Juvenile myoclonic epilepsy (JME) is the most common form of generalized epilepsy, in which seizure activity occurs in the entire brain at once. JME makes up about 5 percent to 10 percent of all cases of epilepsy, according to the journal Epilepsy & Behavior.
Also known as Janz syndrome, JME usually begins during adolescence. Although this type of epilepsy was often not recognized in the past, a deeper understanding of the prevalence, symptoms, and causes of JME has led to better diagnostic processes and treatment options today.
JME symptoms typically develop between the ages of 15 and 18, although this type of epilepsy can also be diagnosed at a much younger age (5 years) and much older (up to 34 years).
JME is marked by the presence of several types of seizures including myoclonic seizures and, in some people, generalized tonic-clonic seizures. Absence seizures may also be present, although they are not necessary for a diagnosis.
Myoclonic seizures involve jerking muscle spasms. During these myoclonic jerks, a person maintains their consciousness or awareness. Some people describe the sensation of myoclonic seizures as similar to jolts of electrical activity.
Tonic-clonic seizures used to be called grand mal seizures. These seizures have two phases: a tonic phase followed by a clonic phase. During the tonic phase, a person loses consciousness, falls, and becomes stiff. They may bite their tongue, salivate, or foam at the mouth. The clonic phase refers to the jerking muscle spasms that occur next. Sometimes, a person may lose control of their bladder during the clonic phase.
Some people have an unusual feeling (an aura) that warns them about a seizure before it happens. For example, sensations such as unusual smells, colors, or déjà vu can act as warning signs that a tonic-clonic seizure is about to begin.
Absence seizures, previously known as petit mal seizures, refer to a brief and sudden lapse in consciousness. Absence seizures are more common in children than in adults.
Scientists believe the causes and risk factors of JME are mostly genetic. Although there isn’t a lot of research in this realm, studies suggest that JME is hereditary and passed along in families.
One risk factor that scientists have identified is a mutation in a protein that makes up the GABA-A receptor. GABA-A, or the gamma-aminobutyric acid receptor subtype A, is important for inhibition in the brain. Without inhibition, the brain becomes overactive, resulting in seizures.
Other research has implicated the EFHC1 gene as a risk factor for JME. This gene encodes a protein that helps regulate calcium channels, which are responsible for gating communication between brain cells. Abnormal calcium channels can cause overactivity in the brain.
Juvenile myoclonic seizure episodes usually occur after waking from sleep or during the evening while relaxing. These seizures may be made worse by lack of sleep and also waking up suddenly.
If you or a loved one is having seizures, see your family doctor. They will likely ask about your symptoms and take a family history to determine if you may have a genetic risk for epilepsy. Often, the doctor will make a referral to a neurologist, who can investigate further and make a diagnosis.
Diagnostic criteria include a history of myoclonic seizures that have been followed by a generalized tonic-clonic seizure. Your neurologist will likely order an electroencephalogram (EEG) test to view your brain waves. They may also use MRI to determine what’s going on in the brain and body and to rule out other possible causes of seizure activity. However, for generalized epilepsies, MRI is not routinely used.
JME often responds successfully to treatment when it’s diagnosed and treated properly. Making appropriate lifestyle adjustments is an important component of managing JME. This can include avoiding triggers, such as getting insufficient sleep or drinking alcohol. Talk to your doctor if getting enough sleep or avoiding alcohol is an issue for you.
Treatment options also generally include medications such as:
The most common side effects of antiseizure medications include dizziness and fatigue. Depending on the medication, other side effects can also occur, including:
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