An Overview of Myoclonic Epilepsy

Forms and Related Disorders

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There are several types of myoclonic epilepsy. They are characterized by a type of seizure that involves sudden, unintended muscle motions that are known as myoclonic jerks.

This type of seizure is usually caused by genetic factors. The seizures usually begin in childhood, with the most common form known as juvenile myoclonic epilepsy (JME). Problems with cognition and development often occur in people diagnosed with this disorder.

This article explains the different types of myoclonic epilepsy and the fairly complex reasons for the condition. It will also help you to understand how this disorder is diagnosed and treated.

Epilepsy Types That Can Cause Myoclonic Seizures
Verywell / Emily Roberts

Symptoms

Myoclonic seizures typically begin in early childhood. These brief jerking motions most often occur right before falling asleep or when waking up. They can occur at other times of the day.

If you have myoclonic seizures, it's also likely that you'll have at least one other type of seizure disorder as well. The classic symptoms of epileptic seizures include

  • Muscle jerks and contractions
  • Loss of consciousness
  • Weakness, usually in a specific body part
  • A feeling of anxiety right before a seizure
  • Staring into space

However, each type of myoclonic seizure will have specific symptoms that arise. How these symptoms present will depend on the different type and cause of myoclonic seizure.

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 seizure.

Some people may feel this type of muscle motion as they are falling asleep. This may happen often, even though the muscle motion does not progress into a seizure.

In other cases, myoclonus can be due to a spinal or nerve disease. Changes in hormones, or in the balance of minerals in the body known as electrolytes, also may cause it.

In some situations, myoclonic jerks may occur only a few times throughout a person’s whole life.

Myoclonic Seizures 

Myoclonic seizures tend to happen more than once over a period of years. Because they are more common in youth, it is not unusual to see the condition improve during one's adult years.

A myoclonic seizure typically lasts for a few seconds. It looks like a sudden, repetitive jerking in an arm, a leg, or the face. Sometimes, myoclonic seizures can involve both sides of the body. They may affect more than one body part, such as an arm and a leg.

During a myoclonic seizure, the muscles become stiff and then relax in a rapid pattern of motions. You may have less voluntary control over your body and an altered state of consciousness.

An aura, or a sense that a seizure is going to happen, may come before a myoclonic seizure. You may feel tired or sleepy after it happens, but that is not always the case.

Recap

Myoclonic seizures are small jerking motions, when compared with the severe shaking or body-wide jerking of a tonic-clonic seizure. They may be rare, as with the slight jerking motions that sometimes happen when falling asleep at night. They also can be a symptom of a much more severe and lifelong condition.

Types and Causes

Myoclonic seizures are caused by abnormal electrical activity in the brain. This is what leads to the myoclonic muscle motion. Other factors can influence this activity. They include:

  • Tiredness
  • Alcohol
  • Fever
  • Infection
  • Photic (light) stimulation
  • Stress

Young children often have absence seizures throughout early childhood. This type of seizure, sometimes called a petit mal seizure, may go unnoticed because there is no obvious muscle motion with them.

Myoclonic seizures may be overlooked in the same way. Once the seizures begin to occur during the day, they may be mistaken for tics or Tourette's syndrome. This is a disorder that also usually has vocal sounds as a symptom too.

Eventually, the rhythm and repetition of the motion makes clear that they are seizures.

JME and other types of progressive myoclonic epilepsies are rare neurological (brain and nervous system) conditions. Each of the myoclonic epilepsies has a different cause. Many of the genetic factors responsible for these conditions have been identified.

Juvenile Myoclonic Epilepsy (JME)

Many people who have JME also have the more classic symptoms of tonic-clonic (grand mal) seizures, in addition to the myoclonic type. The seizures tend to occur throughout life, though they may improve in adulthood. This means that a person with JME will need to be treated across a lifetime.

JME is usually a hereditary condition, meaning it is passed to a person through their family genes. That said, there are some people with it who do not have any known genetic mutations at all.

JME is most strongly linked to a defect in the GABRA1 gene. This gene codes for what is called the α1 subunit, an important part of the GABA receptor in the brain.

GABA is a neurotransmitter, 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 is autosomal dominant, meaning that a child who inherits the defect from one parent is likely to develop JME.

