Share on Facebook Share on Twitter Email
Answers.com

cerebrospinal fluid

 
American Heritage Dictionary:

cerebrospinal fluid

Home > Library > Literature & Language > Dictionary

n. (Abbr. CSF)
The serumlike fluid that circulates through the ventricles of the brain, the cavity of the spinal cord, and the subarachnoid space, functioning in shock absorption.


Search unanswered questions...

Enter a question here...
Search: All sources Community Q&A Reference topics

Britannica Concise Encyclopedia:

cerebrospinal fluid

Top
Home > Library > Miscellaneous > Britannica Concise Encyclopedia

Clear, colourless liquid that surrounds the brain and spinal cord and fills the spaces in them. It helps support the brain, acts as a lubricant, maintains pressure in the skull, and cushions shocks. Analysis of CSF obtained by a spinal tap (lumbar puncture) helps diagnose a number of disorders, including meningitis and hemorrhage in the central nervous system.

For more information on cerebrospinal fluid, visit Britannica.com.

Oxford Companion to the Body:

cerebrospinal fluid

Top
Home > Library > Health > World of the Body

The brain floats on a liquid cushion of cerebrospinal fluid (CSF) within the rigid bony skull. The CSF is contained between layers of the meninges, the membranes that enclose the brain. It fills the subarachnoid space between the delicate arachnoid mater that lines the tough fibrous outer covering, the dura mater, and the pia mater that covers the soft substance of the brain.

A diagrammatic vertical section through the brain showing the location of the ventricles and the direction of flow of cerebrospinal fluid (CSF). CSF is formed by the choroid plexuses (CP), mainly in the lateral ventricles, and drains into the blood via the arachnoid villi and the spinal nerve roots
A diagrammatic vertical section through the brain showing the location of the ventricles and the direction of flow of cerebrospinal fluid (CSF). CSF is formed by the choroid plexuses (CP), mainly in the lateral ventricles, and drains into the blood via the arachnoid villi and the spinal nerve roots



Since the brain floats in CSF, the fluid acts in effect to reduce the weight of the brain from some 1000 g to about 50 g, and also protects the brain from knocks on the head. However, since the brain can move within the CS, it can be damaged on the opposite side by a sudden deceleration such as in a car accident (contra coup injury).

The subarachnoid space on the outside of the brain is in continuity with a similar space around the spinal cord and also with the series of interconnected cerebral ventricles within the brain (see figure). Each of the paired lateral ventricles, in the cerebral hemispheres, contains a leaf-like, highly vascular choroid plexus. It is from these structures that the bulk of the CSF is secreted. From the lateral ventricles CSF drains into the central third ventricle, and thence through the aqueduct in the midbrain into the fourth ventricle. Both the third and fourth ventricles contribute to the flow from their own choroidal tissue. From the fourth ventricle, the CSF exits into the subarachnoid space through several openings, and fills the ‘basal cisterns’ beneath the brain. Thence the flow of CSF is mainly up and over the whole brain surface, whilst some flows down around the spinal cord. Completing the circuit back to the bloodstream, the fluid drains via the valve-like arachnoid granulations into the sagittal sinus, the large venous channel lying centrally on the top of the brain; some is also taken up into veins around spinal nerve roots and into the lymphatics of the nose.

The secretion of CSF is an active transport process that moves fluid and solutes from the blood plasma into the ventricles, the choroid plexuses being a specialized part of the blood-brain barrier. CSF secretion involves the pumping of ions and specialized ion channels, with the energy coming from glucose and oxygen in the blood. In the adult human CSF is formed at a rate of about 0.5 ml/min; the total volume is about 200 ml, of which 30 ml is in the ventricles and the remainder in the subarachnoid space. The circulation of CSF leads to the fluid being completely replaced about every 4 hours.

CSF is a weak salt solution with similar inorganic ion concentrations to plasma, but with small and significant differences, whereas the protein content is about 100 times less than that of plasma (0.5 g/litre compared to 50-70 g/litre). Abnormalities of the CSF can be important in diagnosis of some medical conditions; the fluid can be sampled by lumbar puncture from the extension of the subarachnoid space (the lumbar sac) below the lower end of the spinal cord. CSF is normally a clear, amazingly ‘bright’ fluid, and if it is cloudy or contains a raised level of protein or traces of blood this is usually an indication of brain infection, some types of brain or spinal cord tumour, or trauma.

The pressure within the brain, the intracranial pressure (ICP), is transmitted in the CSF around the spinal cord and down into the lumbar sac. With the body horizontal, it is normally low (about 10 cm H2O) ; it is markedly affected by posture, and raised by straining or coughing.

