Introduction: The prevalence of periodontitis is about 12%. It affects 47% of adults and 70% of people over 65. Periodontal pathogens can also contribute to the pathogenesis of several systemic diseases, such as subarachnoid hemorrhage caused by aneurysm rupture (sSAH). Its pathogenesis is attributed to oral microbial dysbiosis (O), in which Porphyromonas gingivalis plays a critical role by disrupting host immune homeostasis. Our goal was to explore the relationship between O and aSAH.

Method: In our prospective pilot study, we compared the values of 20 aSAH patients with the data of 8 healthy controls. Clinical probing depth measurement and microbiological culture were performed for all participants. To characterize the systemic immune response, serum IL-6, and hsCRP concentration, while NSE and S100B were measured as indicators of brain injury after the index event (24-48 hours). We chose the clinical outcome measured on the basis of the modified Rankin Scale as the primary endpoint (poor outcome: mRS 3-6), and the development of “delayed cerebral ischemia” (DCI) as the secondary endpoint.

Results: During our observation, DCI developed in 10 aSAV patients, in all cases a periodontal pocket ≥5 mm was measured, and significantly higher hsCRP (p<0.05) and IL-6 (p<0.05) serum concentrations were found. The co-presence of anaerobic P. intermedia or P. gingivalis with F. nucleatum showed a correlation with deeper pockets and DCI developing in aSAH patients (p<0.05). Besides, higher hsCRP (p<0.05), NSE (p<0.05), S100B (p<0.05) levels were observed in cases with mRS 3-6 outcomes.

Conclusion: Our results suggest that there is a relationship between the severity of periodontitis and the course as well as the outcome of aSAV. The presence of P. intermedia or P. gingivalis and F. nucleatum in the biofilm can be pathognomonic. Since periodontitis is a preventable and treatable disease, the revealed relationship is of public health importance.