Kindling in humans: Does secondary epileptogenesis occur?

Hippocampal sclerosis in association with Sturge-weber syndrome: An intertwining of 2 epileptogenic lesions

Epilepsy is a common neurological disease that to this day presents a significant neurological challenge worldwide. It has diverse etiologies with different manifestations associated with complex progressive brain alterations. Secondary epileptogenesis was a concept that emerged from the study of drug-refractory focal epilepsy subjects. It implies that repetitive seizure activity originating from a primary source could transform a previously normal cortical region into a secondary epileptogenic focus. Experimental and clinical studies have been searching for this phenomenon and its effects on neural circuitry for a long time. However, despite achieved advancements, the exact mechanisms of underlying secondary epileptogenicity remain a controversial field of study. Our case involves a 34-year-old female with a history of epilepsy, initially presenting with manageable epilepsy in infancy that gradually escalated to drug-refractory epilepsy. Magnetic resonance imaging (MRI) of the patient revealed 2 epileptogenic focuses, left-sided Sturge-Weber syndrome (SWS) and ipsilateral hippocampal sclerosis (HS). Furthermore, the term "Dual pathology" was used in the simultaneous presence of HS with other potential extra-hippocampal epileptogenic lesions and is often used by previous studies as a way of understanding secondary epileptogenicity. Thereby, this newly presented case of dual pathology will be addressed within the framework of secondary epileptogenicity in the review of current literature.

Do Seizures Damage the Brain?-Cumulative Effects of Seizures and Epilepsy: A 2025 Perspective

In 1885, William Gowers proposed that epilepsy is a progressive disease, based on clinical evidence before any effective treatments were available. His long-standing hypothesis has been summarized with the statement "seizures beget seizures." Whether this is the case and related questions about seizure-induced modification and damage of brain circuits are of fundamental importance for neurobiological understanding of epilepsy, development of effective treatment strategies, clinical management, and prognostication. Consensus about progression and seizure-induced damage has remained controversial. Here, we critically review these long-standing questions, incorporating perspectives about perceived inconsistencies in past studies, potential implications of recent longitudinal imaging and cognitive studies, and emphasize experimental and clinical gaps that have proved challenging. Answers to these questions are important for development of management strategies to achieve prompt effective acute control of seizures and prevention of their potential recurrence and long-term comorbidities.

Integrated Proteomics and Lipidomics Analysis of Hippocampus to Reveal the Metabolic Landscape of Epilepsy

Epilepsy encompasses a spectrum of chronic brain disorders characterized by transient central nervous system dysfunctions induced by recurrent, aberrant, synchronized neuronal discharges. Hippocampal sclerosis (HS) is identified as the predominant pathological alteration in epilepsy, particularly in temporal lobe epilepsy. This study investigates the metabolic profiles of epileptic hippocampal tissues using proteomics and lipidomics techniques. An epilepsy model was established in Sprague-Dawley (SD) rats via intraperitoneal injection of pentylenetetrazole (PTZ), with hippocampal tissue samples subsequently extracted for histopathological examination. Proteomics analysis was conducted using isobaric tags for relative and absolute quantitation (iTRAQ) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS), while lipidomics analysis employed ultrahigh-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC Q-TOF/MS). Proteomic analysis identified 144 proteins with significant differential expression in acute epileptic hippocampal tissue and 83 proteins in chronic epileptic hippocampal tissue. Key proteins, including neurofilament heavy (Nefh), vimentin (Vim), gelsolin (Gsn), NAD-dependent protein deacetylase (Sirt2), 2',3'-cyclic-nucleotide 3'-phosphodiesterase (Cnp), myocyte enhancer factor 2D (Mef2d), and Cathepsin D (Ctsd), were pivotal in epileptic hippocampal tissue injury and validated through parallel reaction monitoring (PRM). Concurrently, lipid metabolomics analysis identified 32 metabolites with significant differential expression in acute epileptic hippocampal tissue and 61 metabolites in chronic epileptic hippocampal tissue. Bioinformatics analysis indicated that glycerophospholipid (GP) metabolism, glycosylphosphatidylinositol (GPI)-anchor biosynthesis, and glycerolipid (GL) metabolism were crucial in epileptic hippocampal tissue injury. Integrated proteomics and lipidomics analysis revealed key protein-lipid interactions in acute and chronic epilepsy and identified critical pathways such as sphingolipid signaling, autophagy, and calcium signaling. These findings provide deeper insights into the pathophysiological mechanisms of epileptic hippocampal tissue damage, potentially unveiling novel therapeutic avenues for clinicians.

Mammalian models of status epilepticus - Their value and limitations

Status epilepticus (SE) is a medical and neurologic emergency that may lead to permanent brain damage, morbidity, or death. Animal models of SE are particularly important to study the pathophysiology of SE and mechanisms of SE resistance to antiseizure medications with the aim to develop new, more effective treatments. In addition to rodents (rats or mice), larger mammalian species such as dogs, pigs, and nonhuman primates are used. This short review describes and discusses the value and limitations of the most frequently used mammalian models of SE. Issues that are discussed include (1) differences between chemical and electrical SE models; (2) the role of genetic background and environment on SE in rodents; (3) the use of rodent models (a) to study the pathophysiology of SE and mechanisms of SE resistance; (b) to study developmental aspects of SE; (c) to study the efficacy of new treatments, including drug combinations, for refractory SE; (d) to study the long-term consequences of SE and identify biomarkers; (e) to develop treatments that prevent or modify epilepsy; (e) to study the pharmacology of spontaneous seizures; (4) the limitations of animal models of induced SE; and (5) the advantages (and limitations) of naturally (spontaneously) occurring SE in epileptic dogs and nonhuman primates. Overall, mammalian models of SE have significantly increased our understanding of the pathophysiology and drug resistance of SE and identified potential targets for new, more effective treatments. This paper was presented at the 9th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures held in April 2024.

Laser amygdalohippocampotomy reduces contralateral hippocampal sub-clinical activity in bitemporal epilepsy: A case illustration of responsive neurostimulator ambulatory recordings

Responsive neurostimulation (RNS) is a valuable tool in the diagnosis and treatment of medication refractory epilepsy (MRE) and provides clinicians with better insights into patients' seizure patterns. In this case illustration, we present a patient with bilateral hippocampal RNS for presumed bilateral mesial temporal lobe epilepsy. The patient subsequently underwent a right sided LITT amygdalohippocampotomy based upon chronic RNS data revealing predominance of seizures from that side. Analyzing electrocorticography (ECOG) from the RNS system, we identified the frequency of high amplitude discharges recorded from the left hippocampal lead pre- and post- right LITT amygdalohippocampotomy. A reduction in contralateral interictal epileptiform activity was observed through RNS recordings over a two-year period, suggesting the potential dependency of the contralateral activity on the primary epileptogenic zone. These findings suggest that early targeted surgical resection or laser ablation by leveraging RNS data can potentially impede the progression of dependent epileptiform activity and may aid in preserving neurocognitive networks. RNS recordings are essential in shaping further management decisions for our patient with a presumed bitemporal epilepsy.