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Background: KCNMA1-linked channelopathy is characterized by neurodevelopmental disorder, epileptic seizures and non-epileptic paroxysmal episodes., Objectives: To describe the phenotype of paroxysmal non-epileptic episodes related to KCNMA1 pathogenic variants., Methods: Videos of paroxysmal episodes were reviewed according to a standardized protocol by a group of movement disorders experts., Results: Fourteen videos were reviewed (6 previously published patients and a new patient). The typical pattern of an episode was (i) facial changes including dyskinetic movements of tongue and jaws (ii) behavioral arrest (iii) loss of postural reflexes that could be associated with focal body stiffness, eventually leading to fall (iv) rapid recovery without post-ictal drowsiness. Attacks were brief, with a high daily frequency, occasionally triggered by emotion, and dramatically improved by psychostimulant therapy in three patients., Conclusions: KCNMA1-related attacks are clearly distinguishable from paroxysmal dyskinesia, cataplexy or episodic ataxia indicating a unique phenomenological entity whose recognition will enhance accurate diagnosis and treatment., (© 2024 The Author(s). Movement Disorders Clinical Practice published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.)

Objective: Lennox-Gastaut syndrome (LGS) is typically characterized by drug-resistant epilepsy and subsequent cognitive deterioration. Surgery is a rare but viable option for the control of seizures in a subset of patients with LGS. This study aimed to describe the organization of the epileptogenic zone network (EZN) in patients with LGS using stereoelectroencephalography (SEEG) and to report the outcome of post-SEEG treatment., Methods: A quantitative SEEG signal analysis was conducted in 14 consecutive patients with LGS, in whom a potentially localized EZN was suggested based on a comprehensive noninvasive evaluation. The EZN and the irritative zone network were identified using relevant biomarkers during ictal (epileptogenicity index and connectivity epileptogenicity index) and interictal (spikes and high-frequency oscillations) recordings. The applied post-SEEG treatments were assessed, including SEEG-guided radiofrequency thermocoagulation (RF-TC), surgery, and neurostimulation., Results: The seizure onset patterns showed some specificity by seizure type, with 84% of tonic seizures involving low-voltage fast activity. The EZN of patients with LGS was often, but not always, complex and extensive, involving two or more lobes (79%) and both hemispheres (64%). The lateral neocortical structures, particularly the lateral premotor and dorsolateral prefrontal cortices, were identified as being most frequently involved in the EZN. Among the explored subcortical structures, only the pulvinar, central-lateral thalamic nucleus, and hypothalamic hamartoma belonged to the EZN. Twelve patients (86%) underwent SEEG-guided RF-TC, with 50% experiencing a >50% reduction in baseline seizure frequency. Four patients (29%) underwent curative surgery for significant involvement of a lesion in the EZN, and one case achieved an Engel class I outcome., Significance: This is the first quantitative SEEG study in patients with LGS to demonstrate the utility of SEEG in identifying patients who may benefit from surgery and to perform SEEG-guided RF-TC. Nevertheless, the indications for SEEG should be carefully assessed, as localized EZN is uncommon in LGS., (© 2025 The Author(s). Epilepsia published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)

SLC6A1 (Solute Carrier Family 6 Member 1) variants are associated with SLC6A1-neurodevelopmental disorders (SLC6A1-NDD), which manifest as early-onset epilepsy, intellectual developmental disorder, and autism spectrum disorder. There have been over 300 reported cases so far. A retrospective analysis of 14 patients with de novo SLC6A1 variants was conducted to assess their developmental milestones, epilepsy progression, antiseizure medication, and, for some, a comprehensive neurodevelopmental evaluation. Data from 14 additional families were also collected using the GenIDA participatory database, aiming to better characterize the natural history of genetic forms of NDDs. Most patients exhibited normal early motor development, but delays in communication and language skills were observed. Their intellectual functioning varied, mostly falling within the low average to moderate intellectual developmental disorder range, with a predominant expressive and receptive language disorder. More than half of the group displayed autistic features, particularly stereotypic behavior. Behavioral disorders such as hyperactivity, anxiety, impulsivity, or inhibition were common concerns for parents. The first seizures occurred between 14 months and 5 years, mainly presenting as generalized seizures (atonic falls, absences, atypical absences, myoclonic-atonic seizures). EEG results frequently showed bursts of rhythmic delta activity, persisting from childhood to adulthood, with epilepsy primarily responding well to antiseizure medication in most of the reported cases. This study exhibited a distinct electroclinical and neurodevelopmental phenotype in young children, suggesting the importance of early genetic testing for SLC6A1-NDD diagnosis., Competing Interests: Declaration of competing interest None of the authors have any conflicts of interest related to this study to declare., (Copyright © 2025 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.)