Neuroimaging predictors of AED resistance in new-onset epilepsies

Structural connectivity as a predictive factor for perampanel response in patients with epilepsy

OBJECTIVES

This study aimed to identify clinical characteristics that could predict the response to perampanel (PER) and determine whether structural connectivity is a predictive factor.

METHODS

We enrolled patients with epilepsy who received PER and were followed-up for a minimum of 12 months. Good PER responders, who were seizure-free or presented with more than 50 % seizure reduction, were classified separately from poor PER responders who had seizure reduction of less than 50 % or non-responders. A graph theoretical analysis was conducted based on diffusion tensor imaging to calculate network measures of structural connectivity among patients with epilepsy.

RESULTS

106 patients with epilepsy were enrolled, including 26 good PER responders and 80 poor PER responders. Good PER responders used fewer anti-seizure medications before PER administration compared to those by poor PER responders (3 vs. 4; p = 0.042). Early PER treatment was more common in good PER responders than poor PER responders (46.2 vs. 21.3 %, p = 0.014). Regarding cortical structural connectivity, the global efficiency was higher and characteristic path length was lower in good PER responders than in poor PER responders (0.647 vs. 0.635, p = 0.006; 1.726 vs. 1,759, p = 0.008, respectively). For subcortical structural connectivity, the mean clustering coefficient and small-worldness index were higher in good PER responders than in poor PER responders (0.821 vs. 0.791, p = 0.009; 0.597 vs. 0.560, p = 0.009, respectively).

CONCLUSION

This study demonstrated that early PER administration can predict a good PER response in patients with epilepsy, and structural connectivity could potentially offer clinical utility in predicting PER response.

A scale for prediction of response to AEDs in patients with MRI-negative epilepsy

OBJECTIVES

Antiepileptic drugs (AEDs) are the first choice in magnetic resonance imaging (MRI)-negative patients with epilepsy, although the responses to AEDs are diverse. Preoperative evaluation and postoperative prognosis in MRI-negative epilepsy have been reported. However, there are few tools for predicting the response to AEDs. Herein, we developed an AED response scale based on clinical factors and video-electroencephalography (VEEG) in MRI-negative patients with epilepsy.

METHODS

A total of 132 consecutive patients with MRI-negative epilepsy at the Epilepsy Center of Henan Provincial People's Hospital between August 2016 and August 2018 were included. Patients were further divided into drug-responsive epilepsy ([DSE-MRI (-)]; n = 101) and drug-resistant epilepsy ([DRE-MRI (-)]; n = 31) groups. The clinical and VEEG factors were evaluated in univariate analyses and multivariate logistic regression analyses. A scale was derived and the scores categorized into 3 risk levels of DRE-MRI (-).

RESULTS

A scale was established based on 4 independent risk factors for DRE-MRI (-). The scale had a sensitivity of 83.87%, specificity of 80.20%, positive likelihood ratio of 4.24, negative likelihood ratio of 0.20, and showed good discrimination with the area under the curve (AUC) of 0.886 (0.826-0.946). The categorization of the risk score based on this scale was: low risk (0-3 points), medium risk (3-5 points), and high risk (>5 points).

CONCLUSION

We established a DRE-MRI (-) scale with a good sensitivity and specificity, which may be useful for clinicians when making medical decisions in patients with MRI-negative epilepsy.

Adjunctive perampanel in partial-onset seizures: Asia-Pacific, randomized phase III study

OBJECTIVES

To evaluate the efficacy, safety, and tolerability of perampanel, a selective, non-competitive, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, as an adjunctive treatment for patients with refractory partial-onset seizures (POS) from Asia-Pacific.

MATERIALS & METHODS

This multicenter, randomized, double-blind, placebo-controlled trial (ClinicalTrials.gov identifier: NCT01618695) involved patients aged ≥12 years with refractory POS (receiving 1-3 antiepileptic drugs). Patients were randomized (1:1:1:1) to receive once-daily placebo or perampanel 4, 8, or 12 mg over a 6-week titration and 13-week maintenance double-blind period. Enzyme-inducing antiepileptic drugs were equally stratified between groups. The primary efficacy endpoint was percent change in POS frequency per 28 days (double-blind phase vs baseline). Other efficacy endpoints included ≥50% responder rate and seizure freedom. Treatment-emergent adverse events (TEAEs) were also monitored.

