CSF Flashcards
What produces CSF and where is it produced?
In the lateral fissure by the choroid plexus.
Secretion by choroidial epitelium and important molecules such as glucose are filtrated from the capillarys across the choroidal membrane composed of the epithelial cells.
What are the names of the walls in the brain?
Falx cerebri, falx cerebelli and tentorium cerebelli
What is the pathway for CSF after production?
It moves from the lateral ventricle through the foramen of munro into the third ventricle. Here it moves through the cerrebral aquaduct to the fourth ventricle ad then out the foramen into the subarachnoid space and around the brain ad spinal cord.
How is CSF absorbed?
Through projections of arachnoid villi throug the inner layr of the duramata into the superior sagital sinus so that it is back into the blood low. It is done by drostatic pressure.
What is the composition of healthy CSF
<5x10^6 WBC No RBC No neutrophls protein <0.45 g/l Glucose >2.5 mmol/l
What is the composition of CSF in meningitis patients?
Increase WBC
Increase protein
Decrease glucose
What changes to the composition of CSF in subarachnoid haemorrhage patients?
Increase RBC
Xanthochromia - change of colour due to breakdown of RBC.
What is the function of CSF?
Homeostasis of environment for neurons and glia.
Mechanical cushion for the brain
Counters sudden intracranial pressure increase
What are the features of the blood brain barrier?
Specialised endothelial cells
Thick basement membrane
Astrocytic processes
Endothelial cells have many mitochrondria to facilitate active transport f essential molecules that cant diffuse passively
What affects the passage of molecules across the BBB?
Molecule size Lipid solubility Ionization Protein binding Specific transport mechanism - active or diffusion
What can damage or change the BBB?
Meningitis can breakdown the BBB allowing WBCs and protein into the CSF.
A tumour may produce normal endothelial cells causing leaky blood vessels and oedma
What is the normal CF pressure?
65-200 mmCSF
What is the Monro-Kellie doctrine for ICP?
There are 3 component of the inracranial contents.
CSF (75 ml), brain 1500 ml and blood 75 ml
But the intracranial volume is fixed so if you increase the volume of one then another must be reduced. If not then the ICP is increased.
What is cushing’s triad for detecting elevated intracranial pressure?
Decreased respiratory rate
Slow heart rate
Arterial hypertension
Caused by reduced blood flow to the medulla
What are the types of herniations you can get in the brain?
Trans tentoial herniation: Medial temporal lobe herniating under the tentorium cerebelli (tentorial notch) - puts pressure on the midbrain and brain can be pressed to the ridge of the tentorium on the other side, posterior cerebellar ateries can be compressed causing infarction of the occipital lobes, third cranial nerve can be compressed (dilated pupil).
Cerebellar tonsil herniation. Herniation of the posterior part of the cerebellum into the foramen magnum - medulla and upper spinal cord compression.
