Rare Epilepsies and DEEs

Epilepsy is made up of many disorders that all have one thing in common: the presence of seizures. The underlying cause of epilepsy is known in about 50% of all cases. Of the known causes, many of them are rare epilepsies, meaning they impact fewer than 200,000 people.

“Rare epilepsies” refers to a diagnosis of a rare epilepsy disorder, syndrome, and/or developmental and epileptic encephalopathy (DEE).

What Is Rare Epilepsy?

In the United States, when the cause of epilepsy affects less than 200,000 people, it is considered a rare form of epilepsy. Rare epilepsy can refer to many types of epilepsy, including those with the following causes:

Rare epilepsies affect people across all genders, ages, races, and socioeconomic backgrounds. Most rare epilepsies begin in early childhood, with 60-75% showing first symptoms before age 3. They can begin as early as in utero (before birth) and be diagnosed through adulthood. The first sign of epilepsy differs depending on the diagnosis.

Rare Epilepsy Disorders, Syndromes, and Encephalopathy

Rare diagnoses depend on a person’s specific symptoms and seizure type. A combination of specific seizure types and EEG results may lead to the diagnosis of an epilepsy syndrome. But not everyone with epilepsy will have an epilepsy syndrome. Even when a syndrome is identified, it is important to understand the underlying cause. There are different treatment options for different epilepsy syndromes.

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Epilepsy Syndromes

Developmental and epileptic encephalopathy (DEE) refers to a group of severe brain disorders in children, where both epilepsy and problems in brain development cause delays in learning, thinking, and movement.

Within the same disorder or cause, there may be some that meet the criteria of a syndrome and/or DEE and others that do not. The majority of DEEs are rare epilepsies, but not all rare epilepsies qualify as DEEs. To know if a rare epilepsy has a DEE component, additional evaluations are completed to see if there is an effect on development.

Differences in Diagnoses

Below are some examples of different diagnoses:

A person may have a rare epilepsy disorder diagnosis like the gene SCN8A. The severity of their symptoms may mean that the individual also has a DEE. And they may meet the seizure and EEG criteria for a syndrome like Lennox-Gastaut syndrome.

Another person may have the same diagnosis of the gene SCN8A but not have a DEE. This is based on their symptoms being not as severe. They do not meet the criteria of a separate syndrome like LGS.

A third person may have the diagnosis of a syndrome like LGS and meet the criteria of DEE, given their severity without another known underlying cause.

Seizure Types and Rares

People diagnosed with rare epilepsies and DEEs can have every kind of seizure.

Many people with rare epilepsies have seizures that do not respond to anti-seizure medications. Other treatments may be effective, including diet and surgery. Immediately following a diagnosis, it also important for families to be informed, have rescue medication, become trained in seizure first aid, and create a seizure action plan.

Create Your Seizure Action Plan

Common Symptoms and Medical Conditions

People with rare epilepsies frequently have other symptoms and medical conditions beyond seizures, often referred to as comorbidities. These occur when a medical condition in addition to a primary diagnosis exists. The two or more conditions happen at the same time and require coordination and care across many healthcare professionals.

Examples of common conditions with rare epilepsy:

Neurodevelopmental disorders
Movement disorders
Psychiatric or behavioral symptoms
Cognitive impairments
Gastrointestinal, respiratory, cardiac, skin, and other body issues

How Are Rare Epilepsies Diagnosed?

Rare epilepsies are typically diagnosed through multiple steps and tests over time. These include:

Clinical evaluation
Neuroimaging
EEG
Genetic testing
Metabolic testing (blood and urine)

Often, the road to diagnosis is lengthy and frustrating to individuals and family members. For many rare epilepsies, the average time to diagnosis can be 4-7 years. The process often includes multiple specialist referrals (neurologists, epileptologists, geneticists). There may be tests with uncertain results, misdiagnoses and ineffective treatments, and significant emotional, financial, and psychosocial burden on families. Genetic testing has greatly changed and improved rare epilepsy diagnosis. Genetic testing is increasingly recommended as the first choice to diagnose children with drug-resistant epilepsy, epileptic encephalopathies, or seizures with neurodevelopmental disorders.

