Early myoclonic encephalopathy almost always starts in the newborn period or in very early infancy, before 2 or 3 months of age. It is a syndrome with many causes. One underlying cause is metabolic disorders, such as a condition called non-ketotic hyperglycinaemia. Other causes are brain malformations and neurogenetic disorders (problems with the brain or nerves that are inherited). Sometimes no cause can be found.
Other names for early myoclonic encephalopathy
Neonatal myoclonic encephalopathy
The seizures can be subtle myoclonic seizures, which affect small areas of the body from time to time, massive myoclonic seizures (sudden flexion or extension), focal (partial) motor seizures or, rarely, tonic spasms that affect the whole body and limbs (that cause the body and limbs to stiffen). The seizures are very frequent throughout the day. After several months the seizures may change to infantile spasms (West syndrome).
Epilepsy Action has information about West syndrome.
The EEG, which records the electrical activity in the brain, shows evidence of abnormal discharges, or spikes and waves mixed in with periods of flatness. This type of record is referred to as a ‘suppression-burst’ pattern. It is similar to that seen in Ohtahara syndrome. Infants with this syndrome are often extremely floppy and excessively sleepy. They also have difficulty feeding properly.
If this syndrome is suspected, it is important to test the babies or infants thoroughly for a possible metabolic (biochemical) disorder, in case this in itself can be treated. They should also have detailed genetic-testing. This is to try and predict whether, if another child is born in the family, he or she may also be affected. The choice of medicine is difficult, and it may be safer to use some of the older ones, such as phenobarbital, before others are tried. All babies should receive a trial of pyridoxine (vitamin B6) in case they have pyridoxine dependent seizures or biotin (vitamin B7) in case they have biotinidase deficiency. The seizures are often resistant to epilepsy medicines. Epilepsy medicines that might be helpful include zonisamide (Zonegran) or levetiracetam (Keppra). The epilepsy medicine vigabatrin (Sabril) may make the seizures worse.
Information about treatments for children can be found on the Medicines for Children website.
There may be research studies open that are relevant to this epilepsy syndrome. Your child’s doctor will be able to discuss this with you.
If your child has this syndrome they may have prolonged or repeated seizures. Your child’s doctor will discuss a ‘rescue’ or emergency care plan with you to treat any prolonged or repeated seizures.
Unfortunately infants with early myoclonic encephalopathy make very little developmental progress. They remain totally dependent and often feed poorly. Many will need to have a feeding gastrostomy tube (called a ‘PEG’) inserted through their tummy so that they can be fed. Sadly it is reported that more than half of the infants with this condition die within the first year of life. Those who survive are severely developmentally delayed.
Together for Short Lives
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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 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 Epilepsy Action.
Epilepsy Action would like to thank Drs Richard Appleton and Rachel Kneen (at Alder Hey Children’s Hospital, Liverpool) and Stewart Macleod (at Yorkhill Children’s Hospital, Glasgow), consultants who specialise in children’s epilepsy, who have updated this fact sheet.