Circulation rate at rest and during functional respiratory tests has been studied in 30 patients with insult consequences and in 32 subjects without brain blood supply pathology. The value of linear circulation rate along the medial cerebral artery has been found not to reflect the degree of brain structure involvement. The values of blood flow along the arteries of brain contralateral side can't be considered as norm standard. The vascular reactivity decrease of the brain side involved begins for cyst size > 5 cm3, and the decrease of circulation rate absolute values for brain cyst size > 50 cm3.