CSF Full Form

Cerebrospinal fluid (CSF) is a colorless transparent fluid similar to plasma that swims to the central nervous system (an ultrafiltrate of the plasma). So, CSF flows in the the central spinal canal, ventricular structure, and subarachnoid area.

The concentrations of sodium, chloride and magnesium in CSF are higher, whereas potassium and calcium are lower. CSF contains only trace levels of cells, protein and immunoglobulin, compared to plasma. Although tiny numbers of white blood cells are frequently delivered to the CSF indirectly, however, no cells can flow through the blood-CSF barrier. Despite variations in blood composition and circulation, CSF maintains a consistent composition, ensuring a steady intraventricular environment, which is crucial for sustaining appropriate neural activity.

Physical Properties of Cerebrospinal Fluid

• The normal colour of CSF is colorless. Whereas when it is abnormal then the colour is pink due to the amount of oxyhemoglobin, the color is orange due to heavy haemolysis and the color is yellow because of Bilirubin.
• Appearance is transparent and clear. However, when the CSF is crystal clear then it is due to the viral infection, it is turbid due to the Presence of WBC/Protein/Pus cell or because of the infection, it is bloody due to hemolyzed RBC, Lumbar puncture trauma, Haemorrhage, or Cerebral Malignancy.
• Specific gravity of CSF is equal to 1.004 to 1.007.
• Reaction of CSF is alkaline in nature and it does not coagulate.

Rate of Formation of Cerebrospinal Fluid

• The rate of formation of CSF is 500ml per day.  It is formed by the selected ultra-filtration of the plasma and active secretion by the epithelial membranes. So, the lateral ventricle’s choroid plexus, and the third and fourth ventricles, combine to form this structure and then the ventricles’ choroid plexus actively secretes the cerebrospinal fluid.

Circulation of Cerebrospinal Fluid

• Through the interventricular foramen, CSF circulates starting through the lateral ventricle to the 3rd ventricle via the interventricular foramina (also known as foramen of Monro channels).
• The cerebral aqueduct is a narrow channel that connects the third and fourth ventricles (also known as cerebral Aqueduct of Sylvius).
• The foramina of Luschka (two of them are present) and the foramen of Magendie (one is present) then carry CSF into the subarachnoid area.
• The CSF is absorbed into the bloodstream through structures called arachnoid villi in the SSS.

Cerebrospinal fluid will flow into the bloodstream when the pressure of the cerebrospinal fluid is larger than the pressure of the venous. The arachnoid villi, on the other hand, function as the “one-side valves”: if the cerebrospinal pressure is lower than the pressure of the venous, the villi of the arachnoid will not allow blood to flow to the ventricular system.

Reabsorption of CSF

The arachnoid granulations, which empty Cerebrospinal Fluid to the Dural venous sinus, are involved for CSF reabsorption. As it passes through the cribriform plate, CSF flows into the lymphatic passage through lymph ducts next to the olfactory ducts.

Functions of the Cerebrospinal Fluid

• Supporting System- the CSF sustains the estimated brain weight which is 1500 gram and prevents it in neutral buoyancy at a net weight of roughly 25 gm. As a result, the full density of the brain is cushioned, preventing it from colliding with the bone-like cranium.
• A Shock absorbing fluid – It guards the brain from harm in the event of a head injury. Otherwise, even slight head bobbing might cause serious damage to the brain.
• Aid in Homeostasis – The biochemical substances of the cerebrospinal fluid, as well as its volume, play critical roles in brain homeostasis as it maintains a constant temperature in the CNS. Moreover, the osmotic pressure in control of adequate CSF pressure is maintained by biochemical components and electrolytes, and this pressure is necessary for maintaining appropriate cerebral perfusion. The biochemical waste substances go into the cerebrospinal fluid and are eliminated as the CSF is reabsorbed into venous circulation via arachnoid granulations and a minor amount of CSF also flows to the lymphatic passage.
• Provide Nutrition- the cerebrospinal fluid contains glucose, various lipids, proteins and the electrolytes, all of which are necessary for the nutrition of the Central Nervous System.
• Help in the immune system- the cerebrospinal fluid has immunoglobulin and the cells that are mononuclear.
• CSF also helps to remove waste products from brain metabolism, including peroxidation product, glycosylated protein, excessive neurotransmitters, and debris out from ventricular lining, germs, viruses, and other non-essential molecules.

Leakage of Cerebrospinal Fluid

Cerebrospinal fluid can leak from the subarachnoid area via a gap in the immediate Dura in this scenario. The amount of cerebrospinal fluid gone in a leak varies greatly, ranging from negligible amounts to considerable volumes.

How does CSF affect the human body?

• Syringomyelia is due to the block of the circulation of the cerebrospinal fluid.
• Meningitis is an inflammatory illness where the brain’s coverings become inflamed. Meningitis is divided into two types: aseptic meningitis and bacterial. Aseptic one can be induced by fungus, medicines, or cancer metastases, although viruses are responsible for the vast majority of cases. Classic presenting symptoms include fever, nuchal stiffness, and photophobia. A CSF analysis acquired by LP is used to diagnose a patient.
• The leaking of the blood to the subarachnoid area, where it blends with the cerebrospinal Fluid, is known as subarachnoid haemorrhage (SAH). It is most usually caused by trauma, with aneurysm rupture accounting for eighty percent of nontraumatic SAHs. Arteriovenous malformation and the vasculitis are two more nontraumatic causes of SAH.
• When CSF leaks from the ear, it is called otorrhea.
• When cerebrospinal fluid leaks from the nose it is called rhinorrhea.

Conclusion

In the average young adult, steady CSF secretion contributes to complete CSF renewal four to five times each 24-hour period. The deposition of metabolites seen in aging and neurological disorders may be due to a decline in CSF turnover. Moreover, the CSF composition is tightly controlled, and any deviation can be beneficial for diagnostic purposes.