Table of ContentsView AllTable of ContentsWhat It Looks LikeCausesRelated Epilepsy SyndromesDiagnosisTreatment
Table of ContentsView All
View All
Table of Contents
What It Looks Like
Causes
Related Epilepsy Syndromes
Diagnosis
Treatment
Myoclonic seizuresare atype of seizurethat involves brief jerking or twitching muscle motions. “Myo” means muscle, and “clonus” means a rhythmic spasm. The sudden unintended muscle motions, known as myoclonic jerks, typically last one or two seconds.
Genetic factors usually cause this type of seizure. The seizures usually begin in childhood, with the most common form known asjuvenile myoclonic epilepsy (JME).
This article explains myoclonic seizures. It also details the fairly complex reasons for the condition and how it is diagnosed and treated.
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2:04
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What Does a Myoclonic Seizure Look Like?
A myoclonic seizure typically lasts for a few seconds. Itlooks likea sudden, repetitive jerking in an arm, a leg, or the face. Sometimes, myoclonic seizures can involve both sides of the body. They may affect multiple body parts, such as an arm and a leg.
During a myoclonic seizure, the muscles become stiff and then relax in a rapid pattern of motion. You may have less voluntary control over your body and an altered state of consciousness.
An aura, or a sense that a seizure will happen, may come before a myoclonic seizure. You may feel tired or sleepy after it happens, but that is not always true.
Myoclonic seizures tend to happen more than once over the years. Because they are more common in youth, it is not unusual to see the condition improve during adulthood.
Myoclonic seizures typicallybegin in early childhood. These brief jerking motions often occur right before falling asleep or waking up. They can occur at other times of the day.
If you have myoclonic seizures, you’ll likely have at least one other type of seizure disorder. The classic symptoms of epileptic seizures include:
However, each type of myoclonic seizure will have specific symptoms that arise. The way in which these symptoms present depends on the different types and causes of myoclonic seizures.
Myoclonic Jerks
“Myoclonus” is the term used to describe the rapid muscle jerks associated with a myoclonic seizure. In some cases, people may experience this type of muscle activity even though they are not diagnosed with one of the common types of myoclonic seizures.
Some people may feel this muscle motion as they fall asleep. This may happen often, even though the muscle motion does not progress into a seizure.
Myoclonus can also be due to a spinal or nerve disease. Changes inhormones, or the balance of minerals in the body known aselectrolytes, may also cause it.
In some situations, myoclonic jerks may occur only a few times throughout a person’s life.
Infantile Spasms
One seizure disorder that features myoclonic jerks is infantile spasms. These usually start between ages 3 months to 12 months. The spasms are similar to myoclonic jerks. They often occur as the infant is waking from sleep.Infants with infantile spasms have a unique tracing on EEG calledhypsarrhythmia, which consists of irregular patterns of brain waves.
Historically, professionals have called infantile spasmWest Syndrome. However, West syndrome includes myoclonic jerks and regression in the infant’s milestones, so it is unique from infantile spasms alone.
Associated Seizures
People who have myoclonic seizures may also experience other types of seizures. It depends on the underlying cause of the seizures. Other types of seizures that people with myoclonic seizures may experience include:
People who experience myoclonic seizures can develop tonic-clonic (grand mal) seizures as they get older. In people with epilepsy, myoclonic seizures can precede tonic-clonic seizures.
Sleep Myoclonus
Myoclonic jerks can often occur during or near sleep. This is known as sleep myoclonus. Some people experience a sudden jerking motion as they drift off to sleep. Usually, it is one jerking motion rather than persistent myoclonus. Not everyone with sleep myoclonus requires treatment.It may occur once in a while, or it may be more frequent.
Epilepsy
Certain types of epilepsy can lead to myoclonic seizures. Epileptic myoclonus occurs when someone who has epilepsy experiences myoclonus, and it may be the primary manifestation of their epilepsy, or it may occur alongside other types of seizures, such as tonic-clonic, atonic, or absence seizures.
