Subarachnoid space

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The subarachnoid space , also subarachnoid space ( Spatium subarachnoideum , Cavitas subarachnoidea , cavum subarachnoideale , cavum hyparachnoidicum or cavum leptomeningicum ), a gap-shaped space around the central nervous system ( brain and spinal cord ) between the two meninges arachnoid and pia mater . Since the cerebrospinal fluid ( liquor cerebrospinalis ) circulates in it, it is also referred to as the external liquor space . It is connected to the ventricular system, which is to be understood as the internal liquor space . The subarachnoid space continues along the vessels that pull into the brain from outside, known as the Virchow-Robin space (after Rudolf Virchow , 1821–1902, and Charles-Philippe Robin , 1821–1885) or the perivascular space .

Cisterns

The subarachnoid space is widened at the points where the specific shape of the brain requires greater distances from the skull capsule. They are called cisterns ( Cisternae subarachnoideae ). The cisternography is a specially adapted to these cisterns imaging technique .

Cisterna cerebellomedullaris

The cisterna cerebellomedullaris (also cisterna magna ) lies on the neck side between the cerebellum ( cerebellum ) and the spinal cord ( medulla spinalis ). This enlargement can be punctured through the gap between the occiput and atlas to remove the CSF . This suboccipital puncture is only performed in exceptional cases and the lumbar puncture is usually preferred.

Cisterna fossae lateralis cerebri

The Cisterna fossae lateralis cerebri (also: Cisterna valleculae lateralis cerebri ) is located on the cerebrum in the area of ​​the island between the temporal, parietal and frontal lobes of the cortex .

Cisterna chiasmatica

The cisterna chiasmatica lies on the underside of the diencephalon around the junction of the optic nerves ( chiasma opticum ).

Interpeduncular cistern

The interpeduncular cistern is located on the midbrain in the area of ​​the cerebral legs ( crura cerebri ). Cisterna interpeduncularis and Cisterna chiasmatica are collectively referred to as Cisterna basalis.

Quadrigeminal cistern

The quadrigeminal cistern is located in the area of ​​the four-hill plate ( lamina tecti ) on the dorsal midbrain. Cisterna quadrigeminalis and cisterna interpeduncularis are collectively referred to as cisterna ambiens, which includes the midbrain.

Cisterna pericallosa

The cisterna pericallosa is located between the surface of the beam ( corpus callosum ) and the lower edge of the cerebral sickle .

Cisterna pontocerebellaris superior

The superior pontocerebellar cistern is located on the lateral part of the bridge ( pons ) on the border with the cerebellum.

Cisterna pontocerebellaris inferior

The inferior pontocerebellar cistern lies in the cerebellopontine angle .

Cisterna ambiens

The cisterna ambiens is caudal to the third ventricle and to the side of the midbrain. It includes the posterior cerebral artery and the superior cerebellar artery .

Clinical Notes

The puncture of the CSF space to remove cerebrospinal fluid is mainly carried out in the lumbar spine area (lumbar cistern) ( lumbar puncture ). A puncture of the cerebellomedullary cistern is also possible, but far more risky, as structures of the brain stem can be injured here.

The injection of water - soluble X - ray contrast media into the subarachnoid space is used for X-ray imaging of the spinal canal and spinal cord structures ( myelography ). In certain cases, drugs are administered intrathecally , i.e. directly into the liquor space.

With subarachnoid hemorrhage , blood enters the subarachnoid space, where it mainly accumulates in the cisterns.

Perivascular space

When the arteries and veins enter the central nervous system (CNS) through the meninges, the subarachnoid space continues along a narrow space around the veins, the so-called perivascular space (space perivascular or Virchow-Robin space). This space has a central function in the disposal of waste in the CNS. Pathological expansions of these spaces can be represented by imaging methods , and it is being investigated (as of 2017) to what extent biomarkers for the early detection of neurodegenerative diseases can be developed as a result.

Functions in waste disposal of the brain

The perivascular space forms the start and end of the micro-cycle of the CNS for waste disposal, the glymphatic system discovered in 2012 . Through the perivascular space around the arteries - driven by the wave movements of the arterial walls triggered by the pulse - a small part of the cerebrospinal fluid from the subarachnoid space flows into all areas of the CNS.

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, presumably partly directly into the dura mater , namely into the collection vessels of the lymphatic system , the normal disposal system , which were only discovered there in 2015 the rest of the body. 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).

Potential clinical importance as a biomarker

Pathological expansions of perivascular spaces can be visualized by magnetic resonance imaging (MRI). Furthermore, indications have already been found that such widening can indicate minor vascular damage, an increased risk of stroke , and the development of dementia . For this reason, intensive research is being carried out (as of 2017) to what extent biomarkers for the detection of early signs of neurodegenerative diseases can be found in this way .

Individual evidence

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  4. ↑ Peter Reuter: Springer Lexicon Medicine. Springer, Berlin a. a. 2004, ISBN 3-540-20412-1 , p. 390.
  5. ^ 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).
  6. ↑ 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).
  7. ↑ RM Kwee, TC Kwee: Virchow-Robin spaces at MR imaging. In: Radiographics: a review publication of the Radiological Society of North America, Inc. Volume 27, Number 4, 2007 Jul-Aug, pp. 1071-1086, doi : 10.1148 / rg.274065722 , PMID 17620468 (review), PDF .
  8. ^ S. Groeschel, WK Chong, R. Surtees, F. Hanefeld: Virchow-Robin spaces on magnetic resonance images: normative data, their dilatation, and a review of the literature. In: Neuroradiology. Volume 48, Number 10, October 2006, pp. 745-754, doi : 10.1007 / s00234-006-0112-1 , PMID 16896908 (Review), PDF .
  9. ↑ J. Ramirez, C. Berezuk, AA McNeely, F. Gao, J. McLaurin, SE Black: Imaging the Perivascular Space as a Potential Biomarker of Neurovascular and Neurodegenerative Diseases. In: Cellular and molecular neurobiology. Volume 36, Number 2, March 2016, pp. 289-299, doi : 10.1007 / s10571-016-0343-6 , PMID 26993511 (Review), PDF .

Sources and literature