Cerebrospinal fluid
The cerebrospinal fluid or cerebrospinal fluid , and cerebrospinal fluid (CSF), cerebrospinal (s) liquid and colloquially cerebrospinal fluid , cerebrospinal fluid , or cerebrospinal fluid called, is a typically clear and colorless body fluid that the tissue fluid of the brain is and linked her the composition is very similar. The cerebrospinal fluid is formed by specially differentiated epithelial cells of the vein plexuses of the brain chambers . François Magendie is considered to be the discoverer of liquor and its communication channels .
composition
Normal liquor is clear, colorless and contains very few cells. Most of them are lymphocytes (up to 3 per µl CSF) and in rare cases also monocytes . The lymphocytes are predominantly T-lymphocytes , only about one percent of the lymphocytes in the CSF are B-lymphocytes (in contrast, the proportion of B-lymphocytes in all lymphocytes in the blood is about five to ten percent). The protein content of the liquor is about 0.15 to 0.45 grams per liter of liquor, well below the average protein content of the serum (75 grams per liter). This property can be used to diagnose a disruption of the blood-cerebrospinal fluid barrier with the help of parallel albumin measurement in CSF and serum . The normal sugar content is 50 to 70 percent of the serum blood sugar value .
pressure
The cerebrospinal fluid pressure when lying down with a typical measurement using the ascending tube principle using a lumbar puncture on the cross is physiologically 70 to 220 mmH 2 O (= approx. 690–2160 Pa) and fluctuates rhythmically by up to 20 mmH 2 O (approx. 200 Pa), depending on the heartbeat , Type of breath (pressed or relaxed) and the way you lie down. A decreased pressure is called hypoliquorrhea .
anatomy
A distinction is made between an outer CSF space and an inner CSF space.
External liquor space
The spinal cord located in the vertebral canal ( canalis vertebralis ) and the brain located in the skull ( cranium ) are surrounded by two soft ( pia mater and arachnoid , leptomeninges) and one hard membrane or spinal cord ( dura mater , pachymeninx). Between the two soft meninges there is a space called the subarachnoid space through which the cerebrospinal fluid circulates.
Inner liquor space
As in other chordates, the human central nervous system emerges from the neural tube . The internal CSF spaces correspond to the lumen of the embryonic neural tube.
In the spinal cord, the central canal ( canalis centralis ) is a remnant of the neural tube lumen. After birth, however , the central canal hardly plays a role in the outflow of the liquor and often loses its patency.
In the brain, through various development phases, the lumen of the neural tube creates a system of cavities connected in series in the form of four brain ventricles :
- two lateral ventricles ( ventriculi laterales ) in the telencephalon (cerebrum)
- a third ventricle ( ventriculus tertius ) in the diencephalon (interbrain)
- a fourth ventricle ( ventriculus quartus ) in the rhombencephalon (hindbrain)
The two lateral ventricles are each connected to the third ventricle via a foramen interventriculare (Foramina Monroi). From there the aqueduct ( Aquaeductus mesencephali ) runs to the fourth ventricle, to which the central canal of the spinal cord is connected caudally . The ventricular system in the hindbrain is connected to the subarachnoid space via two lateral apertures (foramina Luschkae) and a median aperture (foramen magendii). Via these openings in the wall of the fourth ventricle, the liquor formed in the choroid plexus and released into the cerebral ventricle reaches the outer liquor space.
CSF formation
Adults have about 120 to 200 ml of CSF, depending on the volume of the CSF space. These are largely formed in the ventricles by the specially differentiated epithelial cells of the choroid plexus at a rate of about 0.3 to 0.4 ml per minute, mainly through ultrafiltration of the blood . About 500 to 700 ml of liquor are produced every day. The extent to which ependymal cells are involved in secretion is still the subject of current research.
CSF absorption
Since around 500–700 ml of CSF are formed every day, it has to be reabsorbed as otherwise the intracranial pressure would rise continuously and hydrocephalus ("head of water") would develop. The liquor reaches the third ventricle from the side ventricles via the respective interventricular foramen, then via the aqueduct into the fourth ventricle and from there on the one hand to the central canal of the spinal cord and on the other hand via the lateral openings (foramina Luschkae) and the lower opening (foramen magendii ) into the external CSF space, which corresponds to the subarachnoid space. The resorption is caused by protuberances of the arachnoid , which protrude into the venous blood ducts of the dura mater in the skull and are called arachnoid villi (Pacchioni granulations, Granulationes arachnoideae ). Similarly, in the root pockets surrounding the spinal nerve roots, there are also small protuberances through which the liquor is filtered into veins.
In the area of the root pockets, the arachnoid merges into the perineurium. Through this connection, a few milliliters of the CSF flow out along the cranial and spinal nerves to the periphery, where it is absorbed by the lymphatic system .
Functions of the CSF
General
The purely physical functions of the liquor are to neutralize gravity (avoid pressure damage by floating in liquid ) and to cushion the brain and spinal cord. Possible nutritional functions and involvement in signal cascades are the subject of research.
Disposal system of the brain
The circulating liquor is also a transport medium, especially for the microcirculation of the brain to remove non-usable organic residues. It thus belongs to the glyphatic system discovered in 2012 .
The arteries of the CNS have after the entry through the meninges around its outer wall an additional liquid space, the perivascular space ( Spatium perivascular ) of the blood vessels in the central nervous system (CNS) the designation Virchow-Robin space bears. A small part of the liquor from the subarachnoid space reaches all areas of the CNS through this space in a constant current - driven by the wave movements of the arterial walls triggered by the pulse beat .