Blockage in the drainage pathways for CSF is one of the causes of a raised ICP, since the CSF is actively ‘pumped’ into the ventricular system. In an adult this raised pressure can cause expansion of the ventricles, with loss of neural tissue by compression against the rigid skull. In infants, when CSF drainage pathways have failed to develop normally, the raised ICP causes the head to swell because the junctions between the skull bones are not fused, resulting in hydrocephalus — ‘water on the brain’.

A raised intracranial pressure can often be recognized by looking into the eye with an ophthalmoscope, an instrument which shines a beam of light on to the retina at the back of the eye. The beam is focused onto the ‘optic disc’, where the nerves of the eye converge to pass to the brain. Normally this appears as a clearly-defined, pale concave disc, but if the pressure in the CSF is raised, the disc may bulge forwards into the cavity of the eye. As well as by blockage of CSF circulation, raised pressure can be caused by an expanding tumour or blood clot, or by swelling of a damaged or diseased brain.

The CSF also acts as a drainage route for waste products of brain metabolism, additional to their direct excretion into the capillary blood vessels everywhere in the brain across the blood-brain barrier.

— Malcolm Segal

See also blood-brain barrier; hydrocephalus; meninges.

Oxford Dictionary of Biochemistry:

cerebrospinal fluid

Top
Home > Library > Science > Biochemistry Dictionary

abbr.:CSF; a clear fluid, containing little protein and few cells, that fills the subarachnoid space and ventricles of the brain, and the central canal of the spinal cord. About 80% of the protein is derived from plasma, the rest is brain-specific and includes myelin basic protein, glial fibrillary acid protein, creatine kinase (BB isozyme), and neuronal enolase.

Previous:cerebroside-sulfatase, cerebroside, cerebronate
Next:cerebrotendinous xanthomatosis, ceroid, ceroid lipofuscinosis
Mosby's Dental Dictionary:

cerebrospinal fluid

Top
Home > Library > Health > Dental Dictionary

n

The fluid that flows through and protects the four ventricles of the brain, subarachnoid space, and spinal canal.

Random House Word Menu:

categories related to 'cerebrospinal fluid'

Top
Home > Library > Literature & Language > Word Menu Categories
Random House Word Menu by Stephen Glazier
For a list of words related to cerebrospinal fluid, see:
Wikipedia on Answers.com:

Cerebrospinal fluid

Top
Home > Library > Miscellaneous > Wikipedia
4 vials of CSF

Cerebrospinal fluid (CSF), Liquor cerebrospinalis, is a clear, colorless, bodily fluid, that occupies the subarachnoid space and the ventricular system around and inside the brain and spinal cord. In essence, the brain "floats" in it.

The CSF occupies the space between the arachnoid mater (the middle layer of the brain cover, meninges), and the pia mater (the layer of the meninges closest to the brain). It constitutes the content of all intra-cerebral (inside the brain, cerebrum) ventricles, cisterns, and sulci (singular sulcus), as well as the central canal of the spinal cord.

It acts as a "cushion" or buffer for the cortex, providing a basic mechanical and immunological protection to the brain inside the skull.

It is produced in the choroid plexus.

Contents

Circulation

MRI showing pulsation of CSF

CSF is produced in the brain by modified ependymal cells in the choroid plexus (approx. 50-70%), and the remainder is formed around blood vessels and along ventricular walls. It circulates from the lateral ventricles to the foramen of Monro (Interventricular foramen), third ventricle, aqueduct of Sylvius (Cerebral aqueduct), fourth ventricle, foramen of Magendie (Median aperture) and foramina of Luschka (Lateral apertures); subarachnoid space over brain and spinal cord. CSF is reabsorbed into venous sinus blood via arachnoid granulations.

It had been thought that CSF returns to the vascular system by entering the dural venous sinuses via the arachnoid granulations (or villi). However, some[1] have suggested that CSF flow along the cranial nerves and spinal nerve roots allow it into the lymphatic channels; this flow may play a substantial role in CSF reabsorbtion, in particular in the neonate, in which arachnoid granulations are sparsely distributed. The flow of CSF to the nasal submucosal lymphatic channels through the cribriform plate seems to be especially important.[2]

Amount and constitution

Intracranial volumetric distribution of cerebrospinal fluid, blood, and brain parenchyma
Volumetric distribution of cerebrospinal fluid

