electroencephalogram (EEG) for at least 6 months postoperatively.

RESULTS

This study included 145 children with a median follow-up duration of 40 months. Early ASM tapering was attempted postoperatively in 99 (68.3 %) children. Postoperative ASM discontinuation was attempted in 87 (60.0 %) children. Nine (9.1 %) children experienced seizure recurrence during the ASM reduction stage, and 10 (11.5 %) experienced recurrence after ASM discontinuation. Incomplete resection (P = 0.003) and postoperative seizures before ASM tapering (P = 0.003) were independent predictors of seizure recurrence during and after early ASM withdrawal.

SIGNIFICANCE

ASM withdrawal is viable and safe to be initiated in children who are seizure-free postoperatively and have no IEDs on the scalp EEG for at least 6 months. Children with incomplete resection and postoperative seizures before ASM withdrawal are at a higher risk of seizure recurrence and may need to continue ASM for a longer period.

Withdrawal of antiseizure medications after MRI-Guided laser interstitial thermal therapy in extra-temporal lobe epilepsy

PURPOSE

This study investigated the success rate of antiseizure medications (ASMs) withdrawal following MRI Guided Laser Interstitial Thermal Therapy (MRg-LITT) for extra-temporal lobe epilepsy (ETLE), and identified predictors of seizure recurrence.

METHODS

We retrospectively assessed 27 patients who underwent MRg-LITT for ETLE. Patients' demographics, disease characteristics, and post-surgical outcomes were evaluated for their potential to predict seizure recurrence associated with ASMs withdrawal.

RESULTS

The median period of observation post MRg-LITT was 3 years (range 18 - 96 months) and the median period to initial ASMs reduction was 0.5 years (range 1-36 months). ASMs reduction was attempted in 17 patients (63%), 5 (29%) of whom had seizure recurrence after initial reduction. Nearly all patient who relapsed regained seizure control after reinstitution of their ASMs regimen. Pre-operative seizure frequency (p = 0.002) and occurrence of acute post-operative seizures (p = 0.01) were associated with increased risk for seizure recurrence post ASMs reduction. At the end of the observation period, 11% of patients were seizure free without drugs, 52% were seizure free with drugs and 37% still experienced seizures despite ASMs. Compared with pre-operative status, the number of ASMs was reduced in 41% of patients, unchanged in 55% of them and increased in only 4% of them.

CONCLUSIONS

Successful MRg-LITT for ETLE allows for ASMs reduction in a significant portion of patients and complete ASMs withdrawal in a subset of them. Patients with higher pre-operative seizure frequency or occurrence of acute post operative seizures exhibit higher chances relapse post ASMs reduction.

Withdrawal of antiepileptic drugs after stereotactic laser amygdalohippocampotomy for mesial temporal lobe epilepsy

OBJECTIVE

This retrospective study investigated the success rate of withdrawal of antiepileptic drugs (AEDs) following stereotactic laser amygdalohippocampotomy (SLAH) for mesial temporal lobe epilepsy (MTLE), and identified predictors of seizure recurrence.

MATERIALS AND METHODS

We retrospectively assessed 65 patients who underwent SLAH for MTLE (59 lesional). Patients' demographics, disease characteristics and post-surgical outcomes were evaluated for their potential to predict seizure recurrence associated with withdrawal of AEDs.

RESULTS

The mean period of observation post SLAH was 51 months (range 12-96 months) and the mean period to initial reduction of AEDs was 21 months (range 12-60 months). Reduction of AEDs was attempted in 37 patients (57 %) who were seizure free post SLAH and it was successful in approximately 2/3 of them. From the remainder 1/3 who relapsed, nearly all regained seizure control after reinstitution of their AEDs. The likelihood of relapse after reduction of AEDs was predicted only by pre-operative seizure frequency. At the end of the observation period, approximately 14 % of all SLAH patients were seizure free without AEDs and approximately 54 % remained seizure free on AEDs. Compared with preoperative status, the number of AEDs were reduced in 37 % of patients, unchanged in 51 % of them and increased in 12 % of them.

