Differentiating aetiologies in perimesencephalic SAH: clinical insights into basilar artery perforator aneurysms.
Publication/Presentation Date
9-14-2026
Abstract
BACKGROUND/OBJECTIVE: Perimesencephalic subarachnoid haemorrhage (pmSAH) has traditionally been considered benign and of venous origin. However, advanced imaging increasingly identifies basilar artery perforator aneurysms (BAPAs) as a subset of cases historically labelled as non-aneurysmal, atraumatic (NAA) pmSAH. The objective was to compare clinical characteristics and outcomes of patients with NAA, BAPA and ruptured posterior circulation aneurysms (r-pc-AN), assessing the impact of pmSAH aetiology on patient outcomes.
METHODS: This retrospective, multicentre, observational cohort study included BAPA cases from the international PERForator Aneurysm registry (2013-2025, 60 centres, 19 countries). Comparison cohorts were from a single high-volume tertiary care centre (2004-2025). The study included 444 patients (n=167 NAA, n=157 BAPA, n=120 r-pc-AN). Excellent outcome was defined as a modified Rankin Scale score of 0-1 at 3-6 months.
RESULTS: Excellent outcomes were achieved in 137/167 (82%) of NAA, 96/140 (69%) of BAPA and 56/102 (55%) of r-pc-AN cohorts (p< 0.001). Mortality rates were 1% (NAA), 11% (BAPA) and 18% (r-pc-AN). cCompared with BAPA, NAA patients had significantly higher odds of excellent outcome (adjusted OR, aOR 2.0, 95% CI 1.2 to 3.4, p=0.01), while r-pc-AN were associated with significantly lower odds of excellent outcome (aOR 0.5, 95% CI 0.3 to 0.9, p=0.01). Hydrocephalus and external ventricular drain rates were highest in r-pc-AN (83% and 87%), followed by BAPA (48% and 44%) and NAA (28% and 16%) (p< 0.001).
CONCLUSIONS: While pmSAH has been considered benign, our findings challenge this assumption. Patients with BAPA-related pmSAH demonstrated significantly worse outcomes than NAA but better outcomes than r-pc-AN. Further research is needed to distinguish BAPA-pmSAH from NAA-related pmSAH and to establish diagnostic and therapeutic guidelines.
TRIAL REGISTRATION NUMBER: NCT06189014.
Volume
97
Issue
10
First Page
937
Last Page
944
ISSN
1468-330X
Published In/Presented At
Rajbhandari, S., Serrallach, B. L., Raabe, J. M., Piechowiak, E. I., Goldberg, J., Seiffge, D. J., Rentzos, A., Zhu, F., Scarcia, L., Narata, A., Amans, M. R., Premat, K., Demerath, T., Moehlenbruch, M., Kumar, R., Limbucci, N., Piano, M., Burel, J., Bellanger, G., Dorn, F., … PERFAN registry (PERforator ANeurysm registry) collaborators (2026). Differentiating aetiologies in perimesencephalic SAH: clinical insights into basilar artery perforator aneurysms. Journal of neurology, neurosurgery, and psychiatry, 97(10), 937–944. https://doi.org/10.1136/jnnp-2026-338621
Disciplines
Business Administration, Management, and Operations | Health and Medical Administration | Management Sciences and Quantitative Methods
PubMedID
42448461
Department(s)
Administration and Leadership
Document Type
Article