The CSF is produced at a rate of 500 ml/day. Since the brain can contain only 135 to 150 ml, large amounts are drained primarily into the blood through arachnoid granulations in the superior sagittal sinus. Thus the CSF turns over about 3.7 times a day. This continuous flow into the venous system dilutes the concentration of larger, lipid-insoluble molecules penetrating the brain and CSF.[3]

The CSF contains approximately 0.3% plasma proteins, or approximately 15 to 40 mg/dL, depending on sampling site.[4]

CSF pressure, as measured by lumbar puncture (LP), is 10-18 cmH2O (8-15 mmHg or 1.1-2 kPa) with the patient lying on the side and 20-30cmH2O (16-24 mmHg or 2.1-3.2 kPa) with the patient sitting up.[5] In newborns, CSF pressure ranges from 8 to 10 cmH2O (4.4–7.3 mmHg or 0.78–0.98 kPa). Most variations due to coughing or internal compression of jugular veins in the neck. When lying down, the cerebrospinal fluid as estimated by lumbar puncture is similar to the intracranial pressure.

There are quantitative differences in the distributions of a number of proteins in the CSF. In general, globular proteins and albumin are in lower concentration in ventricular CSF compared to lumbar or cisternal fluid.[6]

The IgG index of cerebrospinal fluid is a measure of the immunoglobulin G content, and is elevated in multiple sclerosis. It is defined as:
IgG index = (IgGCSF / IgGserum ) / (albuminCSF / albuminserum)[7]
A cutoff value has been suggested to be 0.73, with a higher value indicating presence of multiple sclerosis.[7]

Reference ranges

Reference ranges for ions and metals in CSF
Substance Lower limit Upper limit Unit Corresponds to % of that in plasma
Osmolality 280[8] 300[8] mmol/L
Sodium 135[8] 150[8] mmol/L
Potassium 2.6[8] 3.0[8] mmol/L
Chloride 115[8] 130[8] mmol/L >100%[8]
Calcium 1.00[8] 1.40[8] mmol/L ~50%[8]
Magnesium 1.2[8] 1.5[8] mmol/L >100%[8]
Iron 0.2[8] 0.4[8] µmol/L
Reference ranges for other molecules in CSF
Substance Lower limit Upper limit Unit Corresponds to % of that in plasma
Glucose 50[9] 80[9] mg/dL ~60%[8]
2.2,[10] 2.8[8] 3.9,[10] 4.4[8] mmol/L
Protein 15[8][9] 40,[4] 45[8][9] mg/dL ~1%[8]
Albumin 7.8[11] 40[11] mg/dL 0[12] - 0.7[12]
- this fraction is called the albumin (CSF/serum) quotient
Lactate 1.1[8] 2.4[8] mmol/L
Creatinine 50[8] 110[8] µmol/L
Phosphorus 0.4[8] 0.6[8] µmol/L
Urea 3.0[8] 6.5[8] mmol/L
Carbon dioxide 20[8] 25[8] mmol/L
Reference ranges for other CSF constituents
Substance Lower limit Upper limit Unit Corresponds to % of that in blood plasma
RBCs n/a[9] 0[9] / negative cells/µL or
cells/mm3
WBCs 0[9] 3[9] cells/µL
cells/mm3
pH 7.28[8] 7.32[8] (unitless)
PCO2 44[8] 50[8] mmHg
5.9[13] 6.7[13] kPa
PO2 40[8] 44[8] mmHg
5.3[13] 5.9[13] kPa


Functions

CSF serves four primary purposes:

  1. Buoyancy: The actual mass of the human brain is about 1400 grams; however, the net weight of the brain suspended in the CSF is equivalent to a mass of 25 grams.[14] The brain therefore exists in neutral buoyancy, which allows the brain to maintain its density without being impaired by its own weight, which would cut off blood supply and kill neurons in the lower sections without CSF.[15]
  2. Protection: CSF protects the brain tissue from injury when jolted or hit. In certain situations such as auto accidents or sports injuries, the CSF cannot protect the brain from forced contact with the skull case, causing hemorrhaging, brain damage, and sometimes death.[15]
  3. Chemical stability: CSF flows throughout the inner ventricular system in the brain and is absorbed back into the bloodstream, rinsing the metabolic waste from the central nervous system through the blood-brain barrier. This allows for homeostatic regulation of the distribution of neuroendocrine factors, to which slight changes can cause problems or damage to the nervous system. For example, high glycine concentration disrupts temperature and blood pressure control, and high CSF pH causes dizziness and syncope.[15]
  4. Prevention of brain ischemia: The prevention of brain ischemia is made by decreasing the amount of CSF in the limited space inside the skull. This decreases total intracranial pressure and facilitates blood perfusion.