CONCLUSIONS

Successful SLAH for MTLE allows for reduction of AEDs in a significant portion of patients and complete withdrawal of AEDs in a subset of them. Patients with higher pre-operative seizure frequency exhibit a greater chance of relapse post reduction of AEDs.

Ambulatory EEG Usefulness in Epilepsy Management

SUMMARY

Long-term video-EEG monitoring has been the gold standard for diagnosis of epileptic and nonepileptic events. Medication changes, safety, and a lack of recording EEG in one's habitual environment may interfere with diagnostic representation and subsequently affect management. Some spells defy standard EEG because of ultradian and circadian times of occurrence, manifest nocturnal expression of epileptiform activity, and require classification for clarifying diagnostic input to identify optimal treatment. Some patients may be unaware of seizures, have frequent events, or subclinical seizures that require quantification before optimal management. The influence on antiseizure drug management and clinical drug research can be enlightened by long-term outpatient ambulatory EEG monitoring. With recent governmental shifts to focus on mobile health, ambulatory EEG monitoring has grown beyond diagnostic capabilities to target the dynamic effects of medical and nonmedical treatment for patients with epilepsy in their natural environment. Furthermore, newer applications in ambulatory monitoring include additional physiologic parameters (e.g., sleep, detection of myogenic signals, etc.) and extend treatment relevance to patients beyond seizure reduction alone addressing comorbid conditions. It is with this focus in mind that we direct our discussion on the present and future aspects of using ambulatory EEG monitoring in the treatment of patients with epilepsy.

When should we obtain a routine EEG while managing people with epilepsy?

More than eight decades after its discovery, routine electroencephalogram (EEG) remains a safe, noninvasive, inexpensive, bedside test of neurological function. Knowing when a routine EEG should be obtained while managing people with epilepsy is a critical aspect of optimal care. Despite advances in neuroimaging techniques that aid diagnosis of structural lesions in the central nervous system, EEG continues to provide critical diagnostic evidence with implications on treatment. A routine EEG performed after a first unprovoked seizure can support a clinical diagnosis of epilepsy and differentiate those without epilepsy, classify an epilepsy syndrome to impart prognosis, and characterize seizures for antiseizure management. Despite a current viral pandemic, EEG services continue, and the value of routine EEG is unchanged.

Focal cortical dysplasia: etiology, epileptogenesis, classification, clinical presentation, imaging, and management

BACKGROUND

Focal cortical dysplasia (FCD) is the most prevalent cause of intractable epilepsy in children. It was first described by Taylor et al. in 1971. In 2011, the International League against Epilepsy described an international consensus of classification for FCD. However, the exact mechanism causing this pathology remains unclear. The diagnosis and recognition of FCD increase with the advances in neuroradiology and electrophysiology.

FOCUS OF REVIEW

In this paper, we discuss the literature regarding management of FCD with a focus on etiology, pathophysiology, classification, clinical presentation, and imaging modalities. We will also discuss certain variables affecting surgical outcome of patients with FCD.

CONCLUSION

Based on our review findings, it is concluded that surgical management with complete resection of the lesion following preoperative localization of the epileptogenic zone in patients with FCD subtypes can provide a seizure-free outcome.

The Concept of Drug-Resistant Epileptogenic Zone

Resective surgery is the most effective way to treat drug-resistant epilepsy. Despite extensive pre-surgical evaluation, only 30–70% patients would become seizure-free after surgery. New approaches and strategies are needed to improve the outcome of epilepsy surgery. It is commonly observed in clinical practice that antiepileptic drugs (AEDs) could maintain seizure freedom in a large proportion of patients after surgery, who were uncontrolled before the operation. In some patients cessation of AEDs leads to seizure recurrence which, in most cases, can be controlled by resuming AEDs. These observations suggest that the surgery has converted the epilepsy from drug-resistant to drug-responsive, implying that the operation has removed the brain tissue accounting for pharmacoresistance, rather than the pathological substrate of epilepsy (at least not completely). Based on these observations, it is hypothesized that there is a drug-resistant epileptogenic zone (DREZ) which overlaps with the epileptogenic zone (EZ), and has both epileptogenic and drug-resistant properties. DREZ is necessary and sufficient to cause drug-resistant epilepsy, and its remove would render the epilepsy drug-responsive. Testing the hypothesis requires the development of new methods to define the DREZ, which may be used to guide surgical planning when the epileptogenic zone cannot be completely excised. This concept can also help understand the mechanisms of drug-resistant epilepsy, leading to new therapeutic strategies.

