Combined Responsive Neurostimulation and Focal Resection for Super Refractory Status Epilepticus: A Systematic Review and Illustrative Case Report

Therapeutic potential of ketamine in management of epilepsy: Clinical implications and mechanistic insights

Epilepsy, a widespread neurological disorder, affects approximately 50 million people worldwide. This disorder is typified by recurring seizures due to abnormal neuron communication in the brain. The seizures can lead to severe ischemia and hypoxia, potentially threatening patients' lives. However, with proper diagnosis and treatment, up to 70 % of patients can live without seizures. The causes of epilepsy are complex and multifactorial, encompassing genetic abnormalities, structural brain anomalies, ion channel dysfunctions, neurotransmitter imbalances, neuroinflammation, and immune system involvement. These factors collectively disrupt the crucial balance between excitation and inhibition within the brain, leading to epileptic seizures. The management of treatment-resistant epilepsy remains a considerable challenge, necessitating innovative therapeutic approaches. Among emerging potential treatments, ketamine-a drug traditionally employed for anesthesia and depression-has demonstrated efficacy in reducing seizures. It is noteworthy that, independent of its anti-epileptic effects, ketamine has been found to improve the balance between excitatory and inhibitory (E/I) activities in the brain. The balance is crucial for maintaining normal neural function, and its disruption is widely considered a key driver of epileptic seizures. By acting on N-methyl-D-aspartate (NMDA) receptors and other potential mechanisms, ketamine may regulate neuronal excitability, reduce excessive synchronized neural activity, and counteract epileptic seizures. This positive impact on E/I balance reinforces the potential of ketamine as a promising drug for treating epilepsy, especially in patients who are insensitive to traditional anti-epileptic drugs. This review aims to consolidate the current understanding of ketamine's therapeutic role in epilepsy. It will focus its impact on neuronal excitability and synaptic plasticity, its neuroprotective qualities, and elucidate the drug's potential mechanisms of action in treating epilepsy. By scrutinizing ketamine's impact and mechanisms in various types of epilepsy, we aspire to contribute to a more comprehensive and holistic approach to epilepsy management.

NORSE/FIRES: how can we advance our understanding of this devastating condition?

Introduction

New onset refractory status epilepticus (NORSE) is a rare and devastating condition characterised by the sudden onset of refractory status epilepticus (RSE) without an identifiable acute or active structural, toxic, or metabolic cause in an individual without a pre-existing diagnosis of epilepsy. Febrile infection-related epilepsy syndrome (FIRES) is considered a subcategory of NORSE and presents following a febrile illness prior to seizure onset. NORSE/FIRES is associated with high morbidity and mortality in children and adults.

Methods and results

In this review we first briefly summarise the reported clinical, paraclinical, treatment and outcome data in the literature. We then report on existing knowledge of the underlying pathophysiology in relation to in vitro and in vivo pre-clinical seizure and epilepsy models of potential relevance to NORSE/FIRES.

Discussion

We highlight how pre-clinical models can enhance our understanding of FIRES/NORSE and propose future directions for research.

Surgical management of status epilepticus: A systematic review

Status Epilepticus (SE), unresponsive to medical management, is associated with high morbidity and mortality. Surgical management is typically considered in these refractory cases. The best surgical approach for affected patients remains unclear; however, given the lack of controlled trials exploring the role of surgery. We performed a systematic review according to PRIMSA guidelines, including case reports and series describing surgical interventions for patients in SE. Cases (157 patients, median age 12.9 years) were followed for a median of 12 months. Patients were in SE for a median of 21 days before undergoing procedures including: focal resection (36.9%), functional hemispherectomy (21%), lobar resection (12.7%), vagus nerve stimulation (VNS) (12.7%), deep brain stimulation (DBS) (6.4%), multiple subpial transection (MST) (3.8%), responsive neurostimulation (RNS) (1.9%), and cortical stimulator placement (1.27%), with 24 patients undergoing multiple procedures. Multiple SE semiologies were identified. 47.8% of patients had focal seizures, and 65% of patients had focal structural abnormalities on MRI. SE persisted for 36.8 ± 47.7 days prior to surgical intervention. SE terminated following surgery in 81.5%, terminated with additional adjuncts in 10.2%, continued in 1.9%, and was not specified in 6.4% of patients. Long-term seizure outcomes were favorable, with the majority improved and 51% seizure-free. Eight patients passed away in follow-up, of which three were in SE. Seizures emerging from one hemisphere were both more likely to immediately terminate (OR 4.7) and lead to long-term seizure-free status (OR 3.9) compared to nonunilateral seizures. No other predictors, including seizure focality, SE duration, or choice of surgical procedure, were predictors of SE termination. Surgical treatment of SE can be effective in terminating SE and leading to sustained seizure freedom, with many different procedures showing efficacy if matched appropriately with SE semiology and etiology. PLAIN LANGUAGE SUMMARY: Patients with persistent seizures (Status Epilepticus) that do not stop following medications can be treated effectively with surgery. Here, we systematically review the entirety of existing literature on surgery for treating status epilepticus to better identify how and when surgery is used and what patients do after surgery.

