The mandatory seizure type for this syndrome is the focal autonomic seizure. Autonomic features are mainly gastrointestinal (nausea, retching, vomiting), such that the seizure can mistaken for acute gastroenteritis. Other autonomic features that can be seen include pupillary (e.g. mydriasis), thermoregulatory, circulatory (e.g. pallor, cyanosis) and cardiorespiratory (breathing and heart rate) changes. There may be incontinence and excessive salivation. Apnoea and cardiac asystole can occur but only exceptionally are these severe. Two thirds of seizures start in sleep. Seizures are often prolonged (minutes to hours), constituting autonomic status epilepticus, however the child recovers without residual neurological or cognitive deficits. As the seizure evolves, loss of responsiveness, head and eye deviation, and hemiclonic activity (often with a Jacksonian march) may develop. Some seizures may have prominent fronto-parietal opercular features.