Metalloproteases and intracranial vascular lesions

Recent studies have suggested that metalloproteinases (MMP) might be involv ed in the pathogenesis of cerebral aneurysm formation and rupture and that elevated serum levels of MMP may effectively be considered as possible mark ers of cerebrovascular malformations The present study was planned in order to verify if serum levels of MMPs may be the mirror of the MMP activity in the wall of intracranial aneurysms, reflecting the predisposition to aneur ysm development and/or rupture. A series of 84 patients operated for intrac ranial cerebrovascular lesions (63 aneurysms and 21 artero-venous malformat ions (AVM)) and 20 controls entered the study. Among the 63 cases of intrac ranial aneurysms, nine were discovered before rupture, while 54 patients we re included after subarachnoid hemorrhage (SAH). Using radioimmunoassay, pl asma elastase levels were measured in all cases, while in 25 cases, when an eurysmectomy was possible, the activity of elastase and collagenase were me asured in aneurysm samples. Mean plasma elastase level in patients bearing both an intracranial aneurysm or an intracranial AVM was significantly high er than in controls, while there was no significant difference between plas matic level of elastase in patients with aneurysms when compared with patie nts bearing an intracranial AVM; there was no significant difference betwee n mean elastase level in patients who suffered SAH and patients bearing an intracranial unruptured aneurysm. The activity of elastase and collagenase measured in the aneurysm wall were significantly higher in cases of rupture d than in unruptured aneurysms. The present results show that plasmatic lev el of elastase does not reflect the activity of MMP as measured in the aneu rysm wall and that the patterns of MMP activities measured in the aneurysm wall differ considerably at different stages of SAH. This suggests that loc al rather than systemic changes in metalloproteases activity might be invol ved in cerebral aneurysm formation and rupture.