JME can also be caused by mutations in the EFHC1 gene. 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 it is with GABRA1 and EFHC1 genes.

Recap

Juvenile myoclonic epilepsy has a genetic link in many but not all cases. People with JME have a higher than average incidence of having family members with epilepsy. As with many myoclonic epilepsy conditions, researchers continue to identify the gene mutations that lead to a diagnosis.

Progressive Myoclonic Epilepsy

There are a number of epilepsy syndromes that cause myoclonic seizures. Together, they are often known as progressive myoclonic epilepsy.

Each of these syndromes has its own signs and symptoms. They also have their own signs of progression and prognosis, or outcomes.

They do, however, have several features in common. These include:

  • Multiple seizure types
  • Difficult-to-control seizures
  • Lifelong learning and developmental issues
  • Physical impairments

Myoclonic seizures often improve during adulthood. Other types of seizures, such as tonic-clonic seizures, often get worse throughout adulthood. Some epilepsy conditions feature both, and tend to have a genetic reason for what are typically more serious conditions.

The epilepsy syndromes that fall under the category of progressive myoclonic epilepsies include:

Progressive Myoclonus 1 (EPM1)

This genetic condition, also called Unverricht–Lundborg disease, is rare. It is known by 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 a normal life expectancy.

Progressive Myoclonus 2 (EPM2A)

This condition, also known as Lafora disease, is a rare and inherited metabolic disorder. It is known by both its myoclonic and tonic-clonic seizures. People who have this type of epilepsy also tend to have seizures in response to flashing lights.

Lafora disease is usually caused by a mutation in the EPM2A or the NHLRC1 genes. 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.

Mitochondrial Encephalomyopathy

Mitochondrial diseases impair the body’s ability to produce energy. These rare, inherited conditions begin with symptoms of low energy and myopathy, or muscle disease. They can also cause brain dysfunction, also known as encephalopathy.

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. A biopsy, or sample of muscle tissue, may show evidence of the disorder when examined under a microscope. Sometimes, genetic testing may be helpful.

Batten Disease

Batten disease refers 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 as neuronal ceroid lipofuscinosis (NCL). It can occur in infants, children, teens, or adults.

NCL is known by the symptoms of:

  • Severe balance problems
  • Learning deficits
  • Loss of vision
  • Multiple types of seizures

Children who develop this disease in early childhood don’t normally survive for longer than 10 years after diagnosis. Adults who develop the disease may have a normal life expectancy.

For a child to develop this disorder, it's believed that they need to inherit the defective gene from both parents. The hereditary pattern also means that parents may not know that they can carry the disease.

This genetic defect causes malfunction of lysosomes. These are structures that eliminate waste materials from the body. This, in turn, disrupts normal brain function and results in symptoms.

Recap

Myoclonic seizures are a symptom found in a number of progressive seizure disorders. They are typically rare. Some, like EPM1, cause severe symptoms in childhood but overall life expectancy is normal. Others, such as Lafora disease, will prove fatal within 10 years.

Epilepsy Syndromes

Several epilepsy syndromes are known for their patterns of developmental problems and seizures, including myoclonic epilepsy. 

Lennox-Gastaut Syndrome

Lennox-Gastaut Syndrome (LGS) is a neurological disorder. Symptoms include many types of 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 among the options often considered for LGS.  

Rett Syndrome

Rett Syndrome, a rare genetic disorder, is a developmental condition that affects those 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 the seizures.

Dravet Syndrome

Dravet Syndrome is 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.

There is a high fatality rate linked to people who are diagnosed with this disorder. It has been associated with SCN1A genetic mutations in 70% to 80% of cases.

Recap

Myoclonic seizures are found in some syndromes that also are known for cognitive and developmental difficulties. They include Rett syndrome and Dravet syndrome.

Diagnosis

The diagnosis of myoclonic seizures begins with a description of the seizures. In most cases, you're likely to tell a healthcare provider that you or your child have repetitive muscle jerks. They may come with or without loss of consciousness.

The provider may want to do several tests to help with a diagnosis of the epilepsy. They often include a look at brain wave patterns found on electroencephalogram (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 as multiple sclerosis that may be at work.

Many of these seizure disorders are hereditary. For this reason, it's likely that blood tests and genetic tests will be needed to help arrive at the right diagnosis.

