Intro Flashcards
Describe ventricular anatomy
lateral ventricles (frontal, temporal, occipital horns; body, atrium/trigone) => 3rd ventricle => cerebral aqueduct => 4th ventricle => foramen of Luschka/lateral or foramen of Magendie (midline) ==> obex/opening to spinal canal
parts of the third ventricle
chiasmatic/supraoptic recess, infundibular recess, suprapineal recess, pineal recess, cerebral aqueduct, and massa intermedia
massa intermedia
interthalamic adhesion
CSF is produced by?
choroid plexus – located in body/temporal horn of lateral ventricles, roof of 3rd/4th
CSF volume
- ventricle
- subarachnoid space
150: 25 + 125 mL
CSF production in a day
~500 mL/day
CSF absorption
arachnoid granulations and lesser extent by lymphatic system/cerebral veins
cytotoxic edema
cell swelling by damaged Na K ATPase ion pumps
most commonly due to infarct, restricted diffusion
vasogenic dema
interstitial edema, increased capillary permeability
common with neoplasm, infection, infarct
interstitial edema
imbalances in CSF flow, commonly due to obstructive hydrocephalus
transependymal flow of CSF, periventricular
subfalcine herniation
cingulate gyrus slides under falx; compression ACA
contralateral hydrocephalus from foramen of monro obstruction
transtentorial herniation
DOWNWARD:
medial temporal lobe slides under tentorium
ipsilateral CN3 paresis, compression PCA, duret hemorrhages, compression contralateral cerebral peduncle
UPWARD: superior transtentorial herniation of vermis due to posterior fossa mass effect
obstructive hydrocephalus from aqueductal compression
cerebellar tonsillar herniation
displaced through foramen magnum, compression of medulla
communicating hydrocephalus
venticular enlargement, no obstructing lesion
subarachnoid hemorrhage or normal pressure hydrocephalus
noncommunicating hydrocephalus
obstructive lesion
3rd ventricle colloid cyst
posterior fossa mass obstructing 4th ventricle
intra vs extra-axial:
beneath pia
meninges/subarachnoid
intra-axial
extra-axial
perimesencephalic cisterns/basal cisterns
suprasellar, prepontine, interpeduncular, ambient, quadrigeminal
surround midbrain/pons
T1 shortening signal
T2 shortening signal
bright
dark
brain lesions demonstrate pathologic prolongation of longitudinal recovery
T1 dark, T2 bright
causes of T1 hyperintensity
gadolinium, fat, protein
melanin, mineralization, slow-flow blood, calcium, paramagnetic stages of blood (intra/extracellular methemoglobin)
causes of T1 hypointensity
paramagetic states of blood (except hyperacute blood, extracellular methemoglobin), calcification, fibrous lesion, highly cellular tumors, vascular flow voids, muscin
FLAIR
T2 weighted signal with suppresion of water based on T1 characteristics
white matter darker than gray matter
PD sequence
conventional spin echo proton density
highest signal to noise ratio
useful to evaluate MS, demyelinating plaques in posterior fossa