RESUMO
BACKGROUND: An adequate cerebral blood flow is critical in maintaining obligatory metabolic function of cerebral neurons. The occlusion of these flows may cause impairment of the cellular metabolic function. Therefore, the early detection and treatment of this can have a direct impact on the prognosis. This study is designed to determine the changes of electroencephalography (EEG) waves with power spectral analysis during and after cerebral blood flow impairment with reversible middle cerebral artery occlusion in rats. METHODS: Five rats were anesthetized with ketamine and the left middle cerebral artery was reversibly occluded. Neurologic deficit and the EEG were evaluated. The principal procedure consisted of the following: All branches of the external carotid artery and pterygopalatine artery of the internal carotid artery were interrupted. At this point, the internal carotid artery is the only branch of the common carotid artery. Afterwards, the external carotid artery was interrupted. A 4-0 monofilament nylon suture, its tip rounded, was introduced into the external carotid artery lumen and advanced to block blood flow into the middle cerebral artery. The suture was withdrawn to permit reperfusion after 2 hours. Monitoring of the EEG was performed before the occlusion, after 10, 30, 60, and 120 minutes of occlusion, and after 10, 30 and 60 minutes of reperfusion. The neurologic findings were scored on a five-point scale. RESULTS: In the spectral power analysis of EEG, the total power of the EEG amplitude decreased significantly after left middle cerebral artery occlusion, increased after 30 minutes of occlusion, and decreased significantly after reperfusion. The theta, alpha and beta waves changed significantly after occlusion. Theta and beta waves were reversed slowly. After reperfusion, theta and alpha waves decreased significantly. CONCLUSIONS: It is suggested that the spectral analysis of an EEG is useful in early detection and treatment of ischemia in patients with cerebrovascular disease.