Blood Tests and Lumbar Puncture

Epilepsy is not diagnosed on the basis of blood tests or lumbar puncture, also called a spinal tap. However, 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 are common in epilepsy syndromes.

Brain imaging also may reveal the 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 it is accompanied by EEG changes. A sleep-deprived EEG is particularly helpful for 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 called ictal EEG. Another pattern, called interictal EEG, will appear between seizures.

There are specific EEG patterns for other types of myoclonic epilepsy and the related syndromes. For example, with LGS, there is an interictal slow spike and wave pattern.

Genetic Testing

JME and some of the progressive epilepsy 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 to understand the prognosis, and may help with family planning as well.

Recap

It can be complicated to diagnose an epilepsy syndrome that includes myoclonic seizures. The history of the seizures, along with brain imaging, genetic tests, and other procedures, may be used to identify the exact condition.

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 as well, which makes 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.

Ideally, just one anti-seizure medication would be used at a tolerable dose to limit side effects. In these cases, though, more than one drug may be needed to reduce seizures.

The drugs most often used to prevent myoclonic seizures include:

  • Depakote (sodium valproate)
  • Keppra (levetiracetam)
  • Topamax (topiramate)
  • Zonegran (zonisamide)

When myoclonic seizures happen, they are usually brief. It is rare for them to progress to convulsive status epilepticus. This is a severe seizure that won't stop and requires emergency intervention.

For difficult-to-treat epilepsy, a combination of treatment strategies is usually needed. Options may include the ketogenic diet, epilepsy surgery, and anti-seizure devices such as the vagal nerve stimulator.

Recap

Treatment of myoclonic seizures can be difficult. That's because other types of seizures and related conditions often are part of a more complex diagnosis. Anti-seizure drugs don't always work. In many cases, people are treated by using more than one therapy option at the same time.

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, when compared with body-wide seizures. In some cases, children with myoclonic seizures will outgrow them. For others, including those with juvenile myoclonic epilepsy, they will need to be treated for JME all their lives.

Myoclonic seizures are often seen in far more serious and oft-fatal epilepsy syndromes. These conditions, such as Lennox-Gastaut Syndrome or Batten disease, are linked to a known genetic mutation in many cases.

Diagnosis and treatment of these typically rare disorders can be complicated. Your healthcare provider may develop a treatment plan that includes more than one strategy, including drugs, diet changes, and medical devices meant to control seizure activity.

Frequently Asked Questions

  • Are Myoclonic Seizures Linked With Other Conditions?

    They can be.  Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis are among the conditions that may lead to seizures. In fact, some of the drugs used to treat seizures are now being tried to treat these closely linked conditions.

  • Can Genetic Testing Be Helpful for Adults With Seizures?

    Yes. Most of the research has focused on children, but a study of 2,008 adults with seizure disorders found that 10.9% of them 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.

  • What Should Children Know About Myoclonic Epilepsy?

    The answer depends on the child. Factors like the child's age, the severity of the seizures, the overall level of disability, and the expected long-term outcome all come into play. Your healthcare provider can talk with you and your family to discuss the best ways to share age-appropriate information.

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24 Sources
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  1. Epilepsy Foundation, "Juvenile Myoclonic Epilepsy"

  2. Falco-Walter JJ, Scheffer IE, Fisher RS. The new definition and classification of seizures and epilepsyEpilepsy Research. 2018;139:73-79. doi: 10.1016/j.eplepsyres.2017.11.015

  3. Wolfensberger B, Ferri R, Bianco G, Abbafati M, Miano S, Kaelin-Lang A, et al. From physiological neck myoclonus to sleep related head jerkJ Sleep Res. 2019;28(5). doi: 10.1111/jsr.12831

  4. Kälviäinen R. Progressive Myoclonus Epilepsies.Semin Neurol. 2015 Jun;35(3):293-9. doi:10.1055/s-0035-1552620.

  5. Valdés Galván RE, González Calderón G, Castro Martínez E. Epidemiología del descontrol de la epilepsia en un servicio de urgencias neurológicasRevNeurol. 2019;68(08):321. doi: 10.33588/rn.6808.2018218

