Although electrographic seizures are known to have an outcome on clinical prognosis, the implications of periodic and rhythmic patterns are less clear. The outcomes of adults with these patterns have been reported and are often poor; however, the outcomes in pediatric populations are less well characterized and may be different than in the adult population, as the etiologies of periodic and rhythmic patterns may differ in children and adults. In adults, generalized periodic discharges are highly associated with toxic–metabolic disturbances, infection, and anoxic injury; 30% to 64% of patients have poor outcomes. By contrast, in pediatric patients, generalized periodic discharges are more commonly associated with refractory status epilepticus, with good outcomes in 50% to 77%. The underlying etiology of the periodic or rhythmic pattern has a large influence on overall morbidity and mortality.