Pathology and laboratory diagnosis

Cerebrospinal fluid (CSF) at glance.

When CSF pressure is elevated, cerebral blood flow may be constricted. When disorders of CSF flow occur, they may therefore affect not only CSF movement but also craniospinal compliance and the intracranial blood flow, with subsequent neuronal and glial vulnerabilities. The venous system is also important in this equation. Infants and patients shunted as small children may have particularly unexpected relationships between pressure and ventricular size, possibly due in part to venous pressure dynamics. This may have significant treatment implications, but the underlying pathophysiology needs to be further explored.

CSF connections with the lymphatic system have been demonstrated in several mammalian systems. Preliminary data suggest that these CSF-lymph connections form around the time that the CSF secretory capacity of the choroid plexus is developing (in utero). There may be some relationship between CSF disorders, including hydrocephalus and impaired CSF lymphatic transport.

CSF can be tested for the diagnosis of a variety of neurological diseases.[16] It is usually obtained by a procedure called lumbar puncture. Removal of CSF during lumbar puncture can cause a severe headache after the fluid is removed, because the brain hangs on the vessels and nerve roots, and traction on them stimulates pain fibers. The pain can be relieved by intrathecal injection of sterile isotonic saline. Lumbar puncture is performed in an attempt to count the cells in the fluid and to detect the levels of protein and glucose. These parameters alone may be extremely beneficial in the diagnosis of subarachnoid hemorrhage and central nervous system infections (such as meningitis). Moreover, a CSF culture examination may yield the microorganism that has caused the infection. By using more sophisticated methods, such as the detection of the oligoclonal bands, an ongoing inflammatory condition (for example, multiple sclerosis) can be recognized. A beta-2 transferrin assay is highly specific and sensitive for the detection for, e.g., CSF leakage.

Cause Appearance Polymorphonuclear cell Lymphocyte Protein Glucose
Pyogenic bacterial meningitis Yellowish, turbid Markedly increased Slightly increased or Normal Markedly increased Decreased
Viral meningitis Clear fluid Slightly increased or Normal Markedly increased Slightly increased or Normal Normal
Tuberculous meningitis Yellowish and viscous Slightly increased or Normal Markedly increased Increased Decreased
Fungal meningitis Yellowish and viscous Slightly increased or Normal Markedly increased Slightly increased or Normal Normal or decreased

Lumbar puncture

Lumbar puncture can also be performed to measure the intracranial pressure, which might be increased in certain types of hydrocephalus. However a lumbar puncture should never be performed if increased intracranial pressure is suspected because it could lead to brain herniation and ultimately death.

Baricity

This fluid has an importance in anesthesiology. Baricity refers to the density of a substance compared to the density of human cerebral spinal fluid. Baricity is used in anesthesia to determine the manner in which a particular drug will spread in the intrathecal space.

Alzheimer's disease

A 2010 study showed analysis of CSF for three protein biomarkers can indicate the presence of Alzheimer's disease. The three biomarkers are CSF amyloid beta 1-42, total CSF tau protein and P-Tau181P. In the study, the biomarker test showed good sensitivity, identifying 90% of persons with Alzheimer's disease, but poor specificity, as 36% of control subjects were positive for the biomarkers. The researchers suggested the low specificity may be explained by developing but not yet symptomatic disease in controls.[17][18]

