Clinicopathological Study and Clinical Significance of ‘Silent’ Hemorrhage in Arteriovenous Malformations of the Brain

Abstract

Operative procedures for cerebral arteriovenous malformations (AVMs) and histological study of the specimens may reveal old hemorrhage in some cases of AVMs with no clinical history of hemorrhage. Such asymptomatic hemorrhage has been reported as ‘silent’ hemorrhage. The authors analysed the incidence of silent hemorrhage of cerebral AVMs and its correlation with: patient's age, sex, location and size of AVMs, type of symptoms, number of attacks, interval from the onset to operation, CSF protein content, and CT scan findings. The clinical material consisted of 16 cases of supratentorial AVMs without evidence of a clinical history of hemorrhage. They had histories of either epilepsy or transient hemiparesis. All AVMs were totally excised microsurgically and the specimens were examined histologically for detection of iron containing granule cells. Silent hemorrhage was confirmed either surgically or histologically in 5 cases (31%). Presence or absence of silent hemorrhage had a tendency to be correlated with the location, size of AVMs, interval from clinical onset to operation, CSF protein content, and CT scan findings. However, statistical significance was not seen except in CSF protein content. Therefore, preoperative prediction of the presence of silent hemorrhage was not possible. This investigation indicated that the incidence of silent hemorrhage of cerebral AVMs was unexpectedly high. Since it was not possible to diagnose preoperatively, the possibility of silent hemorrhage should be kept in mind in determining the indication of surgical management for unruptured AVMs. Surgical management of unruptured AVMs should be justified in patients who have small or mediumsized AVMs mainly situated in silent areas.