# Dravet Syndrome > SCN1A-related severe myoclonic epilepsy of infancy, seizure triggers, drug choices and newer therapies in NEET-SS Paediatric Neurology. - Canonical URL: https://prepelephant.com/topics/neet-ss/paediatric-neurology/dravet-syndrome - Exam / course: NEET-SS · Subject: Paediatric Neurology - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Dravet Syndrome", PrepElephant, https://prepelephant.com/topics/neet-ss/paediatric-neurology/dravet-syndrome ## Direct answer Dravet syndrome — severe myoclonic epilepsy of infancy — begins at five to eight months with prolonged febrile hemiclonic seizures alternating sides in an otherwise normal baby, and is driven in about 80 per cent of cases by de novo loss-of-function mutations in SCN1A, the gene for the neuronal sodium channel Nav1.1. Development is normal before onset and then regresses, with myoclonic and focal seizures, ataxia and a characteristic crouch gait emerging in the second year. The therapeutic rule that defines this syndrome in exams: sodium-channel blockers — carbamazepine, phenytoin and lamotrigine — worsen it, while valproate with clobazam, stiripentol, fenfluramine and cannabidiol are the mainstays, alongside the ketogenic diet. ## What you must remember - The opening seizure is characteristic: a prolonged (often over 15–30 minutes) febrile hemiclonic seizure in a previously normal infant, frequently mismanaged as simple febrile status until the second, contralateral event. - Triggers are part of the phenotype: fever, hot baths, prolonged sun exposure, lights and illness — parents in hot Indian climates must be counselled on heat and fever management as seriously as on medication. - SCN1A loss of function reduces sodium current in inhibitory interneurons, so the epileptic network is disinhibited — the biological reason sodium-channel blockers, which further reduce sodium current, aggravate the seizures. - Seizure evolution: febrile hemiclonic to afebrile focal, myoclonic and atypical absence seizures, with photosensitivity in many; status epilepticus is common and a major cause of morbidity and hospitalisation. - Neurological regression: normal first-year milestones, then slowing, ataxia, pyramidal signs and the crouch gait by mid-childhood; cognition stabilises at an impaired but not uniformly severe level. - Drugs that help: valproate plus clobazam as the foundation; stiripentol added for its specific trial evidence; fenfluramine and pharmaceutical cannabidiol with strong randomised data; topiramate and the ketogenic diet as further options; levetiracetam is often tried with variable results. - Drugs that harm: lamotrigine, carbamazepine, phenytoin and oxcarbazepine — a diagnosis of Dravet made after a catastrophic deterioration on lamotrigine is a classic exam narrative. - Non-seizure burdens: growth and nutrition, infection-related decompensation, sudden unexpected death in epilepsy at a higher rate than ordinary epilepsies, and family stress requiring a coordinated care plan. ## The drug-choice pathway Work a real case: a seven-month-old with a 25-minute left-sided hemiclonic seizure during fever, normal examination, treated as febrile status and discharged; two months later the same event right-sided, and by fourteen months myoclonic jerks on waking. The diagnostic step is early SCN1A testing — in India increasingly available as a targeted panel — because the result changes the drug list before harm is done. Assume the test confirms a pathogenic variant: the regimen is valproate at full therapeutic dose with clobazam added, and a written rescue plan of buccal or intranasal midazolam for anything over five minutes, since prolonged febrile status is the recurring emergency. Audit the existing prescriptions and strike lamotrigine or carbamazepine immediately — the withdrawal itself often reduces seizures, the single most satisfying intervention in the disease. Add stiripentol when seizures persist — it inhibits CYP metabolism, raising clobazam and norclobazam levels, a pharmacokinetic fact examiners enjoy — and in referrals with access to newer agents, fenfluramine (with cardiac screening for valvulopathy history, though risk at antiepileptic doses appears low in trials) or purified cannabidiol (watching for transaminase rise on valproate and interactions via CYP2C19). Layer on the ketogenic diet for refractory disease, and hand the family the trigger list — aggressive antipyretics, cool baths, hydration in summer, hats and water safety, and annual influenza vaccination — because in Dravet, prevention of fever is half the treatment. ## The examiner's trap The planted stem is always the same: an infant with febrile seizures started on carbamazepine or lamotrigine who then explodes with myoclonus and status. The expected answer is not "add another drug" but "suspect Dravet, stop the sodium-channel blocker, test SCN1A". The reverse trap asks which genetic epilepsy is safe to treat with sodium-channel blockers — the answer is SCN2A- and SCN8A-related epilepsy, gain-of-function disorders, and candidates who can make that contrast demonstrate mechanism-level understanding. A third favourite is the gait question: the wide-based crouch gait of a school-aged Dravet child, which examiners pair with ataxia to test whether you know the motor phenotype beyond seizures. ## Frequently asked questions ### Which gene is most often mutated in Dravet syndrome? SCN1A, with de novo loss-of-function variants in about 80 per cent of cases impairing inhibitory interneuron firing. ### Why do sodium-channel blockers worsen Dravet syndrome? Because the mutation is loss of function — further reducing sodium current deepens the inhibitory deficit and increases seizures. ### What is the classic first seizure of Dravet syndrome? A prolonged febrile hemiclonic seizure in a previously normal infant aged around five to eight months, often alternating sides between episodes. ### Which add-on drug has specific evidence in Dravet syndrome? Stiripentol, given with valproate and clobazam, acting partly by raising clobazam and norclobazam levels. ### What non-drug measures matter in Dravet syndrome? Fever and heat avoidance, aggressive antipyresis, a written rescue-benzodiazepine plan, water safety and infection prevention including influenza vaccination.