Juvenile Myoclonic Epilepsy (JME)

Guidance for primary care clinicians diagnosing and managing children with juvenile myoclonic epilepsy
Juvenile myoclonic epilepsy (JME) is an idiopathic generalized epilepsy syndrome. It presents in adolescents 12-18 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 normal. 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.

Other Names

Janz syndrome
JME (juvenile myoclonic epilepsy)

Key Points

Teratogenic effects of anti-epileptic medications
Women of childbearing age should be counseled regarding the possible teratogenic effects of anti-epileptic medications on a fetus. [Hill: 2010] Women on oral contraceptives should understand that anti-epileptic medications can interfere with oral contraceptive serum levels (Antiepileptic Drugs and Contraception (US Pharmacist), [Hill: 2010]).
Seizure activity restrictions
Typical seizure activity restrictions should be discussed and documented for this generalized epilepsy syndrome. Please see Safety Precautions for Children with Seizures.

Diagnosis

Juvenile myoclonic epilepsy 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. An EEG when the patient is sleep deprived is helpful to confirm the diagnosis. EEG typically shows rapid generalized polyspike waves not only during seizures but interictally. Neuroimaging in the classical clinical setting is not necessarily required.

Prevalence

The JME risk in the general population is approximately 5.6 per 10000 people. It constitutes close to 10% of epilepsy, although this may be a low number as JME is often misdiagnosed unless the myoclonic jerks are specifically sought. [Syvertsen: 2017]

Genetics & Inheritance

Juvenile myoclonic epilepsy is an idiopathic hereditary form of epilepsy not associated with organic brain pathology. It may be inherited (up to 50% of patients have family members who have experienced seizures). Juvenile myoclonic epilepsy 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.

Treatment & Management

Valproic acid is currently the medication of choice and most effective. Newer medications such as lamotrigine and levetiracetam (approved for adjunctive therapy for the 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 long-term. [Crespel: 2013]

Prognosis

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.

ICD-10 Coding

G40.B11, Juvenile myoclonic epilepsy, intractable, with status epilepticus

Resources

Information & Support

Related Portal Content
Assessment and management information for the primary care clinician caring for the child with seizures: Answers to questions frequently asked by families with a child diagnosed with seizures: Families may also benefit from:

For Professionals

Epliepsy, Myoclonic Juvenile; EJM (OMIM)
Clinical features, genetics, and inheritance of JME; Online Mendelian Inheritance in Man.

Juvenile Myoclonic Epilepsy (StatPearls)
dentifies the frequency of juvenile myoclonic epilepsy, describe the epidemiology of juvenile myoclonic epilepsy in males compared to females, review the possible causes of juvenile myoclonic epilepsy, summarize the evaluation and treatment of juvenile myoclonic epilepsy and the role of the interprofessional team in managing this condition.

For Parents and Patients

Juvenile Myoclonic Epilepsy (Epilepsy Foundation)
Answers to frequently asked questions about JME.

Services for Patients & Families in Montana (MT)

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* number of provider listings may vary by how states categorize services, whether providers are listed by organization or individual, how services are organized in the state, and other factors; Nationwide (NW) providers are generally limited to web-based services, provider locator services, and organizations that serve children from across the nation.

Authors & Reviewers

Initial publication: February 2009; last update/revision: December 2022
Current Authors and Reviewers:
Author: Lynne M. Kerr, MD, PhD
Reviewer: Cristina Corina Trandafir, MD, PhD
Authoring history
2019: update: Lynne M. Kerr, MD, PhDA
2009: first version: Lynne M. Kerr, MD, PhDA
AAuthor; CAContributing Author; SASenior Author; RReviewer

Page Bibliography

Crespel A, Gelisse P, Reed RC, Ferlazzo E, Jerney J, Schmitz B, Genton P.
Management of juvenile myoclonic epilepsy.
Epilepsy Behav. 2013;28 Suppl 1:S81-6. PubMed abstract

Hill DS, Wlodarczyk BJ, Palacios AM, Finnell RH.
Teratogenic effects of antiepileptic drugs.
Expert Rev Neurother. 2010;10(6):943-59. PubMed abstract / Full Text

Syvertsen M, Hellum MK, Hansen G, Edland A, Nakken KO, Selmer KK, Koht J.
Prevalence of juvenile myoclonic epilepsy in people <30 years of age-A population-based study in Norway.
Epilepsia. 2017;58(1):105-112. PubMed abstract