Head Injury

Question 1

What are the two stages of insult?

Answer 1

Primary and secondary

Question 2

Describe the primary insult

Answer 2

Focal and/or diffuse brain trauma

Question 3

Describe the secondary insult

Answer 3

• Hypotension
• Hypoxia
• Infection
• Haematoma

Question 4

What is used to assess conscious level?

Answer 4

Glasgow Coma Scale

Question 5

Describe the outcome of Glasgow coma scale

Answer 5

Correlates with severity of head injury:
• 13-15 - mild injury
• 9-12 - moderate injury
• 3-8 - severe injury

Question 6

Name seven complications of head injury?

Answer 6

1. Permanent physical disability – paralysis, loss of motor function or speech
2. Post traumatic epilepsy
3. Intracranial infection
4. Psychiatric illness – depression, PTSD
5. Chronic subdural haemorrhage
6. ‘Punch-drunk’ dementia
7. Fatal outcome (uncommon)

Question 7

What are some reasons a person might fall?

Answer 7

• Accidental (falls, RTAs)
• Homicide - consequence of being struck by a weapon
• Natural disease can cause collapse with resulting head injury which can prove misleading on initial investigation

Question 8

What are the five layers of the scalp

Answer 8

Skin, Connective tissue, Aponeurotic fascia, Loose connective tissue, Pericranium

Question 9

What does the skull consist of?

Answer 9

Compact bone separated by spongy bone

Question 10

Describe the meninges

Answer 10

• Dura mater (dense, tough, fibrous, adherent to inner surface of the skull)
• Arachnoid mater (delicate, transparent, envelopes the brain)
• Pia mater (delicate, applied to the brain surface)

Question 11

Describe scalp injuries

Answer 11

• Laceration clean cut and bleed profusely
• Blunt force trauma may no be visible on the scalp
• Hair can obscure injuries
• May only have bruising/bleeding in the deeper layers of the scalp or between the scalp and skull

Question 12

What are the two element to the skull?

Answer 12

• Skull vault (upper part) - frontal bone, squamous temporal bone and occipital, separated by sutures
• Skull base which can be divided into the anterior, middle and posterior cranial fossa

Question 13

What are five different types of skull fractures?

Answer 13

• Linear
• Depressed
• Comminuted (mosaic
• Ring fracture
• Contre-coup

Question 14

Describe linear skull fractures

Answer 14

Commonly temporo-parietal from blow or fall onto side or top of the head and may continue onto the skull base; “hinge” fracture as it will split along a suture i.e. sagittal and then the two sutures coming off of it

Question 15

Describe focal skull fractures

Answer 15

Focal impact which may push fragments inwards to damage the meninges, blood vessels and the brain; risk of meningitis and post-traumatic epilepsy. Not typical of a fall from standing onto a flat surface

Question 16

Describe committed (mosaic) fractures

Answer 16

Fragmented skull

Question 17

Describe ring fractures

Answer 17

Fracture line encircling the foramen magnum caused by a fall from height, usually landing on the feet, but sometimes the head, leading to the skull base and cervical spine being forced together

Question 18

Describe contre-coup fractures

Answer 18

Fracturing of the orbital plates (anterior fossa) caused by a fall onto the back of the head

Question 19

How are intracranial haemorrhages named?

Answer 19

By their position in the skull i.e extradural, subdural and subarachnoid haemorrhage

Question 20

What is an intracranial haemorrhage?

Answer 20

Accumulation of blood within the rigid skull which causes an increase in intracranial pressure (ICP) and results in compression of the brain –> this compression causes symptoms, including reduction in conscious level

As ICP increases, without intervention, death will occur by compression of the brainstem due to herniation of the cerebellar tonsils into the foramen magnum

Question 21

What is an extra dural haemorrhage?

Answer 21

Bleeding occurring between the dura and the skull; accumulating blood strips the dura from the inner surface of the skull

Most due to damage to an artery is association with skull fracture

Question 22

What artery classically causes an extra dural haemorrhage?

Answer 22

Middle meningeal artery where is crosses the inner aspect of the squamous temporal bone due to fracture of that bone with secondary damage to the artery in the vicinity of the fracture

Question 23

Describe the outcomes of an extradural haemorrhage

Answer 23

Causes raised intracranial pressure with developing neurological symptoms; the time period for the development of symptoms is variable

“Lucid interval” can occur - victim of injury initially seems to be okay, without neurological symptoms, but can deteriorate catastrophically later

Question 24

What is a subdural haemorrhage?

Answer 24

Bleeding occurring beneath the dura (and above the arachnoid)

Usually caused by bleeding from bridging veins which pass from the surface of the brain to drain into the large venous channels within the dura

Question 25

What is the pathway behind formation of a subdural haematoma?

Answer 25

Any motion which causes rotational or “shearing” forces can cause the veins to be stretch and torn due to the relative movement between the brain and the dura - frequently occurs with skull fracture. Chronic subdural haemorrhage can occur, usually in elderly, and may be a cause of chronic confusion (may be mistaken with dementia)

Question 26

Why are individual with atrophic (small) brains at an increased risk of a subdural haematoma?

Answer 26

The smaller brain has greater capacity for movement and the veins may be already stretched to some degree

Question 27

What is a subarachnoid haemorrhage?

Answer 27

Bleeding beneath the arachnoid membrane

Question 28

What is the most common cause of a subarachnoid haemorrhage?

Answer 28

Natural disease; rupture of a cerebral artery ('berry') aneurysm - main risk factor is hypertension

Question 29

Name a specific type of subarachnoid haemorrhage

Answer 29

Traumatic basal SAH

Question 30

What is traumatic basal SAH?

Answer 30

Result of a forceful impact to the upper part of the side of the neck causing abrupt rotational movement of the head leading to rupture of the vertebra-basilar circulation and SAH on the base of the brain Collapse is usually rapid and death can occur very quickly due to the irritant effects of blood in the subarachnoid space.

Question 31

What are two potential consequences of intrinsic brain injury?

Answer 31

* Cerebral oedema | * Cerebral contusion and laceration

Question 32

Describe cerebral oedema

Answer 32

Can develop in minutes and lead to massive brain swelling with raised intracranial pressure and "coning" (herniation)

Question 33

Describe cerebral contusion and laceration

Answer 33

Direct mechanical damage to the brain substance which can occur anywhere on the brain Two types: coup and contre-coup

Question 34

Describe the two types of cerebral contusion and laceration injuries

Answer 34

* Coup - occurs directly under site of impact * Contrecoup - caused by a moving head striking a fixed object or unyielding surface - contusions are found diametrically opposite the site of head impact

Question 35

What is an axon?

Answer 35

Elongated processes of nerve cells which permit transmission of signals between different parts of the brain and between the brain and body