Relationship Between Venules and Perivascular Spaces in Sporadic Small Vessel Diseases

Abstract

Background and Purpose— Perivascular spaces (PVS) around venules may help drain interstitial fluid from the brain. We examined relationships between suspected venules and PVS visible on brain magnetic resonance imaging. Methods— We developed a visual venular quantification method to examine the spatial relationship between venules and PVS. We recruited patients with lacunar stroke or minor nondisabling ischemic stroke and performed brain magnetic resonance imaging and retinal imaging. We quantified venules on gradient echo or susceptibility-weighted imaging and PVS on T2-weighted magnetic resonance imaging in the centrum semiovale and then determined overlap between venules and PVS. We assessed associations between venular count and patient demographic characteristics, vascular risk factors, small vessel disease features, retinal vessels, and venous sinus pulsatility. Results— Among 67 patients (69% men, 69.0±9.8 years), only 4.6% (range, 0%–18%) of venules overlapped with PVS. Total venular count increased with total centrum semiovale PVS count in 55 patients after accounting for venule-PVS overlap (β=0.468 [95% CI, 0.187–0.750]) and transverse sinus pulsatility (β=0.547 [95% CI, 0.309–0.786]) and adjusting for age, sex, and systolic blood pressure. Conclusions— Despite increases in both visible PVS and suspected venules, we found minimal spatial overlap between them in patients with sporadic small vessel disease, suggesting that most magnetic resonance imaging-visible centrum semiovale PVS are periarteriolar rather than perivenular.

Physiology and Clinical Relevance of Enlarged Perivascular Spaces in the Aging Brain

“…First, ePVS that occur in the basal ganglia often track well with penetrating lenitculostriate arteries and second, ePVS in the centrum semiovale are often correlated with CAA-related imaging findings and CAA pathology, 18 conditions primarily affecting arteries and arterioles. Additional evidence of MRI-visible PVS corresponding to arteries and arterioles was published by Jochems et al 19 as they showed low spatial overlap between PVS and venules visible on 3T brain MRI. However, further research is needed to investigate whether ISF efflux can occur along both para-arterial and paravenous pathways simultaneously.…”

All Central Nervous System Neuro- and Vascular-Communication Channels Are Surrounded With Cerebrospinal Fluid

“…Historically, the CNS is considered an immune-privileged site and therefore it was believed that antigens in the CNS did not communicate with the immune system (56)(57)(58). However, about 14-47% of radiolabeled tracers make their way into the lymphatic system, following CSF or intra-parenchymal injections (59). Therefore, antigens are transported to the immune system and can induce an immune response (56)(57)(58).…”

The glymphatic system and its role in cerebral homeostasis

“…Under normal conditions, the capillary cell types do not make direct contact with the PVS and are always separated by the basal lamina (82, 89). In humans, the PVS can be detected in the brain parenchyma by magnetic resonance imaging (MRI) as tube-like structures which run perpendicular to the brain's surface in directions that are spatially correlated with perforating vessels thought to be primarily arterial (51,106). Cortical PVS can be observed in young, healthy brain (Fig.…”