An observational study in Subarachnoid Hemorrhage, Spontaneous, Subarachnoid Hemorrhage, Aneurysmal and Perimesencephalic Subarachnoid Hemorrhage, sponsored by Insel Gruppe AG, University Hospital Bern. Recruiting at 1 site in Switzerland. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-06.
Sponsored by Insel Gruppe AG, University Hospital Bern · Observational
Background:
Perimesencephalic subarachnoid hemorrhage (pmSAH) is a distinct subtype of traumatic subarachnoid hemorrhage (SAH) characterized by a localized bleeding pattern around the midbrain not resulting from a ruptured aneurysm of a posterior circulation main artery. Traditionally considered benign with generally good prognosis, pmSAH has been attributed to a presumed venous etiology. However, recent advances in imaging technology have led to the identification of previously occult vascular lesions, most notably basilar artery perforator aneurysms (BAPAs) that may present a potential cause in a subset of patients with pmSAH. Preliminary data from the international PERFAN registry which retrospectively included 148 patients with ruptured BAPAs, challenge the benign perception of pmSAH as a whole. Interestingly, in this biggest case collection so far, patients diagnosed with BAPAs experienced significantly higher rates of complications and worse functional outcomes compared to cases of non-aneurysmal pmSAH (NA-pmSAH). To date, prospective data on prevalence, presentation and outcome of BAPA-associated pmSAH (BAPA-pmSAH) is missing, thus complicating decisions on management of this increasingly diagnosed entity.
Aims:
The DECIPHER-pmSAH study aims to establish a prospective registry to:
Design:
The DECIPHER-pmSAH is a prospective, multicenter, observational study. For an adequately powered study, we are aiming at enrollment of at least 264 patients over the course of three years, starting on January 1st, 2026. For recruiting participating sites, we are aiming to build upon the previously established collaboration with multiple international centers contributing to the PERFAN registry, in which cases of perforator aneurysms were retrospectively collected.
Methods:
This study will include cases of atraumatic pmSAH where no aneurysm of main arteries of the posterior circulation was detected. Predefined diagnostic workup criteria must be met for patient enrollment, including cross-sectional imaging (CT or MRI) at baseline, whenever possible and clinically justified at least one digital subtraction angiography (DSA) with high-resolution three-dimensional rotational angiography (3D-RA) and collection of clinical data at index presentation, hospital discharge and 90 days follow-up. Anonymized imaging data will be centrally analyzed by trained neuroradiologists, blinded to clinical data in a core lab at the Inselspital, Bern. The primary endpoint to be examined is the prevalence of ruptured BAPA and non-aneurysmal hemorrhage in cases of pmSAH. Secondary and tertiary endpoints include clinical outcomes at 90 days after index presentations and specific radiological findings respectively.
510 studies on the registry are indexed under Subarachnoid Hemorrhage; 128 are open to participants now.
This study's planned enrollment of 264 is above the median of 120 across 226 observational studies indexed under Subarachnoid Hemorrhage.
Browse Subarachnoid Hemorrhage studies →Insel Gruppe AG, University Hospital Bern is the lead sponsor of 741 studies on the registry; 180 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Patients from participating centers, diagnosed with a perimesencephalic subarachnoid hemorrhage (pmSAH) not resulting from a mechanical trauma or from a ruptured aneurysm of the main arteries of the posterior circulation (V4, Basilar trunk, basilar tip, AICA, PICA, PCA). Taking into account further exclusion criteria (see above), this leaves 2 possible etiologies for pmSAH: 1) basilar artery perforator aneurysms (BAPA); 2) "sine materia" = no vascular lesion could be identified as the source of the pmSAH
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The only study-specific intervention is the collection of a patient-reported outcome measure (PROM) in the form of the EQ-5D questionnaire at 3-month follow-up for all patients. All other analyzed data are collected as part of routine clinical care.
Diagnostic Test: Completion of a patient-reported outcome measure (PROM) in the form of a EQ-5D questionnaire
The only study-specific intervention is the collection of a patient-reported outcome measure (PROM) in the form of the EQ-5D questionnaire at 3-month follow-up.
Rate of BAPAs in pmSAH where at least one high-resolution 3D-rotational angiography (3D-RA) of the dominant vertebral artery was performed within 7 days after the index presentation
Time frame: Within 7 days after pmSAH diagnosis
Rate of patients with excellent functional outcome (Modified Rankin Scale 0-1) at 3 months
Time frame: 3 months after enrollment
Rate of patients with favorable functional outcome (Modified Rankin Scale 0-2) at 3 months
Time frame: 3 months after enrollment
Patient-Reported Outcome (EQ-5D-5L questionnaire) at 3 months
Time frame: 3 months after enrollment
Modified Rankin Scale (mRS, range 0-6 with higher scores indicating worse functional status) at hospital discharge
Time frame: 21 days after enrollment or hospital discharge (if discharged earlier)
National Institutes of Health Stroke Scale (NIHSS, range 0-42 with higher scores indicating greater neurological impairement) at hospital discharge
Time frame: 21 days after enrollment or hospital discharge (if discharged earlier)
Rate of rebleeding
Time frame: From enrollment to 3-month follow-up
Rate of hydrocephalus requiring EVD or lumbar drain
Time frame: From enrollment to 3-month follow-up
Rate of symptomatic vasospasm
Time frame: From enrollment to 3-month follow-up
Rate of BAPAs in pmSAH overall (regardless of 3D-RA acquisition)
Time frame: From enrollment to 3-month follow-up
Plan to share: Yes
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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