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

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).

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.

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.

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.