RESULTS

Of 710 randomized patients, seizure frequency data were available for 704 patients. Median percent changes in POS frequency per 28 days indicated dose-proportional reductions in seizure frequency: -10.8% with placebo and -17.3% (P = .2330), -29.0% (P = .0003), and -38.0% (P < .0001) with perampanel 4, 8, and 12 mg, respectively. In total, 108 (15.3%) patients discontinued treatment; 44 (6.2%) due to TEAEs. TEAEs occurring in ≥5% of patients, and reported at least twice as frequently with perampanel vs placebo, included dizziness and irritability.

CONCLUSIONS

Adjunctive perampanel (8 and 12 mg/d) significantly improved seizure control in patients with refractory POS. Safety and tolerability were acceptable at daily doses of perampanel 4-12 mg.

Quantitative Pharmaco-Electroencephalography in Antiepileptic Drug Research

Pharmaco-electroencephalography (pharmaco-EEG) has never gained great popularity in epilepsy research. Nevertheless, the electroencephalogram (EEG) is the most important neurological examination technique in this patient population. Development and investigation of antiepileptic drugs (AEDs) involves EEG for diagnosis and outcome evaluation. In contrast to the common use of the EEG for documenting the effect of AEDs on the presence of interictal epileptiform activities or seizures, quantitative analysis of drug responses in the EEG are not yet standard in pharmacological studies. We provide an overview of dedicated pharmaco-EEG studies with AEDs in humans. A systematic search in PubMed yielded 43 articles, which were reviewed for their relevance. After excluding studies according to our exclusion criteria, nine studies remained. These studies plus the retrieved references from the bibliographies of the identified studies yielded 37 studies to be included in the review. The most prominent method in pharmaco-EEG research for AEDs was analysis of the frequency content in response to drug intake, often with quantitative methods such as spectral analysis. Despite documenting the effect of the drug on brain activity, some studies were conducted in order to document treatment response, detect neurotoxic effects, and measure reversibility of AED-induced changes. There were some attempts to predict treatment response or side effects. We suggest that pharmaco-EEG deserves more attention in AED research, specifically because the newest drugs and techniques have not yet been subject to investigation.

Automated Online Quantification Method for 18F-FDG Positron Emission Tomography/CT Improves Detection of the Epileptogenic Zone in Patients with Pharmacoresistant Epilepsy

Aims

To assess the validity of an online method to quantitatively evaluate cerebral hypometabolism in patients with pharmacoresistant focal epilepsy as a complement to the visual analysis of the ¹⁸F-FDG positron emission tomography (PET)/CT exam.

Methods

A total of 39 patients with pharmacoresistant epilepsy and probable focal cortical dysplasia [22 patients with frontal lobe epilepsy (FLE) and 17 with temporal lobe epilepsy (TLE)] underwent a presurgical evaluation including EEG, video-EEG, MRI, and ¹⁸F-FDG PET/CT. We conducted the automated quantification of their ¹⁸F-FDG PET/CT data and compared the results with those of the visual-PET analysis conducted by experienced nuclear medicine physicians. For each patient group, we calculated Cohen’s Kappa coefficient for the visual and quantitative analyses, as well as each method’s sensitivity, specificity, and positive and negative predictive values.

Results

For the TLE group, both the visual and quantitative analyses showed high agreement. Thus, although the quantitative analysis could be used as a complement, the visual analysis on its own was consistent and precise. For the FLE group, on the other hand, the visual analysis categorized almost half of the cases as normal, revealing very low agreement. For those patients, the quantitative analysis proved critical to identify the focal hypometabolism characteristic of the epileptogenic zone. Our results suggest that the quantitative analysis of ¹⁸F-FDG PET/CT data is critical for patients with extratemporal epilepsies, and especially those with subtle MRI findings. Furthermore, it can easily be used during the routine clinical evaluation of ¹⁸F-FDG PET/CT exams.

Significance

Our results show that quantification of ¹⁸F-FDG PET is an informative complementary method that can be added to the routine visual evaluation of patients with subtle lesions, particularly those in the frontal lobes.

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.

Treatment registry in focal epilepsy (TRIP): multicenter observational study in Lebanon

PURPOSE

Treatment of newly diagnosed epilepsy with a single antiepileptic drug (AED) is the favored approach for seizure management. This observational study aimed to assess, under daily practice conditions, remission and retention rates with the first AED prescribed as monotherapy in patients newly or recently diagnosed with focal epilepsy.

METHODS

The treatment registry in focal epilepsy (TRIP) study was conducted on 234 Lebanese patients with newly or recently diagnosed focal epilepsy, requiring treatment with an AED. Demographics, baseline focal seizure characteristics and results of the Clinical Global Impression (CGI) scale at the 12-month visit were reported. The primary objective of this study was to assess the percentage of patients who achieved a 6-month terminal seizure remission at the 12-month visit following treatment with a first AED administered as monotherapy. Secondary outcome variables included the calculation of the 6-month terminal seizure remission according to the baseline seizure types and patient retention at the 12 and 18 month visits. In addition, bivariate and multivariate analyses were conducted to identify independent predictors of 6-month terminal seizure remission at the 12-month visit.

