Symptoms and Causes of Dravet Syndrome

Dravet syndrome causes wide-ranging effects, including cognitive impairment, motor deficits, and epilepsy. The symptoms are significant, begin within the first few years of life, and can become more noticeable and limiting as a child gets older.

The condition is caused by extensive brain dysfunction, and it is associated with a genetic abnormality, although it is not inherited. 

Frequent Symptoms 

Seizures and mental and physical disabilities are the most notable symptoms of Dravet syndrome. Parents may begin to notice the effects as early as during the first year of a baby’s life, but signs of the condition are not usually apparent at birth. 

Severe epilepsy with frequent seizures that are not easily controlled is a major feature of Dravet syndrome. A prolonged febrile seizure (associated with a high fever) can be the first sign of the condition.

Several different seizure types can occur with Dravet syndrome, usually with impairment of consciousness and convulsive movements. Myoclonic seizures are especially common in Dravet syndrome. These seizures are characterized by jerking of one muscle group or one area of the body.

Other common symptoms include:

• Developmental decline: Children who have Dravet syndrome may lose cognitive and motor skills that they have already attained beginning around age 1 or 2.
• Cognitive and intellectual impairment: There is a range in the severity of intellectual disability in Dravet syndrome. Some people living with this condition can learn and manage some aspects of self-care, while many are completely dependent on caregivers.
• Crouched walking: Children and adults who have Dravet syndrome are described as having a crouched gait when walking. Walking abilities decline throughout childhood.
• Hypotonia: Diminished muscle tone will be apparent with a clinical physical examination, but it also can be noticeable due to limp or weak movements.
• Impaired coordination: People who have Dravet syndrome will have difficulty coordinating movements such as walking, as well as having trouble with fine motor movements.
• Behavioral problems: Issues with communication, impaired attention, and hyperactivity are common with Dravet syndrome. They could be related to the cognitive limitations caused by the condition.

Parents may notice that these effects become more prominent as a child reaches school age and adolescence. Most people who have Dravet syndrome cannot independently care for themselves and require substantial assistance with daily tasks.

Rare Symptoms 

Dravet syndrome is rare, affecting approximately one out of every 20,000 to 40,000 people. The less common effects of Dravet syndrome might not be recognized due to their relatively subtle symptoms.

Autonomic Impairment

One of the effects of this condition is autonomic dysfunction. This is altered functioning of the autonomic hormones and nerves that control the organs of the body, such as the heart and digestive system.

Children and adults living with Dravet syndrome might not notice subtle signs of autonomic dysfunction and can experience serious consequences, such as loss of consciousness.

Children who have Dravet syndrome can have heart problems, such as arrhythmia (irregular heart rhythm). This can cause shortness of breath and/or loss of consciousness.

Autonomic dysfunction in Dravet syndrome can also cause slow or altered breathing patterns.

Adults

Dravet syndrome is associated with early mortality due to complications. However, many people who are diagnosed with Dravet syndrome survive into adulthood. 

Adults who have Dravet syndrome can have some different symptoms than children.

• Seizures have been noted to decrease in frequency and severity during the adult years.
• Adults may develop Parkinsonian symptoms, which are symptoms similar to those of Parkinson's disease, such as tremors and bradykinesia (slow movements).

Complications

Dravet syndrome may cause serious and life-threatening complications. Sometimes these problems can come completely unexpectedly. Illness, fever, and temperature changes may trigger complications of Dravet syndrome, but they can occur without a known provoking cause.

• Status epilepticus: Status epilepticus is a type of seizure that does not resolve unless it is medically treated. It can cause loss of consciousness, impaired breathing, and brain damage.
• Sudden unexpected death in epilepsy (SUDEP): The leading cause of death in Dravet syndrome is SUDEP. Autonomic dysfunction can contribute to this fatal outcome.

When To See a Doctor/Go To the Hospital

Children and adults who have Dravet syndrome need to have ongoing medical management of health issues and attention to urgent medical issues that can arise due to the condition. 

It is important for family members or professional caregivers who are taking care of someone who has Dravet syndrome to be able to recognize situations that warrant urgent medical attention:

• Prolonged seizure: Get urgent medical attention if a seizure lasts for longer than usual or if it is different than previous seizures. 
• Fever: Body temperature changes and fevers can trigger a seizure for people who have Dravet syndrome. Fevers can be caused by a variety of problems, including infections. Seek medical advice regarding whether a fever should be lowered with over-the-counter medication or whether in-person medical attention is necessary.
• Change in consciousness: This can occur due to autonomic dysfunction or a seizure.
• Injury: Due to the impaired coordination and cognitive limitations caused by Dravet syndrome, children or adults who have this condition can become injured due to falling or other types of traumatic injuries.

If you are unsure whether a situation could be dangerous, call your healthcare professional to get their opinion. Consider taking a video if you think it will be difficult to describe behavior changes or a seizure-like episode.

Common Causes 

Dravet syndrome is considered an encephalopathy, which is a dysfunction or disease of the brain. It has been associated with extensive brain dysfunction involving the cerebral cortex and the cerebellum (the area of the brain that controls physical balance and coordination).

The condition is usually associated with a genetic defect, but it is not hereditary. There are no known lifestyle or other risk factors that are believed to predispose to Dravet syndrome.

About 80% of those who are diagnosed with Dravet syndrome have a mutation (genetic alteration) in the SCN1A gene. The gene has not been found to be inherited. It arises without a known risk factor or pattern.

This gene normally plays a role in the production of ion channels in the brain that regulate nerve transmission. A defect in these channels can disrupt brain function.

Summary

Dravet syndrome is a severe neurological condition with a range of effects that cause substantial limitations. Children who have this condition require a great deal of care and are not able to eventually become independent. This syndrome is not caused by any lifestyle habit or preventable factors.

If you have a loved one who has been diagnosed with Dravet syndrome, you will be able to get guidance and professional help as you navigate the challenges of taking care of their health. As a caregiver, you can also seek out support so that you will not become overwhelmed with the day-to-day responsibilities.