Differentiating early clinical features of Panayiotopoulos syndrome from acute encephalopathy.

Background: Panayiotopoulos syndrome (PS) is a common benign epilepsy in childhood, characterized by predominantly autonomic symptoms such as emesis, pallor, and seizures, which are often prolonged. In an emergency room (ER), particularly when unconsciousness is prolonged, differentiating PS from acute encephalopathy is challenging. In this study, we aimed to elucidate the differences in clinical features of patients with PS and acute encephalopathy who visited our ER.

Methods: We retrospectively reviewed 18 patients who were transferred to our ER because of status epilepticus later diagnosed as PS, and 30 patients with acute encephalopathy, between July 2012 and July 2017. We compared patient demographics, clinical characteristics, and treatment.

Results: Most patients (90%) with acute encephalopathy had convulsive seizures of greater than or equal to 15 min, whereas only three patients (17%) with PS had convulsive seizures of greater than or equal to 15 min (P < 0.001). In addition, seizures were treatable in all patients with PS with a small dose of midazolam (0.1 mg/kg), but all patients with acute encephalopathy required midazolam at 0.3 mg/kg or more (P < 0.001). More patients with PS had autonomic symptoms compared to those with acute encephalopathy (e.g., vomiting [78% vs. 3%, P < 0.001]). Non-convulsive status epilepticus was observed in 22% of PS patients, but not in any acute encephalopathy patients. In contrast, fever was observed in all patients with acute encephalopathy (100%), but less frequently in those with PS (11%, P < 0.001).

Conclusion: PS was characterized by 1) convulsive seizures shorter than 15 min, 2) seizures treatable with small doses of midazolam, and 3) autonomic symptoms. PS could be differentiated from acute encephalopathy in the early stages of the syndrome.