Aim: To identify the aetiology and outcome of seizure-like events leading to hospital referrals in infants and to identify early predictors of epilepsy and delayed neurodevelopment. Methods: This Norwegian population-based study focused on all children born in Sør-Trøndelag county, who were up to one year of age in 2014-2015. They were identified by diagnostic codes for seizure-like events and electroencephalography (EEG) examinations. Hospital records were examined up to 1.5 years of age. Results: The one-year prevalence of seizure-like events was 1.5% (114/7430). Epilepsy was diagnosed in 17%, 57% had non-epileptic paroxysmal events (NEPE), 16% had febrile seizures, and 10% had other acute symptomatic epileptic seizures. Neurodevelopmental delay occurred in 21%. The cumulative incidence was 0.22% for epilepsy and 0.79% for NEPE. Abnormal brain magnetic resonance imaging, abnormal first EEGs and neonatal care increased the likelihood of epilepsy and delayed development. Identifying situation-related factors decreased the epilepsy risk. Occurrence at a younger age increased the risk of delayed development. Absence of unambiguous motor symptoms was less common in epilepsy than in NEPE. Conclusion: Seizure-like events were common in infants and most were not caused by epilepsy. Specific anamnestic clues, and detailed descriptions of the entire event, helped to predict adverse outcomes
