Head Injury

Question 1

Why is traumatic brain injury a problem

Answer 1

• it is common
• it significantly affects young adults
• prevention and treatment can make a difference

Question 2

Describe the epidemiology of traumatic brain injury

Answer 2

• 6% of A&E attendance
• UK incidence 0.4 – 1%/year
• 700,000 A&E attendances
• 110,000 admissions
• 4,000 neurosurgical interventions
• falls, assaults and RTAs
- roughly 25% mortality for severe head injury
- half of adult inpatients with head injury have long term disability
- estimated that the socio-economic burden of RTAs to Europe is 180 billion euros

Question 3

the principles determinate of long term outcome from…..

Answer 3

• principle determinate of long term outcome from polytrauma and head injury accounts for 50% of traumatic mortality

Question 4

what has made a difference to reducing the death from traumatic brain injury in the last 30 years

Answer 4

• over the last 30 years the mortality of severe head injury has fallen from 50% to 25%
• seatbelts reduce road traffic accident mortality by 40-60%
• speed limits, airbags, driver education, licensing, old age fall prevention, playground safety

Question 5

what is the good thing and bad thing about the skull

Answer 5

• the skull provides some protection to he brain from trauma
• but if the brain swells or a haematoma takes up extra space then the brain will become squashed and this can cause the brain to become damaged

Question 6

who came up with the idea that the skull is fixed

Answer 6

Munro-kelly Doctrine

Question 7

what does the munro-Kelly Doctrine explain

Answer 7

• It explains the relationship between the intracranial content and the intracranial pressure

Question 8

describe the physiology behind the munro-telly doctrine

Answer 8

• this is the idea that the intracranial volume is fixed
• the brain, CSF and blood are the usual contents
• if something else is added to that space for example in the context of trauma that can be a swollen bruised part of the brain or haematoma
• these to start with are compensated for by displacement of the CSF into the spine through the foramen magnum or the venous blood back into the circulation therefore this is compoesnated
• once these compensated mechanisms are exhausted there is no where else for them to go
• therefore the pressure ICP has to rise
• this is uncompensated and can happen quickly

Question 9

what are the compensation mechanisms for the brain swelling

Answer 9

by displacement of the CSF into the spine through the foramen magnum or the venous blood back into the circulation therefore this is compensated as it makes more space for the brain

Question 10

when the ICP increases what happens

Answer 10

• as the ICP increases there is effective perfusion pressure of the brain (cerebral perfusion pressure CPP) decreases
• As the CPP falls the cerebral blood flow falls
• therefore there is less perfusion to the brain and it becomes hypoxic

Question 11

write the equation to work out CPP

Answer 11

• CPP=MAP-ICP

Question 12

what can happen when ICP raises

Answer 12

• ICP can squeeze the brain out of the skull and cause herniation

Question 13

name 4 different types of herniation

Answer 13

• subfalcine
• uncal
• tonsillar herniation
• lateral tentorial and central tentorial herniation

Question 14

describe what happens in a subfalcine herniation

Answer 14

• this is when the medial part of the hemisphere is squeezed under the fall
• this part fo the brain is damaged and bruised and start to swell
• usually parts of the cingulate gyrus
• can also result in damage of some key vessels such as the anterior cerebral arteries

Question 15

describe what happens in an uncal herniation

Answer 15

• compression of cranial nerve III

Question 16

describe what happens in tonsils herniation

Answer 16

this is when the ICP rises and the tonsils of the brain are pushed through the foramen magnum

• this can squeeze the medulla and upper spinal cord as well as the bottom of the cerebellum
• damages processes of breathing, control of blood pressure and pulse rate and this is often terminal

Question 17

describe what happens in lateral tentorial and central tenurial herniation

Answer 17

this is herniation through the tentorium cerebellum and the medial aspect of the temporal lobe herniates through the tentorial notch,
- this also starts to squeeze the midbrain = pupil can start to dilate

Question 18

where is the extradural space

Answer 18

this is between the periosteal layer and meningeal layer of the dura mater

Question 19

describe what shape an epidural haemotoma is

Answer 19

biconvex

- can be due to damage to a middle meningeal artery

Question 20

where is the subdural space

Answer 20

between the dura mater and subarachnoid

Question 21

where is the subarachnoid space

Answer 21

between the subarachnoid and Pia mater

Question 22

what shape is a subdural haemoatoma

Answer 22

sickled shaped

Question 23

what do sinuses do to the skull

Answer 23

• these are associated with the nose and ears
• make skull lighter
• allows the skull to have responses
• filter the air as it comes in to remove the microbes

Question 24

describe how the brain can become infection

Answer 24

• sinuses are closed to the Brain
• head injury can damage these spaces and cause them to fill up with blood, this happens when there is fracture to the base of the skull
• this is important as the sinuses are usually filled with mucous and bacteria therefore if these enter the brain this can lead to assess formation and meningitis

Question 25

what can happen structurally after a traumatic brain injury

Answer 25

• axons separate
• the ends of the axons form retraction balls
• neurones undergo apoptosis
• injured cells having lost their energy and therefore sodium enters the cell and is no longer pumped out by the sodium ATPase therefore the cells lose their ion metabolism and swell and cause cytotoxic oedema

Question 26

what therapies are aimed at preventing structural changes after a traumatic Brian injury

Answer 26

• neuroprotection – therapy aimed at preventing neuronal cell death after injury with the effect of improving outcome

• brain repair – mechanisms for the generation of new neurons and growth of new axons
– the adult human brain has negligible capacity for brain repair and no therapeutic intervention has been effective in changing this

Question 27

what is the difference between a moderate and severe TBI

Answer 27

difference between moderate and severe is presentation of coma
- coma is present in severe TBI

Question 28

on the Glasgow coma scale what number is defined as a coma

Answer 28

8 or lower

Question 29

what happens to bodily systems in a coma

Answer 29

• depresses cough, gag and swallow
• slows ventilation (CO2 rises)
• decreases BP
• adequate perfusion of oxygenated blood vital

Question 30

what are the principles of management used in traumatic brain injury

Answer 30

• prevention of primary brain injury
• prevention of secondary brain injury
• resuscitation
• CT scan to identify a haemotoma
• rapid referral to neurosurgery
• neurointestive care