The cerebrospinal fluid has many important functions. removing unnecessary metabolic products from the central nervous system, but also it simply protects the nervous tissue from damage. When a variety of conditions - especially neurological ones - are suspected, the cerebrospinal fluid may be collected for certain tests. However, in what situations is the cerebrospinal fluid collected from patients and what can the deviations found in the examination indicate?

Cerebrospinal fluid(CSF for short) has been of fundamental interest to those who have been studying human anatomy for a long time. Already Hippocrates, describing patients with hydrocephalus, mentioned the water that surrounds the human brain. Galen, in turn, talked about the fluid that is present in the ventricles of the brain - in his opinion, inhaling the fluid through the nose was responsible for its presence.

Later, for many centuries, the time about the cerebrospinal fluid was not mentioned at all. Why this liquid, important for the human body, was omitted - it is not known, it is suspected that it could be a result of the way in which autopsies were carried out in the past.

In the past, at the beginning of the autopsy, the head was separated from the rest of the body - therefore the cerebrospinal fluid could simply not be noticed in the subsequent autopsy due to its leakage.

Cerebrospinal fluid was not really mentioned until the 18th century. Then it was, among others Emanuel Swedenborg described the liquid that is produced in the fourth chamber and from there it goes, among others into the medulla, at a similar time Albrecht von Haller mentioned the fluid secreted in the ventricles of the brain.

Many years have passed since then, during which many other researchers were interested in the cerebrospinal fluid, and finally today we know much more about it - we have knowledge about its production and functions as well as various pathologies related to with this liquid.

Cerebrospinal fluid - production and circulation

Cerebrospinal fluid is found in the ventricular system of the brain and in the subarachnoid space that extends throughout the brain and spinal canal.

In one moment, about 150 ml of the cerebrospinal fluid circulates in a human, of which 100 mlis located in the subarachnoid space, and the rest in the ventricles of the brain.

The daily production of fluid, however, is much higher - it is formed around 450-500 ml, but due to the fact that it is constantly reabsorbed into the venous system, it is also present in the body at the same time, just mentioned above, about 150 ml .

CSF is produced by choroidal plexuses - choroid plexuses located in the lateral chambers have the largest share in its production, other elements of the ventricular system, as well as structures located in the subarachnoid space, also produce it, but in much smaller quantities.

Cerebrospinal fluid is produced from filtered plasma - this is why CSF and plasma have somewhat similar compositions. The fluid formed in the side chambers enters the third ventricle, from where - via the brain's water supply - it finally reaches the fourth ventricle.

When CSF leaves the ventricular system, it enters the arachnoid space of the brain and the spinal canal. Eventually, it reaches the arachnoid villi - they form part of the arachnoid dura and bulge into the venous sinuses of the dura mater. Through these villi, the cerebrospinal fluid enters the venous system.

Cerebrospinal fluid - Features

The liquid in the structures of the nervous system has a lot of important tasks. The functions of the cerebrospinal fluid include:

  • buoyancy: just as the human brain weighs about 1.5 kg, when it is immersed in the CSF, this weight is balanced to just 25 grams - this is especially important because it makes it possible to maintaining the density of the brain tissue without the risk that certain parts of the brain - especially the lower ones - could be subject to pressure that could seriously damage the nervous tissue
  • protection of the central nervous system: the cerebrospinal fluid absorbs the brain and spinal cord in various situations, incl. in the event of a fall or other accident
  • participation in the circulation of various substances in the brain: CSF, which circulates in various structures of the nervous system, transports many mediators (including hormones), and it can also drain waste products of metabolism produced by nerve cells

Cerebrospinal fluid - diseases

Many different disease entities can be associated with the cerebrospinal fluid. One of the best known is hydrocephalus, which can be caused both by impaired flow of this fluid in the ventricular system (then non-communicating hydrocephalus is diagnosed),as well as its excessive production or the impaired absorption of CSF (this is when communicating hydrocephalus develops).

The composition of the cerebrospinal fluid may change due to a wide variety of medical conditions in a patient. Examples of units in which abnormalities in the composition of the cerebrospinal fluid may occur include:

  • various infections of the central nervous system (e.g. meningitis, both viral and bacterial),
  • Guillain-Barré syndrome
  • subarachnoid bleeding
  • multiple sclerosis
  • primary tumor of the central nervous system or metastasis of some other tumor to the CNS
  • Alzheimer's disease

Different diseases lead to different abnormalities in the composition of the cerebrospinal fluid. However, to be able to find any, the cerebral fluid must first be collected and then sent for specialist examination.

