Epilepsy Myoclonic Absences
What is epilepsy with myoclonic-absences?
Epilepsy with myoclonic-absences is a rare form of epilepsy. Fewer than 1 in 100 children seen in a specialty center for epilepsy have this syndrome.
- These seizures typically begin between 2 and 12 years of age with the majority starting around 7 years of age.
- They are seen more often in boys than in girls.
- In up to 3 in 10 children, an inborn or acquired brain injury may be found.
- The cause of this epilepsy syndrome is unknown.
The cause of this epilepsy syndrome is unknown. It has been reported that about 1 in 5 children with this condition will have a family member with a form of epilepsy, usually generalized epilepsy.
What types of seizures are seen?
The most characteristic seizure type is a myoclonic-absence seizure. During a seizure, the child’s neck, back, and arms become stiff or rigid (tonic contraction). There is ratchet-like (repeated starts and stops) jerking of the head, arms, and legs. The child is not aware and has a staring facial expression. The loss of awareness might be subtle and hard to notice.
- Some children might stop breathing during the tonic or stiffening part of the seizure. They could also lose control of their urine.
- Seizures last 10-60 seconds and happen several times a day. They may occur in groups or clusters when the child is waking up.
- Falls during a seizure can happen but are not common.
Over time, 70% of children will have other types of seizures, including generalized tonic-clonic, clonic, absence, and atonic seizures. In the other 30%, myoclonic-absence is the only seizure type. In up to 40% of children, generalized tonic-clonic seizures are noted before myoclonic-absence begin.
Seizure Triggers
Breathing heavily or hyperventilation can trigger seizures during an EEG (electroencephalogram). Seizures triggered by intermittent light stimulation are rare.
How is epilepsy with myoclonic-absences diagnosed?
Diagnosis begins with getting a typical clinical history and seizure description, along with an EEG (electroencephalogram). Find tools and forms to help you describe the seizures in our toolbox.
- Your doctor will take a good history and may ask your child to hyperventilate (breathe fast and deep) during the examination.
- The EEG is the most important test. The EEG shows a typical pattern of normal background activity, but a 3 per second spike-wave activity during a seizure. Other abnormalities like spikes and spike-wave discharges may also be seen.
- MRI (magnetic resonance imaging) scans might be ordered to look for a structural change in the brain. The MRI is usually normal and shows no abnormalities from a specific or known cause.
How is epilepsy with myoclonic-absences treated?
Seizures in this syndrome usually don’t respond well to anti-seizure medication.
- Medications often tried are valproic acid (Depakote/Depakene), ethosuximide (Zarontin), lamotrigine (Lamictal), and clobazam (Onfi), amongst others.
- Recently rufinamide was also reported to be useful.
- Usually, several medications are needed in combination to maximize seizure control.
- Medications such as carbamazepine, oxcarbazepine, eslicarbazepine and phenytoin should be avoided as they tend to worsen seizures.
Surgery is generally not an option.
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Find Your Local Epilepsy FoundationWhat is the outlook?
- Approximately 7 in 10 children with epilepsy with myoclonic-absences will eventually be diagnosed with learning disabilities.
- Some children will develop multiple seizure types - that are resistant to treatment and have a characteristic EEG pattern - called Lennox-Gastaut syndrome.
- In more than half of the children, seizures will persist into adulthood. In others, they may disappear after a mean period of 5.5 years from onset.
- Prognosis is more favorable if medication can control the seizures early.
Resources
- Lennox-Gastaut Syndrome Foundation, a member of the Rare Epilepsy Network (REN)
- International League Against Epilepsy (ILAE) on epilepsy with myoclonic-absences
- What’s a clinical trial and why should you join one? Find a Clinical Trial
- Information on current clinical trials also can be found at www.clinicaltrials.gov.
- Find epilepsy therapies in various stages of development in our Epilepsy Pipeline Tracker
References
- Genton P, Bureau M. Epilepsy with myoclonic absences. CNS Drugs. 2006;20(11):911-6.
- Häusler M, Kluger G, Nikanorova M. Epilepsy with myoclonic absences - favourable response to add-on rufinamide treatment in 3 cases. Neuropediatrics. 2011 Feb;42(1):28-9.
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