Outcome after seizure recurrence on antiepileptic drug withdrawal following temporal lobectomy

Analysis of clinical characteristics and histopathological transcription in 40 patients afflicted by epilepsy stemming from focal cortical dysplasia

OBJECTIVE

This study aims to comprehensively analyze the clinical characteristics and identify the differentially expressed genes associated with drug-resistant epilepsy (DRE) in patients with focal cortical dysplasia (FCD).

METHODS

A retrospective investigation was conducted from July 2019 to June 2022, involving 40 pediatric cases of DRE linked to FCD. Subsequent follow-ups were done to assess post-surgical outcomes. Transcriptomic sequencing and quantitative reverse transcription polymerase chain reaction (qRT-PCR) were used to examine differential gene expression between the FCD and control groups.

RESULTS

Among the 40 patients included in the study, focal to bilateral tonic-clonic seizures (13/40, 32.50%) and epileptic spasms (9/40, 22.50%) were the predominant seizure types. Magnetic resonance imaging (MRI) showed frequent involvement of the frontal (22/40, 55%) and temporal lobes (12/40, 30%). In cases with negative MRI results (13/13, 100%), positron emission tomography/computed tomography (PET-CT) scans revealed hypometabolic lesions. Fused MRI/PET-CT images demonstrated lesion reduction in 40.74% (11/27) of cases compared with PET-CT alone, while 59.26% (16/27) yielded results consistent with PET-CT findings. FCD type II was identified in 26 cases, and FCD type I in 13 cases. At the last follow-up, 38 patients were prescribed an average of 1.27 ± 1.05 anti-seizure medications (ASMs), with two patients discontinuing treatment. After a postoperative follow-up period of 23.50 months, 75% (30/40) of patients achieved Engel class I outcome. Transcriptomic sequencing and qRT-PCR analysis identified several genes primarily associated with cilia, including CFAP47, CFAP126, JHY, RSPH4A, and SPAG1.

SIGNIFICANCE

This study highlights focal to bilateral tonic-clonic seizures as the most common seizure type in patients with DRE due to FCD. Surgical intervention primarily targeted lesions in the frontal and temporal lobes. Patients with FCD-related DRE showed a promising prognosis for seizure control post-surgery. The identified genes, including CFAP47, CFAP126, JHY, RSPH4A, and SPAG1, could serve as potential biomarkers for FCD.

PLAIN LANGUAGE SUMMARY

This study aimed to comprehensively evaluate the clinical data of individuals affected by focal cortical dysplasia and analyze transcriptomic data from brain tissues. We found that focal to bilateral tonic-clonic seizures were the most prevalent seizure type in patients with drug-resistant epilepsy. In cases treated surgically, the frontal and temporal lobes were the primary sites of the lesions. Moreover, patients with focal cortical dysplasia-induced drug-resistant epilepsy exhibited a favorable prognosis for seizure control after surgery. CFAP47, CFAP126, JHY, RSPH4A, and SPAG1 have emerged as potential pathogenic genes for the development of focal cortical dysplasia.

Surgical treatment of epilepsy - Initial experience from a comprehensive epilepsy program in coastal South India

Objectives

The objectives of this study were to share our initial experience with epilepsy surgery and provide an overview on the surgical treatments of epilepsies.

Materials and Methods

This was a retrospective analysis of the demographics and clinical and investigative features of patients who underwent epilepsy surgery between January 2016 and August 2021. Postoperative seizure outcome was categorized according to modified Engel's classification, and the minimum period of follow-up was 1 year.

Results

The study group included 30 patients with an age ranging from 6 years to 45 years (mean: 22.28 years, median: 20 years) and a male: female ratio of 20:10. The epilepsy duration before surgery ranged from 3 years to 32 years (median: 7 years). Majority of our patients underwent resective surgeries (28/30 = 93.3%), and disconnection procedures were done in two patients. This included one functional hemispherotomy and one posterior quadrantic disconnection. Temporal lobe resective surgery was the most common procedure (16/30 = 53.3%), followed by eight frontal lobe and two parietal lobe surgeries. Among resective surgeries, majority were lesional surgeries and the pathologies included mesial temporal sclerosis (4), dysembryoplastic neuroepithelial tumor (8), ganglioglioma (6), cavernoma (4), focal cortical dysplasia (2), gliosis (1), and one case of hypothalamic hamartoma. Intraoperative electrocorticography was used in all cases for optimizing surgical resection/disconnection. Nearly two-thirds of our patients (66.6%) had an Engel's Class I outcome, five patients had Engel's Class II outcome, three patients had Class III outcome, and one patient did not have any worthwhile improvement. Temporal lobe surgery patients had a better seizure outcome compared to extratemporal surgeries (84% vs. 74%). Overall, complications were minimal and short lasting, and comprised meningitis in three patients (5.6%) and transient worsening of hemiparesis following hemispherotomy in two patients. There was no mortality or long-lasting major morbidity in our patients.

Conclusion

In carefully selected patients with drug-resistant epilepsy, surgery offers an excellent chance of becoming seizure-free with significant improvement in overall quality of life. Majority of the common epilepsy surgery procedures can be performed through a multidisciplinary approach even in centers with limited resources.

