eLife Assessment: Skull Bone Marrow Drainage and Its Associations with Inflammation, Sleep Quality, and Cognitive Performance

Recent studies using human craniotomy samples and murine models have revealed channels that connect the inner skull cortex to the skull marrow cavities. While cerebrospinal fluid (CSF) tracer access to skull bone marrow has been described in CSF circulation disorders, evidence on regional patterns and clinical correlates in broader clinical cohorts is limited.Three-dimensional imaging was performed at baseline, 4.5, 15, and 39 hours post-gadolinium administration in 87 patients with neurological conditions. Signal changes in skull bone marrow near the superior sagittal sinus, lateral fissure, and cisterna magna were recorded. CSF drainage function was characterized as the percentage changes in the signal unit ratio within the skull bone marrow from baseline to time points post administration of gadolinium.The tracer drained from CSF into the skull bone marrow, highlighting the drainage variations nearby different regions. Reduced drainage was associated with female sex, hypertension, diabetes, and elevated neutrophil levels (p < 0.05). Drainage near the superior sagittal sinus was inversely associated with sleep quality and positively associated with cognitive scores, and partially accounted for the association of sleep quality with cognitive function (indirect effect Δβ = −0.092; bootstrap 95% CI -0.195 to -0.004; proportion mediated ≈ 38%).These results support the presence of skull bone marrow adjacent routes for CSF tracer movement and suggest that skull bone marrow tracer dynamics relate to systemic inflammation, sleep quality, and cognitive performance in this clinical cohort.