Absence of bacteria in intracranial aneurysms

This study aimed to detect the presence of bacteria in the walls of both unruptured and ruptured aneurysms in a French population.

Patients treated between January 2018 and July 2018 were included in a prospective study when specimens from ruptured or unruptured aneurysm walls were obtained intraoperatively. Samples from superficial temporal artery, dura mater, and middle meningeal artery were obtained from each patient during the same surgical procedure to be used as a negative control. Direct bacterial analysis, aerobic and anaerobic bacterial culture, and bacterial DNA detection were performed on each sample.

There were 21 women and 9 men with a mean age at treatment of 54 years (range 31-70 years). Eighteen patients were smokers. Hypertension was present in 18 patients and hyperlipidemia in 5 patients. Chronic alcoholism was found in 6 patients. Polycystic kidney disease was present in 1 patient. Fifteen patients had multiple intracranial aneurysms. Ten patients had a ruptured aneurysm and 20 had an unruptured aneurysm. The mean diameter of all aneurysms was 8.5 mm (range 2.5-50 mm). No presence of bacteria was detected with direct bacterial analysis and culture in any of the samples. No bacterial DNA was detected in any of the samples.

Unlike in Finnish patients, no bacterial presence was found in the wall of aneurysms in French patients. This absence of bacterial infection might explain the lower risk of aneurysm rupture in the French population compared to the Finnish population.