Antiepileptic Drug Withdrawal after Surgery in Children with Focal Cortical Dysplasia: Seizure Recurrence and Its Predictors

Background and Purpose

This study investigated the seizure recurrence rate and potential predictors of seizure recurrence following antiepileptic drug (AED) withdrawal after resective epilepsy surgery in children with focal cortical dysplasia (FCD).

Methods

We retrospectively analyzed the records of 70 children and adolescents with FCD types I, II, and IIIa who underwent resective epilepsy surgery between 2004 and 2015 and were followed for at least 2 years after surgery.

Results

We attempted AED withdrawal in 40 patients. The median time of starting the AED reduction was 10.8 months after surgery. Of these 40 patients, 14 patients (35%) experienced seizure recurrence during AED reduction or after AED withdrawal. Half of the 14 patients who experienced recurrence regained seizure freedom after AED reintroduction and optimization. Compared with their preoperative status, the AED dose or number was decreased in 57.1% of patients, and remained unchanged in 14.3% after surgery. A multivariate analysis found that incomplete resection (p=0.004) and epileptic discharges on the postoperative EEG (p=0.025) were important predictors of seizure recurrence after AED withdrawal. Over the mean follow-up duration of 4.5 years after surgery, 34 patients (48.6% of the entire cohort) were seizure-free with and without AEDs.

Conclusions

Children with incomplete resection and epileptic discharges on postoperative EEG are at a high risk of seizure recurrence after drug withdrawal. Complete resection of FCD may lead to a favorable surgical outcome and successful AED withdrawal after surgery.

Postoperative seizure outcome and timing interval to start antiepileptic drug withdrawal: A retrospective observational study of non-neoplastic drug resistant epilepsy

This study aimed to investigate the impact of timing interval to start AED withdraw (TIW) after surgery on the seizure outcome in non-neoplastic drug resistant epilepsy (DRE). TIW were divided into three groups (respectively,<1 year, 1-<2 years, and ≥2 years). The seizure outcome at the different time points after starting AED withdrawal were compared among three groups. Other factors that related to seizure recurrence and TIW were included into the multiple analysis to investigate the predictors of seizure-free. Altogether, 205 patients were involved in the study. 102 individuals (50%) had seizure recurrence and 127 (62%) had seizure-free at the final follow up. 115 of them have attempted AED reduction and had not seizure recurrence before AED reduction. The rate of seizure-free had no significant difference among people with different TIW. Multiple analysis indicated that temporal surgery is a favorable predictor of seizure-free at the first year after starting AED withdrawal, and preoperative secondary generalized seizures is an unfavorable predictor of seizure-free at the final follow up. In patients with non-neoplastic DRE, TIW is not the mainly influence factor on seizure outcome, however, preoperative secondary generalized seizures and extra-temporal surgery are negatively associated with seizure-free.

Outcome after seizure recurrence on antiepileptic drug withdrawal following temporal lobectomy

OBJECTIVE

To study the long-term outcome following seizure recurrence on antiepileptic drug (AED) withdrawal after anterior temporal lobectomy for mesial temporal lobe epilepsy.

METHODS

We retrospectively studied the AED profile of patients who had a minimum of 5 years of postoperative follow-up after anterior temporal lobectomy for mesial temporal lobe epilepsy. Only those patients with hippocampal sclerosis or normal MRI were included. AED withdrawal was initiated at 3 months in patients on ≥2 drugs and at 1 year for patients on a single drug.

