CSF and intercranial pressure Flashcards
what is CSF
cerebrospinal fluid
clear, colourless liquid
where is CSF found
ventricles and subarachnoid space
how much CSF is made per day
500ml, with 125ml circulating at a time
function of CSF
buoyancy (gross brain weight is 1.4-5kg, net weight is 25-50g)
protection from physical injury
maintenance of brain perfusion
homeostasis
clearing waste
how does CSF maintain brain perfusion
reduction in CSF production drops intercranial pressure encouraging cerebral perfusion
what is the Munro-Kellie doctrine
skull is a ‘bony box’, it contains 3 non-compressible elements (brain, blood and CSF)
increasing the volume of one component requires a reduction in one or both of the other components to maintain the same intercranial pressure
normal volumes of CSF, blood and brain parenchyma
CSF - 150ml
blood - 150ml
brain parenchyma - 1400ml
normal features of ICP and CSF
normal pressure range - 10-20cm h2o lying on side, 20-30cm h2o sitting up
composition- rbc=0, WBC<5/ul, protein 0.1-0.45g/l, glucose >50%blood level
special tests used for CSF
gram stain and culture
oxyhaemoglobin and bilirubin
oligoclonal bands
lumbar puncture (gives insight into brain)
what could elevated WBC suggest
meningitis or inflammatory nerve disease
what do RBCs in CSF suggest
brain bleed
features of high ICP
headache that is worse upon lying down, coughing, sneezing, stooping, straining)
visual obstructions (grey/black out with ICP spikes)
causes of high ICP
CSF overproduction
blocked CSF circulation
blocked CSF drainage
an increase in blood or brain tissue within the skull
cause of CSF overproduction
idiopathic intercranial hypertension
causes of blocked CSF circulation
obstruction due to physical mass or intracerebral bleeding
