Dravet syndrome (DS), previously known as severe myoclonic epilepsy of infancy (SMEI), is a rare form of epilepsy usually presenting in the first 1-2 years of life.
Patients usually present in first six months to one year of life with tonic-clonic seizures in a febrile child, almost indistinguishable from febrile seizures. These progress to myoclonic seizures at age 4-5 years and are drug resistant 4.
DS is caused by a mutation in the neuronal sodium channel gene, SCN1A. Though mutated SCN1A gene is absent in about 20% of the patients who fulfill all the diagnostic criteria of the syndrome. Therefore it is possible that genes other than SCN1A such as GABAA-receptor gamma 2 subunit might be involved 1.
Only a small number of patients with DS demonstrate abnormality on MRI, which may include 5:
- focal brain atrophy
- cortical dysplasia
- hippocampal sclerosis
Treatment and prognosis
DS is one of the most pharmacoresistant epilepsy syndromes. Valproate is used as a first-line agent to prevent the recurrence of febrile seizures and oral/nasal/rectal benzodiazepine is used for any long-lasting seizures. Stiripentol (Diacomit) was approved as an orphan drug in 2007 in Europe for adjunctive therapy in DS 2. Ketogenic diet may be used as an adjunct to treatment.
It was named after Charlotte Dravet who described this condition for the first time in 1978 as severe myoclonic epilepsy (SME).3
- 1. Harkin LA, Bowser DN, Dibbens LM et-al. Truncation of the GABA(A)-receptor gamma2 subunit in a family with generalized epilepsy with febrile seizures plus. Am. J. Hum. Genet. 2002;70 (2): 530-6. doi:10.1086/338710 - Free text at pubmed - Pubmed citation
- 2. Chiron C, Dulac O. The pharmacologic treatment of Dravet syndrome. Epilepsia. 2011;52 Suppl 2: 72-5. doi:10.1111/j.1528-1167.2011.03007.x - Pubmed citation
- 3. Dravet C: Les epilepsies graves de l'enfant. Vie Med 1978, 8:543-8.
- 4. Dravet C, Bureau M, Oguni H et-al. Severe myoclonic epilepsy in infancy: Dravet syndrome. Adv Neurol. 2004;95: 71-102. Pubmed citation
- 5. Guerrini R, Striano P, Catarino C et-al. Neuroimaging and neuropathology of Dravet syndrome. Epilepsia. 2011;52 Suppl 2: 30-4. doi:10.1111/j.1528-1167.2011.02998.x - Pubmed citation