Hyperperfusion syndrome is a condition when blood-flow is exceeding metabolic demands of the cerebral tissue. It may accompany various neuro-surgical disorders and their treatment (predominantly in the sphere of vascular neurosurgery) and may be manifested by a broad scale of clinical symptoms. Although there are lots of definitions, accurate pathophysiology of hyperperfusion syndrome remains unclear so far. Irrespective of a provoking cause, it is accompanied with characteristic pathophysiological states (arterial hypertension, vasodilatation, disturbed hematoencephalic barrier and subsequent development of oedema). A pathologic-anatomical correlate is subcortical oedema and minute haemorrhage, but pathophysiological changes without any organic response are often the problem. Hyperperfusion syndrome is seen most frequently after carotic endarterectomy the most serious complication of which is intracerebral haemorrhage. In spite of typical clinical symptoms and risk factors of postendarterectomic hyperperfusion syndrome, it is difficult in clinical practice to differentiate hyperperfusion from thromboembolism. After introducing methods that enable to evaluate cerebral perfusion, diagnostics has become univocal but the therapy remains empirical. The problems have been documented by the incidence of hyperperfusion syndrome of various etiology in two patients that was manifested by different clinical symptoms. One observation is a typical example of a postendarterectomic hyperperfusion syndrome manifested by epileptic paroxysms. The other case-report describes a transient visual disorder based on hyperperfusion of occipital lobes after embolization of a cerebellar arteriovenous malformation. While hyperperfusion syndrome after carotic endarterectomy is a well-known complication with the incidence of 0.3%–1.2%, its occurrence after endovascular embolizations has been seldom described.

        Key words: hyperperfusion syndrome, carotic endarterectomy, intracerebral haemorrhage, embolization of arteriovenous malformation, epileptic paroxysm, disturbed vision