Specialized Care

When someone is diagnosed with a rare epilepsy, specialized care is critical. Specialized care can be found at centers that specialize in epilepsy. These centers may offer advanced diagnostic and genetic testing to identify underlying causes of epilepsy. They may also have a referral network of local support programs to help with care and costs. For severely impacted patients, hospice or palliative care may also be an option to support the family in caring for their loved one.

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Working with Your Healthcare Team

Rare Epilepsy Treatment

Like generalized epilepsy, current treatment approaches for rare epilepsies include anti-seizure medications, dietary therapies, and surgery.

While 30-40% of all epilepsies are drug-resistant, resistance rates for rare epilepsies are often 70% or higher. Many people need multiple treatment types which may increase side effects. Most treatments address symptoms, not the underlying genetic or molecular causes.

There have been some positive responses to dietary therapies like the ketogenic diet which can be a less restrictive alternative, or a low glycemic index treatment.

There have been many advances in surgical interventions for rare epilepsies, including:

Promising developments include gene therapies, antisense oligonucleotides, and gene-specific small molecules that target underlying mechanisms rather than just symptoms.

For the most up-to-date information on treatments by individual disorders, visit the Rare Epilepsy Network. A list of patient advocacy groups have information on current treatments and management by disorder.

Contact the REN network for resources.

Safety for Rare Epilepsies

Safety is a top priority for people diagnosed with a rare epilepsy. Safety at home, at school, and in activities means making sure potential risks are limited. This also includes safety risks to drowning, fire, and other accidents. There are devices and other interventions for night-time monitoring and remote notification systems for caregivers.

In rare epilepsies, comprehensive safety planning often means talking with both epileptologists and rare disease specialists about syndrome-specific risks and emergency practices. This may include:

Seizure first aid- Everyone that plays a role in caring for a loved one with a rare epilepsy should be trained.
Seizure action plans or acute plans- Provide detailed information about care required to people that often interact with your loved one. Information should include syndrome-specific information, seizure descriptions, response steps, and contact details.
Rescue medication- Medications used in an emergency work quickly to stop seizures. Rescue medications vary depending on the rare epilepsy. Details should be included in the seizure action plan.

SUDEP and Early Death Risks

Risks of death related to epilepsy and other causes is higher for people diagnosed with rare epilepsies.

SUDEP

Sudden and unexpected death in epilepsy (SUDEP) is 15-40 times higher for people with certain rare epilepsies than for people with general epilepsy. Risk factors can be syndrome-specific, as well as age related. For many rare epilepsies, age-related vulnerability is the highest for children and adolescents.

Other Causes of Early Death

Not all mortality risks are related to SUDEP. Non-SUDEP-related deaths related to seizures include:

Status epilepticus
Aspiration or respiratory complications
Accidents and injuries
Sepsis

Treatment-Related Deaths

There are additional treatment-related mortality risks in rare epilepsies that can include medication toxicity, dietary therapy complications, and surgical complications.

Ways to Reduce Early Death

There are ways to reduce the risk of early death for people with rare epilepsy including:

Optimized seizure control- particularly nighttime convulsive seizures
Monitoring- acoustic, motion, or cardiorespiratory monitoring during sleep
Positioning- semi-prone recovery position after seizures
Seizure response devices- alert caregivers to nighttime seizures
Safety in the home and community
Medication monitoring- effectiveness, toxicity, and side effects

Transition from Pediatric to Adult Care

Successful transitions require long-term planning and collaboration between pediatric and adult care teams. The goal is continuity of care while supporting appropriate independence and quality of life for adults living with rare epilepsies.

The transition from pediatric to adult care may have many challenges. These challenges include issues with care, providers, and insurance, planning for school, work, and housing, and many other medical and social factors. Planning for transitions should be done over time and include readiness assessments, ensuring the person with epilepsy can manage their medication and other individual tasks. It’s helpful to keep a care notebook documenting transitions, key care providers, medications, and community resources.

Visit Rare Epilepsy Network for comprehensive resources for transitioning patients with rare epilepsies.

Resources:

Resources

Epilepsy Centers

Epilepsy centers provide you with a team of specialists to help you diagnose your epilepsy and explore treatment options.

Epilepsy Medication

Find in-depth information on anti-seizure medications so you know what to ask your doctor.

Epilepsy and Seizures Helpline

Call our Epilepsy and Seizures Helpline and talk with an epilepsy information specialist or submit a question online.

Tools & Resources

Get information, tips, and more to help you manage your epilepsy.

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