What is epilepsy? Here are some key facts

A seizure-causing spectrum of disorders

By Scottie Andrew and Geetha Parachuru, CNN
Copyright 2019 CNN

BETHESDA, Md. - More than 3.4 million people in the United States are diagnosed with epilepsy, but researchers struggle to fully understand the spectrum of neurological disorders and its causes.

Epilepsy is a general term for several diagnoses that involve recurring seizures. It's considered a spectrum of disorders for its wide range of causes, types of seizures and severity of impact, according to the National Institute of Neurological Disorders and Stroke.

The family of Disney Channel star Cameron Boyce, who died in his sleep, said his fatal seizure was caused by epilepsy.

During a seizure, neurons misfire and send an abnormally large and quick surge of electrical signals to the brain. This can cause involuntary changes in body movement, behavior, sensation and, in some cases, loss of consciousness.

Here's what you need to know about epilepsy, seizures and its impact on patients' general health.

Symptoms of epilepsy vary based on their type

Epilepsy symptoms manifest differently based on their severity, from convulsions and a loss of consciousness to a brief lapse in awareness accompanied by rapid blinking, the National Institute of Neurological Disorders and Stroke says.

Focal seizures occur in one isolated part of the brain. Symptoms of these epileptic seizures vary, from an intense sensation of déjà vu and a sudden change in mood to a dreamlike feeling and repetitive movements like blinking, twitching and swallowing.

Generalized seizures impact both sides of the brain, and symptoms include staring blankly, slightly twitching, stiffening, jerking and losing consciousness.

About 50% of epilepsy cases have no identifiable cause

Half of epilepsy cases have no known cause. For the other half, epilepsy is linked to:

Genetic mutation The institute estimates that hundreds of genes are attributable to the illness. The mutations affect neuronal functioning in different ways, causing different forms of epilepsy. Other genetic mutations don't cause epilepsy but can increase patients' susceptibility to seizures.

Traumatic brain injury A study from the Centers for Disease Control and Prevention found that 1 in 10 teens developed epilepsy three years after they were hospitalized for head trauma.

Brain conditions When the brain attempts to heal itself after disruptions like benign tumors or Alzheimer's disease, it may inadvertently disturb neuronal functioning. Stroke, which occurs when blood flow is cut off from an area of the brain, is the leading cause of epilepsy in adults over 35.

High fever

Infectious diseases, like HIV and meningitis.

Epilepsy is often accompanied by a host of other chronic conditions, like heart disease, depression or asthma, which can complicate treatment, the CDC says.

Not all seizures are related to epilepsy

An epilepsy diagnosis requires a patient to experience two or more "unprovoked" seizures that occur at least 24 hours apart. Seizures that are "provoked," or those caused by factors like a high fever, acute traumatic brain injury or drops in blood sugar levels aren't considered epileptic.

There's no cure for epilepsy, but it can be controlled in most cases

About 70% of people diagnosed with epilepsy can manage the disorder with surgery or medicine, according to the National Institute of Neurological Disorders and Stroke. Anti-epileptic medication can decrease the frequency and intensity of seizures and in some cases, particularly among children, end patients' seizures entirely. At least half of people with a new epilepsy diagnosis can live seizure-free after their first prescription, the Mayo Clinic says.

Surgery is suggested when medication fails to control seizures and physicians can pinpoint the exact area of the brain where seizures originate, as long as operating on that area won't interfere with speech, language or motor function.

Patients with treatment-resistant epilepsy who aren't candidates for surgery can opt to implant a vagus nerve stimulator in their chest that sends electrical bursts through the vagus nerve and to the brain, which inhibits seizures up to 40%.

But the other 30% of epilepsy patients cannot control their seizures with available treatment. While most seizures won't cause significant brain damage, this form of the disorder, called intractable or treatment-resistant epilepsy, subjects patients to frequent, uncontrolled seizures, which can be life-threatening.

A drug made with a marijuana compound has reduced severe seizures in child patients

Though epilepsy is still incurable, researchers have developed unconventional treatments to lessen the effects of severe forms. A 2017 study found that cannabidiol, a chemical in marijuana that doesn't produce a high, decreased the frequency of convulsive seizures for child patients with Dravet syndrome, a typically treatment-resistant form of pediatric epilepsy.

The FDA approved the drug in 2018 for use in patients 2 and older diagnosed with Dravet and Lennox-Gastaut syndromes.

One in 1,000 people experience sudden and unexpected death in epilepsy every year

People with epilepsy have an increased risk of dying suddenly for reasons researchers are still working to understand. Sudden unexpected death in epilepsy, known as SUDEP, can occur across the spectrum of epilepsy, no matter the severity or type of seizure.

A June study found that among 530 participants with epilepsy, 237 experienced SUDEP over the course of eight years. More than 70% of the deaths occurred during sleep, and the average victim was 26 years old, though SUDEP can occur at any age.

Despite its unknown causes, researchers advise epilepsy patients to take prescribed dosages of medication regularly. Failure to do so could heighten the risk of SUDEP.

Epilepsy is more common among people with autism

People with autism are 20% more likely to experience epilepsy, but autism spectrum disorder hasn't been proven to cause epilepsy. Two epileptic syndromes in particular, Landau-Kleffner and West, have repeatedly been studied to co-occur with autism.

The severity of epilepsy increases for patients with autism spectrum disorder, too. In a 2010 study of children with autism, more than one-third of patients also had treatment-resistant epilepsy.

The link between the disorders is still unknown.

For more information about epilepsy treatment and resources, visit epilepsy.com.

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