What are Dravet Spectrum Disorders: Diagnosis

How are Dravet Spectrum Disorders diagnosed?

Diagnoses of all the disorders are clinical; there is no single test that will positively diagnose all patients with a Dravet Spectrum Disorder. The doctor will:

• review the patient’s medical history, including birth and developmental history
• obtain a detailed description of the patient’s seizure history
• ask regarding seizures or a diagnosis of epilepsy in any other family members
• do blood testing to rule out other causes of seizures
• do testing to record brain waves (electroencephalogram; EEG)
• use imaging techniques to ‘see’ structures inside the brain (magnetic resonance imaging; MRI)

Clinical findings might be enough to confirm a diagnosis of a Dravet Spectrum Disorder. Genetic testing is usually ordered to confirm a suspected case. It also helps make an early diagnosis of a Dravet Spectrum Disorder.

Medical History

The doctor will want to know if other underlying medical issues are involved. The presence of other diseases may rule out Dravet Spectrum Disorders, or make them less likely. Past history of significant head trauma, exposure to toxins, or other known causes of seizures may also rule out Dravet. The doctor may first suspect a Dravet Spectrum Disorder if fever or illness are present when the first seizures occur in an otherwise healthy infant younger than one year.

Seizure History

The most important factor in making a diagnosis of Dravet Spectrum Disorders is the patient’s seizure history. Information needed includes:

• what age seizures began
• if a fever or illness was present in seizures during infancy or early childhood
• if seizures are triggered by fever, heat, activity, light, or strong emotion
• what the seizure looked like (type of seizure)
• how often seizures happen
• how long seizures last
• what medication for seizures have been tried, and if seizures have been controlled with them
• if any medications for seizures made them worse instead of better
• if there are any changes in seizure type/appearance over time

Family History

A family history of seizures is seen in some patients diagnosed with Dravet Spectrum Disorders. About one out of four patients with Dravet syndrome report some type of family history of seizures. These family members may have experienced febrile seizures as children (seizures triggered by fever) or they may have had a diagnosis of idiopathic epilepsy (epilepsy with no known cause).

Blood Tests

When a first seizure occurs, a complete blood count is usually obtained, particularly if the child has an infection or fever. It is a screen for infection. Other studies obtained evaluate for a low or high blood sugar, low sodium, low calcium, low magnesium, and, at times, some thyroid disorders. After the diagnosis of recurring seizures (epilepsy) is established, additional tests for metabolic or genetic problems may be obtained. These depends on each individual‘s history and clinical story.

EEG

An electroencephalogram, commonly called an EEG, is a test used to evaluate electrical activity in the brain. This painless procedure records brain wave patterns. Small metal discs with thin wires (electrodes) are placed on the surface of the scalp. Brain wave signals detected are sent to a computer and recorded. Results are read and interpreted by a neurologist. EEGs may vary in complexity and duration.

EEG results are often normal when Dravet Spectrum Disorder seizures first begin in infancy. As children grow and seizures continue, EEG results become abnormal.

Brain Imaging Techniques

Imaging technology is used to try to find an area of brain injury or structural change (like a scar or developmental abnormality) that might cause seizures. MRI (magnetic resonance imaging) scans are needed; a CT (computed tomography) scan is not sensitive enough. PET (positron emission tomography) gives images of the brain similar to the MRI but can show some chemical changes that the MRI cannot.

Genetic Testing

Genetic mutations, or changes, of the sodium channel SCN1A gene have been linked to Dravet syndrome and related disorders. Early diagnosis of these diseases in infancy or early childhood provides the opportunity for best outcome. An early diagnosis will help patients avoid medicines known to aggravate seizures in Dravet syndrome. Older children and adults with clinical features and medical history consistent with these diseases also benefit from genetic testing. Genetic testing can provide the reason the person has epilepsy. It also can lead to screening for associated conditions, and help the family know what to expect in the future.

The Dravet Clinical Research and Comprehensive Care Network (CCR-CCN)

CCR-CCN is a network of referral centers committed to providing high quality care and treatment of patients with Dravet syndrome and related disorders. Participating centers focus on multidisciplinary care. A health care team made up of neurologists, nurse practitioners, nurses, social workers, and others address and treat the medical and non-medical needs of the patient.
Learn more about these expert care centers.