CNS Trauma

Question 1

What components make up the blood brain barrier?

Answer 1

tight intercellular junctions
endothelium has low pinocytotic rate and basement membrane
dynamic interaction of endothelium with astrocytes and pericytes

Question 2

What types of substances can cross the BBB?

Answer 2

small substances and small lipophilic molecules

Question 3

What types of substances are unable to cross the BBB?

Answer 3

large substances and hydrophilic molecules (require active transport)

Question 4

What is cerebral edema?

Answer 4

accumulation of excess fluid in intracellular or extracellular spaces of the brain

Question 5

What is the major consequence of cerebral edema?

Answer 5

increased intracranial pressure

Question 6

What is another name for vasogenic edema?

Answer 6

extracellular edema

Question 7

What is vasogenic edema?

Answer 7

disruption (increased permeability) of BBB
results in shift of fluid from intravascular to the extravascular compartment
predominately involves white matter

Question 8

What are the most common causes of vasogenic edema?

Answer 8

primary or secondary brain turmors
abscesses
contusions
intracerebral hematomas

Question 9

What is another name for cytotoxic edema?

Answer 9

intracellular edema

Question 10

What is cytotoxic edema?

Answer 10

occurs secondary to cellular energy failure
results in a shift of water from the extracellular to intracellular comparment
intracellular swelling-large amounts of Na enters cells, H2O follows
histologically brain tissue vacuolation
predominately in gray matter

Question 11

What are the most common causes of cytotoxic edema?

Answer 11

ischemia/infarct
meningitis
trauma
seizures
hepatic encephalopathy

Question 12

What can increased intracranial pressure lead to?

Answer 12

decreased perfusion and/or herniation syndromes

Question 13

What is a subfalcine herniation?

Answer 13

cingulate gyrus herniates under the falx

may result in ACA compression, leading to infarct

Question 14

What causes subfalcine herniation?

Answer 14

asymmetric expanding hemispheric lesions

Question 15

What is a transtentorial uncal herniation?

Answer 15

medial temporal lobe displaced through tentorial opening because of asymmetric expanding lesion

Question 16

What are complications of transtentorial uncal herniation?

Answer 16

ipsilateral CNIII nerve compression with pupillary dilation
contralateral peduncular compression (kernohan’s notch) causing ipsilateral hemiparesis
PCA compression (ipsi or bilateral)
duret hemorrhage

Question 17

What is a duret hemorrhage?

Answer 17

fatal brainstem hemorrhage

secondary to progression of uncal herniation and resultant tearing of vessels in the midbrain/pons

Question 18

What is cerebellar tonsillar herniation?

Answer 18

caudal cerebellar structures “tonsils” attempting to escape through the foramen magnum

Question 19

What causes tonsillar herniation?

Answer 19

symmetric expansion of supratentorial contents into posterior fossa or expanding mass lesion in posterior fossa

Question 20

What is a complication of cerebellar tonsillar herniation?

Answer 20

medullary compression resulting in cardiorespiratory arrest

Question 21

What is hydrocephalus?

Answer 21

enlargement of ventricles associated with increase in CSF volume

Question 22

What causes communicating/non obstructive hydrocephalus?

Answer 22

decreased absorption at arachnoid granulations

Question 23

What causes non-communicating/obstructive hydrocephalus?

Answer 23

obstruction within ventricular system, preventing communication between the ventricles proximal and distal to the obstruction
(ie/tumor, congenital malformation, thick meninges at base of brain)

Question 24

What are the two types of head trauma?

Answer 24

blunt/nonmissile (most common)

penetrating/missile

Question 25

What is primary damage seen in head trauma?

Answer 25

immediate

scalp lac, skull fx, cerebral contusions, cerebral lacs, intracranial hem, DAI

Question 26

What is secondary damage seen in head trauma?

Answer 26

delayed
ischemia
hypoxia
cerebral swelling
infection

Question 27

What typically results from focal injury?

Answer 27

focal neurological deficits/epilepsy

Question 28

What typically results from diffuse injury?

Answer 28

coma/vegetative state

Question 29

Describe the 3 types of skull fractures

Answer 29

linear: single fracutre line, through entire thickness of skull
comminuted: multiple linear fractures radiate from point of impact
depressed: bone fragments displaced inward

Question 30

What is a concussion?

Answer 30

pathophysiologic process induced by traumatic biomechanical forces (also called mild TBI)
constellation of physical, cognitive, emotional and or sleep-related sx that may or may not involve loss of consciousness

Question 31

What is a contusion?

Answer 31

superficial bruise of the brain
usually at crests of gyri
occur overlying rough area of inner skull (ie/orbital and temporal regions)

Question 32

How do acute contusions appear?

Answer 32

wedge shaped

superficial hemorrhage in cortex and meninges

Question 33

How do old contusions appear?

Answer 33

gyri indented, cavitated, with brown/orange discoloration

Question 34

What is the difference between a coup and contrecoup contusion?

Answer 34

coup contusions occur at the point of impact while contrecoup contusions occur directly opposite the point of impact

Question 35

Describe diffuse axonal injury

Answer 35

occurs with deceleration/acceleration injury and/or angular accel
loss of consciousness at onset WITHOUT lucid interval
unconscious or disabled until death

Question 36

What lesions are seen with DAI?

Answer 36

clusters of petechial hemorrhages and soft hemorrhagic foci acutely
hydrocephalus ex vacuo, thinned corpus callosum and gray discoloration of white matter chronically

Question 37

What microscopic changes are seen with DAI? (needed to confirm DAI dx)

Answer 37

axons are disrupted, axonal transport continues and causes axonal swellings

acute: axonal swellings, positve for B amyloid protein and silver stains
subacute: microglia and axonal swellings
chronic: degeneration of involved fiber tracts

Question 38

What commonly causes epidural hematomas?

Answer 38

skull fx & mca tear

slow accumulation because of adherence between skull and dura

Question 39

What are the signs/symptoms of an epidural hematoma?

Answer 39

lucid interval

Question 40

What are signs/symptoms of a subdural hematoma?

Answer 40

headache, confusion

Question 41

What causes a subdural hematoma/

Answer 41

tearing of bridging veins extending from subarachnoid space to dura
more common in elderly w/brain atrophy

Question 42

How does chronic subdural hematoma occur?

Answer 42

recurrent bleeds from friale vessels in granulation tissue, originally injury occurred months ago

Question 43

What does a chrnoic subdural hematoma look like?

Answer 43

well organized membrane enclosing the hematoma

Question 44

How do subarachnoid hemhorrages occur?

Answer 44

contusions, lacerations, skull base fractures, escape of blood from ventricular system

Question 45

Why does post-traumatic hydrocephalus occur?

Answer 45

obstruction of CSF resorption due to subarachnoid space hemorrhage

Question 46

What are sequelae of brain trauma?

Answer 46

post-traumatic hydrocephalus
post-traumatic epilepsy
chrnoic traumatic encephalopathy

Question 47

What is chronic traumatic encephalopathy associated with?

Answer 47

mild repetitive traumatic brain injury

ie/in athletes and veterans

Question 48

What are the signs/symptoms of chronic traumatic encephalopathy?

Answer 48

initially: impulsivity, aggression, depression, short-term memory loss
eventually: dementia, gait, speech abn, parkinsonism

Question 49

What pathology is seen in chronic traumatic encephalopathy?

Answer 49

extensive deposition of tau in form of neurofibrillary and glial tangles and TDP-43 inclusions