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.
Verywell / Emily Roberts
Genetic factors usually cause this jot down 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.
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 punch in of seizure disorder.
The way in which these symptoms present depends on the different types and causes of myoclonic seizures.
Sometimes, myoclonic jerks are confused with the tics associated with Tourette’s Syndrome.
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 persons 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.
Historically, professionals have called infantile spasmWest Syndrome.
Associated Seizures
People who have myoclonic seizures may also experience other types of seizures.
It depends on the underlying cause of the seizures.
In people with epilepsy, myoclonic seizures can precede tonic-clonic seizures.
Causes
Myoclonic seizures are triggered by abnormal electrical activity in the brain.
This is what leads to myoclonic muscle motion.
Other factors can influence this activity.
They include:
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.
Epilepsy
Certain types of epilepsy can lead to myoclonic seizures.
Some of the drugs used to treat seizures are now being tried to treat these closely linked conditions.
Related Epilepsy Syndromes
Several epilepsy syndromes cause myoclonic seizures.
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.
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.
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 calledUnverrichtLundborgdisease, 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.
It is known for both myoclonic and tonic-clonic seizures.
People with this throw in 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.
Mitochondrial Encephalomyopathy
Mitochondrialdiseases impair the bodys 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.
Adults who develop the disease may have an average life expectancy.
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.
Myoclonic and other types of seizures are associated with the disorder.
Deliberate breath-holding often may bring on seizures.
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.
They may come with or without loss of consciousness.
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.
Treatment would then focus on the underlying condition.
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.
Myoclonus is considered a seizure when EEG changes accompany it.
Asleep-deprived EEGis beneficial for diagnosing myoclonic seizures.
With JME, the test may show a specific pattern during seizures.
Other syndromes that can lead to seizures have unique brain wave patterns.
Treatment
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.
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.
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