Head Injury

Question 1

Occurrence of head injuries?

Answer 1

Leading cause of deaths in those <40 years old

Question 2

Types of head injury?

Answer 2

Head injury really means brain injury

Primary brain injury - occurs at the time of the injury

Secondary brain injury - due to consequences of injury, i.e: these are partially preventable

Question 3

Pathophysiology of head injuries?

Answer 3

Release of excitatory amino acids, e.g: glutamate, aspartate, which bind to receptors, e.g: NMDA receptors

This leads to:
• Release of IC calcium
• Activation of phospholipases
• Breakdown of the cell membrane
• Cell swelling
• Activation of apoptosis

Question 4

How can secondary brain injuries occur?

Answer 4

Loss of blood-brain barrier, leading to leukocyte infiltration and inflammation

Loss of cerebral autoregulation of BP, leading to ischaemia

Loss of cerebral autoregulation of blood flow, leading to metabolic decoupling; result is even more ischaemia, causing further cerebral oedema

Question 5

Explain the Monro-Kellie hypothesis

Answer 5

An increase in volume of one compartment must produce a decrease in another compartment, otherwise the ICP will rise

This is because the skull is a closed, inelastic cavity of constant volume; this volume consists of brain, circulating blood and CSF

Question 6

Formula for cerebral perfusion pressure?

Answer 6

CPP = MAP - ICP

Cerebral perfusion pressure = mean arterial pressure - intracranial pressure

Question 7

CPP aim after a head injury?

Answer 7

NOTE - hypotension has a major on cerebral perfusion pressure

Aim for a CCP >60 mmHg after head injury, i.e: MAP >80 mmHg and ICP <20 mmHg

Question 8

Normal adult ICP?

Answer 8

9-11 mmHg

Question 9

Types of head injuries?

Answer 9

Open, e.g: penetrating wounds (missile) - uncommon in the UK

Closed - acceleration/deceleration/rotation (non-missile)

Question 10

Examination of a head injury?

Answer 10

Scalp swelling and location

If there is a skull vault fracture, is it:
• Linear
• Depressed
• Compound

If there is a skull base fracture, is it in the:
• Anterior cranial fossa
• Middle cranial

Question 11

Signs of anterior cranial fossa fracture (skull base)?

Answer 11

Periorbital ecchymosis (AKA raccoon/panda eyes)

Question 12

Signs of middle cranial fossa fracture (skull base)?

Answer 12

“Battle sign” over the mastoid area (AKA mastoid ecchymosis)

Question 13

Focal signs caused by a head injury?

Answer 13

Lateralising motor signs (allow localisation of damage to a specific area of the brain)

3rd nerve palsy can cause issues with pupillary responses to light

Question 14

How to assess consciousness?

Answer 14

Glasgow Coma Score (GCS)

Question 15

Explain how GCS is used

Answer 15

Eyes:
1 - does not open eyes
2- open eyes to painful stimuli
3 - opens eyes in response to voice
4 - opens eyes spontaneously 

Verbal:
1 - makes no sounds
2 - incomprehensible sounds
3 - utters incoherent words
4 - confused, disoriented
5 - oriented, converses normally

Motor:
1 - makes no movements
2 - extension to painful stimuli (decerebrate response)
3 - abnormal flexion to painful stimuli (decorticate response)
4 - flexion / withdrawal to painful stimuli
5 - localises to painful stimuli
6 - obeys command

Question 16

What is a coma?

Answer 16

Patient does not open their eyes, obey commands or speak

Question 17

Various GCS scores?

Answer 17

Best response - 15
Comatose patient - ≤8
Totally unresponsive - 3

Question 18

What causes fatalities with head injuries?

Answer 18

Hypoxia

Hypotension

Raised ICP

Question 19

Acute treatment of head injuries?

Answer 19

ABC

Question 20

When should a CT scan be requested in a patient with head trauma?

Answer 20

Any patient:
• With a skull fracture
OR
• Not orientated (GCS < 15)
OR
• With focal neurological signs
OR
• Taking anti-coagulants (warfarin)

Question 21

Types of traumatic intracranial bleeding?

Answer 21

From superficial to deep:
• Extradural haematoma
• Subdural haematoma 
• Traumatic subarachnoid haemorrhage
• Intracerebral contusion
• Intracerebral haematoma
• Intraventricular haemorrhage

Question 22

Intensive care Mx of a head injury?

Answer 22

Sedation:
• Reduces cerebral metabolic rate
• Reduces cerebral blood flow
• Reduces ICP

Ventilation:
• Maintain adequate oxygenation (PO2 13-15 kPa)
• Maintain normocapnia (PCO2 4-4.5 kPa)

Blood pressure (manipulate to maintain CPP >60 mmHg)

Glucose (maintain normoglycaemia)

Temperature (maintain euthermia)

Question 23

Methods of cerebral protection following a head injury?

Answer 23

CSF drainage reduces ICP

Mannitol improves micro-perfusion; it is also a diuretic and reduces cerebral oedema
Hypertonic saline (may be better than mannitol)

Hyperventilation (temporary effect for 2-4 hours)

Hypothermia (weak evidence)

Decompressive craniectomy (trials underway)

Question 24

Late effects of a head injury?

Answer 24

Epilepsy:
• If it occurs early, within the first 2 weeks, there is a low risk of persistence
• If it occurs late, it is likely to become established

CSF leak (into the nose or the middle ear)

Cognitive problems:
• Post-concussion syndrome of poor conc, headache, poor memory and lethargy) can affect 30% of all adults with head injuries