SERUM ELASTASE AND ALPHA-1-ANTITRYPSIN LEVELS IN PATIENTS WITH RUPTURED AND UNRUPTURED CEREBRAL ANEURYSMS

DESPITE ADVANCES IN surgical treatment and postoperative care, subarachnoid hemorrhage from ruptured cerebral aneurysms remains a devastating event. Excellent surgical results in treating unruptured aneurysms suggest the utility of screening tests to identify high-risk individuals. Unfortunately, none of the known risk factors for subarachnoid hemorrhage correlates strongly enough with the illness to warrant widespread screening for occult aneurysms. Other disease entities suggest that protease-antiprotease imbalances contribute to somatic vessel wall degradation and aneurysm formation. Detection of similar imbalances in selected patients may identify a predisposition to cerebral aneurysm formation. Serum concentrations of elastase and alpha-1-antitrypsin (AAT), important proteolytic and antiproteolytic enzymes, were measured in a series of 19 patients with unruptured aneurysms, 41 patients with ruptured aneurysms, and 27 age-matched operative and nonoperative controls. The elastase:AAT ratio was nearly twice as high in patients with unruptured aneurysms as in operative controls (0.527 +/- 0.1 versus 0.285 +/- 0.06; P < 0.04). Elastase:AAT ratios in patients with ruptured aneurysms (subarachnoid hemorrhage <48 h) were roughly twice those of controls (0.582 +/- 0.095; P < 0.01). There was no statistical difference between elastase:AAT ratios for patients with ruptured and unruptured aneurysms. Likewise, elastase-AAT values for operative controls and nonoperative volunteers were not significantly different. Differences in serum elastase:AAT ratios between patients with aneurysms and controls reflected differences in elastase concentration (99 +/- 56 mu g/ml versus 67 +/- 56 mu g/ml; P < 0.03), not in AAT levels (147 +/- 56 mu g/ml versus 141 +/- 56 mu g/ml; P < 0.72). Parametric statistical analysis (Student's t test) shows a nonsignificant trend for higher elastase-AAT levels in patients with ruptured aneurysms, smokers, and patients younger than 55 years. There was no such trend when gender and hypertensive status were analyzed. These findings support the contention that a protease-antiprotease imbalance may contribute to the formation of cerebral aneurysms and suggest a future role for plasma protease assays in attempting to identify cerebral aneurysms before hemorrhage.