Subarachnoid haemorrhage from undiagnosed mycotic aortic aneurysm in a child

Causal Associations Between Gut Microbiota and Cerebrovascular Diseases

BACKGROUND

Numerous studies suggest that the gut microbiota closely linked to cerebrovascular diseases, such as Intracranial aneurysm (IA) and aneurysmal subarachnoid hemorrhage (aSAH). Nevertheless, the confirmation of a definitive causal connection between gut microbiota, IA, and aSAH is still pending. The aim of our research is to explore the potential bidirectional causality among them.

METHODS

This bidirectional Mendelian Randomization (MR) study used single nucleotide polymorphisms linked to gut microbiota, IA, and aSAH from Genome-Wide Association Studies. The Inverse Variance Weighted (IVW) method was used to explore causality. To assess the robustness of the result, sensitivity analyses were further performed, including weighted-median method, MR-Egger regression, Maximum-likelihood method, MR pleiotropy residual sum and outlier test and leave-one-out analysis.

RESULTS

In the IVW method, the family Porphyromonadaceae (odds ratio [OR] 0.63; 95% CI 0.47-0.85; P: 0.002) and genus Bilophila (OR 0.66; 95% CI 0.50-0.86; P: 0.002) showed a significant negative association with the risk of IA. Similarly, the genus Bilophila (OR: 0.68; 95% CI: 0.50-0.93; P: 0.017) and genus Ruminococcus1 (OR: 0.48; 95% CI: 0.30-0.78; P: 0.003) were linked to reduced risk of aSAH. The sensitivity analysis yielded similar outcomes in the IVW approach. Through the adoption of reverse MR analysis, a potential correlation between IA and decreased abundance of genus Ruminococcus1 was identified (OR 0.94; 95% CI 0.90-0.99; P 0.024).

CONCLUSIONS

This MR analysis investigated the causal associations between gut microbiota, IA, and aSAH risks. The findings expanded current knowledge of the microbiota-gut-brain axis and offered novel perspectives on preventing and managing these conditions.

Acute convexity subarachnoid hemorrhage (cSAH) in infectious endocarditis (IE): imaging features and follow-up

AIM

To assess: (1) the prevalence of convexity subarachnoid hemorrhage (cSAH) in infective endocarditis (IE); (2) its relationship with IE features; (3) the associated lesions; (4) whether cSAH is a predictor of future hemorrhage; (5) whether cSAH could cause cortical superficial siderosis (cSS).

METHODS

We retrospectively evaluated the MRI data in 240 IE-patients: At baseline, the location of cSAH and associated lesions; at follow-up, the occurrence of new lesions and of cSS. Patients with and without cSAH were compared.

RESULTS

There were 21 cSAH-IE patients without (Group 1a) and 10 with intracranial infectious aneurysms (IIAs) (Group 1b). cSAH was revealed by headache (16.1%), confusion (9.7%), acute meningeal syndrome (3.2%) and was incidental in 71%. In most cases, the cSAH was: in the frontal (61.3%) and the parietal lobe (16.1%), unifocal, and mainly localized within a single sulcus (80.7%), appearing as a thick intrasulcal dark line on T2* in 70% of IIA patients. Valvular vegetations (87.1%, p < 0.0001), vegetations length ≥ 15 mm (58.1%, p < 0.0001) and mitral valve involvement (61.3%; p = 0.05) were significantly associated. There was no significant difference between the two groups in terms of pathogen distribution, valve characteristics and clinical expression. Associated lesions were: CMBs (77.4%), DWILs (51.6%), brain hemorrhages (16.1%) brain micro-abscesses (3.2%) meningitis (3.2%), visceral emboli (45.2%). At follow-up: no SAH recurrence or neurological event. cSS disappeared in 7/12 cases.

CONCLUSION

cSAH in IE is mostly an incidental finding but may be the telltale sign of an IIA. cSAH is not a marker of poor prognosis in non-IIA patients.