- Epilepsy with myoclonic-atonic seizures (EMAS) is typically known as myoclonic-astatic epilepsy or Doose Syndrome.
- EMAS starts in early childhood with the first seizure occurring between 7 months to 6 years of age. For most, it starts around 2 to 4 years of age.
- It accounts for about 1 to 2% of all childhood-onset epilepsies and affects boys more than girls.
- More than half of the cases of EMAS start with a febrile or non-febrile generalized tonic-clonic seizure.
- Children with EMAS may have multiple seizure types. About a third of children may have episodes of non-convulsive status epilepticus.
- EMAS is considered part of the generalized epilepsies with febrile seizures plus (GEFS+).
- EMAS genetics are still not well understood, but many gene mutations are thought to be involved.
- Seizures associated with EMAS typically don't respond well to seizure medication.
- Prognosis is variable. Some children have seizures that remit or go away and have normal intelligence. Other children will have seizures resistant to medication and have intellectual disabilities.
What is epilepsy with myoclonic-atonic seizures (myoclonic-astatic epilepsy or Doose Syndrome)?
Epilepsy with myoclonic-atonic seizures (EMAS), typically known as myoclonic-astatic epilepsy or Doose Syndrome, was first described by Dr. Herman Doose from Germany in 1970. It is an uncommon childhood epilepsy syndrome that accounts for 1 to 2 out of 100 (1 to 2%) of all childhood-onset epilepsies.
- Usually the first seizure occurs between 7 months and 6 years of age. Most will start between 2 and 4 years of age.
- Boys tend to be affected more than girls (2 out of 3 children with EMAS will be boys). Yet when this form of epilepsy starts in the 1st year of life, the incidence is the same in both sexes.
- More than half of the cases of EMAS start with a generalized tonic-clonic seizure with or without fever. Month later, myoclonic-astatic seizures begin. Most children with EMAS are developing normally when seizures begin.
Is Doose Syndrome genetic or inherited?
Genetics plays an important role in this disorder. About 1 out of 3 family members of children with EMAS have seizures. About 2 out of 3 immediate family members have been found to have abnormal EEGs, photosensitivity being the most common.
EMAS is considered part of the group of generalized epilepsies with febrile seizures plus (GEFS+). These are typically associated with a gene mutation or are inherited. Though the genetics of EMAS is still not well understood, most consider this epilepsy syndrome to have more than one gene mutation responsible for the disorder.
What do the seizures in Doose Syndrome look like?
Children with EMAS may have multiple seizure types:
- myoclonic and myoclonic followed by atonic occur in everyone
- generalized tonic-clonic seizures are seen in 3 out of 4 people
- generalized tonic-clonic seizures with fever occur in 1 out of 3
- absence seizures occur in 2 out of 3 people
Though all seizure types can result in status epilepticus, about 1 in 3 children with EMAS may have episodes of non-convulsive status epilepticus. Tonic seizures generally do not occur, though a few cases have been reported in which tonic seizures are seen later in the course of the disorder.
Seizures tend to occur more often early in the morning than during the day.
How is Doose Syndrome diagnosed?
EMAS is diagnosed based on the description of the seizures, with myoclonic-astatic seizures being the most common seizure type. Information also comes from tests such as:
- EEG (electroencephalogram): children with EMAS may have normal EEGs at first, but most have abnormal EEGs that show frequent synchronous (generalized) spike wave activity at times in brief bursts of 2 to 5 Hz. Background may be normal or abnormal. (See the photo at the top of the page.)
- MRI (magnetic resonance imaging) of the brain: Children with EMAS have a normal MRI of the brain.
How is Doose Syndrome treated?
Medications: Seizures in children with EMAS tend to be difficult to treat and are usually don't respond well to medication. Medications are chosen based on the seizure types:
- Generalized tonic-clonic, myoclonic, and myoclonic-atonic seizures are typically treated with valproic acid/divalproex, lamotrigine, levetiracetam, topiramate, zonisamide, rufinamide, clobazam, and felbamate in the United States.
- Absence seizures in EMAS are typically treated with ethosuximide, valproic acid/divalproex, or lamotrigine.
Other medications that have been used to treat EMAS include adrenocorticotrophic hormone, methylprednisolone, prednisone, or dexamethasone.
Some seizure medications should not be used in children with EMAS because they can worsen certain seizure types. These include carbamazepine, oxcarbazepine, phenytoin, and vigabatrin.
Rescue therapies: Children with EMAS who have long or clusters of seizures may need emergency medical treatment or treatment with a rescue therapy. Examples of rescue therapies may include diazepam rectal gel (Diastat) or another form of benzodiazepine given into the nose (intranasally) or under the tongue.
- Parents of children with EMAS should talk to their treating neurologist or health care provider to learn about seizure emergencies.
- Talk to the health care team about what kind of rescue therapy could be used and when to use it.
- When seizures last longer than usual or if a generalized seizure lasts too long (generally considered 5 minutes or longer), a child may need emergency medical care.
What is the outlook for children with Doose Syndrome?
The prognosis for children with EMAS can vary. About 2 out of 3 children may have seizure that go away or remit. Others will have seizures that persist despite medicines. 2 out of 3 children have normal intelligence, and others have mild to severe intellectual disabilities.
Signs of an unfavorable prognosis in EMAS may include:
- generalized tonic-clonic seizures in the first 2 years of life,
- abnormal EEG background,
- early episodes of convulsive and non-convulsive status epilepticus,
- seizures that happen when falling asleep,
- development of myoclonic seizures after age 4.
The good news is that children with EMAS are doing better now than in the past. Outcomes have improved over the years due to early recognition and better treatment options including the ketogenic diet.