Both the brain and spinal cord are surrounded by a protective fluid called cerebrospinal fluid (CSF). In neuromedicine, it is used as an indicator of potential sites of inflammation within the central nervous system. Malignant diseases, but also bacterial or viral infections, which can be the trigger for encephalitis, meningitis or Lyme disease, are detected in this way.
Through targeted puncture in the lower region of the lumbar vertebrae, nervous fluid is taken from the patient so that, after closer examination, conclusions can be drawn about pathological changes within the central nervous system.
Performance of a lumbar puncture
During a lumbar puncture, cerebrospinal fluid (CSF) is usually collected while the patient is sitting or lying on his or her side. In this procedure, the physician inserts a puncture needle between the 3rd/4th or 4th/5th lumbar vertebrae into the dural sac of the lower spinal canal. Nerve fluid is obtained by slow dripping through a cannula. However, contrary to common belief, the needle does not come into contact with the spinal cord, which only extends into the upper region of the lumbar spine. The spinal cord can therefore not be damaged during a lumbar puncture.
A few milliliters of nerve fluid are sufficient to perform a pathological examination for possible pathological changes in the central nervous system. The placement of the puncture needle during a lumbar puncture is largely painless. In addition, pretreatment is carried out using an atraumatic (tissue-sparing) needle in order to minimize possible pain during the actual procedure. In individual cases, the puncture site is numbed with a local anesthetic before the procedure.
Nerve water analysis
After the puncture, initial results can already be seen from the staining of the collected CSF. An unclouded puncture testifies to normal, healthy nerve fluid. In contrast, colored deviations indicate an increased erythrocyte or leukocyte count and an associated focus of inflammation or bleeding in the nervous system.
In addition, statements can be made about cell, immunoglobin, glucose and protein content in the nervous fluid, which are decisive for the further course of treatment. If the patient is treated in the lateral position, a CSF pressure measurement can also be performed.
CSF sampling is used primarily to confirm the diagnosis of suspected multiple sclerosis (MS). In the case of a disease, there is an increased release of the antibody immunoglobin G. This makes inflammatory plaques recognizable. Whereas in the past a new puncture was scheduled after each MS relapse to monitor the course of the disease in multiple sclerosis, today the lumbar puncture is performed only to establish the clinical picture.
Risks and side effects of lumbar puncture
The hollow-needle procedure causes punctate damage between the area of the lumbar vertebrae, which leads to low pressure of cerebrospinal fluid in the spinal canal. This can cause side effects such as headaches, vomiting and nausea. These after-effects are also known as post-puncture syndrome and usually subside some time after the procedure. Only the headaches may take a few weeks to subside.
In general, significant obesity is considered a hindrance to performing a lumbar puncture. Patients with a blood coagulation disorder are also advised not to have their CSF removed, as their risk of spinal hematoma formation is particularly high. It is not feasible to perform CSF sampling in people with increased intracranial pressure.
