This type of epilepsy is uncommon. It affects only 1 to 2 out of every 100 children with epilepsy. It usually starts around the ages of 18 months to 4 years but may occur as young as 9 months of age and as old as 6 years. It is more common in boys than girls.
The cause of myoclonic-astatic epilepsy is not known. It is probably caused by a genetic abnormality, called a ‘mutation’, but this has not been proven. In about a third of cases another family member will also have epilepsy, although not always of the same sort. It is likely that this epilepsy is part of the group of genetic epilepsies with febrile seizures plus (GEFS+). Most of these epilepsies and epilepsy syndromes are thought to be associated with a gene mutation or are inherited, although the mutation has not always been found.
The term ‘atonic’ is sometimes used instead of ‘astatic’. Both of these words mean ‘loss of tone’ which causes the person to fall to the ground. The fall looks as if a puppet’s strings have been suddenly cut and the puppet collapses.
Myoclonic-astatic epilepsy is sometimes called Doose syndrome.
The seizures can be of different types. They include jerks (myoclonic seizures), sudden falls to the ground (atonic or astatic seizures), or sometimes a jerk followed by a fall (myoclonic-astatic seizure). Absence seizures can happen (when consciousness is lost briefly). In some cases, there may be seizures with stiffness and jerking of the whole body (generalised tonic-clonic seizure). Approximately one third of children with myoclonic-astatic epilepsy will have prolonged seizures at some time during childhood or adolescence. This can include absence or convulsive status-epilepticus.
The EEG (electroencephalogram), which records the electrical activity in the brain, is usually abnormal. It shows evidence of epileptic discharges from both sides of the brain at the same time, and sometimes from all over the brain. The EEG during drowsiness and sleep may show an increase in epileptic discharges. The type of abnormal activity is called ‘spike and wave’ or ‘polyspike and wave’ activity. Children with myoclonic-astatic epilepsy are not usually photosensitive.
Brain scans, including magnetic resonance imaging (MRI) scans, and blood tests are usually normal.
There is not yet any genetic blood tests that can be done to find a mutation for this epilepsy syndrome.
Treatment of myoclonic-astatic epilepsy is often very difficult. The epilepsy medicines that have been most successful are sodium valproate (Epilim), topiramate (Topamax), lamotrigine (Lamictal) and occasionally clobazam (Frisium), ethosuximide (Zarontin), zonisamide (Zonegran) or nitrazepam. Levetiracetam (Keppra) may also be helpful, particularly for the myoclonic seizures. Children will usually need to be treated with a combination of two epilepsy medicines.
Importantly, this type of epilepsy can respond well to the ketogenic diet. Because of this the ketogenic diet should be considered when the seizures have not stopped after treatment with two epilepsy medicines used either singly or in combination.
Sometimes a short course of a steroid medicine, called prednisolone, is also used. This is often very helpful when the child is having many brief myoclonic or myoclonic-astatic seizures a day. The course is usually only given for 2 to 4, and no longer than 6 weeks.
There is a surgical treatment which may very occasionally be used in children with myoclonic-astatic epilepsy – but in only one situation. This is when children have many seizures each and every day when they fall or drop to the ground and that have not stopped with epilepsy medicines and the ketogenic diet. The surgical treatment is called a ‘corpus callosotomy’. This operation should only be performed in highly specialised centres, called the Children’s Epilepsy Surgery Service (CESS).
Information about treatments for children can be found on the Medicines for Children website.
There may be research studies that are going on in this epilepsy syndrome. This may include new medicines that have been shown to be helpful in Dravet syndrome and Lennox-Gastaut syndrome. Your child’s hospital doctor will be able to discuss this with you.
If your child has this syndrome there is a high chance that they may have prolonged or repeated seizures, including status epilepticus. Your child’s hospital doctor (paediatrician or paediatric neurologist) will discuss a ‘rescue’ or emergency care plan with you to treat any prolonged or repeated seizures. It is important that all children with myoclonic-astatic epilepsy have an up-to-date rescue or emergency care plan.
The outlook for children with myoclonic-astatic epilepsy is variable. In about half of cases there is a good response to epilepsy medicines, but the children will usually have some learning difficulties. In a few cases the seizures come under control and the child’s learning will be satisfactory or possibly only a little slow or delayed. In the remainder of cases, seizures continue despite epilepsy medicines and the ketogenic diet. These children usually develop moderate or sometimes severe learning disabilities. The prognosis is generally worse in children where the epilepsy begins with generalised tonic-clonic seizures, or if seizure control does not respond to the first or second epilepsy medicine that is prescribed.
What is a syndrome?
A syndrome is a group of signs and symptoms that, added together, suggest a particular medical condition. In epilepsy, examples of these signs and symptoms would be things like the age at which seizures begin, the type of seizures, whether the child is male or female and whether they have physical or learning disabilities, or both. The results of an electroencephalogram (EEG) are also used to help identify epilepsy syndromes.
If you would like to know more about an epilepsy syndrome, please speak to your doctor. If you would like to know more about epilepsy in general, please contact the Epilepsy Action Helpline.
Epilepsy Action would like to thank Dr Richard Appleton, consultant paediatric neurologist and honorary professor in paediatric neurology at Alder Hey Children’s Hospital, Liverpool, UK for preparing this information.