RESULTS

Three hundred eighty-four patients with median postoperative follow-up of 12 years (range, 7-17 years) were included. Of them, 316 patients (82.3%) were seizure-free during the terminal 1 year. AED withdrawal was attempted in 326 patients (84.9%). At last follow-up, AEDs were discontinued in 207 patients (53.9%). Seizure recurrence occurred in 92 patients (28.2%) on attempted withdrawal. After a median postrecurrence follow-up of 7 years, 79 (86%) of them were seizure-free during the terminal 2 years. AEDs could be stopped in 17 patients (18.5%) and doses were reduced in another 57 patients (62%). Patients with febrile seizures, normal postoperative EEG at 1 year, and duration of epilepsy of <20 years (FND20 score) had 17% risk of seizure recurrence on attempted AED withdrawal. We also formulated a score to predict the chances of AED freedom for the whole cohort.

CONCLUSION

Patients with seizure recurrence on AED withdrawal have good outcome with 86% becoming seizure-free and 18% becoming drug-free after initial recurrence. A FND20 score helps in predicting recurrence on AED withdrawal.

Uncertainties from a worldwide survey on antiepileptic drug withdrawal after seizure remission

Background

We sought to determine differences in practice for discontinuation of antiepileptic drugs (AEDs) after seizure remission and stimulate the planning and conduction of withdrawal trials.

Methods

We utilized a worldwide electronic survey that included questions about AED discontinuation for 3 paradigmatic cases in remission: (1) focal epilepsy of unknown etiology, (2) temporal lobe epilepsy after surgery, and (3) juvenile myoclonic epilepsy. We analyzed 466 complete questionnaires from 53 countries, including the United States. Statistical analysis included χ² and multivariate logistic regression.

Results

Case 1: responders in practice for <10 years were less likely to taper AEDs: odds ratio (OR) (95% confidence interval [CI]) 0.52 (0.32-0.85), p = 0.02. The likelihood of stopping AEDs was higher among doctors treating children: OR (95% CI): 11.41 (2.51-40.13), p = 0.002. Doctors treating children were also more likely to stop after 2 years or less of remission: OR (95% CI): 6.91 (2.62-19.31), p = 0.002, and the same was observed for US physicians: OR (95% CI): 1.61 (1.01-2.57), p = 0.0049. Case 2: responders treating children were more likely to taper after 1 year or less of postoperative remission, with the goal of discontinuing all medications: OR (95% CI): 1.91 (1.09-3.12), p = 0.015, and so were US-based responders: OR (95% CI): 1.73 (1.21-2.41), p = 0.003. Case 3: epileptologists were less likely to withdraw the medication: OR (95% CI): 0.56 (0.39-0.82), p = 0.003, and so were those in practice for 10 or more years: OR (95% CI): 0.54 (0.31-0.95), p = 0.025.

Conclusions

We observed several differences in practice for AED withdrawal after seizure remission that highlight global uncertainty. Trials of AED discontinuation are needed to provide evidence-based guidance.

Does early postoperative drug regimen impact seizure control in patients undergoing temporal lobe resections?

OBJECTIVE

To evaluate the impact of postoperative antiepileptic drug (AED) load on seizure control in patients who underwent surgical treatment for pharmacoresistant mesiotemporal lobe epilepsy during the first two postoperative years.

PATIENTS AND METHODS

532 consecutive patients (48.7% males and 51.7% females) who underwent surgical treatment for mesiotemporal lobe epilepsy were retrospectively evaluated regarding effects of AED load on seizures control during the first 2 years following epilepsy surgery. We analyzed whether postoperative increases in postoperative AED load are associated with better seizure control in patients initially not seizure free, and if postoperative decreases in postoperative AED load would increase the risk for seizure persistence or recurrence. For statistical analyses, Fisher's exact and Wilcoxon test were applied.

