Epilepsy with myoclonic absences with early onset: a follow-up study

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.

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

PURPOSE

The purpose of this article was to study the electroclinical characteristics and seizure outcome of children with epilepsy with myoclonic absences (EMA).

METHOD

In this descriptive cohort study, we reviewed clinical records of patients who met the criteria for EMA. Each patient's demographic data, birth/developmental history, seizure semiology/pattern, antiepileptic drugs (AED), clinical examination, video-electroencephalography (VEEG), and neuroimaging data were reviewed. Response to AED and change in seizure frequency/pattern on follow-up were noted. Responders were defined by seizure freedom/>50% reduction in seizure frequency on follow-up.

RESULT

Twelve children were diagnosed with EMA between 2008 and 2013 [50% male; mean age of onset: 3.5years]. Main seizure types were the characteristic myoclonic absences (100%) and generalized tonic-clonic seizures (42%). Ictal correlate on VEEG was 3- to 3.5-Hz spike-and-wave discharges (82%) and fast recruiting bifrontal rhythm (25%). One patient had specific MRI abnormalities. Mean duration of follow-up was 23.9months. Seizure frequency had significantly improved on follow-up (p=0.005), and at last follow-up, nine patients were in the responder group: four seizure-free for at least 1year, two with >90%, and three with >50% reduction in seizure frequency. The number of AED reduced significantly between initial visit and last follow-up among responders. Two patients on follow-up developed different seizure patterns, with generalized tonic and complex partial seizures. One responder expired because of unprovoked generalized convulsive status epilepticus.

CONCLUSION

This cohort, the largest from the Indian subcontinent on the rare syndrome of EMA, suggests mild heterogeneity in a seemingly homogenous electroclinical phenotype. Clinical semiology while unique may demonstrate focality and variable ictal patterns. Most patients respond to either valproate monotherapy or valproate-lamotrigine combination; however, the prognosis remains guarded. The seizures of a minority of patients remain drug-refractory and may evolve into tonic or complex partial seizures.

Absence seizures in the first 3 years of life: an electroclinical study of 46 cases

PURPOSE

Early onset absence seizures have been considered a rare heterogeneous group with a poor prognosis. Only few patients may be categorized into well-known syndromes. We have evaluated electroclinical features, evolution, and the nosologic boundaries of early onset absence seizures.

METHODS

Forty-six neurologically normal patients with absence seizures associated with bilateral, synchronic, or asynchronic, and symmetric or asymmetric spike-and-wave paroxysms with onset in the first 3 years of life were included. Patients with abnormal neurologic examination and brain imaging were excluded from the study.

KEY FINDINGS

In our study, 39 patients met the clinical and electroencephalography (EEG) criteria of well-defined epileptic syndromes. Childhood absence epilepsy was found in 11 patients, benign myoclonic epilepsy in infancy in 18 patients, eyelid myoclonic epilepsy in 4, and epilepsy with myoclonic absences in 6. We did not find clinical and EEG criteria of well-recognized epileptic syndromes in seven children. Nine of 11 patients with simple absence seizures became seizure free. All these patients had normal neurologic and neuropsychological evaluations. Of the 35 patients who had absence seizures associated with myoclonic seizures, 20 became seizure free. Fifteen of 35 children continue having seizures. At the last visit, 20 of these 35 patients had normal neurologic and neuropsychological evaluations, 11 presented with mild mental retardation, and 4 with severe mental retardation.

SIGNIFICANCE

Epilepsies with absence seizures of early onset are relatively uncommon. Most of the patients had well-defined epileptic syndromes with a variable evolution. The evolution depended on the epileptic syndromes.

