Dravet Syndrome (DS)

Dravet syndrome (DS) is a rare, early-onset epileptic encephalopathy that significantly impacts individuals throughout their lifetime. It is associated with mutations in the sodium channel alpha 1 subunit (SCN1A) gene in over 80% of patients.¹

As compared to other epilepsy disorders, Dravet syndrome has a higher mortality rate, which is estimated to range between 15% to 20% by adulthood. While sudden unexpected death in epilepsy (SUDEP) is the most common cause of mortality, other causes of death include status epilepticus (second most common cause), infections, and seizure-related injuries and accidents, such as drowning.¹

The long-term prognosis of DS is influenced by the persistence of uncontrolled seizures, developmental and cognitive impairments, and accumulating comorbidities.¹ 

General Prognosis of DS

Currently, there is no cure for DS. However, earlier diagnosis and advances in treatment have improved the prognosis and life expectancy of DS, with more than 80% of patients surviving beyond the age of 20 years.^2,3

Patients with DS face several challenges that require extensive testing and medical support, including medications, dietary interventions, and other therapies. Although drugs and therapies for controlling or minimizing seizures are available, seizures in DS are often resistant to treatment; therefore, becoming seizure-free may not be possible for many patients. Research is ongoing for newer effective therapies, and experts anticipate that the prognosis of DS may continue to improve with the development of effective therapies and increased awareness of the disease.^2,3

Read more about DS life expectancy

Effect of Uncontrolled Seizures on DS Prognosis

Dravet syndrome generally begins in infancy or early childhood, between the ages of 2 months and 15 months. Initially, children with DS experience focal or generalized convulsive seizures that are often frequent, prolonged, and difficult to treat, which may or may not be associated with fever. As patients reach 1 year of age, additional seizure types emerge, such as myoclonic, focal impaired awareness, atypical absence, atonic, and tonic-clonic seizures, as well as nonconvulsive (obtundation) status epilepticus. Children with DS may frequently experience status epilepticus, a state of continuous seizing that requires emergency medical care, particularly in the first 5 years of life.^4-6

Seizures persist throughout the clinical course of disease, but as patients age, their seizures become less frequent and less severe. Older patients also tend to have seizures during sleep and seizures that are less sensitive to fever.^4-6

The management of seizures and emergency medical interventions can reduce the risk of death in patients with DS. Medications like Tegretol® (carbamazepine), Lamictal® (lamotrigine), Sabril® (vigabatrin), Trileptal® (oxcarbazepine), and Dilantin® (phenytoin) are contraindicated in Dravet Syndrome. Dilantin is useful in treatment of status epilepticus but should be avoided as a daily medication.⁷

Read more about DS therapies

Prognosis Associated with Developmental and Cognitive Impairments

The development of children with DS is initially normal but can become significantly delayed as patients age, with progressive regression of developmental skills evident from 12 to 60 months after seizure onset. Electroencephalography (EEG) also shows abnormal background activity with increasing age.^6-8

Other symptoms become apparent as children grow, such as changes in appetite, growth or nutrition issues, cognitive decline, speech delay, reduced mobility and balance, ataxia, dysarthria, hypotonia, gait worsening (crouched gait), sleep issues, gastrointestinal issues, and chronic infections. Photosensitivity and pattern sensitivity tend to disappear before the age of 20, but motor abnormalities are common.^6-8 

Read more about DS complications

Prognosis Associated with Comorbidities

Many patients with DS experience comorbid conditions such as autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), and dysautonomia. Thus, most adults with DS depend on others (family or caregivers) for continued support and cannot live independently.^6-8

Read more about DS comorbidities

References

1. What is Dravet syndrome? Dravet Syndrome Foundation. Accessed March 30, 2023.
2. Meskis MA. Transitioning to adulthood for patients with Dravet syndrome. Dravet Syndrome Foundation. September 23, 2022. Accessed March 30, 2023.
3. Treatments and outcomes. Dravet Syndrome UK. Accessed March 30, 2023.
4. Dravet syndrome. Cleveland Clinic. Accessed March 30, 2023.
5. Dravet syndrome. National Institute of Neurological Disorders and Stroke. Accessed March 30, 2023.
6. The diagnosis and treatment of Dravet syndrome. Dravet Syndrome Foundation. Accessed March 30, 2023.
7. Dravet syndrome. National Organization for Rare Disorders (NORD). Updated July 24, 2020. Accessed March 30, 2023.
8. Genton P, Velizarova R, Dravet C. Dravet syndrome: the long-term outcome. Epilepsia. 2011;52(s2):44-49. doi:10.1111/j.1528-1167.2011.03001.x

Reviewed by Debjyoti Talukdar, MD, on 3/31/2023.

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Erum Naqvi, PhD

Erum Naqvi obtained her Ph.D. in Molecular Medicine from Hannover Medical School (Germany) after completing her Masters in Biomedical Science and Bachelors in Microbiology from University of Delhi (India). She has several years of experience as a science writer.