Incidence of asymptomatic berry aneurysms among patients undergoing carotid endarterectomy

Scattered reports of literature suggest the hypothesis that patients suffering from a severe stenosis of extracranial carotid artery may present an increased rate of intracranial berry aneurysms caused by the hemodynamic stress on the side opposite to the stenosis, namely on physiological shunts. However, this hypothesis has never been verified upon a large and homogeneous series focused on the argument.

We reviewed a consecutive series of 405 patients submitted to carotid endarterectomy for stenosis greater or equal to 70%.

Thirteen aneurysm were found in 11 patients (2.6%). Our patients showed a slight increase of incidence regards to general population (1%), maybe due to the large number of aged patients among our subpopulation. Preoperative TCD evaluation showed the presence of increased flow velocities in the physiological shunts, namely the anterior cerebral artery and the anterior communicating artery, in 65% of the patients, and angiography confirmed the redistribution of intracranial circulation. Nevertheless, according to aneurysm location, no statistically significant correlation (0.3 < p < 0.4) was found between the presence of an aneurysm and the values of velocity in these arteries.

As regards the etiology of berry aneurysms, these data suggest that increased hemodynamic stress per se is not sufficient to cause the origin of berry aneurysms. Maybe, a role is possible only if either congenital, or acquired and age-related factor, peculiar of cerebral arteries, coexist.