CSF - uptake

You can get PMR for research in several ways. It can be collected from the lateral ventricles of the brain, from the large reservoir (by subcopical puncture) and through the lumbar puncture.

The last of the mentioned methods, i.e. the lumbar puncture (lumbar puncture) is the most common method of obtaining cerebrospinal fluid - this is because it is the safest method, and in addition, the lumbar puncture is the easiest way for doctors to obtain this liquid.

The lumbar puncture is performed aseptically, the needle - at an angle of 15 degrees - is usually inserted into the 4th-5th. intervertebral space of the lumbar spine. After the puncture, the patient should be lying down for 24 hours to reduce the risk of post-dural syndrome.

Cerebrospinal fluid - indications and contraindications for its collection

The indications for performing a lumbar puncture are assumptions that the patient suffers from one of the listed diseases or another entity that may lead to deviations in the examination of the cerebrospinal fluid. However, it is not always possible to obtain PMR - the contraindications include:

  • active infection in the place from which the cerebrospinal fluid is to be collected
  • blood coagulation disorders (both due to the use of anticoagulants and severe thrombocytopenia)
  • increased intracranial pressure

Cerebrospinal fluid - testing and interpretation of results

Cerebrospinal fluid during lumbar puncture is generally assessed fromstarting the download itself. Well, even the rate at which this liquid flows out is important - at the correct pressure (8-15 mmHg in the supine position), the cerebrospinal fluid leaks at a rate of 20-60 drops per minute.

After obtaining PMR, it is sent to various laboratory analyzes. Normal CSF is colorless and clear and contains:

  • various cells, 0-5 / mm3
  • protein at a concentration of 15 to 45 mg / dL
  • glucose at a concentration of 50 to 80 mg / dL (typically CSF glucose is about 60-75% of plasma glucose)
  • chlorides at a concentration of 115 to 130 mmol / l
  • lactates at 10-22 mg / dl
  • white blood cells (single amounts, under normal conditions lymphocytes are the dominant cells in the CSF)

The very analysis of the above-mentioned parameters of the cerebrospinal fluid allows to diagnose many different diseases.

For example, in the case of purulent meningitis, the CSF becomes cloudy and yellowish, in addition, neutrophils begin to dominate in it, and the concentration of protein and lactate in it increases significantly with a simultaneous decrease in glucose and chloride levels.

And then, when the patient suffers from viral meningitis, instead of 0 to 5 cells in the fluid, 1 mm of them may appear in the fluid3even several hundred, the protein concentration in it (but definitely less than in the case of purulent inflammation), and the amount of glucose and chloride remain normal or there is a slight decrease in them. At the same time, with viral meningitis, the cerebrospinal fluid remains water-clear and clear.

The cerebrospinal fluid may, however, be subjected to a number of other specialized analyzes. It is possible to determine the concentration of IgG immunoglobulins, the increase of which is noted, among others, in in the case of multiple sclerosis or Guillain-Barré syndrome. CSF can be transferred to perform electrophoresis - the so-called electrophoresis is found in it. oligoclonal bands is one of the stages in the diagnosis of multiple sclerosis.

Bacteriological tests of the cerebrospinal fluid are sometimes performed (which may answer the question of what exactly the bacteria led to neuroinfection in the patient) and serological tests of the cerebrospinal fluid (these include the so-called syphilitic reactions).

It is also possible to detect neoplastic cells in CSF associated with the occurrence of, for example, medulloblastoma or lymphoma of the CNS.

Cerebrospinal fluid - nasal discharge

An issue worth describing when discussing cerebrospinal fluid isrunny nose. In the vast majority of cases, this problem is associated with rhinitis (commonly known as a runny nose).

In some situations, however - especially in people who have suffered a serious head injury or have had neurosurgical surgery - it is necessary to ensure that the patient's nose does not leak cerebrospinal fluid.

Laboratory tests may be performed to differentiate whether the fluid is CSF or normal nasal discharge. When the patient has a nasal discharge, the glucose concentration is low ( <10 mg/dl) i zawarte jest w niej dużo białek (więcej niż 300 mg/dl). Wtedy zaś, gdy ciecz jest płynem mózgowo-rdzeniowym, ma ona stężenia białka i glukozy takie, jak opisano powyżej.

About the authorBow. Tomasz NęckiA graduate of medicine at the Medical University of Poznań. An admirer of the Polish sea (most willingly strolling along its shores with headphones in his ears), cats and books. In working with patients, he focuses on always listening to them and spending as much time as they need.

Category:

Neurology