Juvenile Myoclonic Epilepsy

Juvenile Myoclonic Epilepsy

Overview

Juvenile myoclonic epilepsy (JME) is an hereditary, idiopathic generalized epilepsy that typically begins between ages 12 and 18 and is characterized by myoclonic jerks, especially upon waking. Other seizure types, including generalized tonic-clonic and absence seizures, are also common. Treatment involves a combination of lifestyle management, such as avoiding sleep deprivation and alcohol, and anti-seizure medication, which is highly effective for most people

Symptoms

The main symptom of JME is having myoclonic seizures that occur any time. These are more likely when a person wakes up, either in the morning or from a nap. These seizures involve sudden, quick, small jerks of the arms and shoulder and, less often, the legs. These movements may be limited to the hands. The person may throw or drop something from their hands.

Myoclonic seizures can occur in clusters, affecting one or both sides of the body. These seizures can be a warning sign that a generalized tonic-clonic seizure is about to occur. In a generalized tonic-clonic seizure, the jerking spreads throughout the entire body.

Some children with JME also have absence seizures. These can be very subtle and even go unnoticed. During these seizures, the person will “space out,” staring and becoming unresponsive for short periods of time. No twitching or convulsing occurs during absence seizures.

Certain factors can make seizures more likely in people with JME. Avoiding these triggers can help reduce seizures. For people with JME, these triggers can include:

Inconsistent sleep patterns, being tired

Drinking alcoholic beverages or large amounts of caffeine

Stress

Flickering lights, such as strobe lights, video games or light reflecting off ocean waves or snow

Other Conditions Associated with Juvenile Myoclonic Epilepsy

The most concerning part of juvenile myoclonic epilepsy is the chance for a condition known as “myoclonic status epilepticus.” While uncommon, when this occurs, the person has multiple myoclonic seizures that last for more than five minutes. Patients can significantly reduce their risk for this condition by following a regular sleep schedule and taking their seizure medications as prescribed.

Causes

Genetic factors

Strong genetic link: JME is considered a genetically determined syndrome, and many people have a family history of epilepsy.

Multiple genes involved: The condition is believed to be caused by a combination of different genes, rather than a single gene mutation in most cases.

Specific gene mutations: Mutations have been identified in several genes, including GABRA1 (which is involved in GABA-A receptors, crucial for inhibiting brain signals) and EFHC1 (which plays a role in cell development).

Gene carriers: Some individuals may carry the genetic mutation without developing seizures themselves, but they can pass the gene to their children. 

Other contributing factors

Lack of sleep: Sleep deprivation is a significant trigger for seizures in JME patients.

Stress and fatigue: Emotional stress and general fatigue can also precipitate seizures.

Alcohol consumption: Drinking alcohol can trigger seizures in people with JME.

Flashing lights: A large percentage of JME patients are photosensitive, meaning flashing lights from sources like flickering TVs, computer screens, or even sunlight can trigger seizures.

History of other seizures: Some children with JME may have had earlier seizures, such as childhood absence epilepsy, before the onset of JME symptoms. 

Diagnosis

Medical history and physical exam: A doctor, likely a pediatric neurologist for a child, will take a detailed history of the seizures, looking for characteristic features like subtle myoclonic jerks on waking, followed by generalized tonic-clonic seizures. 

Electroencephalogram (EEG): This is the most important diagnostic test. 

It measures brainwave activity using electrodes on the scalp. 

An abnormal EEG showing a generalized polyspike and wave pattern is a key indicator of JME. 

The abnormalities are often most prominent during sleep or when waking up. 

A normal routine EEG may be followed by a sleep-deprived EEG to help reveal the characteristic patterns. 

Other tests:

MRI or CT scan: These imaging tests are usually normal in JME and are used to rule out other potential causes of seizures, not to diagnose JME itself. 

Video-EEG: This can be considered the diagnostic standard, as it captures a video of the seizure activity and the corresponding EEG to provide definitive evidence. 

Treatment

Medications

Valproic acid: The most effective and first-choice medication for JME. It is effective against myoclonic, absence, and generalized tonic-clonic seizures. However, it requires caution in women of childbearing age due to teratogenicity. 

Other effective medications:

Levetiracetam 

Lamotrigine 

Topiramate 

Zonisamide 

Medications to avoid: Do not use sodium channel-blocking agents like carbamazepine, oxcarbazepine, and phenytoin, as they can worsen JME seizures. 

Other treatments

Lifestyle modifications:

Ensure consistent, quality sleep and avoid sleep deprivation. 

Manage stress through relaxation techniques or other methods. 

Limit or avoid alcohol. 

Other medical options:

If medications are not effective, vagus nerve stimulation (VNS) may be an option. 

Other treatments like the ketogenic diet and responsive neurostimulation are being researched. 

Type of Doctor Department : A neurologist, An epileptologist