Epilepsy surgery: surgical aspects

Current state of the art of traditional and minimal invasive epilepsy surgery approaches

Introduction

Open resective surgery remains the main treatment modality for refractory epilepsy, but is often considered a last resort option due to its invasiveness.

Research question

This manuscript aims to provide an overview on traditional as well as minimally invasive surgical approaches in modern state of the art epilepsy surgery.

Materials and methods

This narrative review addresses both historical and contemporary as well as minimal invasive surgical approaches in epilepsy surgery. Peer-reviewed published articles were retrieved from PubMed and Scopus. Only articles written in English were considered for this work. A range of traditional and minimally invasive surgical approaches in epilepsy surgery were examined, and their respective advantages and disadvantages have been summarized.

Results

The following approaches and techniques are discussed: minimally invasive diagnostics in epilepsy surgery, anterior temporal lobectomy, functional temporal lobectomy, selective amygdalohippocampectomy through a transsylvian, transcortical, or subtemporal approach, insulo-opercular corticectomies compared to laser interstitial thermal therapy, radiofrequency thermocoagulation, stereotactic radiosurgery, neuromodulation, high intensity focused ultrasound, and disconnection surgery including callosotomy, hemispherotomy, and subpial transections.

Discussion and conclusion

Understanding the benefits and disadvantages of different surgical approaches and strategies in traditional and minimal invasive epilepsy surgery might improve the surgical decision tree, as not all procedures are appropriate for all patients.

Patients' Survival with Astrocytoma After Treatment: a Systematic Review and Meta-analysis of Clinical Trial Studies

About half of the brain tumours are primary and the rest are metastatic. The impact of each of these treatments alone or together on the prognosis of patients with astrocytoma tumours, especially low-grade astrocytoma, is unclear which may pose many challenges in the decision-making of surgeons and patients. Considering the importance of patient's outcomes with astrocytoma and lack of general statistics, this study aimed to determine the survival of patients with high-grade astrocytoma and low-grade astrocytoma after treatments. This study follows a systematic review and a meta-analysis approach. Following a systematic review and meta-analysis method, articles dated from 1982 to March 2020 were extracted from Embase, ScienceDirect, Scopus, PubMed and Web of Science (WoS) international databases. Random effects model was used for analysis, and heterogeneity of studies was investigated considering the I 2 index. Data were analysed using the Comprehensive Meta-Analysis software (version 2). According to a meta-analysis of studies, the mean overall survival in patients with high-grade astrocytoma was 31.9 ± 2.7 months, for 2-year survival, 38.1% (95% CI: 27.5-50.1%) and for 5-year survival was 28.6% (95% CI: 24.1-33.4%). Mean overall survival in patients with low-grade astrocytoma was 64.8 ± 7.4 months, for 2-year survival was 74.3% (95% CI: 32.6-94.5%) and for 5-year survival was 74.4% (95% CI: 57.9-86%). The highest mean for survival in patients with high-grade astrocytoma and in chemotherapy and radiation therapy treatments was 45.2 ± 5.2 months, and also the highest mean for survival in patients with low-grade astrocytoma in surgical treatment was 71.4 ± 8.8 months. The results of this study show that the average survival in patients with low-grade astrocytoma is high following the treatment, and in high-grade astrocytoma, there will be the highest survival rate, if the surgical treatment is combined with chemotherapy and radiation therapy. This study summarizes retrospective studies up to 2020 to evaluate the prognosis and survival of patients with brain astrocytoma tumours, and the results of this meta-analysis can be of interest to surgeons and specialists in this field.

Research priorities for idiopathic epilepsy in dogs: Viewpoints of owners, general practice veterinarians, and neurology specialists

BACKGROUND

Epilepsy is the most common chronic neurological disease in dogs that adversely affects the quality of life (QoL) of affected dogs and their owners. Research on epilepsy in dogs is expanding internationally, but where best to focus limited research time, funds, and expertise to achieve better outcomes for affected dogs and their owners has not been studied.

OBJECTIVE

To explore idiopathic epilepsy (IE) research priorities of owners of dogs with IE, general practice veterinarians, and veterinary neurologists.

METHODS

An international online survey was conducted in 2016 and repeated in 2020. Participants rated the absolute importance and relative rank of 18 areas of IE research, which were compared between groups and time points.

RESULTS

Valid responses were received from 414 respondents in 2016 and 414 respondents in 2020. The development of new anti-seizure drugs (ASD) and improving the existing ASD management were considered the most important research priorities. Areas of research with increasing priority between 2016 and 2020 included non-ASD management, with the greatest potential seen in behavioral and dietary-based interventions. Disagreements in priorities were identified between groups; owners prioritized issues that impacted their and their dog's QoL, for example, adverse effects and comorbidities, whereas general practitioner vets and neurologists prioritized clinical issues and longer-term strategies to manage or prevent IE, respectively.

CONCLUSIONS AND CLINICAL IMPORTANCE

Ensuring that voices of owners are heard in the planning of future research should be a broader goal of veterinary medicine, to target research efforts toward areas most likely to improve the QoL of the dog-owner dyad.

