Cerebral hyperperfusion syndrome(CHS)has been well described in medical literature after carotid artery stenting.The clinical presentation may vary from acute onset of focal edema(stroke-like presentation)and intracerbral hemorrhage to delayed(>24h hours after the procedure)presentation with seizures,focal motor weakness,or late intracerebral hemorrhage.1 Previous studies found that CHS mostly occurs within one week after carotid artery stenting(CAS)2 but cerebral hyperperfusion syndrome in patient of asymptomatic subtotal conclusion of internal carotid artery more than one week after carotid artery stenting is rare reported.We present a case of 71-year-old man with asymptomatic subtotal conclusion of internal carotid artery.Six weeks after carotid artery stenting,he appeared status seizure and acute onset of cerebral focal edema.The pathophysiology of the syndrome is still obscure[3],in this article we will analyze the mechanisms of the systrome and preventive measures.