Myoclonic absence seizures with complex gestural automatisms

Electroclinical features of myoclonic absence epilepsy: A single-center cohort analysis in Southwest China

BACKGROUND AND OBJECTIVE

To date, few analyses of the electroclinical features and prognosis of patients with epilepsy with myoclonic absences (EMA) have been performed. We reviewed the clinical and electroencephalography (EEG) features, response to antiseizure medications, and long-term prognosis of patients with EMA in a single center in Southwest China, with the goal of increasing the understanding of the disease, strengthening early clinical diagnosis and treatment, and improving prognosis.

METHODS

We retrospectively analyzed the data of 11 children with EMA at the Epilepsy Center of Children's Hospital of Chongqing Medical University. The patients' history of EEG (including ictal EEG), medical history, head magnetic resonance imaging (MRI), medication, cognition and development were retrospectively analyzed.

RESULTS

Eleven patients (7:4 male:female) with an onset age of 7.18 ± 3.72 years had myoclonic-absence (MA) seizures, and four (36.36 %) had asymmetrical features. Nine (75 %) had multiple seizure types, including MA, myoclonic, absence, and generalized tonic-clonic seizures. During the interictal period, generalized 3 Hz spike-slow wave complexes were rhythmically emitted, with two having a small amount of focal discharge. In eight patients, bilateral symmetrically synchronized 3 Hz rhythmic spike-slow wave complex bursts, which showed a lock-in relationship with myoclonic, were recorded. All patients were treated with new or adjusted antiseizure medications and were followed up for 15-44 months. Five patients (45.45 %) had no seizures and no cognitive impairment; and 4/5 (80 %) were treated with valproic acid alone. During follow-up, the EEG results of four patients showed normal. The remaining six patients had drug-resistant epilepsy. Five had daily MA seizures, and one had daily myoclonic seizures. Among these six patients, four (66.67 %) exhibited developmental delay before disease onset, three experienced language delay, one experienced motor delay at follow-up.

CONCLUSION

The clinical manifestations of EMA are highly heterogeneous. Some patients experience seizures with atypical characteristics and exhibit significant clinical heterogeneity in response to antiseizure medications and cognitive impairment. Some patients have a better prognosis, and developmental delay before disease onset may be associated with a poor prognosis.

Research progress on epilepsy with myoclonic absence

Epilepsy with myoclonic absence (EMA) is a rare childhood-onset generalized epilepsy syndrome characterized by myoclonic absence seizures. First discovered by Tassinari et al. in 1969, EMA has been extensively studied by researchers from all over the world. This review synthesizes recent studies on EMA, covering its discovery history, classification, epidemiology, pathophysiology, etiology, clinical manifestations, diagnosis and differential diagnosis, treatment, prognosis and evolution, and especially discusses the etiology and pathophysiology mechanism, to help clinicians understand this relatively rare epilepsy syndrome, reduce the rate of missed diagnosis and misdiagnosis, and effectively guide treatment to alleviate the long-term cognitive impairment in affected individuals.

Duration of epileptic seizure types: A data-driven approach

OBJECTIVE

To determine the duration of epileptic seizure types in patients who did not undergo withdrawal of antiseizure medication.

METHODS

From a large, structured database of 11 919 consecutive, routine video-electroencephalograpy (EEG) recordings, labeled using the SCORE (Standardized Computer-Based Organized Reporting of EEG) system, we extracted and analyzed 2742 seizures. For each seizure type we determined median duration and range after removal of outliers (2.5-97.5 percentile). We used surface electromyography (EMG) for accurate measurement of short motor seizures.

RESULTS

Myoclonic seizures last <150 ms, epileptic spasms 0.4-2 s, tonic seizures 1.5-36 s, atonic seizures 0.1-12,5 s, when measured using surface EMG. Generalized clonic seizures last 1-24 s. Typical absence seizures are rarely longer than 30 s (2.75-26.5 s) and atypical absences last 2-100 s. In our patients, the duration of focal aware (median: 27 s; 1.25-166 s) and impaired awareness seizures (median: 42.5 s; 9.5-271 s) was shorter than reported previously in patients undergoing withdrawal of antiseizure medication. All focal seizures terminated within 10 min. Median duration of generalized tonic-clonic seizures was 79.5 s (57-102 s) and of focal-to-bilateral tonic-clonic seizures was 103.5 (77.5-237 s). All tonic-clonic seizures terminated within 5 min.

SIGNIFICANCE

This comprehensive list of seizure durations provides important information for characterizing seizures and diagnosing patients with epilepsy. The upper limits of seizure durations are helpful in early recognition of imminent status epilepticus.

International League Against Epilepsy classification and definition of epilepsy syndromes with onset in childhood: Position paper by the ILAE Task Force on Nosology and Definitions

The 2017 International League Against Epilepsy classification has defined a three-tier system with epilepsy syndrome identification at the third level. Although a syndrome cannot be determined in all children with epilepsy, identification of a specific syndrome provides guidance on management and prognosis. In this paper, we describe the childhood onset epilepsy syndromes, most of which have both mandatory seizure type(s) and interictal electroencephalographic (EEG) features. Based on the 2017 Classification of Seizures and Epilepsies, some syndrome names have been updated using terms directly describing the seizure semiology. Epilepsy syndromes beginning in childhood have been divided into three categories: (1) self-limited focal epilepsies, comprising four syndromes: self-limited epilepsy with centrotemporal spikes, self-limited epilepsy with autonomic seizures, childhood occipital visual epilepsy, and photosensitive occipital lobe epilepsy; (2) generalized epilepsies, comprising three syndromes: childhood absence epilepsy, epilepsy with myoclonic absence, and epilepsy with eyelid myoclonia; and (3) developmental and/or epileptic encephalopathies, comprising five syndromes: epilepsy with myoclonic-atonic seizures, Lennox-Gastaut syndrome, developmental and/or epileptic encephalopathy with spike-and-wave activation in sleep, hemiconvulsion-hemiplegia-epilepsy syndrome, and febrile infection-related epilepsy syndrome. We define each, highlighting the mandatory seizure(s), EEG features, phenotypic variations, and findings from key investigations.

Seizures in Sotos syndrome: Phenotyping in 49 patients

We aimed to describe the phenotypic spectrum of seizures in Sotos syndrome, a genetic condition involving overgrowth, macrocephaly, dysmorphic features, and learning disability, in which 60%‐90% have NSD1 pathogenic variants. Patients were recruited from clinics and referral from support groups. Those with seizures and a clinical diagnosis of Sotos syndrome were included. Phenotyping data were collected via structured clinical interview and chart review. Forty‐nine patients were included. Twenty had NSD1 testing results available; of these, 15 (75%) had NSD1 pathogenic variants. Seizure onset age ranged from 3 months to 12 years. Staring spells (absence or focal impaired awareness seizure) were the most frequently reported semiology (33/49; 67%), followed by febrile seizures (25/49; 51%) and afebrile bilateral tonic‐clonic seizures (25/49; 51%). Most patients (33/49; 67%) had multiple seizure types. The majority (33/49; 67%) had seizures controlled on a single antiseizure medication or no medication. Nine (18%) had drug‐resistant epilepsy. Epilepsy syndromes included febrile seizures plus, Lennox‐Gastaut syndrome, childhood absence epilepsy, and generalized tonic‐clonic seizures alone. The seizure phenotype in Sotos syndrome most commonly involves staring spells, afebrile tonic‐clonic seizures or febrile convulsions; however, other seizure types may occur. Seizures are typically well‐controlled with medication, but drug‐resistant epilepsy occurs in a minority.