RESULTS

68.9, 64.0 and 59.1% of patients were completely seizure free (Engel Ia) at 3, 12 and 24 months after surgery, respectively. Patients in whom daily drug doses were increased did not have a higher rate of seizure freedom at any of the three follow-up periods. Of 16 patients achieving secondary seizure control at 12 months after surgery, only one did so with an increase in drug load in contrast to 15 patients who experienced a running down of seizures independent of drug load increases. Decreases in drug load did not significantly increase the risk for seizure recurrence. Of postoperatively seizure free patients at 3 months after surgery in whom AED were consequently reduced, 85% remained completely seizure free at 1 year and 76% at 1 year after surgery, respectively, as opposed to 86% each when AED was not reduced (differences n.s.). Mean daily drug load was significantly lower in seizure free patients at 12 and 24 months compared to patients with ongoing seizures.

CONCLUSION

In this large patient cohort stratified to the epilepsy syndrome neither did a postoperative reduction in drug load significantly increase the risk for seizure relapse nor did increases in drug dosages lead to improved seizure control. Mean drug load was on average lower in seizure free- than non-seizure free patients at 12 and 24 months of follow-up. Secondary seizure control after initial postoperative seizures in > 90% of cases occurred as a running down, independent of an AED increase. Thus, the effect of the surgical intervention rather than the postoperative drug regimen was the key determinant for seizure control. This finding supports a curative role of temporal lobe surgery rather than an effect rendering the majority of patients' pharmacoresponsive with a critical role of the antiepileptic drug regime for seizure control.

Long-term outcomes of epilepsy surgery in 85 pediatric patients followed up for over 10 years: a retrospective survey

OBJECTIVE The aim of this study was to investigate the treatment outcomes and social engagement of patients who had undergone pediatric epilepsy surgery more than 10 years earlier. METHODS Between 1983 and 2005, 110 patients younger than 16 years underwent epilepsy surgery at the National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders. The authors sent a questionnaire to 103 patients who had undergone follow-up for more than 10 years after surgery; 85 patients (82.5%) responded. The survey contained 4 categories: seizure outcome, use of antiepileptic drugs, social participation, and general satisfaction with the surgical treatment (resection of the epileptic focus, including 4 hemispherectomies). The mean patient age at the time of surgery was 9.8 ± 4.2 (SD) years, and the mean duration of postoperative follow-up was 15.4 ± 5.0 years. Of the 85 patients, 79 (92.9%) presented with a lesional pathology, such as medial temporal sclerosis, developmental/neoplastic lesions, focal cortical dysplasia, and gliosis in a single lobe. RESULTS For 65 of the 85 responders (76.5%), the outcome was recorded as Engel Class I (including 15 [93.8%] of 16 patients with medial temporal sclerosis, 20 [80.0%] of 25 with developmental/neoplastic lesions, and 27 [73.0%] of 37 with focal cortical dysplasia). Of these, 29 (44.6%) were not taking antiepileptic drugs at the time of our survey, 29 (44.6%) held full-time jobs, and 33 of 59 patients (55.9%) eligible to drive had a driver's license. Among 73 patients who reported their degree of satisfaction, 58 (79.5%) were very satisfied with the treatment outcome. CONCLUSIONS The seizure outcome in patients who underwent resective surgery in childhood and underwent followup for more than 10 years was good. Of 85 respondents, 65 (76.5%) were classified in Engel Class I. The degree of social engagement was relatively high, and the satisfaction level with the treatment outcome was also high. From the perspective of seizure control and social adaptation, resective surgery yielded longitudinal benefits in children with intractable epilepsy, especially those with a lesional pathology in a single lobe.

The withdrawal of antiepileptic drugs in patients with low-grade and anaplastic glioma

INTRODUCTION

The withdrawal of antiepileptic drugs (AEDs) in World Health Organization (WHO) grade II-III glioma patients with epilepsy is controversial, as the presence of a symptomatic lesion is often related to an increased risk of seizure relapse. However, some glioma patients may achieve long-term seizure freedom after antitumor treatment, raising questions about the necessity to continue AEDs, particularly when patients experience serious drug side effects. Areas covered: In this review, we show the evidence in the literature from 1990-2016 for AED withdrawal in glioma patients. We put this issue into the context of risk factors for developing seizures in glioma, adverse effects of AEDs, seizure outcome after antitumor treatment, and outcome after AED withdrawal in patients with non-brain tumor related epilepsy. Expert commentary: There is currently scarce evidence of the feasibility of AED withdrawal in glioma patients. AED withdrawal could be considered in patients with grade II-III glioma with a favorable prognosis, who have achieved stable disease and long-term seizure freedom. The potential benefits of AED withdrawal need to be carefully weighed against the presumed risk of seizure recurrence in a shared decision-making process by both the clinical physician and the patient.

