Head Injuries

Question 1

Types of head injury

Answer 1

Penetrating
- gunshot
Non-penetrating
- blunt force trauma - RTC, fall from height

Question 2

Key features of head injury

Answer 2

Major cause of death and disability in developed countries
- RTA
- Assault
- Accidents
Head is heavy, freely mobile and unstable
Vulnerable to impact, rotation and acceleration/declaration
Movement of brain within skull

Question 3

Assessment of head injury

Answer 3

Prognosis related to length and depth of unconsciousness
Glasgow Coma Scale /15
-  motor response /6
- verbal response /5
- ocular response /4

Question 4

Anatomy of head injury

Answer 4

Scalp
Skull
- rigid structure
- one exit foramen magna
Dura
- cranial cavity divided by reflections of dural membrane - into Rand L by falx and upper and lower by tentorium cerebelli
Brain
- semi solid consistency
- vulnerable to impact, rotation, acceleration, deceleration and swelling

Question 5

Features of primary head injury

Answer 5

Scalp
- abrasion 
- bruising + swelling -> haematoma
- laceration - rich blood supply -> heavy bleeding
Skull fracture
Intracranial haemorrhage
Brain injury

Question 6

Factors affecting force required to cause skull fracture

Answer 6

Thickness of hair
Thickness of scalp
Thickness of skull - hyperostosis
Site of impact
Direction of impact

Question 7

Types of skull fracture

Answer 7

Linear
Comminuted - greater than 2 fragments
Radiating
Spider's web
Depressed
Hinge - goes across base of skull creating hinge
Ring
Contre-coup - occur opposite point of impact

Question 8

Types of intracranial haemorrhage

Answer 8

If forms distinct mass called haematoma
Extradural
Subdural
Subarachnoid
Intracerebral

Question 9

Features of extradural haematoma

Answer 9

Due to blow to temple
May cause LOC
Fracture tears an artery within groove in inner table of skull
- usually middle meningeal artery inside thing temporal bone
- rarely may arise from venous sinus
Arterial bleeding forcibly strips dura off skull
Localised to enlarging haematoma by dura
Lucid interval
Later pressure effects (LOC) from enlarging haematoma
If untreated 75-100mls maybe fatal
Amenable to surgical decompression

Question 10

Features of subdural haemorrhage

Answer 10

Due to fall or blow - often trivial
Common in alcoholics, elderly and children
Not usually associated with skull fracture
Shearing of bridging veins spanning subdural space - between dural sinuses and cortical veins
Blood spreads widely over brain surface
50-100mls life threatening
Often asymptomatic

Question 11

Causes of subarachnoid haemorrhage

Answer 11

Natural
- ruptured berry aneurysm
Traumatic
- arising from contusion or laceration to brain surface
- blow to chin - traumatic basal SAH

Question 12

Features of traumatic basal SAH

Answer 12

Blow to chin or angle of jaw jerks head
-> stretching and rupture of vertebral artery
Immediate collapse and death - minutes
Strong association with alcohol intoxication
Death comes as surprise to all
Culpable homicide
- as usually not intentional

Question 13

Causes of intracerebral haemorrhage

Answer 13

Natural
- rupture of small artery
- most common in hypertension
Traumatic
- arising from contusion or laceration to brain surface
- shearing and tearing of deep blood vessels

Question 14

Features of brain injuries

Answer 14

Cerebral contusion - bruising to brain surface
- coup - at point of impact
- contre-coup - diagonally opposite point of impact
Cerebral laceration
- from impact or fracture
Diffuse traumatic axonal injury
Cerebral swelling and hypoxia

Question 15

Features of concussion

Answer 15

Transient LOC
Retrograde amnesia
Temporary nerve cell dysfunction due to impact
No residual structural damage

Question 16

Head injury and alcohol intoxication

Answer 16

BFT to head/face whilst intoxicated very dangerous - sudden death common
Suggested mechanism
- brain and neurones sensitise by alcohol
- blows cause jerking movements to neck
- acute brainstem dysfunction
- fatal respiratory arrest or cardiac arrhythmia

Question 17

Secondary effects of head injury

Answer 17

Death - sudden or delayed
Raised ICP
Brain swelling
Cerebral hypoxia
Late complications
- meningitis
- cerebral abscess
- post-traumatic epilepsy

Question 18

Features of raised ICP

Answer 18

3 main factors
- cranial cavity confined bony space
- intracranial haemorrhage
- brain swelling
Brain squeezed downwards
- subfalcine herniation of cingulate gyrus
- subtentorial herniation of cerebrum under tentorial edge
- tonsillar coning of cerebellum into foramen magnum
Secondary infarction and necrosis
Pontine haemorrhage from stretched vessels