Other Conditions
Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and multiple sclerosis are among the conditions that may lead to seizures. Some of the drugs used to treat seizures are now being tried to treat these closely linked conditions.
Several epilepsy syndromes cause myoclonic seizures. Together, they are often known as progressive myoclonic epilepsy.They have several features in common, including:
Verywell / Emily Roberts
Juvenile Myoclonic Epilepsy
Many people with Juvenile Myoclonic Epilepsy (JME) also have the more classic symptoms of tonic-clonic (grand mal) seizures and the myoclonic type. The seizures tend to occur throughout life, though they may improve in adulthood. This means that a person with JME must be treated for a lifetime.
JME is most strongly linked to a defect in the GABRA1 gene.This gene codes for the α1 subunit, an essential part of the GABA receptor in the brain.
GABA is aneurotransmitter, a chemical that is naturally produced. It regulates brain activity. This defect leads to changes in the brain’s GABA receptors. It also lowers the number of them. The brain becomes more excitable because of this, which leads to seizures.
Researchers believe there is a known pathway for how the GABRA1 gene defect is inherited. It isautosomal dominant, meaning a child inheriting the defect from one parent is likely to develop JME.
Mutations in the EFHC1 gene can also cause JME. This gene gives instructions for making a protein that regulates the activity of neurons in the brain. A few other gene mutations, such as CHD2, may be linked to JME, but the evidence is not as strong as with GABRA1 and EFHC1 genes.
JME is usually a hereditary condition, meaning it is passed to a person through their family genes. That said, some people with it do not have any known genetic mutations at all.
Progressive Myoclonus 1 (EPM1)
This genetic condition, also calledUnverricht–Lundborgdisease, is rare. It is known for its severe childhood myoclonic seizures. But it also comes with generalized tonic-clonic seizures, balance problems, and learning difficulties.
It is linked to mutations of the CSTB gene that cause it to lengthen. People with this condition can have an average life expectancy.
Progressive Myoclonus 2 (EPM2A)
This condition, also known asLafora disease,is a rare and inherited metabolic disorder. It is known for both myoclonic and tonic-clonic seizures. People with this type of epilepsy also tend to have seizures in response toflashing lights.
A mutation in the EPM2A or the NHLRC1 genes usually causes Lafora disease. These genes normally help the neurons in the brain to survive.
Vision loss and severe learning disabilities can occur with Lafora disease. People with this condition are expected to survive about 10 years after diagnosis.
Myoclonic seizures are not life-threatening on their own. However, some rare progressive conditions that feature myoclonic seizures as a symptom can be associated with a shortened life expectancy.
Mitochondrial Encephalomyopathy
Mitochondrialdiseases impair the body’s ability to produce energy. These rare, inherited conditions begin with symptoms of low energy andmyopathyor muscle disease. They can also cause brain dysfunction, also known asencephalopathy.
Symptoms include severe muscle weakness and coordination and balance problems. The disease causes several types of seizures, especially myoclonic seizures.
The disorder can be diagnosed when blood tests show abnormalities, such as high lactic acid levels. Abiopsy, or sample of muscle tissue, may show evidence of the disorder when examined under a microscope. Sometimes,genetic testingmay be helpful.
Batten Disease
Batten diseaserefers to a group of inherited diseases. The name originally referred to its juvenile forms, but it is now used to describe all forms of what is known asneuronal ceroid lipofuscinosis(NCL).It can occur in infants, children, teens, or adults.
Children who develop this disease in early childhood don’t usually survive for longer than ten years after diagnosis. Adults who develop the disease may have an average life expectancy.
For a child to develop this disorder, it’s believed that they must inherit the gene from both parents. The hereditary pattern also means parents may not know they can carry the disease.
Lennox-Gastaut Syndrome
Lennox-Gastaut Syndrome(LGS) is a neurological disorder. Symptoms include seizures, severe learning disabilities, and serious physical limitations. LGS seizures are hard to treat and often resistant to drug therapies.
The ketogenic diet and epilepsy surgery are often considered for LGS.
