Cerebrospinal fluid (CSF) analysis

Cerebrospinal fluid (CSF) analysis:
Is a set of laboratory tests that examine a sample of the fluid surrounding the brain and spinal cord. This fluid is an ultrafiltrate of plasma (Plasma is the liquid portion of blood). CSF is clear and colorless. It contains glucose, electrolytes, amino acids, and other small molecules found in plasma, but it has very little protein and few cells. CSF protects the central nervous system from injury, cushions it from the surrounding bone structure, provides it with nutrients, and removes waste products by returning them to the blood.
Purpose
The purpose of a CSF analysis is to diagnose medical disorders that affect the central nervous system. Some of these conditions are as follows:
? Meningitis and encephalitis, which may be viral, bacterial, fungal, or parasitic infections.
? Tumors (e.g., leukemia) and central nervous system tumors that shed cells into the CSF.
? Syphilis, a sexually transmitted bacterial disease.
? Bleeding (hemorrhaging) in the brain and spinal cord.
? Guillain-Barré a demyelinating disease involving peripheral sensory and motor nerves.
Sample collection
Lumbar puncture
CSF is withdrawn from the subarachnoid space through a needle by a procedure called a (Lumbar puncture) or (Spinal tap). Lumbar puncture is performed by inserting the needle between the fourth and fifth lumbar vertebrae (L4-L5). This location is used because the spinal cord stops near L2, and a needle introduced below this level will miss the cord.
Usually three or four tubes are collected. The first tube is used for chemical and/or serological analysis, and the last two tubes are used for hematology and microbiology tests. This method reduces the chances of a falsely elevated white cell count caused by a traumatic tap (bleeding into the subarachnoid space at the puncture site), and contamination of the bacterial culture by skin germs or flora.