Lumbar puncture and cerebrospinal fluid analysis
The brain and spinal cord are well protected by the meninges and surrounded by a clear fluid, the cerebrospinal fluid (CSF). The CSF, which is produced in the ventricles of the brain, circulates throughout the brain and spinal cord. Its composition can provide important information about neurological diseases.
Lumbar puncture is a practical way to obtain CSF for examination or to administer drugs directly into the spinal canal. This procedure involves a puncture of the spinal canal in the lower back, typically between the fourth and fifth lumbar vertebrae. During the procedure, the pressure in the CSF system can also be measured. CSF analysis can provide valuable information about diseases of the nervous system.
When is a lumbar puncture performed?
A lumbar puncture is mainly performed to investigate the following conditions:
How is a lumbar puncture performed?
The examination is performed in the sitting position or lying on one side under local anesthesia. After careful disinfection, a thin and long hollow needle is inserted between two lumbar vertebrae into the spinal canal. This is done between the fourth and fifth lumbar vertebrae, far below the spinal cord, so that it cannot be damaged.
Once CSF drips from the needle, a manometer can be attached to determine the pressure. Then, a small amount of CSF is collected, and in some cases, where too much CSF is being produced, up to 50 ml can be taken. The needle is then removed and the puncture site is covered with a bandage. The patient should lie flat for about 30 minutes before leaving the clinic.
Side effects of lumbar puncture
A lumbar puncture is generally only mildly painful and low-risk. Occasionally, due to the irritation of nerve fibers in the spinal canal, electrifying sensations may occur in the legs. These symptoms disappear when the needle is removed. In some cases, the puncture may be difficult in patients with a severely altered spine.
In some patients, headaches and nausea may occur several hours or a day after the lumbar puncture (post-puncture syndrome). A decrease in pressure caused by the removal of CSF can manifest as position-dependent headaches. Bed rest, sufficient fluid intake, and caffeine can help alleviate these symptoms, which typically resolve quickly.
Cerebrospinal fluid analysis
In the laboratory, CSF is examined for the number and type of cells, protein, glucose, bacteria, and fungi, and other parameters depending on the clinical question. Normal CSF is colorless and contains only a few cell components.
How long does it take to receive a CSF analysis result?
First results, which are needed for the diagnosis of acute meningitis, for example, are available a few hours after the examination at the latest. However, the results of some more specialized tests may take several days to be available.