2022 Volume 59 Issue 1 Pages 110-124
Cerebrospinal and interstitial fluids, which have essentially the same production mechanisms, have recently become known as neurofluids, collectively. Understanding the hemodynamics of neurofluids, especially their absorption mechanisms, is clinically important in the field of cerebrospinal physiology. The central nervous system lacks lymphatic vessels for regulating water balance. In the brain, neurofluids and neurometabolites (e.g., amyloid β peptide) are thought to be excreted from the meningeal lymph vessels via arachnoid granules, cerebral microvessels, the glymphatic system (AQP-perivascular space), and the intramural periarterial drainage pathway. In contrast, in the spinal cord region, the neurofluid drainage system utilizes epidural lymphatic vessels that develop in the upper spinal segment to regulate the cerebrospinal fluid pressure. Maculae cribrosae that form on the inner surface of the spinal dura mater are also indispensable for cerebrospinal fluid trans-lymphatic vessel absorption. Normally, each spinal nerve root sheath is physiologically infiltrated with cerebrospinal fluid up to the spinal ganglion, suggesting in a broad sense, that this part is a subarachnoid space that also serves as a functional reservoir of cerebrospinal fluid. The water balance in the central nervous system is influenced by the anatomical features of meningeal-prelymphatic channels and postnatal development of epidural lymphatic networks (such as during age-related involution), which are linked to the channels.
