Arterial dissections of penetrating cerebral arteries causing hypertension-induced cerebral hemorrhage

Object. For the past 130 years, it has been believed that hypertension-indu ced cerebral hemorrhages are the result of ruptures of microaneurysms or ru ptures of arteries that have degenerative changes. The majority of previous investigations have focused on autopsied brain. In this study, the authors attempted to verify the cause of hypertension-induced cerebral hemorrhage by using surgical specimens of the penetrating arteries responsible for the hemorrhages. Methods. Between 1997 and 1999. the authors performed pathological studies in surgical specimens of lenticulostriate arteries that had been confirmed during microsurgery to be the cause of hypertension-induced hemorrhage of t he putamen. Nineteen lenticulostriate arteries were collected from 12 patie nts. Fifteen of these arteries were verified as the pathological causes of hemorrhage. They included six arterial dissections, six arterial ruptures w ith substantial degenerative changes, and three arterial ruptures with few degenerative changes. The pathological findings in the lenticulostriate art ery dissections were similar to those of typical arterial dissections in ma jor cerebral arteries. Conclusions. To the best of the authors' knowledge, arterial dissections of lenticulostriate arteries have not been identified as a cause of hypertens ion-induced cerebral hemorrhages. When penetrating arteries are included as causative vessels, cerebral arterial dissections may be much more common t han previously thought.