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CSF Information

CSF PPT

QuestionAnswer
Where is CSF found? In sub-arachnoid space & ventricles of brain
Functions of CSF Preserve homeostasis (reservoir, nourishes brain tissue); Buoyancy for brain; Drains brain of unwanted stuff; Cushion; Path for pineal secretions to get to pituitary
Where is CSF formed? Choroid Plexuses
CSF pH Lower than blood pH
CSF Production Continuously produced, even if resorption rates decrease
Main Sites of CSF Absorption Arachnoid villi; Dural venous sinuses (esp sup. sagittal sinus)
What causes absorption into venous sinuses? CSF Pressure > Venous Sinus Pressure; Rate of absorption of CSF thru arachnoid villi controls CSF pressure
Sub-Arachnoid Extensions Around optic n. to back of eyeball; Arachnoid & pia mater fuse to sclera; Central a. & v. of retina cross extension to enter optic n. & may be compressed in pts with increased CSF pressure
Cisterns Brain surface separated from skull
Where are some major cisterns? Cistern cerebellomedullaris (cesterna magna); Medullary cistern; Cisterna pontis; Cisterna interpeduncularis; Quadrigeminal (superior) cistern; Chiasmatic
Where is the limit of sub-arachnoid space? S2
Permeability of B-B Barrier/Blood-CSF Barrier? Inversely related to size of molecules, directly related to lipid solubility; Gases/water pass quickly; Glucose, electrolytes pass slower; Not permeable: plasma proteins, large organic molecules
Tight Junctions Hard for things to pass through
What population has an increased permeability? Newborns
Where is the blood-CSF barrier? Choroid plexus; tight junctions b/c choroidal epithelial cells = barrier
What 3 structures separate CSF from nervous tissue? Pia- covered surface of brain & SC; Perivascular extensions of sub-arachnoid space into nervous tissue; Ependymal surface of ventricles- lines ventricles
What are intercellular channels? Free communication b/t ventricular cavity & extracellular neuronal space
What is the importance of barriers? 2 important semi-permeable barriers protect brian/SC from potentially harmful substances; Permit gases & nutrients to enter nervous tissue
B-B Barrier readily absorbs what? Glucose & Oxygen
Brain capillaries possess what? Tight junctions; Few pinocytotic vessels (fluid pockets); Foot processes of astrocytes encasing capillaries; Lots of mitochondria
Barrier Permeability Likes: small molecules, carrier-mediated substances (transported by proteins), highly soluble lipid substances HATES: substances bound to serum proteins; larger proteins
What causes brain edema? Increased brain volume due to increased water & sodium
Vasogenic Edema Most common; Due to increased permeability of brain capillary endothelial cells to large molecules
Cellular (Cytotoxic) Edema Swelling of cell elements of the brain with accompanying decrease in volume of extracellular space
Interstitial (Hydrocephalic) Edema Increased water and sodium in peri-ventricular white matter b/c of mvmt of CSF across ventricular walls
What can brain edema cause? Gyri flattening, brain herniation through tentorial notch or foramen magnum, or death
Papilledema Increase in CSF pressure due to tumor: compression of thin walls of retinal vein -> congestion of vein, bulging of optic disc & papilledema; Persisten papilledema- optic n. atrophy/death, blindness
Hydrocephalus Abnormal increase in CSF volume
If hydrocephalus accompanied by increased ICP it's due to? Abnormal increase in CSF formation; Blockage of CSF circulation; Decreased absorption- b/c of inflammatory exudate, venous thrombosis, venous sinus pressure, int. jugular v. obstruction
What happens with obstructed IV foramen? Blocks drainage of lateral ventricle which leads to distended ventricle & atrophy of surrounding neuronal tissue
What happens with obstructed cerebral aqueduct (congenital, b/c of tumor pressure)? Symmetrical dilation of both lateral ventricles & 3rd ventricle; Obstruciton of foramen of Magendia & foramina of Luschka b/c of inflammatory exudate or tumor growth will produce symmetrical distention of all ventricles
What happens with hydrocephalus secondary to meningitis? Inflammatory exudate blocks sub-arachnoid space with obstructed flow over outer surface or cerebral hemispheres; entire ventricular system would become distended
Non-Communicating Hydrocephalus Increased pressure b/c of blockage
Communicating Hydrocephalus No obstruction within or to outflow CSF- sub-arachnoid space under normal pressure Normal- pressure disorder characterized by tried
Triad that comes with communicating hydrocephalus Dementia; Unsteady gait; Urinary incontinence
Tumor of SC/Meninges Flow of CSF blocked, normal variation in pressure corresponding to pulse-respiration are decreased/absent during lumbar puncture
Compression of Internal Jugular vv in neck Increased cerebral venous pressure & inhibits CSF absorption in arachnoid villi & granulations- increased CSF pressure during lumbar puncture
Tumor completely occupying vertebral canal near cauda equina No flow of CSF during lumbar puncture
What kind of drugs enter the brain faster/better? Lipid-Bound
Any obstruction to normal passage of CSF causes? Increased fluid in ventricles; General ICP; Swelling of optic n. (papilledema)
S/sx of Brain Tumor Persistent HA & vomiting, usually worse in morning May be improved by sitting/standing (Gravity drains CSF)
BS/cblm tumors Close to ventricles, so can cause increased ICP when relatively small; +/- papilledema
4th Ventricle Tumors May arise in vermis or pons & invade 4th ventricle or ependymoma Pt will display s/sx cblr deficiency Pressure on vital BS centers in floor of 4th ventricle (medulla)
Created by: 1190550002