Epilepsy and variation in the frontal lobe artery.

A patient with a rare variation of fronto-orbital artery (FOA) that developed generalized tonic and clonic seizures is reported. The epilepsy focus was in her left frontal region, where blood was supplied by the contralateral fronto-orbital artery. The region was vulnerable to ischemic changes due to a decrease in blood CO2 gas caused by an increase in endogenous progesterone in the luteal period. The anomaly illustrates an important mechanism of ischemia in epilepsy.