Distinct Inflammatory Profiles in Angiography-Negative Subarachnoid Hemorrhage: A Focused Case Series.

Area of Science:

• Neuroscience
• Inflammation Research
• Cerebrovascular Diseases

Background:

• Intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH) are severe stroke types with distinct pathophysiologies.
• Understanding early inflammatory responses, particularly in cerebrospinal fluid (CSF), may reveal differences between hemorrhage subtypes.
• Angiography-negative SAH (anSAH) represents a significant proportion of SAH cases, and its specific inflammatory profile remains less understood compared to aneurysmal SAH (aSAH).

Purpose of the Study:

• To compare early CSF cytokine profiles between ICH and SAH.
• To specifically investigate the cytokine profiles of anSAH in comparison to aneurysmal SAH (aSAH) and ICH.
• To correlate early cytokine patterns with functional outcomes in hemorrhagic stroke patients.

Main Methods:

• Retrospective observational cohort study of adult patients with spontaneous hemorrhagic stroke (ICH or SAH).
• Analysis of early CSF samples (within 72 hours) from patients with external ventricular drains (EVDs).
• Multiplex bead-based assay to quantify cytokines including IL-6, IL-8, VEGF-A, CCL2, and G-CSF; log-transformation of concentrations.
• Functional outcomes assessed using modified Rankin Scale (mRS) at discharge and 3 months.

Main Results:

• ICH patients exhibited higher early CSF levels of IL-8 and VEGF-A compared to SAH patients.
• ICH patients also demonstrated worse functional outcomes at discharge and 3 months.
• Within the SAH cohort, anSAH showed higher CSF IL-8 and VEGF-A than aSAH, with a cytokine profile resembling ICH, particularly in cases without vascular malformations.

Conclusions:

• Early CSF cytokine patterns indicate that anSAH possesses an inflammatory signature more akin to ICH than to aSAH.
• These findings suggest that anSAH may represent a biologically distinct phenotype within the spectrum of SAH.
• The distinct inflammatory profiles highlight potential differences in underlying mechanisms and therapeutic targets for hemorrhagic stroke subtypes.