Liquor puncture – nerve fluid for diagnostics

Nervous system disorders can be life-threatening. They often cannot be detected by a simple  blood test  . It is possible, however, to take spinal fluid and examine it in the laboratory for changes.

What is liquor?

The brain and spinal cord are surrounded by a water-clear fluid that is formed in the brain and is connected to the fluid spaces inside. That is why it is also called brain or nerve water. It protects the sensitive structures from external influences. In the area of ​​the lower lumbar spine (lumbar), the liquor collects in a kind of reservoir that no longer contains the spinal cord and can be safely obtained through a puncture at this point. The procedure is therefore also called a lumbar puncture; the term spinal cord puncture, which is used from time to time, is incorrect.

What can the liquor puncture show?

There is only limited exchange between the blood and the cerebrospinal fluid. This so-called blood-brain barrier acts like a filter, allowing necessary substances such as oxygen, carbon and water to pass through and keeping harmful substances away from the nervous system. However, with some diseases and influences such as electromagnetic radiation, the function of this barrier can be disturbed.

Conclusions about the cause of the disorder can be drawn from the color of the liquid and the type and amount of substances found in the liquor. Red and white blood cells , proteins – especially antibodies -, sugar and lactate and, if necessary, pathogens and cancer cells are determined in the laboratory  . In the assessment, their composition is usually related to the  blood values ​​determined at the same time  . In special laboratories, other substances reserved for specific questions, such as interferons or copper, can be determined.

When is the liquor puncture performed?

  • In  the event of cerebral hemorrhage  , for example after an accident or as a result of a ruptured blood vessel,  red blood cells appear and the cerebrospinal fluid is pink or red.
  • In  infections  such as bacterial and viral meningitis (meningitis) or neuroborreliosis, inflammatory cells and antibodies are present.
  • In  the case of brain tumors , metastases and  leukemia ,  possibly cancer cells. The spinal fluid is then often cloudy white or yellow.
  • In  multiple sclerosis  , typical changes can be detected in many patients (so-called oligoclonal bands).
  • Liquor punctures are also used in the case of sudden severe headaches or loss of consciousness, sometimes also to diagnose unclear metabolic diseases, especially in childhood.

How is the examination performed?

No special patient preparation is required. If he is very excited, he will be given medication in advance. Blood is taken about half an hour before the puncture. Relaxed back muscles and as wide an intervertebral space as possible are important for the puncture. Therefore, the patient is in a squatting position in which the lumbar spine is curved. When lying down he curls up like an embryo, when sitting he bends his head and back as far forward as possible, a helper holds his shoulders from the front.

First, the puncture area is thoroughly disinfected and locally anesthetized. Then a long, thin hollow needle is inserted between two vertebrae into the liquor space. Three small portions of spinal fluid are drained and sent to the laboratory. The needle is pulled out, the puncture site is squeezed and closed with a plaster. The entire procedure usually takes no longer than 5 minutes. Depending on the needle used, the patient must remain in bed for between 4 and 24 hours.

Are there any complications?

In principle, this is a fairly harmless, less painful procedure that is rarely associated with complications. Headaches can occur 24 to 72 hours after the puncture, particularly when sitting or standing, possibly with neck stiffness, vomiting and hearing loss (“post-puncture syndrome”), especially if bed rest is not maintained and if you drink too little.

Infections or signs of paralysis occur very rarely. A lumbar puncture is dangerous if there is increased intracranial pressure and coagulation disorders or if you are taking anticoagulant medication. Then it may only be carried out in exceptional cases.

 

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