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Epilepsy with myoclonic absences: Electroclinical characteristics in a distinctive pediatric epilepsy phenotype
Paresh Zanzmera1, Ramshekhar N Menon1, Kalyani Karkare1
1R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Department of Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum 695011, India.
Insights
Epilepsy with myoclonic absences (EMA) in children shows improved seizure frequency with treatment, though prognosis remains guarded due to potential drug resistance and evolving seizure patterns. Most patients respond to valproate-based therapies.
Area of Science:
- Pediatric Neurology
- Epileptology
Background:
- Epilepsy with myoclonic absences (EMA) is a rare epilepsy syndrome.
- Understanding its electroclinical characteristics and seizure outcomes is crucial for effective management.
Purpose of the Study:
- To investigate the electroclinical features and seizure outcomes in children diagnosed with epilepsy with myoclonic absences (EMA).
Main Methods:
- A descriptive cohort study reviewed clinical records of 12 children diagnosed with EMA.
- Data included demographics, seizure semiology, antiepileptic drugs (AEDs), VEEG, and neuroimaging.
- Seizure response was defined as seizure freedom or >50% reduction in frequency.
Main Results:
- The study identified 12 children with EMA, with a mean age of onset at 3.5 years.
- Characteristic myoclonic absences were the primary seizure type, often associated with 3- to 3.5-Hz spike-and-wave discharges on VEEG.
- Significant seizure frequency improvement was observed, with 9 out of 12 patients responding to treatment, primarily valproate-based regimens.
Conclusions:
- EMA exhibits mild heterogeneity despite a seemingly homogenous phenotype, with potential for focality and variable ictal patterns.
- While most patients respond to valproate monotherapy or combination therapy, the prognosis is guarded.
- A minority of patients may develop drug-refractory seizures or evolving seizure patterns, and one case resulted in mortality.
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.
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