Not all that glitters is gold: A guide to surgical trials in epilepsy

Epilepsy surgery is often the only effective treatment in appropriately selected patients with drug‐resistant epilepsy, a disease affecting about 30% of those with epilepsy. We review the evidence supporting the use of epilepsy surgery, with a focus on randomized controlled trials (RCTs). Second, we identify gaps in knowledge about the benefits of epilepsy surgery for certain populations, the challenges of individualizing the choice of surgery, and our lack of understanding of the mechanisms of surgical outcomes. We conducted a search (MEDLINE, Embase, Cochrane, Clinicaltrials.gov) on March 2, 2016, to identify epilepsy surgery RCTs, systematic reviews, or health technology assessments (HTAs). Abstracts were screened to identify resective, palliative (e.g., corpus callosotomy, multiple subpial transection [MST]), ablative (e.g., Laser interstitial thermal therapy [LITT], gamma knife radiosurgery [RS]), and neuromodulation (e.g., cerebellar stimulation [CS], hippocampal stimulation [HS], repetitive transcranial magnetic stimulation [rTMS], responsive neurostimulation [RNS], thalamic stimulation [TS], trigeminal nerve stimulation [TNS], and vagal nerve stimulation [VNS]) RCTs. Study characteristics and outcomes were extracted. Knowledge gaps were identified. Of 1,205 abstracts, 20 RCTs were identified (resective surgery including corpus callosotomy [n = 7], MST [n = 0], RS [n = 1, 3 papers], LITT [n = 0], CS [n = 1], HS [n = 2], RNS [n = 1], rTMS [n = 1], TNS [n = 1], TS [n = 1], and VNS [n = 5]). Most studies targeted patients with temporal lobe epilepsy (TLE) and none examined the effectiveness of resective surgical therapies in patients with extra‐TLE (ETLE) or with specific lesions aside from mesial temporal lobe sclerosis. No pediatric surgical RCTs were identified except for VNS. Few RCTs address the effectiveness of surgery in epilepsy and most are of limited generalizability. Future studies are needed to compare the effectiveness of different surgical strategies, better understand the mechanisms of surgical outcomes, and define the ideal surgical approaches, particularly for patients with high or very low cognitive function, normal imaging, or ETLE.

Outcomes after Epilepsy Surgery

Epilepsy surgery is a highly effective and durable treatment for specific types of drug resistant epilepsy such as temporal lobe epilepsy. assessment of outcomes is essential in epilepsy surgery, which is an irreversible intervention for a chronic condition. Excellent short-term results of resective epilepsy surgery have been established. In the last years more information regarding long term outcomes have been published. This article reviews the best available evidence about the best measures to assess outcomes and the most important evidence. The outcomes reviewed in this article are the following: seizure outcome, social and psychiatric outcomes, complications and mortality.

Prognostic Tests and Antiepileptic Drug Withdrawal After Epilepsy Surgery

Approximately one in three patients with a successful epilepsy surgery will have seizure recurrence following antiepileptic drugs (AED) withdrawal. The value of postoperative testing for predicting seizure relapse after AED tapering is not clear. The purpose of this study was to review the literature for evidence on the use of postoperative investigations before AED discontinuation after successful epilepsy surgery. We were unable to identify studies on the prognostic value of postoperative magnetic resonance imaging and AED blood levels. The literature review yielded seven studies on the predictive value of electroencephalography. Four studies found no association between interictal discharges (IED) and seizure relapse. These studies suffered from various limitations due to their retrospective design and generally small cohorts. Two of the three studies reporting a positive association were prospective and provided strong evidence of an increased risk of seizure recurrence with presence of postoperative IED in successfully operated patients undergoing AED withdrawal.

