02-26-2015 Trauma

Question 0

Cytotoxic edema

Answer 0

“intracellular edema”
o Secondary to cellular energy failure
o Results in shift of water from extracellular to intracellular compartment
 Intracellular swelling -> lots of sodium enters cells, water follows
 Histo: Brain tissue vacuolation
o Mostly grey matter
o Most common causes: ischemia/infarct, meningitis, trauma, seizures, hepatic encephalopathy
o Mech: dysfunction of neuronal and astrocytic membrane pumps (excess glutamate, extracellular K+, inflammatory cytokines)

Question 1

Vasogenic edema

Answer 1

“extracellular edema”
o Disruption of BBB -> shift of fluid from intravascular to extravascular
o Mostly white matter
o Most common causes: primary or secondary brain tumors, abscesses, contusions, intracerebral hematomas
o Mech: newly formed vessels deficient in tight junctions, VEGF by tumor cells, Production of inflammatory mediators/chemokines/cytokines/GFs
o Responds to corticosteroids and anti-VEGF antibody (bevacizumab)

Question 2

Subfalcine herniation

Answer 2

o Cingulate gyrus herniates under the falx
o Caused by asymmetric expanding hemispheric lesions
o May cause compression of ACA -> infarct

Question 3

Transtentorial uncal herniation

Answer 3

o Medial temporal lobe displaced through the tentorial opening because of asymmetric expanding lesion
o Complications
 Ipsilateral 3rd nerve compression with pupillary dilation
 Compression of brainstem against tentorial edge opposite the direction of herniation (Kernohan’s notch)
 PCA compression (ipsi- or bilateral)
 Duret hemorrhage

Question 4

Cerebellar tonsillar herniation

Answer 4

o Caused by SYMMETRIC expansion of supratentorial contents into posterior fosa or expanding mass lesion in posterior fossa
o Caudal cerebellar structures attempt to escape through the foramen magnum
o Medullary compression results in cardiorespiratory arrest

Question 5

Hydrocephalus

Answer 5

Enlargement of ventricles associated with increase in CSF volume

1. Communicating (non-obstructive) hydrocephalus
   a. Ventricular system is patent
   b. Increased size of ventricles may be due to: arachnoid villi obstruction due to decreased absorption at arachnoid granulations
   c. OR overproduction of CSF from a choroid plexus papilloma
2. Non-communicating hydrocephalus
   a. Obstruction within ventricular system
   b. Prevents “communication” between ventricles proximal and distal to obstruction
   c. Examples of causes: tumor in ventricles blocking flow, congenital malformation, thick meninges at base of brain blocking flow

Question 6

Concussion

Answer 6

o Pathophysiologic process induced by traumatic biomechanical forces
o Caused by direct/indirect forces to head
o Biochemical and physiologic abnormalities occur, typically no structural abnormalities on imaging acutely
o Constellation of physical/cognitive/emotion/sleep-related symptoms that may or may not involve loss of consciousness