{
  "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.",
  "authors": [
    {
      "affiliations": [
        "Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland"
      ],
      "name": "Saujanya Rajbhandari"
    },
    {
      "affiliations": [
        "Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland"
      ],
      "name": "Bettina Lara Serrallach"
    },
    {
      "affiliations": [
        "Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland"
      ],
      "name": "Johann Maximilian Raabe"
    },
    {
      "affiliations": [
        "Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland"
      ],
      "name": "Eike I Piechowiak"
    },
    {
      "affiliations": [
        "Department of Neurosurgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland"
      ],
      "name": "Johannes Goldberg"
    },
    {
      "affiliations": [
        "Department of Neurology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland"
      ],
      "name": "David J Seiffge"
    },
    {
      "affiliations": [
        "Department of Radiology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Goteborg, Sweden",
        "Department of Radiology, Section of Diagnostic and Interventional Neuroradiology, Sahlgrenska University Hospital, Region Västra Götaland, Goteborg, Sweden"
      ],
      "name": "Alexandros Rentzos"
    },
    {
      "affiliations": [
        "Department of Diagnostic and Therapeutic Neuroradiology, CHRU Nancy - IADI INSERM U1254 Université de Lorraine, Nancy, France"
      ],
      "name": "François Zhu"
    },
    {
      "affiliations": [
        "Department of Neuroradiology, Henri Mondor Hospital, Creteil, France"
      ],
      "name": "Luca Scarcia"
    },
    {
      "affiliations": [
        "Department of Neuroradiology, University Hospital of Southampton, Southampton, UK"
      ],
      "name": "Ana Narata"
    },
    {
      "affiliations": [
        "Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, USA"
      ],
      "name": "Matthew R Amans"
    },
    {
      "affiliations": [
        "Department of Neuroradiology, Pitié-Salpêtrière Hospital, Paris, France"
      ],
      "name": "Kevin Premat"
    },
    {
      "affiliations": [
        "Department of Neuroradiology, Medical Center, University of Freiburg, Freiburg, Germany"
      ],
      "name": "Theo Demerath"
    },
    {
      "affiliations": [
        "Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany"
      ],
      "name": "M Moehlenbruch"
    },
    {
      "affiliations": [
        "Department of Interventional Neurology, G S Neuroscience Clinic and Research Center Pvt. Ltd, Patna, India"
      ],
      "name": "Rahul Kumar"
    },
    {
      "affiliations": [
        "Neurovascular Interventional Unit, Careggi University Hospital, Florence, Italy"
      ],
      "name": "Nicola Limbucci"
    },
    {
      "affiliations": [
        "Department of Neuroradiology, Niguarda Cà Granda Hospital, Milan, Italy"
      ],
      "name": "Mariangela Piano"
    },
    {
      "affiliations": [
        "Department of Radiology, Rouen University Hospital, Rouen, France"
      ],
      "name": "Julien Burel"
    },
    {
      "affiliations": [
        "Department of Neuroradiology, Toulouse University Hospital, Toulouse, France"
      ],
      "name": "Guillaume Bellanger"
    },
    {
      "affiliations": [
        "Department of Neuroradiology, University Hospital Bonn, Bonn, Germany"
      ],
      "name": "Franziska Dorn"
    },
    {
      "affiliations": [
        "Department of Diagnostic and Interventional Neuroradiology, University Hospital Tübingen, Tübingen, Germany"
      ],
      "name": "Florian Hennersdorf"
    },
    {
      "affiliations": [
        "Department of Radiology, Neuroendovascular Program, University Medical Center Münster, Münster, Germany"
      ],
      "name": "Paul Stracke"
    },
    {
      "affiliations": [
        "Department of Neuroradiology, Umberto I Hospital, Rome, Italy"
      ],
      "name": "Luca Milonia"
    },
    {
      "affiliations": [
        "Neuroradiology Unit, IRCCS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy"
      ],
      "name": "Luigi Cirillo"
    },
    {
      "affiliations": [
        "Department of Radiology, Neuroradiology, Skåne University Hospital, Lund University, Lund, Sweden"
      ],
      "name": "Johan Wasselius"
    },
    {
      "affiliations": [
        "Interventional Neuroradiology, Nottingham University Hospitals NHS Trust (Queen’s Medical Centre), Nottingham, UK"
      ],
      "name": "Rob Lenthall"
    },
    {
      "affiliations": [
        "Interventional Neuroradiology, Royal Infirmary of Edinburgh, Edinburgh, UK"
      ],
      "name": "Liam Flynn"
    },
    {
      "affiliations": [
        "Interventional Neuroradiology, Glasgow Institute of Clinical Neurosciences (Glasgow Queen Elizabeth University Hospital), Glasgow, UK"
      ],
      "name": "Peter Keston"
    },
    {
      "affiliations": [
        "Radiology & Neurosurgery, NYU Grossman School of Medicine",
        "Endovascular Neurosurgery, Bellevue Hospital Center, New York, New York, USA"
      ],
      "name": "Eytan Raz"
    },
    {
      "affiliations": [
        "Department of Neuroradiology, Monash Health",
        "Monash University, Melbourne, Australia, Melbourne, Victoria, Australia"
      ],
      "name": "Enrique Barvulsky"
    },
    {
      "affiliations": [
        "Neuroradiology, Regional University Hospital Centre Tours Radiology Diagnostic and Interventional Neuroradiology, Tours, France"