Treatment of epileptic seizures in brain tumors: a critical review

Epileptic seizures represent a common signal of intracranial tumors, frequently the presenting symptom and the main factor influencing quality of life. Treatment of tumors concentrates on survival; antiepileptic drug (AED) treatment frequently is prescribed in a stereotyped way. A differentiated approach according to epileptic syndromes can improve seizure control and minimize unwarranted AED effects. Prophylactic use of AEDs is to be discouraged in patients without seizures. Acutely provoked seizures do not need long-term medication except for patients with high recurrence risk indicated by distinct EEG patterns, auras, and several other parameters. With chronically repeated seizures (epilepsies), long-term AED treatment is indicated. Non-enzyme-inducing AEDs might be preferred. Valproic acid exerts effects against progression of gliomatous tumors. In low-grade astrocytomas with epilepsy, a comprehensive presurgical epilepsy work-up including EEG-video monitoring is advisable; in static non-progressive tumors, it is mandatory. In these cases, the neurosurgical approach has to include the removal of the seizure-onset zone frequently located outside the lesion.

Reducing versus stopping antiepileptic medications after temporal lobe surgery

Objective

To study the safety of antiepileptic drug (AED) withdrawal after temporal lobe epilepsy (TLE) surgery.

Methods

We reviewed patients who underwent TLE surgery from 1995 to 2011, collecting data on doses, dates of AED initiation, reduction, and discontinuation. Predictors of seizure outcome were defined using Cox-proportional hazard modeling and adjusted for, while comparing longitudinal seizure-freedom in patients for whom AEDs were unchanged after resection as opposed to reduced or stopped.

Results

A total of 609 patients (86% adults) were analyzed. Follow-up ranged from 0.5 to 16.7 years. Most (64%) had hippocampal sclerosis. Overall, 229 patients had remained on their same baseline AEDs, while 380 patients stopped (127 cases) or reduced (253 cases) their AEDs. Mean timing of the earliest AED change was shorter in patients with recurrent seizures (1.04 years) compared to those seizure-free at last follow-up (1.44 years; P-value 0.03). Whether AEDs were withdrawn 12 or 24 months after surgery, there was a 10–25% higher risk of breakthrough seizures within the subsequent 2 years. However, 70% of patients with seizure recurrence after AED discontinuation reachieved remission, as opposed to 50% of those whose seizures recurred while reducing AEDs (P = 0.0001). Long-term remission rates were similar in both AED discontinuation and “unchanged” groups (82% remission for AEDs withdrawn after 1 year and 90% for AEDs withdrawn after 2 years), while only 65% of patients whose recurrences started during AED reduction achieved a 2-year remission by last follow-up.

Interpretation

AED withdrawal increases the short-term risk of breakthrough seizures after TLE surgery, and may alter the long-term disease course in some patients.

Current challenges in the practice of epilepsy surgery

The accurate prediction of individual outcomes after epilepsy surgery represents a key challenge facing clinicians. It requires a precise understanding of surgical candidacy and the optimal timing of surgery to maximize a range of outcomes, including medical, psychosocial, cognitive, and psychiatric outcomes. We promote careful consideration of how epilepsy has affected an individual's developmental trajectory as key to constructing more differentiated profiles of postsurgical risk or resilience across multiple outcome measures. This life span approach conceives surgery as a crucial "turning point" in an individual's development from which varied outcome trajectories may follow. This helps clinicians understand the expectations patients and families bring to surgery, and emphasizes the interplay of factors that determine a patient's outcome. It also promotes comprehensive, longitudinal assessment of outcome using data analytical techniques that capture individual differences and identify subgroups with similar trajectories. An ongoing challenge facing clinicians is the development of an outcome classification system that incorporates outcomes other than seizures. We illustrate two emerging areas of research shaping how we define surgical candidacy and predict outcome: (1) using cortico-cortical evoked potentials to identify pathways of seizure propagation and cortico-cortical networks mediating cortical functions, and (2) predicting postoperative depression using a model that incorporates psychosocial and neurobiological factors. The latter research points to the importance of routine follow-up and postoperative psychosocial rehabilitation, particularly in patients deemed at "high risk" for poor outcomes so that early treatment interventions can be implemented. Significantly more research is needed to characterize those patients with poor outcomes who may require re-surgery.