Deep Brain Stimulation: Expanding Applications

For over two decades, deep brain stimulation (DBS) has shown significant efficacy in treatment for refractory cases of dyskinesia, specifically in cases of Parkinson's disease and dystonia. DBS offers potential alleviation from symptoms through a well-tolerated procedure that allows personalized modulation of targeted neuroanatomical regions and related circuitries. For clinicians contending with how to provide patients with meaningful alleviation from often debilitating intractable disorders, DBSs titratability and reversibility make it an attractive treatment option for indications ranging from traumatic brain injury to progressive epileptic supra-synchrony. The expansion of our collective knowledge of pathologic brain circuitries, as well as advances in imaging capabilities, electrophysiology techniques, and material sciences have contributed to the expanding application of DBS. This review will examine the potential efficacy of DBS for neurologic and psychiatric disorders currently under clinical investigation and will summarize findings from recent animal models.

Safety, feasibility and complications during resective pediatric epilepsy surgery: a retrospective analysis

Background

Resective epilepsy surgery is an established and effective method to reduce seizure burden in drug-resistant epilepsy. It was the objective of this study to assess intraoperative blood loss, transfusion requirements and the degree of hypothermia of pediatric epilepsy surgery in our center.

Methods

Patients were identified by our epilepsy surgery database, and data were collected via retrospective chart review over the past 25 years. Patients up to the age of 6 years were included, and patients with insufficient data were excluded.

Results

Forty-five patients with an age of 3.2 ± 1.6 (mean ± SD) years and a body weight of 17 [14; 21.5] kg (median [25%, 75% percentile]) were analysed. Duration of surgery was 3 h 49 min ± 53 min, which was accompanied by an intraoperative blood loss of 150 [90; 300] ml. This corresponded to 11.7 [5.2; 21.4] % of estimated total blood volume, ranging from 0 to 75%. A minimal haemoglobin count of 8.8 ± 1.4 g/dl was measured, which was substituted with erythrocyte concentrate (100 [0; 250] ml) in 23 patients. Body core temperature dropped from 36.0 ± 0.7°C at baseline to a minimum of 35.7 ± 0.7°C, and increased significantly (p < 0.001) thereafter to 37.1 ± 0.7°C until the end of surgery. A significant (p = 0.0003) correlation between duration of surgery and blood loss (Pearson r = 0.52) was observed. However, age, minimal body temperature or number of antiepileptic drugs seemed to have no impact on blood loss.

Conclusion

Resective epilepsy surgery is a safe procedure even in the pediatric population, however it is associated with significant blood loss especially during long surgical procedures.

Non-pharmacological treatment options for refractory epilepsy: an overview of human treatment modalities and their potential utility in dogs

Refractory epilepsy is a common disorder both in humans and dogs and treatment protocols are difficult to optimise. In humans, different non-pharmacological treatment modalities currently available include surgery, the ketogenic diet and neurostimulation. Surgery leads to freedom from seizures in 50-75% of patients, but requires strict patient selection. The ketogenic diet is indicated in severe childhood epilepsies, but efficacy is limited and long-term compliance can be problematic. In the past decade, various types of neurostimulation have emerged as promising treatment modalities for humans with refractory epilepsy. Currently, none of these treatment options are used in routine daily clinical practice to treat dogs with the condition. Since many dogs with poorly controlled seizures do not survive, the search for alternative treatment options for canine refractory epilepsy should be prioritised. This review provides an overview of non-pharmacological treatment options for human refractory epilepsy. The current knowledge and limitations of these treatments in canine refractory epilepsy is also discussed.

Responsive neurostimulation for the treatment of medically intractable epilepsy

With an annual incidence of 50/100,000 people, nearly 1% of the population suffers from epilepsy. Treatment with antiepileptic medication fails to achieve seizure remission in 20-30% of patients. One treatment option for refractory epilepsy patients who would not otherwise be surgical candidates is electrical stimulation of the brain, which is a rapidly evolving and reversible adjunctive therapy. Therapeutic stimulation can involve direct stimulation of the brain nuclei or indirect stimulation of peripheral nerves. There are three stimulation modalities that have class I evidence supporting their uses: vagus nerve stimulation (VNS), stimulation of the anterior nuclei of the thalamus (ANT), and, the most recently developed, responsive neurostimulation (RNS). While the other treatment modalities outlined deliver stimulation regardless of neuronal activity, the RNS administers stimulation only if triggered by seizure activity. The lower doses of stimulation provided by such responsive devices can not only reduce power consumption, but also prevent adverse reactions caused by continuous stimulation, which include the possibility of habituation to long-term stimulation. RNS, as an investigational treatment for medically refractory epilepsy, is currently under review by the FDA. Eventually systems may be developed to enable activation by neurochemical triggers or to wirelessly transmit any information gathered. We review the mechanisms, the current status, the target options, and the prospects of RNS for the treatment of medically intractable epilepsy.