Hydrocephalus Revisited: New Insights into Dynamics of Neurofluids on Macro- and Microscales

Abstract

New experimental and clinical findings question the historic view of hydrocephalus and its 100-year-old classification. In particular, real-time magnetic resonance imaging (MRI) evaluation of cerebrospinal fluid (CSF) flow and detailed insights into brain water regulation on the molecular scale indicate the existence of at least three main mechanisms that determine the dynamics of neurofluids: (1) inspiration is a major driving force; (2) adequate filling of brain ventricles by balanced CSF upsurge is sensed by cilia; and (3) the perivascular glial network connects the ependymal surface to the pericapillary Virchow–Robin spaces. Hitherto, these aspects have not been considered a common physiologic framework, improving knowledge and therapy for severe disorders of normal-pressure and posthemorrhagic hydrocephalus, spontaneous intracranial hypotension, and spaceflight disease.

Paediatric pineal region cysts: enigma or impaired neurofluid system?

“…This upward stream is necessary for the preload of the interstitial fluid flow system and the termination of complaints. This has already been shown by our group for ETV in the treatment of obstructive hydrocephalus [ 19 , 20 ] and confirms our hypothesis of a deregulated aqueductal function as the main cause of the disease.…”

“…All datasets were acquired on a 3 Tesla scanner (Magnetom Prisma Fit, Siemens Healthcare) using real-time phase-contrast flow MRI based on highly undersampled radial FLASH sequences as described [ 20 - 22 , 29 , 30 ]. Measurements in sagittal or coronal orientation to the stoma in the floor of the 3rd ventricle were conducted with a 64-channel head coil.…”

Deep breathing couples CSF and venous flow dynamics

“…The notion of a dynamic interplay between CSF and venous flow is in line with an increasingly popular holistic view on brain fluids 13 , 14 . Mounting clinical evidence substantiates the importance of the cerebral venous systems for maintaining intracranial pressure (ICP) and hence its role in a broad spectrum of neurological diseases like communicating hydrocephalus and myelopathy 15 , 16 .…”

“…Transmissions of intrathoracic and also intraabdominal pressure changes into the bony spinal canal are assumed to be facilitated by the presence of abundant connections from the extraspinal paravertebral venous plexus through the intervertebral foramina to the epidural spaces 19 , 20 . As a result, the high-capacity, valveless epidural venous plexus have been found to be kept open by negative pleural and epidural transmural pressures 14 , 19 , 21 , 22 . However invasive in vivo measurements of intrathoracic or intraabdominal pressures were not obtained in this study.…”

“…Multiple studies assigned the dominance of IJV drainage to the supine position and pointed to the EV systems as the major pathway in the upright position 31 . The bony spinal canal protects the thin valveless venous plexus from direct exposure to the thoracic and abdominal pressure changes and constant negative pleural and epidural pressures as well as bridging trabeculae within their lumen prevent the collapse of the vessels 14 , 19 , 20 , 31 , 32 . In contrast, forced breathing might expose the IJV to various pressure changes along its course in the neck and at the entrance to the thoracic cavity.…”