Epilepsy with myoclonic absences: Electroclinical characteristics in a distinctive pediatric epilepsy phenotype

Neuropsychiatric comorbidities and cognition in epilepsy with eyelid myoclonia: A retrospective pediatric case series

OBJECTIVE

Epilepsy with eyelid myoclonia (EEM) is a rare epileptic syndrome classified within the Genetic Generalized Epilepsies of childhood. It is characterized by a high drug resistance, and little is known about prognostic factors and neurodevelopmental comorbidities. The aim of this study was to describe the clinical features, cognitive profile, and prognostic factors in a series of children with EEM.

METHODS

This is a retrospective observational study of patients diagnosed with EEM from 2012 to 2022 in a tertiary pediatric hospital.

RESULTS

Seventeen patients were analyzed (mean age at symptom onset 5.8 years). Neuropsychiatric comorbidities were present in 76.4% (attention deficit hyperactivity disorder 58.8%, behavioral disorder 11.8%, autism spectrum disorder 11.8%, and psychotic outbreaks 11.8%). Neurocognitive assessment was performed in 75%, revealing cognitive impairment in 66.6% (62.5% with borderline intellectual function and 37.5% with -IQ <70-), with predominant difficulties in executive functions, comprehensive language, and motor skills. Cognitive deterioration was observed in one patient in parallel onset with psychotic symptoms. High refractoriness to antiseizure medication (ASM) was observed, with only 23.5% of the patients being seizure-free after a mean follow-up of 7 years. The most effective ASM was valproic acid, and two of them received ketogenic diet with good response. Regarding prognostic factors, psychotic symptoms were associated with a greater number of antiseizure medication (p < .05) implying a more drug-resistant epilepsy.

SIGNIFICANCE

In our study, we found a high rate of cognitive and psychiatric comorbidities and high refractoriness. These data support the concept of EEM as an intermediate entity between idiopathic generalized epilepsy and epileptic and/or neurodevelopmental encephalopathy. Making a proper diagnosis and management of these comorbidities is necessary to improve prognosis and quality of life in EEM.

Genetic mechanisms in generalized epilepsies

The genetic generalized epilepsies (GGEs) have been proved to generate from genetic impact by twin studies and family studies. The genetic mechanisms of generalized epilepsies are always updating over time. Although the genetics of GGE is complex, there are always new susceptibility genes coming up as well as copy number variations which can lead to important breakthroughs in exploring the problem. At the same time, the development of ClinGen fades out some of the candidate genes. This means we have to figure out what accounts for a reliable gene for GGE, in another word, which gene has sufficient evidence for GGE. This will improve our understanding of the genetic mechanisms of GGE. In this review, important up-to-date genetic mechanisms of GGE were discussed.

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.

A Case of a Seven-Year-old boy with Epilepsy with Myoclonic Absence: Importance of Seizure Semiology, Genetic Etiology, and Electroencephalogram Correlation for Timely Intervention

Epilepsy with myoclonic absence (EMA) is a rare disorder with a mean age of onset of 7 years. It is characterized clinically by rhythmic, myoclonic jerking of the head, extremities or both, with impairment of consciousness and an ictal electroencephalogram (EEG) pattern of 3 Hz bilateral, synchronous and symmetrical spike and wave discharges. Prognosis is guarded and most patients are pharmaco-resistant. We present a case of EMA, found to have a FOXP1 gene pathogenic variation and a variance of unknown significance in the MBD5 gene, who was admitted to the intensive care unit in super-refractory status epilepticus. Given the overlap in symptoms of syndromes including myoclonic-astatic epilepsy, childhood absence epilepsy and juvenile myoclonic epilepsy, a detailed seizure semiology with EEG correlation, cannot be over emphasized. In this case, the genetic etiology may lend an interesting insight to the severity and prognosis.

Drug-resistant epilepsy at the age extremes: Disentangling the underlying etiology

The incidence of epilepsy is highest at the extreme age ranges: childhood and elderly age. The most common syndromes in these demographics - self-limited epilepsies of childhood and idiopathic generalized epilepsies in pediatric age, focal epilepsy with structural etiology in older people - are expected to be drug responsive. In this work, we focus on such epilepsy types, overviewing the complex clinical background of unexpected drug-resistance. For self-limited epilepsies of childhood and idiopathic generalized epilepsies, we illustrate drug-resistance resulting from syndrome misinterpretation, reason on possible unexpected courses of epilepsy, and explicate the influence of inappropriate treatments. For elderly-onset epilepsy, we show the challenges in differential diagnosis possibly leading to pseudoresistance and analyze how drug-resistant epilepsy can arise in stroke, neurocognitive disorders, brain tumors, and autoimmune encephalitis. In children and senior people, drug-resistance can be regarded as a hint to review the diagnosis or explore alternative therapeutic strategies. Refractory seizures are not only a therapeutic challenge, but also a cardinal sign not to be overlooked in syndromes commonly deemed to be drug-responsive.

Epilepsy with myoclonic absences: a case series highlighting clinical heterogeneity and surgical management

OBJECTIVE

Epilepsy with myoclonic absences is a rare epilepsy syndrome with distinct features and high rates of drug resistance. Identifying this syndrome may help guide treatment decisions. We highlight clinical heterogeneity in this case series and two cases in which corpus callosotomy was performed.

METHODS

Medical records were reviewed between 2017 and 2021 to identify demographics, comorbidities, age at onset, EEG findings, diagnostic evaluations, seizure semiologies, seizure frequency, anti-seizure medications, diet therapy and surgical treatments in patients with myoclonic absences.

RESULTS

Ten patients were identified including twins with myoclonic absence status epilepticus. Forty percent had an atonic component, 20% presented with myoclonic absence status epilepticus and 60% had incomplete control of seizures at last follow-up visit. Two patients with epilepsy with myoclonic absences with atonia underwent corpus callosotomy; one patient was seizurefree eight months after surgery and the other had greater than 50% seizure reduction over a five-month period.

SIGNIFICANCE

Phenotypic heterogeneity was evident based on seizure semiologies, comorbidities, seizure frequency and response to anti-seizure medications and non-medication treatments. Of patients with an atonic component, 75% did not achieve seizure freedom with medication alone. Corpus callosotomy was performed in two of these patients with encouraging seizure response thus far, however, the efficacy of this treatment should be further evaluated in a larger study.

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.

Myoclonic absence seizures with complex gestural automatisms

Epilepsy with myoclonic absences is a rare generalized epilepsy syndrome with distinctive seizures. Two unrelated children had mild developmental impairment and onset of myoclonic-absences at 3 and 8 years. Seizures were characterized by bilateral 3 Hz myoclonic jerks superimposed on tonic abduction of the upper limbs. Events lasted 10-60 s, and complex gestural automatisms were often observed; in one case, a boy undid his seatbelt and attempted to exit a moving vehicle. Post-ictally, both children immediately regained awareness without recollection of their actions. Ictal EEGs showed 3 Hz generalized spike-wave. Complex automatisms have not been described in myoclonic absence seizures. This generalized seizure type can be confused with focal seizures when these ictal behaviours occur.