Cerebral Hyperperfusion Syndrome and Related Conditions.

Cerebral vasoconstriction is a normal physiological response under determined conditions to preserve a normal cerebral blood flow. However, there are several syndromes, with impaired cerebral autoregulation and cerebral vasoconstriction, not related with infection or inflammation, which share the same radiological and clinical presentation. We review here the cerebral hyperperfusion syndrome and related conditions such as hypertensive encephalopathy, posterior reversible encephalopathy syndrome, and reversible cerebral vasoconstriction syndrome. These syndromes might share the same pathophysiological mechanism with endothelial damage, cerebral vasoconstriction, blood-brain barrier disturbance, cerebral edema, and, occasionally, intracerebral hemorrhage, with fatal cases described in all. Despite knowledge of these syndromes, they still remain unknown to us. Why these entities present in some patients and not in others goes further than the actual understanding of these diseases. We have to consider that a genetic susceptibility and molecular disturbances may be involved. Thus, more studies are needed in order to better characterize such syndromes.