1 Chapter 9 Cerebrospinal Fluid Professor A. S. Alhomida Disclaimer The texts, tables, figures and images contained in this course presentation (BCH 376) are not my own, they can be found on: References supplied Atlases or The web King Saud University College of Science Department of Biochemistry

2 2 Cerebrospinal Fluid 1.Cerebrospinal fluid (CSF) is a clear fluid present in the ventricles of the brain, the central canal of the spinal cord, and the subarachnoid space 2.Normal: almost no blood cells, little protein

3 3 3.Its rate of formation, flow, and absorption is sufficiently high to cause its replacement several times daily Measuring its pressure, performing cell counts, and analyzing levels of various biochemical constituents is accomplished with a spinal tap Cerebrospinal Fluid, Cont’d

4 4 4.An understanding of the formation, flow, and absorption of CSF is essential to an understanding of these diagnostic procedures and the pathophysiology of hydrocephalus Cerebrospinal Fluid, Cont’d

5 5 1.A clear, colorless fluid that surrounds and permeates the CNS. Offers support, protection and nourishment 2.Functions: Protection of cranial contents Modulates pressure changes (same specific gravity as brain) Serves as a chemical buffer to maintain constant ionic environment Serves as a transport medium for nutrients and metabolites, endocrine substances and even neurotransmitters Cerebrospinal Fluid, Cont’d

6 6 Location of Cerebrospinal Fluid Two lateral ventricles Third ventricle Fourth ventricle Spinal cord central canal Subarachnoid space Continuous with extracellular fluid of brain parenchyma

7 7 Location of Cerebrospinal Fluid, Cont’d

8 8 Choroid plexuses of lateral, third and fourth ventricles Ependymal lining of ventricular system Pia-glial membrane Blood vessels Formation of Cerebrospinal Fluid

9 9 Cells are believed to actively secrete Na + into the ventricular system in exchange for K +. Sodium ions electrically attract Cl - and osmotically draw water from the blood vascular system to constitute the CSF Formation of Cerebrospinal Fluid, Cont’d

10 Cerebrospinal fluid collection

11 Composition of Cerebrospinal Fluid

12 Clinical Significance of Cerebrospinal Fluid, Cont’d

13 Clinical Significance of Cerebrospinal Fluid, Cont’d

14 Correlation of Cerebrospinal Fluid and Serum

15 Diagnostic of Cerebrospinal Fluid

16 Clinical Significance of Cerebrospinal Fluid Tests

17 Blood-Brain Barrier Direct injection of large molecules (e.g., a dye) into the venous system will often penetrate all tissues except the brain. This observation led to the notion of a physiological barrier to flow of substances from blood to brain tissue – the blood brain barrier The BBB functions to preserve a stable environment for neurons and glia of the CNS

18 Blood-Brain Barrier, Cont’d 1.Lipid soluble molecules will cross 2.Negatively charged molecules cross more freely than positively charged ones 3.High CO 2 /low O 2 produce vasodilation and decrease resistance of BBB 4.Injury or inflammation decreases resistance of BBB (allows some antibiotics to be used for treatment)

19 5.Selected brain areas are not protected by the BBB – the circumventricular organs (CVO) bordering on the 3 rd and 4 th ventricles parts of the hypothalamus - median eminence Neurohypophysis pineal gland area postrema subfornical organ subcommissural organ Blood-Brain Barrier, Cont’d

20 Blood – CSF Barrier 1.Barrier from blood to the CSF 2.Similar structural mechanism to the BBB

21  -Globulins in CSF 1.Recently considerable interest has been focused on the CSF changes of  –globulins in multiple sclerosis 2.In multiple sclerosis there is a predominant increase in IgM and oligoclonal  –globulin bands derived from plasma cells and lymphocytes are often present 3.In multiple sclerosis, the IgM antibodies may be antimyelin which accumulate in plasma of de-myelination

22 Index of  –Globulins 1.Attempts has been made to define an index which would give good discrimination between multiple sclerosis and neurosyphilis in one hand and other neurological conditions on the other 2.After estimation of  -globulins by standard method, it is expressed as percent (%) of CSF proteins 3.Above 29% has been suggested as indicating multiple sclerosis and nuerosyphilis

23 THE END Any questions ?