There it is distributed with the help of the glia (supporting cells) and at the end - with the removal of waste materials - it flows off again, probably partly directly into special vessels of the dura mater , namely into the collecting vessels of the lymphatic system that were discovered there in 2015 . They are transported out of the brain through the perivascular space around the outer walls of the veins . The extent to which it is fed into the lymphatic vessels of the dura mater or the more distant lymphatic tracts on the neck has not yet been clarified (as of 2017).
Diagnosis
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Liquor, which was first described by the Italian anatomist Domenico Cotugno (1736–1822), can be obtained for diagnostic purposes by puncturing the spinal canal ( liquor extraction ). Such a puncture is mainly carried out to examine the nerve water if there is suspicion of inflammation in the nervous system ( meningitis , encephalitis , encephalomyelitis , myelitis , polyradiculitis ), for example as part of an infection of the brain and / or spinal cord by bacteria , viruses , fungi , Parasites, or an autoimmune disease (e.g. multiple sclerosis) occurs. Smaller subarachnoid hemorrhages can sometimes only be detected by a CSF examination.
Inflammation of the brain tissue or the meninges ( meningitis ) changes the composition of the liquor: the number of cells increases ( pleocytosis ), the protein concentration increases, the sugar in the liquor decreases, and lactate increases. In addition, there is an increase in immunoglobulins in the CSF relative to the blood . This is determined using the Reiber diagram .
In addition to an increase in the number of cells, pathological processes can also change the composition of the cell compartment. In bacterial meningitis, for example, there is a massive invasion of neutrophilic granulocytes into the CSF space, while physiologically they are not found there. In contrast, in the case of inflammatory processes caused by viruses, lymphocytes preferentially migrate into the CSF space. Furthermore, the microscopically assessed cell morphology allows conclusions to be drawn about the age and activation level of cells.
Sometimes the pathogens ( bacteria , viruses ) can be detected directly. A viral infection can often only be recognized indirectly by the higher specific antibody concentration in the CSF than in the blood .
If tumor cells are detectable in the CSF, this is an indication of tumor involvement of the meninges. One then speaks of a meningiosis neoplastica . Subgroups of meningitis are neoplastica example, in cancer diseases a carcinomatous meningitis in leukaemias a meningitis leucemica or lymphoma , a lymphomatous meningitis .
Substances such as amyloid -β (Aβ) (1-42), T-tau , and P-tau can also be used as diagnostic markers in the CSF to assess Alzheimer's disease .
Macroscopic assessment
The “three-glass sample” has proven itself for the visual assessment of the liquor immediately after its collection. The liquor is fractionated in three test tubes. During the removal process, an artifact caused by bleeding from the puncture site can be distinguished from a subarachnoid hemorrhage if the last tube remains clear.
The turbidity and coloration are assessed. Normal liquor is clear and colorless. If the number of leukocytes is significantly increased, the liquor will be slightly cloudy to creamy / creamy. Strongly increased protein values lead to a yellowish color. The CSF appears just as yellow in older subarachnoid hemorrhages after the red blood components ( erythrocytes ) have settled at the base.
In this way, you can roughly but quickly obtain the following important information:
| Appearance | possible conclusions |
|---|---|
| slight to moderate cloudiness | White blood cell count increased |
| strong cloudiness (creamy, creamy), higher viscosity | classic bacterial, |
| yellowish (xanthochrome) | Protein content greatly increased, stopping liquor |
| reddish cloudy | Erythrocytes, due to bleeding |
literature
- Uwe K. Zettl, Reinhard Lehmitz, Eilhard Mix (eds.): Clinical Liquordiagnostik. 2nd Edition. de Gruyter, Berlin a. a. 2005, ISBN 3-11-018169-X .
Individual evidence
-
^ Roche Lexicon Medicine, 5th edition (online version) , under
Liquordruck. - ^ RL Drake, W. Vogl, AWM Mitchell: Gray's Anatomie für Studenten Übers. U. Edited by Friedricht Paulsen. Elsevier, Munich, 2007, Chapter 8, p. 816, ISBN 978-3-437-41231-8
- ^ NA Jessen, AS Munk, I. Lundgaard, M. Nedergaard: The Glymphatic System: A Beginner's Guide. In: Neurochemical research. Volume 40, number 12, December 2015, pp. 2583-2599, doi : 10.1007 / s11064-015-1581-6 , PMID 25947369 , PMC 4636982 (free full text) (review).
- ↑ D. Raper, A. Louveau, J. Kipnis: How Do Meningeal Lymphatic Vessels Drain the CNS? In: Trends in neurosciences. Volume 39, number 9, September 2016, pp. 581-586, doi : 10.1016 / j.tins.2016.07.001 , PMID 27460561 , PMC 5002390 (free full text) (review).
- ^ Rainer Brömer: Domenico Cotugno. In: Werner E. Gerabek , Bernhard D. Haage, Gundolf Keil , Wolfgang Wegner (eds.): Enzyklopädie Medizingeschichte . De Gruyter, Berlin 2005, ISBN 3-11-015714-4 , p. 276.
- ↑ A. Anoop, PK Singh, RS Jacob, SK Maji: CSF Biomarkers for Alzheimer's Disease Diagnosis. In: International journal of Alzheimer's disease. Volume 2010, 2010, S., doi: 10.4061 / 2010/606802 , PMID 20721349 , PMC 2915796 (free full text).
Web links
- Publications by H. Reiber et al. for CSF diagnostics by Hansotto Reiber .
- A. Anoop, PK Singh, RS Jacob, SK Maji: CSF Biomarkers for Alzheimer's Disease Diagnosis. In: International journal of Alzheimer's disease. Volume 2010, 2010, S., doi : 10.4061 / 2010/606802 , PMID 20721349 , PMC 2915796 (free full text).