Early Myoclonic Encephalopathy (EME)

Reviewed by: HU Medical Review Board | Last reviewed: October 2022

Early myoclonic encephalopathy (EME) is also known as "neonatal myoclonic encephalopathy" or "developmental and epileptic encephalopathy-3." Children with EME have drug-resistant seizures, delayed development, and intellectual disability.1,2

EME is in a group of a few other early-age epileptic encephalopathies. This group includes:1-3

Seizures are not uncommon in early childhood brain disorders. But children with EME have accompanying symptoms and are diagnosed very early in life.1-3

What are the causes or risk factors for EME?

EME can have many different causes. Doctors have found that some EME is genetic, and specifically "autosomal recessive." This means that the gene for EME is passed on from both parents, who are considered carriers but do not have symptoms.2

Another possible cause is an issue with metabolism: your body's process for turning food and drink into energy. There are several metabolic disorders linked to EME, including:1

  • Mitochondrial disorders
  • Non-ketogenic hyperglycinemia
  • Menke syndrome
  • Zellweger syndrome

EME affects all sexes equally.1

What kinds of seizures does EME cause?

Different types of seizures can happen when someone has EME. However, myoclonic seizures are what makes EME different from, for example, Ohtahara syndrome. Myoclonic seizures are frequent, brief, can be single or multiple, and continuous. Some children with EME may also have:1,2

  • Focal motor seizures
  • Tonic seizures
  • Tonic spasms

How is early myoclonic encephalopathy diagnosed?

The most important part of diagnosing EME is electroencephalography (EEG), which is an electrical recording of brain activity. The EEG for children with EME shows big bursts of activity followed by a time of little brain activity. This pattern is typical of EME.1,2

There are also other tests for EME. Magnetic resonance imaging (MRI) is a way of looking at the brain. MRIs can show shrinking of the brain over time and other abnormalities. A doctor can look at these and figure out if the EME is caused by an issue in a specific brain region. Blood work and genetics testing can also be done to look for metabolic or genetic causes.1

EME is usually diagnosed before a child is 3 months old. Sometimes seizures can occur while a child is still in the womb or during the first 10 or so days of their life.1

What are possible treatments and outlook?

The outlook for children with EME is worrisome. Some children with EME may die within the first year of their life. Long term, many children have severe physical and cognitive (thinking) disabilities.1-3

Children with EME can take anti-seizure drugs, but these drugs usually do not control seizures very well. Other treatment options vary depending on what the cause of the child's EME is.1-3

Some children respond well to epilepsy surgery. In this surgery, the part of the brain where seizures are focused is removed. Other times, vagus nerve stimulators or diet changes can be helpful if there is a metabolic cause.1

The Epilepsy Foundation advises that children without a known cause of their EME could be put on vitamin B6 (pyridoxine). This can help if they have B6-dependent seizures or if they have a biotinidase deficiency. Treatment all depends on a child's needs and what your care team feels would be most effective.1

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