Head Injury

Question 1

What can head injuries be a result from?

Answer 1

Accidental: (very common)

• Falls (esp from a height)
• RTA

Homicidal: (also frequent)

• Conseqence of being struck
  (e. g. hammer, axe, brick)

Suicide:
-Fall from height

Natural disease:
-May cause collapse with resulting head injury which can prove misleading on initial investigation

Question 2

What are scalp injuries similar to?

Answer 2

Similar to injuries effecting the skin.

• Abrasions,
• Bruises,
• Lacerations,
• Incisions
• (and burns and scalds

Question 3

Why is the scalp a common site for laceration?

Answer 3

Scalp is closely applied to the skull and tearing associated with the application of force more likely to occur in these circumstances.

The laceration may be suprisingly clean cut, potentially mimicking an incised wound

Question 4

Why can the scalp be decieving in head trauma?

Answer 4

Blunt force injury to the head may not be visible on the surface of the scalp.

hair can obscure sizable injuries to the scalp
-Shaving advisable at autopsy

May only have bruising/bleeding in the deeper layers of the scalp or between the scalp and the skull.
This is of particular note in infant head injury (impact versus shaking)

Question 5

How do adults and infants differ when it comes to skull fracture?

Answer 5

Skull fractures caused by application of force causing deformation of the skull

Adult skulls less likely to cope with distortion.
Infants may resolve distortion as the head grows

Question 6

What are the two elemets to the skull?

Answer 6

Skull vault (upper part) which includes frontal bone, squamous temporal bones and occipital bone separated by sutures

Skull base (upon which the brain rests) which can be divided into the anterior, middle and posterior cranial fossae

Question 7

What are the types of skull fracture?

Answer 7

Linear
Depressed
Comminuted
"Ring" Fracture
"Contre-coup" fracture

Question 8

What is a linear skull fracture?

Answer 8

Commonly temper-parietal from blow or fall onto side or top of the head and may continue onto the skull base, “hinge” fracture

Question 9

What is a depressed skull fracture?

Answer 9

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, e.g. pavement fractures tend to be linear in this scenario

Question 10

What is a comminuted skull fracture?

Answer 10

Mosaic skull fracture

Fragmented skull

Question 11

What is a “Ring” fracture?

Answer 11

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

Question 12

What is a “contre-coup” skull fracture?

Answer 12

Fracturing of the occipital planes (anterior fossa) caused by a fall onto the back of the head

Question 13

How are intracranial haemorrhages named?

Answer 13

By their position within the skull in relation to the meninges
(i.e. extradural, subdural and subarachnoid haemorrhage)

Question 14

Why is diagnosis of intracranial haemorrhage hard?

What helps with this?

Answer 14

The different forms of intracranial haemorrhage may all be caused by trauma, typically blunt force trauma, but by different mechanisms, in varying circumstances and may present to clinical staff in a variety of ways.

Diagnosis is greatly assisted by advances in radiological images, particularly CT scan

Question 15

What does intracranial haemorrhage cause?

Answer 15

Accumulation of blood within the rigid skull causes an increase in ICP and results in compression of the brain.

The compression causes symptoms including reduction in conscious level and if unchecked, will ultimately cause death by compression of the brainstem due to herniation of the cerebellar tonsils into the foramen magnum

Question 16

What is extradural haemorrhage?

Answer 16

Bleeding occuring between the dura and the skull; accumulating blood strips the dura off the inner surface of the skull

Question 17

How do the vast majority of extradural haemorrhages arise?

Answer 17

Damage to an artery in association with a skull fracture (80-90%)
(Usually middle meningeal)

Arterial so under higher pressure than with venous bleeding (very occasionally large venous channels cause EDH

Question 18

What is the “lucid interval” in extradural haemorrhage?

Answer 18

Victum of injury inicially seems to be ok, without neurological symptoms, but can deteriorate catastrophically later, which can be a source of difficulty for clinical staff who may easily miss possibility of intracranial bleeding

Question 19

What is subdural haemorrhage?

Answer 19

Bleeding occuring 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 20

What can cause subdural haemorrhage?

Answer 20

Any motion which causes rotational or “shearing” forces can cause the bridging veins to stretch and tear due to the relative movemnt between brain and dura.

Frequently occurs without a skull fracture

Question 21

What individuals are more at risk of a subdural haemorrhage?

Answer 21

Individuals with atrophic (small) brains are at increased risk because the smaller brain has a greater capacity for movement and the veins may already be stretched to some degree

Question 22

Is a lucid interval seen in subdural haemorrhage?

Answer 22

May be seen

Question 23

What is a chronic subdural haemorrhage?

Answer 23

Chronic presence of blood between arachnoid and dura mater.
Particularly in elderly as brain will be smaller so compensates well with extra fluid.

May be a cause for chronic confusion (and may be mistaken for dementia)

Question 24

What is a subarachnoid haemorrhage?

Answer 24

Bleeding beneath the arachnoid membrane (and above the brain)

Bleeding causes irritation to the brain -> worst headache someone has ever had

Question 25

What is the most common cause of subarachnoid haemorrhage?

Answer 25

Actually natural disease
-Rupture of a cerebral artery (“berry”) aneurysm

Also commonly seen in association wuth cerebral contusions (bruising to brain)

Question 26

What is Traumatic Basal SAH?

Answer 26

Specific entity in forensic medicine

Typically a 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 vertebro-basilar circulation and a concentration of SAH on the base of the brain; precise mechanism leading to rupture is not certain.

Question 27

What is cerebral oedema?

Answer 27

Common and rapid result of brain injury, especially in children (“malignant cerebral oedema”)

Can develop in minutes and lead to massive brain swelling with raised intracranial pressure and “coning”

Question 28

What is cerebral contusion and laceration?

Answer 28

Direct mechanical damage to the brain substance

may occur anywhere on the brain

Question 29

What is a “coup” contusion?

Answer 29

Occurs when a head is struck a heavy blow

-The contusion is found directly under the site of impact

Question 30

What is a “contre-coup” contusion?

Answer 30

Caused by a moving head sriking a fixed object or unyielding surface
-Contusion is found diametrically opposite the site of head impact

e.g. a fall onto the back of the head would result in contusions on the frontal and temporal poles and on the undersurface of the frontal lobes

Question 31

What is Traumatic Diffuse Axonal injury?

Answer 31

tDIA (DIA not just caused by trauma) is a diagnosis that can only be made by microscopy and special staining techniques.
-May get concomitant damage to small blood vessels within the brain which raise suspicions of tDAI
(“diffuse vasular injury”)

Question 32

What are the common scenarios for tDAI?

Answer 32

Vehicular collisions and falls from a height.

Serious rotational forces applied to the brain tissue causing shearing of axons

Question 33

What certain areas of the brain are particularly susceptable to displaying tDAI?

Answer 33

• Corpus Callosum
• Para-Sagittal White Matter
• Posterior Internal Capsule
• Dorsolateral aspects of the rostral brainstem
• Cerebellar Peduncles

Question 34

What state are patients in when tDAI is fully developed?

Answer 34

Comatose