Febrile seizures in young children: role of fluid intake and conservation

Febrile seizures are a common occurrence in young children with incidence rates varying from 3-14%, depending on the geographic region. Studies have suggested that an elevated temperature is a factor in their development, though other factors may synergistically lower the seizure threshold. While it is recognized that excessive or rapid dilute fluid intake can cause seizures in young children, and in adults during strenuous physical activity, less focus has been paid to its involvement during febrile illnesses. Young children are more vulnerable to the development of febrile seizures due to their small skull size relative to brain volume. In animals, reduced serum sodium levels have been shown to lower the threshold to convulsive stimuli, while hypertonic saline has been shown to rapidly reverse these effects. Similarly vasopressin, frequently elevated during acute infections, enhances fluid retention and may also be a precipitating factor for febrile seizures. Although an elevated temperature may augment seizure risk, antipyretics have not been shown to prevent them. In fact, some may increase seizure risk through a reduction in urine output. It has long been observed that fluid retention occurs during febrile infections, followed by diuresis during convalescence. This characteristic observation led to recommendations for restricted fluid intake during acute infections dating back more than 2,000 years. Only recently has there been a return to restricted fluid intake for patients with potentially reduced free water excretion. Further studies are required to determine the role of the overall fluid balance in the etiology of childhood febrile seizures.