Extended follow-up after anterior temporal lobectomy demonstrates seizure recurrence 20+ years postsurgery

OBJECTIVE

Anterior temporal lobectomy (ATL) for medication-resistant localized epilepsy results in ablation or reduction of seizures for most patients. However, some individuals who attain an initial extended period of postsurgical seizure freedom will experience a later seizure recurrence. In this study, we examined the prevalence and some risk factors for late recurrence in an ATL cohort with extensive regular follow-up.

METHODS

Included were 449 patients who underwent ATL at Austin Health, Australia, from 1978 to 2008. Postsurgical follow-up was undertaken 2-3 yearly. Seizure recurrence was tested using Kaplan-Meier analysis, log-rank test, and Cox regression. Late recurrence was qualified as a first disabling seizure >2 years postsurgery. We examined risks within the ATL cohort according to broad pathology groups and tested whether late recurrence differed for the ATL cohort compared to patients who had resections outside the temporal lobe (n = 98).

RESULTS

Median post-ATL follow-up was 22 years (range = .1-38.6), 6% were lost to follow-up, and 12% had died. Probabilities for remaining completely seizure-free after surgery were 51% (95% confidence interval [CI] = 53-63) at 2 postoperative years, 36% (95% CI = 32-41) at 10 years, 32% (95% CI = 27-36) at 20 years, and 30% (95% CI = 25-34) at 25 years. Recurrences were reported up to 23 years postoperatively. Late seizures occurred in all major ATL pathology groups, with increased risk in the "normal" and "distant lesion" groups (p ≤ .03). Comparison between the ATL cohort and patients who underwent extratemporal resection demonstrated similar patterns of late recurrence (p = .74).

SIGNIFICANCE

Some first recurrences were very late, reported decades after ATL. Late recurrences were not unique to any broad ATL pathology group and did not differ according to whether resections were ATL or extratemporal. Reports of these events by patients with residual pathology suggest that potentially epileptogenic abnormalities outside the area of resection may be implicated as one of several possible underlying mechanisms.

Prediction of the recurrence risk in patients with epilepsy after the withdrawal of antiepileptic drugs

Many seizure-free patients who consider withdrawing from antiepileptic drugs (AEDs) hope to discontinue treatment to avoid adverse effects. However, withdrawal has certain risks that are difficult to predict. In this study, we performed a literature review, summarized the causes of significant variability in the risk of postwithdrawal recurrent seizures, and reviewed study data on the age at onset, cause, types of seizures, epilepsy syndrome, magnetic resonance imaging (MRI) abnormalities, epilepsy surgery, and withdrawal outcomes of patients with epilepsy. Many factors are associated with recurrent seizures after AED withdrawal. For patients who are seizure-free after treatment, the role of an electroencephalogram (EEG) alone in ensuring safe withdrawal is limited. A series of prediction models for the postwithdrawal recurrence risk have incorporated various potentially important factors in a comprehensive analysis. We focused on the populations of studies investigating five risk prediction models and analyzed the predictive variables and recommended applications of each model, aiming to provide a reference for personalized withdrawal for patients with epilepsy in clinical practice.

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.

Establishment of low cost epilepsy surgery centers in resource poor setting

PURPOSE

To prospectively assess the feasibility of establishing low cost epilepsy surgery programs in resource poor settings.

METHOD

We started epilepsy surgery centers in Tier 2 and Tier 3 cities in India in private hospitals. This model is based on the identifying and operating ideal epilepsy surgery candidates on the basis of clinical history, interictal and ictal video-EEG data, and 1.5 T MRI without other investigations and without regular involvement of other specialists. Trained epileptologists formed the fulcrum of this program who identified ideal candidates, offered them counseling, and read video-EEG and MRI. We also spread epilepsy awareness among locals and physicians and established focused epilepsy clinics. The expenses were subsidized for deserving patients and policies were devised to keep video-EEG duration and staff requirement to minimum. Difficult epilepsy surgery cases were referred to established centers. Initial surgeries were performed by invited epilepsy surgeons and subsequently by local neurosurgeons.

RESULTS

A total of 125 epilepsy surgeries were performed at three centers since 2012. This included 81(64.8%) temporal lobe resections, 26 (20.8%) extratemporal focal resections, and 13 (10.4%) hemispherotomies. Of the 93 patients with more than 1 year of postoperative followup, 86 (92.5%) had Engel class IA outcome. There were minor complications in 5% patients. Average cost of presurgical evaluation and surgery was Rs. 92,707 (USD 1,324).

CONCLUSIONS

It is possible to establish successful epilepsy surgery programs in resource poor setting with reasonable costs. This low cost model can be replicated in other parts of world to reduce the surgical treatment gap.

Highlights From the Annual Meeting of the American Epilepsy Society 2018

The American Epilepsy Society Meeting in New Orleans attracted more than 5900 attendees. There was a lively exchange of new science, innovation, education, clinical practice, and many other items related to epilepsy. Educational symposia were a major part of the meeting and explored varying topics of interest for all types of epilepsy professionals. This article reviews highlights of the meeting presented in major symposia. Topics ranged from how to treat varying aspects of epilepsy as a consultant in the hospital to finding the scientific underpinning of the interaction between sleep and epilepsy. Pros and cons of novel antiseizure medications, dietary, and stimulation treatments were discussed. Epilepsy may impair memory and we need to learn what is the pathophysiologic relationship. Febrile status epilepticus may have severe consequences for a later life with seizures. Epilepsy professionals should be very well aware of the ethical implications of devasting seizures and their associated disability. These are just a few select topics of the many that we need to study further to archive the final goal to improve the lives of patients with epilepsy.