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.

Stopping antiepileptic drugs: when and why?

After a patient has initiated an antiepileptic drug (AED) and achieved a sustained period of seizure freedom, the bias towards continuing therapy indefinitely can be substantial. Studies show that the rate of seizure recurrence after AED withdrawal is about two to three times the rate in patients who continue AEDs, but there are many benefits to AED withdrawal that should be evaluated on an individualized basis. AED discontinuation may be considered in patients whose seizures have been completely controlled for a prolonged period, typically 1 to 2 years for children and 2 to 5 years for adults. For children, symptomatic epilepsy, adolescent onset, and a longer time to achieve seizure control are associated with a worse prognosis. In adults, factors such as a longer duration of epilepsy, an abnormal neurologic examination, an abnormal EEG, and certain epilepsy syndromes are known to increase the risk of recurrence. Even in patients with a favorable prognosis, however, the risk of relapse can be as high as 20% to 25%. Before withdrawing AEDs, patients should be counseled about their individual risk for relapse and the potential implications of a recurrent seizure, particularly for safety and driving.

Drug withdrawal after successful epilepsy surgery: how safe is it?

Discontinuation of antiepileptic drugs (AEDs) is one reason patients undergo epilepsy surgery, but little is known about the risk of seizure recurrence. We describe a prospective pilot study of withdrawal performed at our epilepsy center. Sixty completely seizure-free patients were included between 1997 and 2003. AED withdrawal was proposed 1 year after surgery after a detailed discussion of the risks and benefits. On the basis of their decision on withdrawal, patients were stratified into two cohorts (withdrawal group, N=34; control group, N=26). Discontinuation was carried out in small tapering steps over 1 year with yearly follow-up visits. Withdrawal was stopped when seizures recurred or the patients objected to further discontinuation. Twenty-six of 34 (76.5%) persons in the withdrawal group and 16 of 26 (61.5%) persons in the control group were seizure free 5 years after surgery. In this study, AED discontinuation 1 year after successful epilepsy surgery was not associated with a risk of seizure recurrence higher than that of controls.

Debate: Should antiepileptic drugs be stopped after successful epilepsy surgery?

There is no consensus on whether or when to stop anticonvulsant drug treatment in patients after apparently successful epilepsy surgery. Although there are compelling reasons to consider antiepileptic drug (AED) discontinuation, there are relatively few data, and no class 1 data, to guide patient and physician decision-making on this topic. This debate lays out a conceptual framework for considering the issue of AED discontinuation, and reviews and critiques the available data. The goal is to provide physicians with the best available data, a context in which to consider it, and a full understanding of its limitations. This article also highlights an area that is ripe for further prospective study.

Prognosis after late relapse following epilepsy surgery

OBJECTIVES

To assess prognosis after late relapse in patients who are seizure free for the first 5 years after epilepsy surgery.

METHODS

Patients who were seizure free for the first 5 years after resective epilepsy surgery were included. Date of first seizure recurrence, current seizure status, medication, age, and type of surgery were prospectively registered. Non-parametric statistics were used.

RESULTS

One hundred and fifty-nine patients were studied. Thirty-two had at least one recurrent seizure. Time to event analysis showed an annual relapse rate of 4% between years 5 and 10 after surgery. At study termination, 143 of 159 patients (89.9%) were in terminal remission. For 30 patients with late relapse and at least 1-year follow-up thereafter, 53% were in terminal remission and 30% had experienced only rare or nocturnal seizures. Medication use was not associated either with likelihood of relapse or entering remission after relapse.

CONCLUSIONS

Patients who are seizure free for the first 5 years after epilepsy surgery remain at risk for seizure recurrence. These relapses are often isolated events, and the long-term prognosis after relapse is often good. Relapse rates were similar in patients on and off AEDs, but the relation between AED taper and relapse is uncertain since patient groups may not be similar.