Determining the Clinical Impact and Prevalence of Hemorrhagic Subtypes in Perimesencephalic Subarachnoid Hemorrhage (DECIPHER-pmSAH)

November 3, 2026 updated by: Insel Gruppe AG, University Hospital Bern

Determining the Clinical Impact and Prevalence of Hemorrhagic Subtypes in Perimesencephalic Subarachnoid Hemorrhage - A Prospective Observational Study

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:

  1. determine and compare the prevalence of BAPA-pmSAH and non-aneurysmal pmSAH
  2. compare short-term and mid-term functional outcomes between patients with BAPA-pmSAH and those with non-aneurysmal pmSAH
  3. evaluate the rate and nature of complications in both these pmSAH subgroups
  4. enhance the understanding of radiological features associated with pmSAH, with the aim of distinguishing between BAPA-pmSAH and non-aneurysmal pmSAH
  5. characterize observed treatment strategies and their outcomes, comparing conservative and active management approaches

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.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Observational

Enrollment (Estimated)

264

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • Switzerland
      • Bern, Switzerland, 3010
        • Recruiting
        • Inselspital, University Hospital Bern
        • Principal Investigator:
          • Tomas Dobrocky, MD
        • Contact:
        • Contact:
        • Sub-Investigator:
          • Luca Noti, MD
        • Sub-Investigator:
          • Johann M Raabe, MD
        • Sub-Investigator:
          • Bettina L Serrallach, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

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

Description

Inclusion Criteria:

  • Patients aged ≥18 years with a non-traumatic pmSAH or limited additional blood in adjacent cisterns (pmSAH "plus")
  • Cross-sectional imaging at baseline (CT or MRI)
  • Written informed consent for study participation was obtained.

Exclusion Criteria:

  • Presence of documented written or verbal refusal
  • pmSAH patients with a presumed traumatic source
  • Saccular/fusiform aneurysm of the main arteries of the posterior circulation (e.g. V4, AICA, PICA, basilar trunk, basilar tip)
  • pmSAH patients with a shunting lesion in the vertebrobasilar territory (i.e. brain AVM, brain/spine AVF)
  • pmSAH patients with a cavernous malformation in the posterior fossa
  • Basilar artery perforator aneurysm group (BAPA group):
  • Aneurysm arising from the basilar artery trunk adjacent to a perforating branch but not involving a perforating artery (Satti Type 1)
  • Flow-related BAPA (i.e. AVM, AVF)
  • Severely impaired renal function defined as KDIGO grade 4 (GFR <30 mL/min/1.73 m2)
  • Pregnancy or suspected pregnancy
  • Known adverse events to iodinated contrast media

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Observational Models: COHORT
  • Time Perspectives: PROSPECTIVE

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
All patients included in the study

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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
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
Within 7 days after pmSAH diagnosis

Secondary Outcome Measures

Outcome Measure
Time Frame
Rate of patients with excellent functional outcome (Modified Rankin Scale 0-1) at 3 months
Time Frame: 3 months after enrollment
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
3 months after enrollment
Patient-Reported Outcome (EQ-5D-5L questionnaire) at 3 months
Time Frame: 3 months after enrollment
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)
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)
21 days after enrollment or hospital discharge (if discharged earlier)
Rate of rebleeding
Time Frame: From enrollment to 3-month follow-up
From enrollment to 3-month follow-up
Rate of hydrocephalus requiring EVD or lumbar drain
Time Frame: From enrollment to 3-month follow-up
From enrollment to 3-month follow-up
Rate of symptomatic vasospasm
Time Frame: From enrollment to 3-month follow-up
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
From enrollment to 3-month follow-up

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Insel Gruppe AG, University Hospital Bern

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 1, 2026

Primary Completion (Estimated)

March 31, 2029

Study Completion (Estimated)

March 31, 2029

Study Registration Dates

First Submitted

October 12, 2026

First Submitted That Met QC Criteria

November 3, 2026

First Posted (Actual)

November 6, 2026

Study Record Updates

Last Update Posted (Actual)

November 6, 2026

Last Update Submitted That Met QC Criteria

November 3, 2026

Last Verified

September 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • CH-2025-01117

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Subscribe