Common Intracranial Pathology

Question 1

how does CSF appear?

Answer 1

black

Question 2

how does the 4th ventricle appear?

Answer 2

u-shaped

Question 3

what is superior/inferior to the 4th ventricle?

Answer 3

superior = cerebellar hemispheres
inferiorly = pons/medulla oblongata

Question 4

how does the suprasellar cistern appear?

Answer 4

anterior to the interpeducunarl cistern;

has a 5-point / 6-point starlike appearance

Question 5

describe the sylvian fissures

Answer 5

bilaterally symmetrical; contain CSF

-separate the temporal from the frontal / parietal lobes

Question 6

what is the lentiform nucleus?

Answer 6

putamen (lateral) + globus pallidus (medial)

Question 7

what are normal calcifications that may be seen on the brain CT?

Answer 7

pineal gland, basal ganglia, chooroid plexus, falx + tentorium

Question 8

what enhances (normally) after IV contrast administration?

Answer 8

venous sinuses
choroid plexus
pituitary gland / stalk

Question 9

what is hypodense on CT?

Answer 9

fat (usually not present in the head)
air (sinuses)
water (CSF)

Question 10

what is isodense on CT?

Answer 10

normal brain

some forms of protein (subacute + subdural hematomas)

Question 11

what is hyperdense on CT?

Answer 11

metal (aneurysm clips / bullets)
iodine (after contrast administration)
calcium
hemorrhage (high protein)

Question 12

how do epidural hematomas occur?

Answer 12

high density, extraaxial biconvex lens-shaped mass

epidural hematomas DO NOT cross suture lines

Question 13

what are the vessels damaged / how do subdural hematomas typically occur?

Answer 13

• decelartion injuries in motor vehical accidents / falls

- damage to the bridging veins: hemorrhage into the potential space b/w the dura mater + arachnoid

Question 14

how do subdural hematomas present?

Answer 14

crescent-shaped, extracerebral bands of high attentuation –> cross suture lines

Question 15

how do you get an intracerebral hemorrhage?

Answer 15

trauma, aneurysm ructure, vasculitis, or atheromatous disease in small vessels

Question 16

what do you call inuries occuring at the point of impact?

Answer 16

coup injuries

Question 17

what do you call injuries occuring opposite the point of impact?

Answer 17

contre-coup injuries

Question 18

what are cerebral contusions?

Answer 18

hemorrhages with associated edema (inferior frontal / temporal lobes) on/near the surface of the brain

Question 19

what do you look for on CT for initial evaluation of trauma?

Answer 19

• blood = hyperintense (collecting in the cisterns, fissures, ventricles, and sub/epidural spaces)
• mass effect (displacement/compression)

Question 20

how does blow-out fracture of the orbit present?

Answer 20

1) orbital emphysema (air in the orbit from the ethmoid/maxillary sinuses)
2) fracture (medial / floor of the orbit)
3) fat entrapment (soft- tissue mass on top of the maxillary sinus)
4) blood in the maxillary sinus

Question 21

tripod fracture?

Answer 21

separation of the zygoma:

1) splitting of the frontozygomatic suture
2) fracture of the orbital floor
3) fracture of the ipsilateral maxillary sinus’ lateral wall

Question 22

what causes intracranial pressure? how does it present symptomatically?

Answer 22

causes:

• cerebral edema (vasogenic [malignancy/infection = permeability] or cytotoxic [cerebral ischemia])
  presents: papilledema, headache, diploplia

Question 23

what are signs of cerebral edema in radiology?

Answer 23

• loss of nL differentiation b/w gray + white matter
• effacement of the nL sulci
• ventricles compressed
• herniation of the brain: basilar cistern effacement

Question 24

where do hypertensive hemorrhagic strokes occur?

Answer 24

60% in the basal ganglia (otherwise, thalamus, pons, cerebellum)

Question 25

what are lacunar infarcts?

Answer 25

20% of cerebral infarctions, often due to co-morbidity of HTN, atherosclerosis, DM2
-low-density, cystic lesions

Question 26

hydrocephalus: define it

Answer 26

expansion of the ventricular system (incr. CSF volume)