Pathology of Head Injury

Question 1

What is the medical word for a bruise?

Answer 1

Contusion

Question 2

What causes contusions?

Answer 2

Blunt force - capillaries are ruptures and blood oozes out into tissues - subcutaneous layer and muscle

Question 3

What does two black eyes normally indicate?

Answer 3

Blood can track within looser tissues. When someone presents with two black eyes it is unlikely to be two separate blows. Instead, immediate suspicion of an injury further up or tracking from somewhere deep in the skull.

Question 4

What are abrasions?

Answer 4

Injuries to superficial part of the skin. scratches and grazes. Skin is affected by tangential blunt force. Might be a bit sore, bleed a little bit. Heal usually without scarring because deeper structures are not damaged

Question 5

What is the difference between an incision and a laceration?

Answer 5

Incision - sharp force injury, object causes cutting of the skin

Laceration - tear / split in the skin as a result of a blunt force injury.

Question 6

What are ring fractures?

Answer 6

When the skull fractures in a ring around the bone

Question 7

Which part of the skull tends to break in a ring fracture?

Answer 7

Skull tends to break at sutures or where softer bone meets harder bone, for example when the petrous part of the temporal bone meets the skull

Question 8

What is a fissure fracture?

Answer 8

Energy dissipates from the point of impact - smaller fracture as a result of blunt force.

Question 9

What is a hairline fracture?

Answer 9

Barely visible fracture affecting only the outer layer of the bone. Often requires no treatment

Question 10

What is a depressed fracture?

Answer 10

A little piece of the bone has been pushed inward. Example of a hammer hitting the skull, leaves indent of the shape of the hammer - important for forensic scientists.

Question 11

Which meningeal layer is separate and not closely applied to the other two layers of meninges?

Answer 11

Arachnoid

Question 12

Where do bridging veins travel?

Answer 12

Travel from arachnoid through the dura and into the venous sinuses

Question 13

What causes epidural haemorrhages?

Answer 13

Caused by bleeding arteries MMA, as part of the head injury. 90% of people with epidural haemorrhage also have a skull fracture.

May die within several hours but they don’t always fall unconscious!

Question 14

What percentage of subdural haemorrhages are not as a result of skull fracture?

Answer 14

90%

Question 15

What causes subdural haemorrhages?

Answer 15

Dura moves in relation to the skull - veins that traverse the subdural space stretch and they burst. They bleed. Accumulation of venous pressure in the subdural space. Subdural haematoma. Result of the moving head against a non-moving force.

Question 16

What is a cortical contusion?

Answer 16

Direct insult to the brain

Question 17

What is a coup?

Answer 17

A deceleration brain injury, where the head strikes, a contusion occurs there. These people’s brains will often have further cortical contusion diametrically opposite where the first force was. (Called a contrecoup)

Question 18

What natural causes intracerebral haemorrhages?

Answer 18

Natural disease e.g hypertensive, AV malformations, amyloid angiopathy - makes the vessels weak.

Question 19

What is diffuse axonal injury?

Answer 19

Occurs where there is a big acceleration/ deceleration force that implies a massive rotational force to the head. Death can be instantaneous. Disruption is global to the brain. Diffuse injury to the neurones. Incompatible with life. Road traffic collisions. Concussion is the very lowest level of diffuse axonal injury.