  6. Albuja AC, Khan GQ. Absence seizure. StatPearls Publishing; 2022.

  7. Gilsoul M, Grisar T, Delgado-Escueta AV, de Nijs L, Lakaye B. Subtle brain developmental abnormalities in the pathogenesis of juvenile myoclonic epilepsyFront Cell Neurosci. 2019;13:433. doi: 10.3389/fncel.2019.00433

  8. Singh N, Ritaccio A. Juvenile myoclonic epilepsy mimic associated with CHD2 gene mutationEpilepsy & Behavior Reports. 2020;13:100355. doi: 10.1016/j.ebr.2019.100355

  9. Franceschetti S, Michelucci R, Canafoglia L, et al. Progressive myoclonic epilepsies: definitive and still undetermined causes. Neurology. 2014;82(5):405–411. doi: 10.1212/WNL.0000000000000077

  10. Äikiä M, Hyppönen J, Mervaala E, Kälviäinen R. Cognitive functioning in progressive myoclonus epilepsy type 1 (Unverricht-lundborg disease, epm1)Epilepsy & Behavior. 2021;122:108157. doi: 10.1016/j.yebeh.2021.108157

  11. Brewer MK, Machio-Castello M, Viana R, Wayne J, Kuchtova A, Simmons Z, et al. An empirical pipeline for personalized diagnosis of Lafora disease mutationsiScience. 2021;24(11):103276. doi: 10.1016/j.isci.2021.103276

  12. Fine AL, Liebo G, Gavrilova RH, Britton JW. Seizure semiology, eeg, and imaging findings in epilepsy secondary to mitochondrial diseaseFront Neurol. 2021;12:779052. doi: 10.3389/fneur.2021.779052

  13. National Institutes of Health. Genetic and Rare Diseases Information Center. Neuronal ceroid lipofuscinosis.

  14. Spoor JKH, Greco T, Kamp MA, Faini S, Senft C, Dibué M. Quantifying the burden of disease in patients with Lennox Gastaut syndromeEpilepsy & Behavior Reports. 2021;16:100508. doi: 10.1016/j.ebr.2021.100508

  15. National Institute of Neurological Disorders and Stroke. Rett syndrome fact sheet.

  16. Connolly MB. Dravet syndrome: diagnosis and long-term courseCan J Neurol Sci. 2016;43(S3):S3-S8. doi: 10.1017/cjn.2016.243

  17. Epilepsy Foundation. Diagnosis 101: what will the doctor do?

  18. Dell KL, Payne DE, Kremen V, Maturana M, Gerla V, Nejedly P, et al. Seizure likelihood varies with day-to-day variations in sleep duration in patients with refractory focal epilepsy: A longitudinal electroencephalography investigationEClinicalMedicine. 2021;37:100934. doi: 10.1016/j.eclinm.2021.100934

  19. Dhamija K, Chaudhry N, Puri V. Modulation of epileptiform EEG discharges in patients with JME.Seizure. 2018 Aug;60:139-143. doi:10.1016/j.seizure.2018.06.018.

  20. Bayat A, Bayat M, Rubboli G, Møller RS. Epilepsy syndromes in the first year of life and usefulness of genetic testing for precision therapyGenes. 2021;12(7):1051. doi: 10.3390/genes12071051

  21. Yacubian EM. Juvenile myoclonic epilepsy: Challenges on its 60th anniversary.Seizure. 2017 Jan;44:48-52. doi:10.1016/j.seizure.2016.09.005.

  22. Sen A, Verner R, Valeriano JP, Lee R, Zafar M, Thomas R, et al. Vagus nerve stimulation therapy in people with drug-resistant epilepsy (Core-vns): rationale and design of a real-world post-market comprehensive outcomes registryBMJ Neurol Open. 2021;3(2):e000218. doi: 10.1136/bmjno-2021-000218

  23. Cano A, Fonseca E, Ettcheto M, et al. Epilepsy in neurodegenerative diseases: related drugs and molecular pathwaysPharmaceuticals. 2021;14(10):1057. doi: 10.3390/ph14101057

  24. McKnight D, Bristow SL, Truty RM, et al. Multigene panel testing in a large cohort of adults with epilepsy: diagnostic yield and clinically actionable genetic findingsNeurol Genet. 2022;8(1):e650. doi: 10.1212/NXG.0000000000000650