From the Guidelines
Spinal fluid, or cerebrospinal fluid (CSF), is crucial for protecting the brain and spinal cord, maintaining chemical balance, and regulating intracranial pressure, as evidenced by its role in reducing the risk of spinal cord injury in thoracic aortic repair patients 1. The primary functions of spinal fluid include acting as a shock absorber, providing buoyancy to the brain, and maintaining the chemical environment necessary for neuronal function. It delivers nutrients to brain tissue and removes waste products, helping to regulate intracranial pressure and maintain a stable environment within the skull. Additionally, CSF serves as a medium for immune system components that protect the brain from infection. Some key points about spinal fluid include:
- It is continuously produced by specialized cells in the brain's ventricles and circulates throughout the central nervous system before being reabsorbed into the bloodstream 1.
- Its pressure can be affected by various factors, including the application of a cross-clamp to the proximal descending aorta and surgical retraction of the aortic arch, which can cause an acute elevation in CSF pressure 1.
- CSF drainage has been shown to be beneficial in reducing the risk of spinal cord injury in open thoracic aortic repairs, with studies demonstrating a significant reduction in the incidence of paraplegia or paraparesis in patients undergoing CSF drainage 1.
From the Research
Purpose of Spinal Fluid
The purpose of spinal fluid, also known as cerebrospinal fluid (CSF), is multifaceted:
- It provides mechanical support and acts as a shock absorber for the central nervous system (CNS) 2
- It transports nutrients and waste products throughout the CNS 2
- It plays a role in maintaining metabolic homeostasis, supplying nutrients, and functioning as a lymphatic system 3
- It helps regulate intracranial pressure 3
Production and Circulation
CSF is produced in the ventricles of the brain and circulates through the brain and spinal cord in a continuous flow 2. The CSF space consists of the intracerebral ventricles, subarachnoid spaces of the spine and brain, and the central spinal cord canal 3. The CSF is renewed 3-5 times daily, with its molecular constituents mainly derived from blood (80%) and the remainder consisting of brain-derived and intrathecally produced molecules (20%) 3.
Barrier Systems
The CSF space is separated from the vascular system by the blood-CSF barrier (BCB), while the blood-brain barrier (BBB) is located between brain parenchyma and the vascular system 3. Both barriers have similar functions but differ in their morphologic and functional properties. The transport of molecules across the BBB and BCB is regulated by passive diffusion and facilitated or active transport 3.
Role in Disease Diagnosis
CSF examination plays a crucial role in the diagnosis of CNS diseases, including the identification of biomarkers indicating disease presence or severity, evaluating treatment effectiveness, and enabling understanding of pathogenesis and disease mechanisms 2, 4, 5.