      ],
      "name": "Francesca Giubbolini"
    },
    {
      "affiliations": [
        "Interventional Neuroradiology, Hôpitaux Universitaires de Strasbourg, Strasbourg, France"
      ],
      "name": "Ian Leonard-Lorant"
    },
    {
      "affiliations": [
        "Interventional Neuroradiology, Fondation Rothschild Hospital, Paris, France"
      ],
      "name": "Stanislas Smajda"
    },
    {
      "affiliations": [
        "Department of Neuroradiology, Helios Klinikum, Erfurt, Germany"
      ],
      "name": "Joachim Klisch"
    },
    {
      "affiliations": [
        "Institute and Polyclinic of Diagnostic & Interventional Neuroradiology, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany"
      ],
      "name": "Daniel P O Kaiser"
    },
    {
      "affiliations": [
        "Interventional Neuroradiology, Ospedale del Mare, Università degli Studi di Napoli Federico II, Naples, Italy"
      ],
      "name": "Michele Rizzuti"
    },
    {
      "affiliations": [
        "Department of Neurosurgery & Neuroendovascular Surgery, Kameda Medical Center, Chiba, Japan"
      ],
      "name": "Michihiro Tanaka"
    },
    {
      "affiliations": [
        "Department of Radiology and Neuroradiology, Istanbul University–Cerrahpaşa, Istanbul, Turkey"
      ],
      "name": "Osman Kizilkilic"
    },
    {
      "affiliations": [
        "Department of Neuroradiology, King’s College Hospital NHS Foundation Trust, London, UK",
        "School of Biomedical Engineering & Imaging Sciences, King’s College London, London, UK"
      ],
      "name": "Thomas C Booth"
    },
    {
      "affiliations": [
        "Interventional Neuroradiology, Miami Neuroscience Institute, Baptist Health South Florida, Miami, Florida, USA"
      ],
      "name": "Italo Linfante"
    },
    {
      "affiliations": [
        "Division of Neuroradiology, Vascular & Interventional Radiology, Medical University of Graz, Graz, Austria"
      ],
      "name": "Stefan L Leber"
    },
    {
      "affiliations": [
        "Interventional Neuroradiology, Faculty of Medicine, Cairo University, Cairo, Egypt"
      ],
      "name": "Farouk Hassan"
    },
    {
      "affiliations": [
        "Department of Radiology/Interventional Neuroradiology, CHU Poitiers, Poitiers, France"
      ],
      "name": "Victor Dumas"
    },
    {
      "affiliations": [
        "Neuroradiology Department, University Hospital of Clermont Ferrand, Gabriel Montpied Hospital, Limoges, France",
        "Institut Pascal, TGI, UMR6602 CNRS SIGMA Université Clermont Auvergne, Clermont-Ferrand, France"
      ],
      "name": "Géraud Forestier"
    },
    {
      "affiliations": [
        "Institute for Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany"
      ],
      "name": "Yan Li"
    },
    {
      "affiliations": [
        "UOSA Neuroradiologia Interventistica, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy"
      ],
      "name": "Andrea Alexandre"
    },
    {
      "affiliations": [
        "Interventional Neuroradiology, Hospital Regional Universitario de Málaga, Malaga, Spain"
      ],
      "name": "Francisco Javier Padilla-Palomo"
    },
    {
      "affiliations": [
        "Department of Radiology and Nuclear Medicine, Luzerner Kantonsspital (LUKS), Luzern, Switzerland"
      ],
      "name": "Grzegorz M Karwacki"
    },
    {
      "affiliations": [
        "Interventional Neuroradiology, Leeds Teaching Hospitals NHS Trust, Leeds, UK"
      ],
      "name": "Nayyar Saleem"
    },
    {
      "affiliations": [
        "Radiology, Boston Medical Center, Boston, Massachusetts, USA"
      ],
      "name": "Mohamad Abdalkader"
    },
    {
      "affiliations": [
        "Department of Neurology, Albany Medical College, Albany, New York, USA"
      ],
      "name": "Nabeel A Herial"
    },
    {
      "affiliations": [
        "Neuroradiology, Department of Radiology, Stanford University School of Medicine, Stanford, California, USA"
      ],
      "name": "Benjamin Pulli"
    },
    {
      "affiliations": [
        "Radiology Department, Can Tho Stroke International Services General Hospital, Can Tho, Viet Nam"
      ],
      "name": "Chi Cuong Tran"
    },
    {
      "affiliations": [
        "Department of Neurosurgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland"
      ],
      "name": "Andreas Raabe"
    },
    {
      "affiliations": [
        "Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland"
      ],
      "name": "Jan Gralla"
    },
    {
      "affiliations": [
        "Department of Neurosurgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland"
      ],
      "name": "David Bervini"
    },
    {
      "affiliations": [
        "Department of Neurosurgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland",
        "Department of Neurology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland"
      ],
      "name": "Werner Josef Z’Graggen"
    },
    {
      "affiliations": [
        "Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland"
      ],
      "name": "Johannes Kaesmacher"
    },
    {
      "affiliations": [
        "Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland"
      ],
      "name": "Tomas Dobrocky"
    },
    {
      "affiliations": [],
      "name": "On behalf of PERFAN registry (PERforator ANeurysm registry) collaborators"
    }
  ],
  "title": "Differentiating aetiologies in perimesencephalic SAH: clinical insights into basilar artery perforator aneurysms",
  "uid": "1cdbe714-b25d-5ca6-a21a-3fcf5a1d3150"
}