# Prognostic Factors and Imaging Strategies in Unknown Subarachnoid Hemorrhage: A Retrospective Study

## TL;DR

This study examines factors affecting outcomes in patients with unknown subarachnoid hemorrhage and evaluates the usefulness of repeat imaging.

## Contribution

The study identifies clinical and radiological factors linked to outcomes and assesses the value of repeat angiography in unknown SAH.

## Key findings

- Focal hemorrhage patterns and higher GCS scores correlate with better outcomes.
- Repeat DSA was more common in good outcome groups but did not reveal new lesions.
- Tailored imaging strategies are recommended based on clinical and radiological risk factors.

## Abstract

Background

Subarachnoid hemorrhage (SAH) without an identifiable vascular lesion on initial angiography, commonly referred to as unknown or angiogram-negative SAH, remains diagnostically and prognostically challenging. Although perimesencephalic patterns tend to be benign, diffuse hemorrhages are associated with worse outcomes. The role of repeat vascular imaging in improving diagnosis and predicting prognosis remains unclear.

Objective

This study aimed to identify clinical and radiological factors associated with outcomes in patients with unknown SAH and evaluate the diagnostic and prognostic value of repeat angiography.

Methods

We retrospectively analyzed 26 patients with spontaneous, non-traumatic SAH and negative findings on initial digital subtraction angiography (DSA). Clinical status, hemorrhage patterns, and imaging data were recorded. Outcomes were assessed at discharge using the modified Rankin Scale (mRS). Repeat angiographic modalities and timing were analyzed in relation to prognosis.

Results

Patients with focal hemorrhage patterns, higher Glasgow Coma Scale (GCS) scores at admission, and absence of hydrocephalus had significantly better outcomes. Repeat DSA was more frequently performed in the good outcome group, although no new vascular lesions were identified.

Conclusion

Unknown SAH is generally associated with favorable outcomes, but vigilance is warranted in diffuse SAH cases. Repeat DSA may not always reveal new lesions, but it plays a valuable role in guiding clinical confidence and management decisions. Tailored imaging strategies based on clinical and radiological risk factors are recommended.