Epilepsy with myoclonic absences

Among the epileptic syndromes that are defined mainly on the basis of a characteristic seizure type, epilepsy with myoclonic absences (EMA) stands out as a somewhat controversial entity. This is because the sound and evident clinical characteristics on which it was identified some 30 years ago have evolved, mostly as a consequence of changes in the practical management of epilepsies and to the description of myoclonic components in a variety of other generalised epilepsies with absences. Myoclonic absences (MA) are described as typical absences with sudden onset and offset that are associated with generalised spike and wave (SW) discharges on the ECG, with distinctive traits. Clinically, absences are associated with axial hypertonia (the subject usually bends forward and slightly raises their shoulders and arms), and jerks synchronous with the SW discharges. Neurophysiologically, axial hypertonia and rhythmic jerks may be recorded on polygraphic surface electromyogram leads in association with the typical SW discharges; as such, despite an ECG, the diagnosis may be missed in the absence of video documentation of the seizure and/or adequate polygraphy. MA need to be distinguished from absences with other types of prominent myoclonic accompaniment (perioral, eyelid, limbs).The prognosis of EMA remains variable. Modern therapeutic combinations, such as valproic acid and ethosuximide, or valproic acid and lamotrigine, are usually effective; however, in a proportion of patients, seizures are resistant to drug treatment. These patients may experience cognitive deterioration and, in some cases, evolution towards a more severe form of epilepsy, including the Lennox-Gastaut syndrome. The more benign cases usually present with MA as the only seizure type, while patients who experience other seizures, especially generalised tonic-clonic seizures, in association with MA may have a less favourable outcome.

Early-onset absence epilepsy: clinical and electroencephalographic features in three children

To describe the clinical and electroencephalographic features of three infants diagnosed as having early-onset absence seizures. Two males and one female, aged 21-29 months were seen in our neuropaediatric outpatient clinic because of daily episodes of motor arrest and loss of contact. Neurological examination and mental development was considered normal in all of them. Two out three had first-degree relatives with seizures with onset in the childhood and favourable evolution in the adulthood. A video-electroencephalogram was requested. Ictal EEG revealed a normal background and generalised spike-and-wave complexes at 3-3.5 Hz accompanied by disruption of ongoing activity in keeping with absence seizures. The duration of seizures ranged from 2 to 10s. One child (patient 2) experienced rhythmic myoclonic jerks in upper limbs and head as those described in myoclonic absences. Clinical and electroencephalographic follow-up ranged from 8 months to 4 years. Two children were on treatment with valproate and in the case of the patient 3, the combination of valproate and ethosuximide was necessary. Control of absence seizures was achieved in all our cases. Absence seizures should be considered as a possible cause of transient impairment of consciousness even among infants minor than 3 years of age. A video-electroencephalogram is the method of choice in the diagnostic evaluation and syndromic classification of these paroxysmal events.

Idiopathic generalized epilepsies: clinical and electroencephalogram diagnosis and treatment

This review concentrates on the principles of the clinical and electroencephalogram diagnosis of idiopathic generalized epilepsies and their treatment. The electroclinical variability of the main seizure types is detailed and particular emphasis is placed on the differential diagnosis from other seizures and nonepileptic conditions that is essential for the optimal management of these patients. The authors review the various idiopathic generalized epilepsy subsyndromes and conditions that are included in both the 1989 International League Against Epilepsy classification system and the recently proposed International League Against Epilepsy scheme, but also syndromes and forms that have not been formally recognized. Finally, the authors describe the principles of antiepileptic drug treatment with the old and newer drugs, and their specific indications and contraindications in the various syndromes and seizure types.

Epilepsy with myoclonic absences

Epilepsy with myoclonic absences is characterized clinically by absences accompanied by marked, diffuse, rhythmical myoclonias, often associated with a progressive tonic contraction. The ictal EEG shows bilateral, synchronous and symmetrical spike and wave discharges repeated at 3 Hz (similar to that observed in typical absences of childhood absence epilepsy) in strict relation with myoclonias recorded on EMG. These seizures occur many times a day. Associated seizures are present in 2/3 of the cases, the most frequent association being GTCS in 45%. The age at onset is about 7 years. There is a male preponderance. The evolution is variable and seems to depend on the existence or not of GTCS. Classical cotherapy with valproate and ethosuximide with appropriate plasma levels is more efficient if myoclonic absences are non-associated with GTCS. In cases where GTCS are associated, there is often an unfavourable outcome, with persistence of myoclonic absences or with modification of the epilepsy with a possible evolution towards a generalized cryptogenic or symptomatic form.