Characteristics and significance of febrile seizure syndromes
| Simple febrile seizure | Complex febrile seizure | Dravet’s syndrome | PCDH19-related epilepsy | |
| Typical age of onset | 6 months to 5 years | 3 months to 5 years | Before 1 year | 3 months to 3 years |
| Seizure type | Generalised clonic Generalised tonic–clonic | Focal symptoms with or without generalisation | Generalised clonic Hemiclonic Myoclonic Focal Atypical absence | Generalised tonic–clonic Clonic Tonic Atypical absence |
| Seizure duration | <15 min | >15 min | Often prolonged >15 min | Generally brief (1–5 min) |
| Significance | Usually benign prognosis 30% risk of recurrent febrile seizure 2%–4% long-term risk of epilepsy | Indication for further investigation and consideration of pharmacotherapy 6%–8% long-term risk of epilepsy | Avoidance of sodium channel agents (eg, lamotrigine) Pharmacoresistant Monitoring for progressive gait changes Awareness of risk of sudden unexpected death in epilepsy | Genetic counselling important due to distinct inheritance pattern Remission in adolescence is common |
| Distinguishing features | Tonic–clonic convulsion Single episode within 24 hours | Often prolonged Focal symptomatology Multiple episodes within 24 hours | Severe epileptic encephalopathy Multiple seizure types Intellectual impairment | Female exclusively Clusters of brief seizures Intellectual disability Autism-spectrum disorders |