Dravet syndrome diagnosis
Fact-checked by Reaching a diagnosis of Dravet syndrome, a rare pediatric epilepsy characterized by prolonged seizures that start in infancy, relies heavily on a child’s symptom history. Genetic testing also plays an important role in diagnosing Dravet syndrome, as SCN1A gene mutations are the most common cause of the disease.
The symptoms of Dravet syndrome can vary between patients and may look similar to other childhood-onset epilepsies, complicating the diagnostic process. However, an early and accurate Dravet syndrome diagnosis is key to ensuring that patients begin appropriate treatment promptly, potentially improving long-term outcomes.
When do signs of Dravet syndrome first appear?
Most patients experience Dravet syndrome seizure onset during the first year of life, often between 3 and 9 months of age, with seizures recurring in the following months. The most common seizure types at this early stage of the disease include:
- tonic-clonic seizures: convulsive seizures characterized by muscle stiffness and abnormal movements, such as rhythmic twitching or jerking, on both sides of the body
- hemiclonic seizures: characterized by abnormal movements limited to one side of the body
Early Dravet seizures also often have the following characteristics:
- last longer than five minutes
- triggered by fevers or vaccines
- recur several times
- don’t respond well to standard epilepsy treatments
- can’t be explained by brain damage or other factors
Dravet syndrome symptoms in infancy are usually limited to seizures, although some subtle motor symptoms, like difficulty with sitting unsupported, may appear after 6 months of age. Other developmental and cognitive issues usually emerge later.
Why Dravet syndrome is often difficult to diagnose
Diagnosing Dravet syndrome can be a complicated and time-consuming process. Several factors can delay an accurate and early diagnosis of Dravet syndrome, particularly its resemblance to other types of pediatric epilepsy. Part of identifying Dravet syndrome versus other epilepsies is excluding alternative explanations for seizures, which can take time.
Even among people with Dravet, symptoms can vary and often change over time, further complicating the diagnosis. Dravet syndrome symptoms that may evolve include:
- seizure type, length, and triggers
- developmental and cognitive changes
- motor problems
Data show that the Dravet syndrome diagnosis timeline is often prolonged, and nearly three-quarters of children may initially receive a different diagnosis. Common Dravet syndrome misdiagnoses include other types of epilepsy, as well as developmental and behavioral disorders.
Steps in diagnosis
The Dravet syndrome testing process usually starts with careful review of a child’s symptom history after seizures emerge.
Under most Dravet syndrome diagnostic criteria, at least four of the following five clinical characteristics should be present:
- normal or near-normal cognitive and motor development before seizure onset
- two or more seizures with or without fever before 1 year of age
- history of myoclonic, hemiclonic, or tonic-clonic seizures
- two or more prolonged seizures lasting longer than 10 minutes
- medication-resistant seizures that persist beyond age 2
Doctors will often run other tests once the disease is suspected, including:
- genetic testing: may identify SCN1A mutations, the most common cause of Dravet syndrome
- MRI scans: imaging scans that can rule out alternative explanations for seizures
- Electroencephalography (EEG): a test used to measure the brain’s electrical activity that can show abnormal signaling patterns linked to Dravet
The order of these diagnostic tests may vary, and confirming a Dravet syndrome diagnosis often relies on a combination of clinical history and other diagnostic tests. Pediatric neurologists and epilepsy specialists with the expertise to identify the rare seizure disorder are typically involved in this process.
Genetic testing
Experts generally recommend Dravet syndrome genetic testing for developmentally normal infants, ages 2-15 months, who have seizures characteristic of Dravet syndrome.
Genetic testing involves collecting a small blood sample and testing it for mutations in the SCN1A gene, which cause Dravet syndrome in most cases. The results may be interpreted as follows:
- positive (a mutation is present): can support a diagnosis if clinical features are consistent with Dravet syndrome, although SCN1A mutations can also cause other epilepsy types, so this result isn’t definitive
- negative (no mutation is present): Dravet syndrome is less likely, but doesn’t exclude a diagnosis
- inconclusive: may indicate a problem with the genetic sample, so the test is often repeated
Depending on the situation, doctors may also perform broader pediatric epilepsy genetic testing to look at other genes that may be causing seizures.
Other tests used
Other Dravet syndrome testing tools may include:
- EEG, which measures electrical activity in the brain
- MRI, which visualizes the brain
EEG findings in Dravet syndrome are often normal between seizures in patients younger than 1 year of age, but many show abnormal signaling patterns after this age, including bursts or spikes of unusual nerve cell activity.
MRI is mainly used to exclude other possible causes of epilepsy, such as brain damage. MRI results in Dravet syndrome are usually normal, although abnormalities are possible.
After diagnosis
After a Dravet diagnosis, patients, caregivers, and a multidisciplinary team of healthcare providers will work together to develop a treatment plan that may include medications and supportive therapies.
An accurate diagnosis is key to guiding treatment choices, because certain anti-seizure medications that are commonly used for other types of epilepsy can make seizures worse for people with Dravet.
Families may also be encouraged to take steps to ensure their child receives the most appropriate care at all times, including keeping a seizure-tracking diary and creating an emergency seizure action plan.
There are various support programs available to help patients and caregivers navigate life with Dravet syndrome and support emotional well-being.
Dravet Syndrome News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
