HISTOPATHOLOGICAL ANALYSIS OF THE MECHANISMS OF INTRACRANIAL HEMORRHAGE COMPLICATING INFECTIVE ENDOCARDITIS

Background and Purpose: We conducted the present study to elucidate the pathological mechanisms leading to intracranial hemorrhage complicating infective endocarditis. Methods: Neurological, neuroradiological, and histopathological analyses were performed in 16 patients (one surgical and 15 autopsy cases), 12 men and four women 26-68 years of age, who had demonstrated central nervous system complications during the course of infective endocarditis. Results: Intracranial hemorrhage was found in all cases; parenchymal hematomas were found in 12 cases, hemorrhagic infarcts in four cases, and primary subarachnoid hemorrhages in two cases. Chronological analysis of neurological examination and computed tomographic scan of the brain confirmed that antecedent cerebral ischemic events had occurred in five of 12 patients showing parenchymal hematomas at autopsy. Hemorrhagic infarct, indicated by petechial or diffuse hemorrhages within the infarct, was seen in another four patients, so that hemorrhagic transformation of the ischemic infarct was confirmed in nine patients. Although mycotic aneurysms were found in five patients, only three of these were ruptured; the other two were occluded with septic emboli. Pyogenic arteritis without aneurysm was found to be distributed in the small cortical arterial branches located in the spaces of cortical sulci, with rupture occurring in five patients. Conclusions: These results suggest that hemorrhagic transformation of the ischemic infarct due to septic emboli is the most frequent mechanism leading to intracerebral hemorrhage encountered in patients dying of infective endocarditis and that rupture of pyogenic arteritis may be responsible for such hemorrhage in many cases, with ruptures of mycotic aneurysms as an alternative mechanism.