Intracranial Fluid Dynamics and Structural Influences

Dr Graham Exelby May 2025

This section is to summary the hydraulic changes seen in POTS and Long COVID

Venous (and Arterial) Haemodynamics:

Changes in venous flow can significantly impact intracranial pressure and CSF dynamics. Venous hypertension, for example, can alter intracranial compliance and affect CSF circulation.

CSF Dynamics:

The balance of CSF secretion, flow, and absorption is crucial for maintaining stable intracranial pressure. Disruptions in this balance can lead to conditions like idiopathic intracranial hypertension. The CSF Canalicular System, that only functions when erect, is gravitationally-driven, may be the most important of the CSF drainage systems.  It is potentially vulnerable to obstruction at the venous angles and at C1

Lymphatic Flow:

The meningeal lymphatic vessels play a role in draining interstitial fluid from the brain. Their interaction with venous flow is complex and contributes to overall fluid dynamics within the cranial cavity. Obstruction at the head and neck level can increase intracranial pressure, compounding glymphatic flow dysfunction—particularly in Ehlers-Danlos Syndrome (EDS), where the cerebellum may descend into the foramen magnum, creating a “plug in the drain” effect.

Postural and Mechanical Influence:

Head-forward posture can significantly alter cerebral blood flow, venous outflow, and CSF circulation. Cervical spine dysfunction—especially in EDS or hypermobility—has a substantial impact on brainstem and cerebral perfusion.

Vascular Compression:

Internal jugular vein (IJV) obstruction at C1 and the base of the neck, as well as compression syndromes like Thoracic Outlet Syndrome (TOS) and Nutcracker Syndrome, play critical roles in the hydrodynamic dysfunction affecting intracranial and spinal fluid regulation.