Juvenile myoclonic epilepsy

Fernando Cendes MD PhD (Dr. Cendes of the University of Campinas - UNICAMP has no relevant financial relationships to disclose.)
Jerome Engel Jr MD PhD, editor. (

Dr. Engel of the David Geffen School of Medicine at the University of California, Los Angeles, received honorariums from Cerebel for advisory committee membership.

)
Originally released October 18, 1993; last updated January 18, 2021; expires January 18, 2024

Overview

In this updated article, the author discusses evidence concerning brain network damage and dysfunction, genetic factors, as well as prognosis and antiepileptic drug treatment in juvenile myoclonic epilepsy.

Key points

 

• Juvenile myoclonic epilepsy is a form of idiopathic generalized epilepsy, also defined as genetic generalized epilepsy. It is characterized by (a) myoclonic jerks (cardinal symptom) that are most frequent in the early morning and (b) generalized tonic-clonic seizures. Typical absence seizures may also occur, but these are infrequent and short and are often ignored by the patient.

 

• The differential diagnosis includes other types of genetic generalized epilepsies, juvenile absence epilepsy, and generalized tonic-clonic seizures alone (formerly known as generalized tonic-clonic seizures on awakening).

 

• Although juvenile myoclonic epilepsy has been considered a long-lasting condition, with frequent seizure relapses after withdrawal of medication, studies have shown that a proportion of patients become seizure-free off medication.

 

• Sodium valproate is the most effective medicine; however, the high risk of fetal malformations and other side effects limit its use in young women. Lamotrigine, levetiracetam, and brivaracetam are good alternatives, but lamotrigine may exacerbate myoclonus. Benzodiazepines may have an adjunctive role, in particular clobazam or clonazepam.

 

• Lifestyle advice is an integral part of the treatment of juvenile myoclonic epilepsy. Patients should avoid sleep deprivation and drinking alcohol.

Historical note and terminology

Juvenile myoclonic epilepsy was first reported in France by Herpin (Herpin 1867). The terminology was variable until Janz and his colleagues in Germany reported 47 cases and proposed the name "impulsive petit mal" as a clinically definable epileptic syndrome (Janz and Matthes 1955; Janz and Christian 1957). The syndrome was later called juvenile myoclonic epilepsy (of Janz) in the English-speaking literature (Asconape and Penry 1984; Delgado-Escueta and Enrile-Bacsal 1984; Commission on Classification and Terminology of the International League against Epilepsy 1989).

Juvenile myoclonic epilepsy is one of the most common “electroclinical” syndromes within the idiopathic generalized epilepsies (Scheffer et al 2017; Elmali et al 2020). There are 4 primary and well‐established epilepsy syndromes within the idiopathic generalized epilepsies: childhood absence epilepsy, juvenile absence epilepsy, juvenile myoclonic epilepsy, and generalized tonic-clonic seizures alone (formerly known as generalized tonic-clonic seizures on awakening) (Scheffer et al 2017). There has been a debate as to whether to define this group of syndromes as idiopathic generalized epilepsies or genetic generalized epilepsies as both terms have pros and cons (Berg et al 2010; Scheffer et al 2017). The ILAE Commission on Classification and Terminology decided to keep both terms to define this group of generalized epilepsies (Scheffer et al 2017).

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