Status epilepticus: what's new for the intensivist

PURPOSE OF REVIEW

Status epilepticus (SE) is a common neurologic emergency affecting about 36.1/100 000 person-years that frequently requires intensive care unit (ICU) admission. There have been advances in our understanding of epidemiology, pathophysiology, and EEG monitoring of SE, and there have been large-scale treatment trials, discussed in this review.

RECENT FINDINGS

Recent changes in the definitions of SE have helped guide management protocols and we have much better predictors of outcome. Observational studies have confirmed the efficacy of benzodiazepines and large treatment trials indicate that all routinely used second line treatments (i.e., levetiracetam, valproate and fosphenytoin) are equally effective. Better understanding of the pathophysiology has indicated that nonanti-seizure medications aimed at underlying pathological processes should perhaps be considered in the treatment of SE; already immunosuppressant treatments are being more widely used in particular for new onset refractory status epilepticus (NORSE) and Febrile infection-related epilepsy syndrome (FIRES) that sometimes revealed autoimmune or paraneoplastic encephalitis. Growing evidence for ICU EEG monitoring and major advances in automated analysis of the EEG could help intensivist to assess the control of electrographic seizures.

SUMMARY

Research into the morbi-mortality of SE has highlighted the potential devastating effects of this condition, emphasizing the need for rapid and aggressive treatment, with particular attention to cardiorespiratory and neurological complications. Although we now have a good evidence-base for the initial status epilepticus management, the best treatments for the later stages are still unclear and clinical trials of potentially disease-modifying therapies are long overdue.

A practical approach to in-hospital management of new-onset refractory status epilepticus/febrile infection related epilepsy syndrome

New-onset refractory status epilepticus (NORSE) is "a clinical presentation, not a specific diagnosis, in a patient without active epilepsy or other preexisting relevant neurological disorder, with new onset of refractory status epilepticus without a clear acute or active structural, toxic, or metabolic cause." Febrile infection related epilepsy syndrome (FIRES) is "a subcategory of NORSE that requires a prior febrile infection, with fever starting between 2 weeks and 24 h before the onset of refractory status epilepticus, with or without fever at the onset of status epilepticus." These apply to all ages. Extensive testing of blood and CSF for infectious, rheumatologic, and metabolic conditions, neuroimaging, EEG, autoimmune/paraneoplastic antibody evaluations, malignancy screen, genetic testing, and CSF metagenomics may reveal the etiology in some patients, while a significant proportion of patients' disease remains unexplained, known as NORSE of unknown etiology or cryptogenic NORSE. Seizures are refractory and usually super-refractory (i.e., persist despite 24 h of anesthesia), requiring a prolonged intensive care unit stay, often (but not always) with fair to poor outcomes. Management of seizures in the initial 24-48 h should be like any case of refractory status epilepticus. However, based on the published consensus recommendations, the first-line immunotherapy should begin within 72 h using steroids, intravenous immunoglobulins, or plasmapheresis. If there is no improvement, the ketogenic diet and second-line immunotherapy should start within seven days. Rituximab is recommended as the second-line treatment if there is a strong suggestion or proof of an antibody-mediated disease, while anakinra or tocilizumab are recommended for cryptogenic cases. Intensive motor and cognitive rehab are usually necessary after a prolonged hospital stay. Many patients will have pharmacoresistant epilepsy at discharge, and some may need continued immunologic treatments and an epilepsy surgery evaluation. Extensive research is in progress now via multinational consortia relating to the specific type(s) of inflammation involved, whether age and prior febrile illness affect this, and whether measuring and following serum and/or CSF cytokines can help determine the best treatment.