What happens if the flow of CSF fluid is disrupted?
Cerebrospinal fluid (CSF) is a clear, plasma-like fluid (an ultrafiltrate of plasma) that bathes the central nervous system (CNS). It occupies the central spinal canal, the ventricular system, and the subarachnoid space. Show Image 1 shows a 3D image of the CSF circulation as it would look inside the skull.
4. Nutrition - The CSF contains glucose, proteins, lipids, and electrolytes, providing essential CNS nutrition. 5. Immune function - The CSF contains immunoglobulins and mononuclear cells.[1] The 5 minute video below is a great summary of the CSF [4]
When the CSF pressure is greater than the venous pressure, CSF will flow into the blood stream. However, the arachnoid villi act as "one way valves"...if the CSF pressure is less than the venous pressure, the arachnoid villi will NOT let blood pass into the ventricular system[5] Image 2 shows Schematic of CSF circulation, CSF outflow systems, and the anatomy of various CSF compartments. The choroid plexus is a group of fenestrated blood capillaries located in the ventricular system. The choroid plexus mostly synthesizes CSF. Arachnoid granulations are responsible for CSF resorption; they drain CSF into the dural venous sinuses. CSF drains into the lymphatic circulation, via lymph ducts contiguous to the olfactory duct, as it passes through the cribriform plate.[1] Hydrocephalus is a pathological condition of abnormal accumulation of CSF caused by increased CSF production, blockage of flow, or decreased absorption. The ventricles distend in order to accommodate elevated CSF volumes, potentially causing damage to the brain by pressing its tissue against the boney skull. Hydrocephalus may be congenital or acquired.[2] CSF Leak is a condition in which CSF is able escape from the subarachnoid space through a hole in the surrounding dura. The volume of CSF lost in a leak is very variable, ranging from insignificant to very substantial amounts. Syringomyelia due to blockage of CSF circulation. Meningitis is a condition in which the coverings of the brain become inflamed. There are two classifications of meningitis: aseptic and bacterial. Aseptic meningitis can be caused by agents such as fungi, medications, and cancer metastasis, but the majority of aseptic meningitis cases are caused by viruses. Fever, nuchal rigidity, and photophobia are classic presenting symptoms. Diagnosis is made via an analysis of CSF obtained through LP. Subarachnoid Hemorrhage (SAH) is the leakage of blood into the subarachnoid space where it mixes with the CSF. SAH is most commonly caused by trauma with 80% of nontraumatic SAHs being caused by aneurysm rupture. Other nontraumatic causes of SAH include arteriovenous malformations and vasculitis.[2] Lumber Puncture and CSF Analysis - Lumbar puncture is a sterile procedure, done to obtain CSF samples for diagnostic purposes. It involves passing a needle into the subarachnoid space at the levels between L2 and L5 vertebrae. However, most commonly lumbar puncture is performed between L4 and L5. Biochemical, microbiologic and cytologic studies are then carried out on the sample.[1] Cerebrospinal fluid (CSF) plays an essential role in maintaining the homeostasis of the central nervous system. The functions of CSF include: (1) buoyancy of the brain, spinal cord, and nerves; (2) volume adjustment in the cranial cavity; (3) nutrient transport; (4) protein or peptide transport; (5) brain volume regulation through osmoregulation; (6) buffering effect against external forces; (7) signal transduction; (8) drug transport; (9) immune system control; (10) elimination of metabolites and unnecessary substances; and finally cooling of heat generated by neural activity. For CSF to fulfil these functions, fluid-like movement in the ventricles and subarachnoid space is necessary.[6] Abnormalities in the CSF flow or introduction of infection and or irritants can seriously affect an individuals functioning. What is the consequence of blocking this return flow of CSF?Disruption of normal CSF circulation and turnover is believed to contribute to the development of many diseases, including neurodegenerative conditions such as Alzheimer's disease, ischemic and traumatic brain injury, and neuroinflammatory conditions such as multiple sclerosis.
What does diminished CSF flow mean?Background: Disruptions in cerebrospinal fluid (CSF) flow during aging could compromise protein clearance from the brain and contribute to the etiology of Alzheimer's Disease (AD).
Can CSF flow be disrupted in meningitis?[29] Infection, meningitis, and subarachnoid hemorrhage lead to an inflammatory response that causes scarring and obstruction of arachnoid granulations with a resultant decrease in CSF absorption and dysregulation of CSF homeostasis.
Why is CSF flow important?It is clinically significant as it is the site of lumbar puncture (extraction of CSF for medical analyses). Given that the spinal and cranial subarachnoid spaces are continuous, the spinal CSF flows back to the cranial subarachnoid space via which it is eliminated into the dural venous sinuses.
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