Head Injury

Question 1

How common is head injury?

Answer 1

it is the leading cause of death in UK population aged less than 40yrs

Question 2

What is the difference between primary and secondary brain injury

Answer 2

Primary- injury to brain tissue occurs at the time of injury

Seconday- occurs as a consequence of the injury ie it is partly preventable

Question 3

Describe the pathophysiology of head injury

Answer 3

Injury –> release of excitatory amino acids (glutamate, aspartate) –> binding to NMDA receptors –> releas of intrecellular calcium, activation of phospholipases, breakdown of cell membrane, cell swelling, activation of apoptosis

Question 4

How does a head injury then lead on to result in secondary brain injury

Answer 4

Loss of BBB, leucocyte infiltration = INFLAMMATION
Loss of cerebral autoregulation of BP = ISCHAEMIA
loss of cerebral autoregulation of blood flow- metabolic de-coupling- even more ischaemia causing further brain oedema

Question 5

What is CPP

Answer 5

CCP= cerebral perfusion pressure
CPP = MAP - ICP
where map is mean arterial pressure and ICP is intracranial pressure

Question 6

What is the aim CPP

Answer 6

more than 60mmHg after head injury

Question 7

what is a normal adult ICP

Answer 7

9-11mmHg (12-15cm H2O)

Question 8

what are the two typs of head injury

Answer 8

open ie penetrating

closed ie acceleration/deceleration/rotation

Question 9

What can be a sign of anterior cranial fossa fracture

Answer 9

‘racoon’ or ‘panda eyes’

Question 10

what is a sign of middle cranial fossa fracture

Answer 10

battle sign over mastoid area

Question 11

what focal signs may occur

Answer 11

lateralising motor signs

pupillary responses to light impaired due to third nerve palsy

Question 12

what is used to assess a patient with a head injury

Answer 12

Glasgow coma scale

Question 13

what are the three parts of the GCS

Answer 13

Eye opening
verbal response
best motor response

Question 14

How is a GCS given

Answer 14

score between three and fifteen
Eyeopening - spontaneously =4
to command =3
to pain=2
none = 1
Verbal -
orientated= 5
confused = 4
inappropriate words= 3
sounds=2
none=1
Motor
obeys commands= 6
localises pain=5
flexes to pain=4
abnormal flexion=3
extension=2
none=1

Question 15

what is the definition of a coma

Answer 15

do not open eyes
do not obey commands
do not speak
ie GCS less than 8

Question 16

how can people die from head injury

Answer 16

hypoxia
hypotensions
raised ICP

Question 17

how much of your cardiac output, oxygen and glucose does your brain use

Answer 17

15 percent of cardiac output
20 percent of circulating oxygen
12 percent of carried glucose

Question 18

how soon will neuronal damage occur after circulatory arrest

Answer 18

five mins

Question 19

when should you get a ct scan in head trauma

Answer 19

Any patient with a skull fracture
or with a GCS less than fifteen ie not orientated
or with focal neuro signs
or on warfarin/anticoagulants

Question 20

from outside to inside what types of traumatic brain bleed can you get

Answer 20

Extradural haematoma
Subdural ''
Traumatic subarachnoid haemorrhage
Intracerebral contusion
Intracerebral haematoma
Intraventricular haemorrhage

Question 21

what is map

Answer 21

(2 x diastolic + systolic)/3 = MAP

Question 22

How is a head injury managed in intensive care

Answer 22

Sedation - reduces, cerebral metabolic rate, cerebral blood flow and ICP
Ventilate- maintain oxygen and normocapnia
BP- manipulate to give CPP of more than 60
Glucose and temp maintanence

Question 23

What are normal oxygen levels

Answer 23

p02 13-15kPa

Question 24

what is normal co2 levels

Answer 24

4-4.5 kPa

Question 25

What can be done to protect the cerebrum after injury

Answer 25

CSF drainage- reduces ICP
Mannito- improves micro perfusion
Hypertonic saline
Hyperventilation
Hypothermia- not much evidence
Decompressive craniectomy

Question 26

What are the sequelae of head injury

Answer 26

Epilepsy- early (first two weeks) or late
CSF leak -into nose or middle ear
Cognition - post concussion syndrome (poor conc, headache, lethargy, poor memory)
Common -30 percent of adults with head injury