Developmental and Epileptic Encephalopathy (DEE)

Developmental and epileptic encephalopathy (DEE) refers to a group of severe epilepsies that are characterized both by seizures, which are often drug-resistant. It is also  encephalopathy, which is a term used to describe significant developmental delay or even loss of developmental skills. In the DEEs, there are two factors that contribute to the developmental delay.

• Developmental encephalopathy implies that developmental delays are the direct result of the underlying cause of their epilepsy.
• In addition, some children with DEEs also have an epileptic encephalopathy due to very frequent seizures and markedly abnormal EEGs, which may substantially worsen developmental problems.

Importantly, if seizure control can be improved, the Epileptic Encephalopathy component of the delay should improve, however the Developmental Encephalopathy component will not change.

Most DEEs begin early in life, often starting in infancy. Children often have very frequent and severe seizures which can be of multiple types. Often epileptic spasms, tonic or atonic seizures and myoclonic seizures can be seen. In most cases, seizures are life long, although less commonly can abate with time with certain syndromes or specific causes.

The electroencephalographs (EEGs) in children with DEEs are typically very abnormal, showing diffuse slowing of the background, and frequent seizure discharges. However, in some cases, the EEGs done early on (before or very shortly after the seizure onset) may not show abnormalities.

What challenges do people with DEEs face?

People with developmental and epileptic encephalopathy (DEE) typically have epilepsy that is often challenging to treat. Seizures are often very frequent, and respond poorly to most medications, meaning they are drug-resistant. In many cases, the specific cause or epilepsy syndrome may guide treatment choice.

In some cases, seizures will go away, but people are often left with a serious neurological disability that has a tremendous impact on their quality of life. In addition to seizures, the following problems are common in children with DEE.

• Intellectual disability – people with DEE all have variable degrees of intellectual disability, relating to the underlying cause of their epilepsy as well as the frequency of seizures. In many cases, developmental delays can become more problematic with time, particularly during periods of very frequent seizures.
• Movement disorders – many people with DEE have various movement disorders including spasticity, choreiform movements, dystonia, and myoclonus. It is important to distinguish these movements from seizures, as treatment is different. If your child develops a new movement, you can often help your health care provider make the correct diagnosis by recording the movement with a cellphone or camera. In other cases, a video-EEG study may be required to confirm which events are seizures versus movement disorders.
• Respiratory issues – Respiratory problems such as aspiration (breathing food, saliva, or stomach contents into the lungs) and recurrent pneumonias are common in people with DEEs. These are mostly seen in those with severe delay with abnormal tone (hypotonia or hypertonia) that limits their ability to roll, turn, or raise their heads or cough. However, superimposed frequent seizures may increase the risk of aspiration.
• Gastrointestinal issues – Many people with DEEs have difficulty with coordinating their swallow, or problems with gastroesophageal reflux (food coming from the stomach into the feeding tube or esophagus). This leads to an increased risk of aspiration and pneumonia. In such cases, a person may need placement of a feeding tube, and surgery to decrease the risk of reflux (Nissen fundoplication). Due to limited mobility, constipation is also common.
• Orthopedic concerns – Orthopedic concerns, such as hip dislocation and scoliosis (curvature of the spine) are commonly seen. Additionally, people with DEEs are at increased risk of bone fractures due to limited mobility and chronic use of antiseizure medications. Vitamin D supplementation is important to try to mitigate this risk.
• Sleep – Sleep problems are commonly seen which can include excessive daytime sleepiness, problems with sleep maintenance and sleep apnea.
• Sudden Unexpected Death in Epilepsy (SUDEP) and increased risk of death – Persons with DEEs have a significantly increased risk of death compared to otherwise healthy individuals. Several factors contribute to this increased risk. Most deaths are in fact unrelated to seizures but the result of significant neurological disability- and in many cases, death is due to pneumonia. Occasionally, deaths can be related to seizures, either due to SUDEP, seizure-related injury or status epilepticus.