Ketogenic Diet for Epilepsy
Rett Syndrome
Rett Syndrome, a rare genetic disorder, is a developmental condition that affects people assigned female at birth.It is known for causing communication and behavioral problems similar to those seen in autism.
Myoclonic and other types of seizures are associated with the disorder. Deliberate breath-holding often may bring on seizures.
What are the Signs and Symptoms of Autism in Girls?
Dravet Syndrome
Dravet syndromeis a severe disorder that causes multiple seizure types, including myoclonic seizures. It begins in early childhood, with seizures often following a history of fever.
The child’s development is often normal during the first year of life. However, learning deficits and cognitive problems follow. Balance and mobility problems also are common.
A high fatality rate is linked to people diagnosed with this disorder. It has been associated with SCN1A genetic mutations in 70% to 80% of cases.
The diagnosis of myoclonic seizures begins with a description of the seizures, likely communicating that you or your child have repetitive muscle jerks. They may come with or without loss of consciousness.
The healthcare provider may want to do several tests to help diagnose epilepsy.They often include a look at brain wave patterns found onelectroencephalogram(EEG) tests.
Besides myoclonic seizures, your provider may test for other symptoms and conditions. They may include tics, a movement disorder, or a disease such asmultiple sclerosisthat may be underlying.
Many of these seizure disorders are hereditary. For this reason, blood tests and genetic tests will likely be needed to help arrive at the correct diagnosis.
Blood Tests and Lumbar Puncture
If you have a seizure, a healthcare professional might order blood tests or alumbar puncture, also called a spinal tap. These tests may be done to see if you have an infection or an electrolyte disorder that may cause seizures. Treatment would then focus on the underlying condition.
Brain Imaging
A magnetic resonance imaging (MRI) or brain computed tomography (CT) scan can identify any structural abnormalities in the brain. Some of these abnormalities can lead to seizures.
Brain imaging also may reveal evidence of tumors, infections, injuries, or strokes. Any of these causes can lead to seizures. They can be treated once they are identified.
EEG and Sleep-Deprived EEG
An EEG is a brain wave test that detects seizure activity in the brain. Myoclonus is considered a seizure when EEG changes accompany it. Asleep-deprived EEGis beneficial for diagnosing myoclonic seizures. This is because the seizures often occur right before or after sleep, and sleep patterns are known to affect seizure activity.
With JME, the test may show a specific pattern during seizures. Other syndromes that can lead to seizures have unique brain wave patterns.
Genetic Testing
JME and some of the progressive syndromes that lead to myoclonic seizures are linked to known genetic mutations. Genetic testing can help in planning treatment.Identifying these syndromes can help families understand the prognosis and may also help with family planning.
While most of the research has focused on children, a study of 2,008 adults with seizure disorders found that 10.9% had a genetic link. The results showed that identifying the genetic cause would open up new treatment possibilities for more than half of this group.
There are several treatment options for myoclonic seizures. However, the treatment plan is often quite complex for several reasons.
Myoclonic seizures are often hard to treat. It’s common for other seizure types to be present, making things even more complicated. While these types of epilepsy can be treated with drugs and other interventions, they are less likely to be fully controlled than other seizure types.
The drugs most often used to prevent myoclonic seizures include:Depakote (sodium valproate)Keppra (levetiracetam)Topamax (topiramate)Zonegran, Zonisade (zonisamide)
The drugs most often used to prevent myoclonic seizures include:
Summary
Myoclonic seizures are a type of mild seizure that can occur on their own or as a part of a larger pattern of symptoms that are quite serious.
The motions are small, brief, and jerky compared to body-wide seizures. In some cases, children with myoclonic seizures will outgrow them. Others, including those with juvenile myoclonic epilepsy, must be treated all their lives.
Diagnosis and treatment of these typically rare disorders can be complicated. Your healthcare provider may develop a treatment plan with multiple strategies, including drugs, diet changes, and medical devices to control seizure activity.
What to Know About Sleep Myoclonus
25 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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