RESULTS

The mean age of the 234 eligible patients was 31.6 years and the majority were males (62%). At baseline, the most common type of focal seizures was focal seizures with impairment of consciousness (45%), and the most frequent topographical localization was in the temporal lobe (47%). In total, 77.6% of the patients achieved a 6-month terminal seizure remission at the 12-month visit. Patients with an epileptogenic lesion on neuroimaging were significantly less likely to achieve a 6-month remission compared to those with no identifiable pathological substrate. Patients with focal motor seizures without impairment of consciousness at baseline had significantly lower odds of achieving a 6-month terminal seizure remission compared to patients with a combination of seizure types. There was no significant association between age or gender and 6-month terminal seizure remission. The retention rates were 95.7% and 88.5% at months 12 and 18 respectively with the great majority of patients (90.7%) reporting marked improvement on the CGI scale.

CONCLUSIONS

A substantial proportion of patients with newly diagnosed epilepsy achieved a 6-month terminal seizure remission following treatment with a first AED administered as monotherapy. Patients with an epileptogenic lesion on neuroimaging and those with focal motor seizures without impairment of consciousness at baseline were significantly less likely to achieve a 6-month terminal seizure remission. This study demonstrated the feasibility of conducting long-term multicenter studies in Lebanon and will hopefully serve as an impetus to conduct randomized studies in the field of epilepsy.

Neuroimaging the epileptogenic process

Epilepsy is one of the most common chronic neurological conditions worldwide. Anti-epileptic drugs (AEDs) can suppress seizures, but do not affect the underlying epileptic state, and many epilepsy patients are unable to attain seizure control with AEDs. To cure or prevent epilepsy, disease-modifying interventions that inhibit or reverse the disease process of epileptogenesis must be developed. A major limitation in the development and implementation of such an intervention is the current poor understanding, and the lack of reliable biomarkers, of the epileptogenic process. Neuroimaging represents a non-invasive medical and research tool with the ability to identify early pathophysiological changes involved in epileptogenesis, monitor disease progression, and assess the effectiveness of possible therapies. Here we will provide an overview of studies conducted in animal models and in patients with epilepsy that have utilized various neuroimaging modalities to investigate epileptogenesis.

Neuroimaging for the prediction of response to medical and surgical treatment in epilepsy

INTRODUCTION

Approximately 30% of patients with epilepsy do not respond to adequate medication and are candidates for surgical treatment. Outcome predictors can improve the selection of more suitable treatment options for each patient. Therefore, the authors aimed to review the role of neuroimaging studies in predicting outcomes for both clinical and surgical treatment of epilepsy.

AREAS COVERED

This review analyzes studies that investigated different neuroimaging techniques as predictors of clinical and surgical treatment outcome in epilepsy. Studies involving both structural (i.e., T1-weighted images and diffusion tensor images) and functional MRI (fMRI) were identified, as well as other modalities such as spectroscopy, PET, SPECT and MEG. The authors also evaluated the importance of fMRI in predicting memory outcome after surgical resections in temporal lobe epilepsy.

EXPERT OPINION

The identification of reliable biomarkers to predict response to medical and surgical treatments are much needed in order to provide more adequate patient counseling about prognosis and treatment options individually. Different neuroimaging techniques may provide combined measurements that potentially may become these biomarkers in the near future.

Neuroimaging in epilepsy: the state of the art

Our understanding of epileptogenesis is still limited. Knowledge is increasing with regard to structural and functional changes in chronic stages of epilepsy. At the same time, we have to appreciate that there is a significant lack of such information in new-onset epilepsy. The First Halifax International Epilepsy Conference tried to fill this gap, focusing on the contribution of advanced neuroimaging in early stages of epilepsy. The following article aims to synthesize the themes that emerged from this meeting. Participants agreed that (1) there is a need for a unified theory of epileptogenesis, addressing the interplay of functional and structural brain changes; (2) neuroimaging reveals widespread brain alterations in epilepsy; (3) advances in neuroimaging challenge the concept of "MRI-negative" (magnetic resonance imaging negative) focal epilepsy; (4) methodologic limitations and potential confounders must be considered in the translation of innovative imaging approaches to clinical practice; and (5) there is an urgent need for longitudinal studies that begin early in the disease process.