Juvenile myoclonic epilepsy (JME)

Juvenile myoclonic epilepsy (JME) is an idiopathic generalized epilepsy syndrome. It presents in adolescents 12 to 18 years of age with myoclonic jerks, generalized tonic-clonic seizures, and sometimes absence seizures. Myoclonic jerks, typically but not exclusively upper extremity, often occur for months or more before the seizures begin and must be specifically asked about as patients often think they are a normal occurrence. Myoclonic jerks typically occur in the morning after awakening and may vary among patients. Some patients describe them as brief tingling sensations, others have myoclonic jerks similar to those the general population experiences upon falling asleep, and others may have them so hard that they throw objects. Leg jerks and sudden falls can also occur. No change in consciousness occurs during the jerks. Seizures may be initiated by light such as strobe lights, lack of sleep, alcohol, and stress. Treatment usually needs to be lifelong.

The JME risk in the general population is approximately 1 case per 1000-2000 people. JME constitutes 5-10% of epilepsy, although this may be a low number as JME is often misdiagnosed unless the myoclonic jerks are specifically sought. [Grunewald: 1993] <

JME is a clinical diagnosis, based on the myoclonic jerks and the generalized tonic-clonic seizures (sometimes absence) in a normally developing child with a normal exam sometimes in the setting of a family history of epilepsy. A sleep deprived EEG is helpful to confirm the diagnosis. EEG typically shows rapid generalized polyspike waves during seizures. Neuroimaging in the classical clinical setting is not necessarily required.

JME is an idiopathic hereditary form of epilepsy not associated with organic brain pathology. JME may be inherited (up to 50% of patients have family members who have experienced seizures). [Delgado-Escueta: 1989] JME is genetically heterogeneous and although usually thought of as an autosomal dominant disorder with reduced penetrance, may have autosomal recessive forms as well. Currently, genes on several chromosomes have been implicated in various populations. (For details see [Omim: 2007])

Valproic acid is currently the medication of choice although newer medications such as lamotrigine and levetiracetam (which has been approved for adjunctive therapy for treatment of myoclonic seizures by the FDA) are also being used in increasing numbers due to better side effect profiles. Treatment is almost always successful, although generally the patients will have to continue on antiepileptic therapy on a very long-term basis. Typical seizure activity restrictions should be discussed and documented for this generalized epilepsy syndrome.

Although children and youth with JME will often need to remain indefinitely on medication, seizures are generally well controlled and intellectual function is not affected.