Pathogenesis of Lober Intracerebral Hemorrhage Related to Cerebral Amyloid Angiopathy

Abstract

Cerebral amyloid angiopathy (CAA) is an important cause of lober intracerebral hemorrhage in the elderly. Although leptomeningeal and cortical arteries with the deposition of the amyloid β-protein (Aβ) have been thought to rupture in CAA, the pathogenesis of CAA-related hemorrhage still remains obscure. We studied 10 cases of CAA according to the Boston criteria from April 2006 to July 2009 in Omaezaki Municipal Hospital. Based on clinical data, we examined the primary site of hemorrhage and hypothesized the mechanisms of bleeding. Intracerebral hematoma evacuation was performed to alleviate neurological deteriolation in 2 patients and to make diagnosis in 3 patients. The surgical specimens were pathologically examined. The characteristic MR images of CAA related hemorrhage were characterized by microbleeds, superficial siderosis, subpial or subarachnoid hemorrhage, subcortical hemorrhage and lober intracerebral hemorrhage. Chronological images obtained in 1 patient revealed that lober intracerebral hemorrhage developed from microbleed with subpial hemorrhage without subarach- noid hemorrhage in one side of the cortex in the affected facing cerebral sulci. Operative findings showed subpial and subarachnoid hemorrhages around the cortical veins on the affected cerebral sulci in all cases. Abnormal fragile vessels existed in one side of the cortex of the affected sulci but not in the other side of the cortex. Complete hamatoma evacuation was performed in 4 cases. The surgical specimens of the hematoma and the adjacent brain parenchyma were pathologically examined by tissue staining with hematoxylin-eosin and Congo red. Many vessels in subpial, subcortical and subarachnoid space along the cerebral sulci were deposited with Aβ. From these findings, we speculated that the primary hemorrhage related to CAA occurred from the cortical arteries with Aβ deposition in the subpial space along the cerebral sulci and formed a lober intracerebral hematoma. Subarachnoid hemorrhage subsequently occurred due to the destruction of the pia matter by the primary hemorrhage.