Seasonality in Epileptic Seizures

Seasonal variation has been reported for several disorders, including those of the nervous system. This variability is usually regarded as reflecting fluctuations in vitamin D level. Although epilepsy has also been reported to exhibit some seasonal features only one previous study assessed seasonal distribution of the epileptic seizures themselves. Based on individual seizure diaries obtained from 62 epilepsy patients we evaluated seizure distribution across calendar months. We found a significant seasonal effect (p=0.026). At the group level seizure counts peaked in January and reached a nadir in August, a seasonal pattern consistent with that found for a variety of other neurologic and systemic disorders. This finding together with other types of evidence suggests a role for vitamin D deficiency in epilepsy.