Epilepsy syndromes by age — branching viva

Opening

Examiner: A seven-month-old is referred to your clinic with two weeks of clustering brief flexion jerks on waking and loss of babbling. The EEG shows hypsarrhythmia. Talk me through your assessment and plan. [2]

Candidate: This is West syndrome — infantile spasms — defined by the triad of epileptic spasms in clusters, hypsarrhythmia on the EEG, and psychomotor regression with the loss of babbling. The peak age is four to eight months, which fits. Because this is a developmental and epileptic encephalopathy, the epileptic activity itself is driving the regression, so I would treat promptly rather than watch and wait, and I would refer urgently to paediatric neurology. [2]

Branch 1 — syndrome-directed treatment

Examiner: What is your first-line treatment and why? [5]

Candidate: First-line is vigabatrin or hormonal therapy with ACTH or high-dose prednisolone. The Cochrane review found hormonal therapy more effective than vigabatrin for short-term spasm cessation in non-tuberous-sclerosis cases, while vigabatrin is preferred when the cause is tuberous sclerosis. The skin examination is normal here and there is no clinical evidence of tuberous sclerosis, so I would favour hormonal therapy. I would start it promptly, because time-to-treatment is a major determinant of developmental outcome. [5]

Examiner (probe): Why does time-to-treatment matter so much here? [2]

Candidate: Because the hypsarrhythmia and the ongoing spasms constitute an epileptic encephalopathy — the abnormal electrical activity is actively eroding the developing brain. Resolving the electroencephalographic burden is treatment of the developmental problem, not just seizure control. The longer the encephalopathy persists, the greater the developmental cost, so early treatment is one of the few modifiable determinants of cognition. [2] [5]

Branch 2 — a different infant: Dravet syndrome

Examiner: Now consider a different infant: a ten-month-old who began having prolonged febrile hemiclonic seizures at six months, one lasting over twenty minutes, and now has emerging myoclonic jerks and brief staring with developmental slowing. What is this and what changes? [6]

Candidate: This is Dravet syndrome, another developmental and epileptic encephalopathy, but with a very different mechanism and treatment. The signature is prolonged febrile or afebrile hemiclonic seizures in the first year, often alternating sides and triggered by fever, followed by myoclonic and atypical absence seizures with developmental regression. Around seventy percent carry a pathogenic loss-of-function variant in SCN1A, and I would arrange genetic testing to confirm it. [2] [6]

Examiner (probe): What is the single most important prescribing rule in this syndrome? [6]

Candidate: Avoid sodium-channel blockers — carbamazepine, oxcarbazepine, lamotrigine and phenytoin. The mechanism is that SCN1A encodes the Nav1.1 sodium channel of inhibitory interneurons; the loss-of-function variant removes inhibition from the circuit, and sodium-channel blockers further suppress those already-deficient inhibitory neurons, so they worsen the seizures. The foundation of treatment is valproate with a benzodiazepine such as clobazam, adding stiripentol, fenfluramine or cannabidiol for refractory disease, and a ketogenic diet as an adjunct. I would give the family a MedicAlert alert and a written list of drugs to refuse. [6]

Branch 3 — the older child and the wrong-drug trap

Examiner: A fifteen-year-old presents with early-morning arm jerks and a generalised tonic-clonic seizure after a late night. His EEG shows polyspike-wave with a photo-paroxysmal response. Someone starts him on carbamazepine and his jerks get worse. Why? [4]

Candidate: This is juvenile myoclonic epilepsy — early-morning myoclonic jerks, generalised tonic-clonic seizures, and fast polyspike-wave with a photo-paroxysmal response in an adolescent. Carbamazepine is a sodium-channel blocker that aggravates the myoclonic and spike-wave burden of the genetic generalised epilepsies, which is why his jerks worsened. The correct first-line is valproate, which is broad-spectrum across myoclonic, absence and tonic-clonic seizures. The lesson is to name the syndrome before prescribing, and if a child's seizures worsen after a new medicine, suspect the syndrome, not the dose. [4]

Examiner (probe): How would you counsel this teenager about the longer term? [4]

Candidate: Juvenile myoclonic epilepsy is typically a lifelong epilepsy in which withdrawal carries a high relapse rate, so I would frame it as long-term management rather than cure. The lifestyle triggers are sleep deprivation, alcohol excess and strobe exposure, so protecting sleep is central. Valproate is teratogenic, so for a young woman I would begin pregnancy-planning counselling years in advance and consider levetiracetam or lamotrigine as alternatives, though lamotrigine can worsen myoclonus. [4]

Close

Examiner: Summarise your approach to paediatric epilepsy syndromes in one line. [1]

Candidate: Name the syndrome from the age, the seizure semiology and the EEG before you prescribe, because the syndrome names the cause, the prognosis and the single best drug — and it names the drug you must not give, above all the sodium-channel blockers that worsen absence, myoclonic and Dravet epilepsies. [1] [4]