Developmental and Epileptic Encephalopathy (DEE)

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

Developmental and epileptic encephalopathy (DEE) is the term for a group of epilepsies. DEEs begin early in life and cause developmental delays. There are 2 parts to DEE: seizures and encephalopathy. Seizures from DEE are generally drug-resistant. Encephalopathy is a general term for a brain disease. Both of these begin early in life.1-3

The reasons DEE affects some children are not entirely understood. But there is active research going on to find out more about what causes DEE and how to treat it.

What are the possible causes of DEE and how is it diagnosed?

The cause of DEE is not well understood. Some researchers think it could have a genetic component. In such a case, copies of the responsible gene would come from one or both parents. If scientists can identify the genes that cause DEE, it may be possible to create drugs that help symptoms.3

However, doctors think that not all DEE cases are genetic. Sometimes, DEE could have an "acquired cause" – an event that causes the DEE to start. This could be a stroke or another type of encephalopathy.3

Diagnosis of DEE is mainly done by electroencephalography (EEG). EEGs are a painless way to record brain activity. EEGs for children with DEE typically show frequent bursts of activity. These bursts represent the seizures, where the brain activates a lot, followed by slowed brain activity.3

Though EEGs are frequently used to diagnose DEE, tests that are done earlier in a child's life or before seizure onset may not show this particular pattern of activity. But the absence of this pattern does not mean the child does not have DEE. Other factors, like symptoms and age of onset, are also important for diagnosing.1

What are the symptoms of developmental and epileptic encephalopathy?

Symptoms of DEE begin early in life. The seizures or epileptic spasms usually appear before a child’s first birthday. Children with DEE have frequent seizures of multiple types. Common types include:1,2

Epileptic spasms can look different for different children. They commonly involve bending at the waist and neck while extending the arms and legs (also called a jackknife spasm). Spasms are usually short but frequent. They generally do not happen while the child is sleeping, but can start right after the child wakes up.2

Another important symptom of DEE is developmental delay. This can be any developmental skill that a child has not picked up or has picked up late. This could also mean that a child loses skills they have already gained, such as:2

  • Sitting
  • Babbling
  • Rolling over

The cause and effect of the developmental delay goes both ways. Developmental delays may be the cause of epilepsy for a child with DEE. But the seizures the child has may also worsen developmental problems.1

What are possible treatments and outlook for DEE?

It is possible that seizures can be controlled with medicine, though this does not always work. Notably, even if seizures are lessened, the developmental encephalopathy will remain. However, any developmental delays caused by seizures should improve.1

Spasms for children with DEE usually stop by age 5. But many people with DEE continue to have seizures and intellectual disability throughout their lives.2

With the identification of genes that could play a role comes the prospect of more therapies. Doctors are continuing to understand the specific genes and variations related to DEE. And they are getting closer and closer to creating diagnostic tools, gene therapies, and personalized treatments.3

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