See also

References

  1. ^ Zakharov A, Papaiconomou C, Djenic J, Midha R, Johnston M (2003). "Lymphatic CSF absorption pathways in neonatal sheep revealed by sub arachnoid injection of Microfil". Neuropathol. Appl. Neurobiol. 29 (6): 563–73. doi:10.1046/j.0305-1846.2003.00508.x. PMID 14636163. 
  2. ^ Johnston M (2003). "The importance of lymphatics in cerebrospinal fluid transport". Lymphat. Res. Biol. 1 (1): 41–4. doi:10.1089/15396850360495682. PMID 15624320. 
  3. ^ Saunders NR, Habgood MD, Dziegielewska KM (1999). "Barrier mechanisms in the brain, I. Adult brain". Clin. Exp. Pharmacol. Physiol. 26 (1): 11–9. doi:10.1046/j.1440-1681.1999.02986.x. PMID 10027064. 
  4. ^ a b Felgenhauer K (1974). "Protein size and CSF composition". Klin. Wochenschr. 52 (24): 1158–64. doi:10.1007/BF01466734. PMID 4456012. 
  5. ^ THE NORMAL CSF from Chapter Fourteen - Cerebrospinal Fluid. Neuropathology. By Dimitri Agamanolis, Northeast Ohio Medical University . Updated: May, 2011
  6. ^ Merril CR, Goldman D, Sedman SA, Ebert MH (March 1981). "Ultrasensitive stain for proteins in polyacrylamide gels shows regional variation in cerebrospinal fluid proteins". Science 211 (4489): 1437–8. doi:10.1126/science.6162199. PMID 6162199. 
  7. ^ a b Hische, E. A.; Van Der Helm, H. J.; Van Walbeek, H. K. (1982). "The cerebrospinal fluid immunoglobulin G index as a diagnostic aid in multiple sclerosis: A Bayesian approach". Clinical chemistry 28 (2): 354–355. PMID 7055958.  edit
  8. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am PATHOLOGY 425 CEREBROSPINAL FLUID [CSF] at the Department of Pathology and Laboratory Medicine at the University of British Columbia. By Dr. G.P. Bondy. Retrieved November 2011
  9. ^ a b c d e f g h Normal Reference Range Table from The University of Texas Southwestern Medical Center at Dallas. Used in Interactive Case Study Companion to Pathologic basis of disease.
  10. ^ a b Department of Chemical Pathology at the Chinese University of Hong Kong, in turn citing: Roberts WL et al. Reference Information for the Clinical Laboratory. In Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, 4th edn. Burtis CA, Ashwood ER and Bruns DE eds. Elsevier Saunders 2006; 2251 - 2318
  11. ^ a b Lab Manual for SFGH > PROTEIN, CSF - IgG INDEX at The University of California, San Francisco. Last updated 10/4/2010.
  12. ^ a b Standardization of procedures and methods in neuroimmunology from the Italian Association of Neuroimmunology. Retrieved January, 2012
  13. ^ a b c d Derived from mmHg values using 0.133322 kPa/mmHg
  14. ^ Noback, Charles; Norman L. Strominger, Robert J. Demarest, David A. Ruggiero (2005). The Human Nervous System. Humana Press. p. 93. ISBN 978-1588290403. 
  15. ^ a b c Saladin, Kenneth (2007). Anatomy and Physiology: The Unity of Form and Function. McGraw Hill. p. 520. ISBN 978-0-07-287506-5. ,
  16. ^ Seehusen DA, Reeves MM, Fomin DA (September 2003). "CSF analysis". Am Fam Physician 68 (6): 1103–8. PMID 14524396. http://www.aafp.org/afp/20030915/1103.html. 
  17. ^ De Meyer, Geert et al (August 2010). "Diagnosis-Independent Alzheimer Disease Biomarker Signature in Cognitively Normal Elderly People". Archive of Neurology 67 (8): 949–56. doi:10.1001/archneurol.2010.179. PMC 2963067. PMID 20697045. http://archneur.ama-assn.org/cgi/content/short/67/8/949. Retrieved 2010-09-08. 
  18. ^ Herskovits, A. Zara; Growdon, John H. (August 2010). "Sharpen That Needle (editorial)". Archive of Neurology 67 (8): 918–20. doi:10.1001/archneurol.2010.151. PMID 20697041. http://archneur.ama-assn.org/cgi/content/extract/67/8/918. Retrieved 2010-09-08. 
Wikimedia Commons has media related to: Cerebrospinal fluid
Layers
Combined
Spaces
Epidural space · Subdural space · Subarachnoid space (Cerebrospinal fluid)


External links


This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

 
 

 

Copyrights:

American Heritage Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
Britannica Concise Encyclopedia. Britannica Concise Encyclopedia. © 1994-2012 Encyclopædia Britannica, Inc. All rights reserved.  Read more
Oxford Companion to the Body. The Oxford Companion to the Body. Copyright © 2001, 2003 by Oxford University Press. All rights reserved.  Read more
 Oxford Dictionary of Biochemistry. Oxford University Press. Oxford Dictionary of Biochemistry and Molecular Biology © 1997, 2000, 2006 All rights reserved.  Read more
Saunders Veterinary Dictionary. Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.  Read more
Mosby's Dental Dictionary. Mosby's Dental Dictionary. Copyright © 2004 by Elsevier, Inc. All rights reserved.  Read more
Random House Word Menu. © 2010 Write Brothers Inc. Word Menu is a registered trademark of the Estate of Stephen Glazier. Write Brothers Inc. All rights reserved.  Read more
Wikipedia on Answers.com. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article Cerebrospinal fluid.  Read more

Related answers
» More
Answer these
» More
Follow us
Facebook Twitter
YouTube