Pathology of Head Injury

Question 1

What are the basic types of mechanical injury?

Answer 1

Bruises (contusions)
Abrasions
Lacerations
Incisions
Thermal Injuries

Question 2

What causes bruises? Particularly why does a black eye form?

Answer 2

Blunt force

Black eye

• direct injury of orbit/socket not that common but blood will move there due to forces
• two black unlikely to be caused by two separate blows
• suspicion should be injury further up, or deeper inside skull
• blood is tracking down to eyes due to gravity/tissue

Question 3

Features of incised injuries?

Answer 3

Sharp force injury

• only damage to this part
• (more) easily stitched

Question 4

Features of lacerations?

Answer 4

Tear/split in skin due to application of energy
- break at weakest point, damage to surrounding area also
- stronger tissues may bridge wound
Blunt force

Question 5

Different types of skull fractures? What type of forces lead to each

Answer 5

Ring fracture - greater energy, comminution
Fissure fracture - lesser energy, usually due to blunt force
Depressed fracture - bone pushed inwards, localised blunt force, shape may represent weapon, +/- comminuted
Hairline fracture - often no treatment needed, difficult when impinge other structures
Sutural Diastasis - abnormal widening of skull sutures

Question 6

What are the different types of intracranial haemorrhage?

What can cause them?

Answer 6

Extradural - bleeding meningeal arteries, 90% fracture associated, usually maintained unconsciousness but not always immediate

Subdural

• most no fracture
• brain movement in relation to dura/skull - emissary veins damaged
• those already with brain shrinkage more prone (veins already stretched)

Subarachnoid

• spontaneous e.g. ruptured aneurysm
• traumatic - small ones e.g. cortical contusions
• traumatic - larger - sudden acceleration/rotation
• – vertebral artery damaged
• – usually quick death

Question 7

What are the different types of intracerebral haemorrhage?

Answer 7

Cortical contusion - brain injured after striking inner aspect of skull

• coup = contusion at site of impact
• contrecoup = contusion at opposite site
• contrecoup often larger

Intracerebral haemorrhage

• natural disease e.g. hypertensive, AV anomaly, amyloid angiopathy, vascular tumours
• traumatic - vulnerable vessels

Diffuse axonal injury

• large accelerational/decelerational forces suggesting rotation
• all neurons suffer
• haemorrhages e.g. in basal ganglia, corpus callosum
• often instantaneous death