Cerebrospinal fluid

The cerebrospinal fluid ( cerebrospinal fluid, cerebrospinal fluid, CSF, non- technical terminology also " nervous water " ) is a clear, colorless bodily fluid, which communicates with the brain tissue in combination and therefore is also very similar in composition. Discoverer of the cerebrospinal fluid and its communication paths is François Magendie. The cerebrospinal fluid is formed by specially differentiated epithelial cells of the choroid plexuses of the cerebral ventricles.

• 7.1 Macroscopic assessment

Composition

Normal cerebrospinal fluid is water- clear, colorless and contains very few cells. Most of them are lymphocytes (up to 3 per microliter CSF ) and in rare cases also monocytes. Lymphocytes are predominantly T- lymphocytes, only about 1% of the lymphocytes are B-lymphocytes in the cerebrospinal fluid ( however, the proportion of B lymphocytes at all lymphocytes in the blood, about 5-10%). The protein content of the cerebrospinal fluid is present from about 0.15 to 0.45 grams per liter of liquor, well below the average protein content of the serum (75 g per liter). This property can be used to diagnose a disorder of the blood -cerebrospinal fluid barrier by means of a parallel measurement in CSF and serum albumin. The normal sugar content is 50 to 70% of the serum blood glucose level.

Pressure

The CSF pressure while lying in typical measurement according to the riser principle by means of lumbar puncture on the cross is physiologically 70 to 220 mmH2O ( = about 690-2160 Pa) and varies rhythmically up to 20 mmH2O ( about 200 Pa) as a function of heart rate, breathing type ( pressed or relaxed ) and the type of lying.

Anatomy

We distinguish an outer CSF space of an inner subarachnoid space.

Outside subarachnoid

The spinal canal ( vertebral canal ) located in the spinal cord as well as the skull (cranium ) into the brain are surrounded by two soft ( pia mater and arachnoid, Leptomeninges ), as well as a hard brain or spinal cord ( dura mater, pachymeninx ). Between the two soft meninges there is a gap called the subarachnoid space and which is circulated through the cerebrospinal fluid.

Inner subarachnoid

In the spinal cord, the central canal ( canalis centralis ) is a remnant of the lumen of the embryonic neural tube, but for the drainage of the cerebrospinal fluid is no longer important. A frequently occurring closure of the central canal and therefore always remain without consequences. In the brain arises from the lumen of the neural tube one after another switched Liquorbildungs ​​and transport system in the form of four cerebral ventricles:

• Two lateral ventricles ( lateral ulcer ) in the telencephalon ( cerebrum )
• A third ventricle ( ventriculus tertius ) in the diencephalon ( diencephalon )
• A fourth ventricle ( ventriculus quartus ) in the rhombencephalon ( hindbrain )

The two lateral ventricles are available through the interventricular foramina ( foramen of Monro ) to the third combined. From there, the aqueduct ( aqueduct of midbrain ) moves to the fourth ventricle, which continues into the central canal of the spinal cord. The central nervous system arises mainly from the neural tube, the inner liquor spaces correspond to the lumen of the neural tube. The ventricular system is also about two Aperturae lateral ( foramina of Luschka ) and one median aperture ( foramen of Magendie ) with the subarachnoid space, the outer CSF space in conjunction.

Liquorbildung

Adult humans have, according to the volume of Liquorraumes, about 120 to 200 ml CSF. These are mostly formed in the ventricles of the specifically differentiated epithelial cells of the choroid plexus at a rate of about 0.3 to 0.4 ml per minute, mainly through an ultrafiltration of the blood. Occur per day about 500 to 700 ml CSF. To what extent ependymal cells are involved in the secretion, is still the subject of current research.

Liquorresorption

Since daily about 500-700 mL of CSF are formed, it must also be reabsorbed, otherwise increase the intracranial pressure continuously and hydrocephalus ( " water on the brain " ) would arise. The cerebrospinal fluid passes from the lateral ventricles via the respective interventricular foramen into the third ventricle, then through the aqueduct into the fourth ventricle and from there the one hand, in the central canal of the spinal cord and via the lateral apertures ( foramina of Luschka ) and the lower opening ( foramen of Magendie ) in the outer CSF, which corresponds to the subarachnoid space. For the absorption protrusions of the arachnoid are responsible for the rise in the skull into the venous sinuses of the dura mater and arachnoid villi ( Pacchioni granulations, arachnoid granulations ) are called. Analog located in the root sleeves that surround the spinal nerve roots, small protuberances over which the cerebrospinal fluid is filtered into veins.

In the area of ​​root pockets the arachnoid becomes the perineurium. Through this connection flow per hour from a few milliliters of cerebrospinal fluid along the cranial nerves and spinal nerves in the periphery, where it is absorbed through the lymphatic system.

Function of the cerebrospinal fluid

The main function of the cerebrospinal fluid is the padding of the brain and spinal cord. Nutritional function and participation in signaling cascades are disputed and also the subject of current research.

Diagnostics

Liquor can be obtained for diagnostic purposes by a puncture of the spinal canal ( Liquorentnahme ).

Such a puncture is especially in cases of suspected inflammation in the area of the nervous system is performed ( meningitis, encephalitis, encephalomyelitis, myelitis, polyradiculitis ), as for example in the context of the brain and / or spinal cord infection by bacteria, viruses, fungi, parasites or an autoimmune disease (e.g. multiple sclerosis) occurs. Smaller subarachnoid hemorrhage can sometimes only be detected by a CSF examination.

Inflammation of the brain tissue or the meninges ( meningitis) change the cerebrospinal fluid composition: The cell number increases ( pleocytosis ), the protein concentration increases, the sugar in the cerebrospinal fluid from drops, lactate increases. Furthermore, it is in the CSF relative to the blood in an increase of the immunoglobulins. This is determined using the driver - diagram.

In addition to an increase in cell number may change due to pathological processes and the composition of the cell compartment. So it is with bacterial meningitis in a massive invasion of neutrophils into the cerebrospinal fluid, while they are physiologically there not to be found. On the other hand wander in virally induced inflammatory processes preferred lymphocytes in the cerebrospinal fluid. Furthermore, the microscopically assessed cell morphology can provide useful data on the age and state of activation of cells.

Sometimes let the pathogens (bacteria, viruses) demonstrate directly. A viral infection can be seen often only indirectly through the CSF compared to the blood higher specific antibody concentration.

If tumor cells are detectable in the cerebrospinal fluid, it is an indication of a tumor involvement of the brain (meninges ). One then speaks of a neoplastic meningitis. Subgroups of neoplastic meningitis are carcinomatous meningitis, in leukemia or lymphoma meningitis leucemica a lymphomatous meningitis, for example, in cancer diseases.

Macroscopic assessment

For visual assessment of CSF directly after production, the "three -glass test " has proven. Here, the liquor is fractionated into three test tubes. So even with the extraction can be an artifact due to hemorrhaging from the site of injection differ in the puncture of a subarachnoid hemorrhage, when the last tube remains clear.

Are assessed turbidity and color. Normal CSF is clear and colorless. Are significantly increased leukocyte count exists, the cerebrospinal fluid is slightly cloudy to creamy / creamy. Greatly increased protein values ​​lead to a yellowish color. Similarly, the CSF appears yellowish in older subarachnoid hemorrhage, after the red blood components ( red blood cells ) have settled to the ground.

In this way, one can roughly but quickly obtain the following important information: