PBL 2

Question 1

what is a traumatic brain injury?

Answer 1

when an external mechanical force injures the head resulting in temporary or permenant brain dysfunction

Question 2

how do we classify the severity of a TBI?

Answer 2

GCS
post traumatic amnesia length
time of loss of conciousness

Question 3

what is considered a mild TBI?

Answer 3

GCS 13-15
<1 day of post traumatic amnesia
0-30 minutes loss of conciousness

Question 4

what is considered severe traumatic brain injury?

Answer 4

GCS of 3-8
>7 days post traumatic amnesia
>24 hour loss of conciousness

Question 5

what is a coup-contrecoup injury?

Answer 5

In head injury, a coup injury occurs under the site of impact with an object, and a contrecoup injury occurs on the side opposite the area that was hit.

Question 6

what is a torque brain injury?

Answer 6

when the brain suspended in the skull twists aginst the thinner stalk of the brain stem and stretching the structures within

Question 7

what area is most affected in a torque injury?

whats the cosequence of this?

Answer 7

the reticular formation

this results in more severe loss of conciousness than other injuries

Question 8

what is secondary impact syndrome?

Answer 8

when the brain swells rapidly shortly after a person suffers a second concussion before symptoms from an earlier concussion have subsided

Question 9

what causes secondary impact syndrome?

Answer 9

damage to neurons in the brain lead to depolarisation in many neurons which causes excessive glutamate release generating more EPSPs and causing even more action potentials to be generated.
this huge increase in metabolic activity increases the brains demand for blood but blood flow decreases right after a concussion so neurons are starved of energy

Question 10

what does an epidural haematoma look like on CT?

Answer 10

convex lens shape
doesnt cross suture lines of the skull
oedema can cause a shift of the midline to the contralateral side (indicates imoending cerebral herniation)

Question 11

what does a subdrual haematoma look like on CT?

Answer 11

concave, crescent shape that crosses suture lines

Question 12

whats the main cause of a subdural haematoma?

Answer 12

bridging veins between cerebral venous sinuses and superficial skull veins are disrupted

Question 13

what does a CT look like in subarachnod haematoma?

Answer 13

blood in ventricular cisterns, interhemispheric fissures and within sulci

Question 14

what drug are patients often given in subarachnoid haematoma?

Answer 14

nimodipine (Ca2+ channel blocker)

Question 15

whats the usual cause of subarachnoid haemorrhage?

Answer 15

head trauma

or spontaneous rupture of intercranial berry aneurysm

Question 16

what are red flags after a head injury?

Answer 16

headache that gets worse and doesnt go away
slurred speech
weakness
numbness
decreased coordination
repeated vomiting or nausea
convulsions or seizures
unsuualy behaviour
increased confusion
restlessness
agitation

Question 17

after a mild TBI or concussion, when is a brain CT recommended?`

Answer 17

if the individual develops a worsening headache, persistent confusion, focal neurological deficit or is on anticoagulation therapy

Question 18

what is ICP usually between?

Answer 18

7-15mmHg

Question 19

how is rising intercranial pressure usually compensated for?

Answer 19

venous constriction and CSF absorption

Question 20

what is the Monro-Kellie hypothesis

Answer 20

the sum of the volumes of brain, CSF and intercranial blood is constant so an increase in 1 should cause a decrease in one or both of the remaining two.

Question 21

what are the 4 stages of rising ICP?

Answer 21

• stage 1 - compensatory reduction is CSF and blood volume so no rise in ICP
• stage 2 - compensatory mechanisms exhausted so slow rise in ICP. drowsy and headaches
• stage 3 - sustained increased ICP and fallinf cerebral perfusion pressure. deteriorating concious level, intermittent elevations in bp and bradycardia
• stage 4 - cerebral perfusion pressure caeses, widespread necrosis begins, compression of brain stem leads to respiratory arrest and death. coma, fixed dilated pupils, death

Question 22

whats the equation for ICP?

Answer 22

ICP= mean bp - cerebral perfusion pressure

Question 23

what is Cushing’s triad?

Answer 23

The signs that indicate raised ICP

bradycardia, irregular respirations, and hypertension