1. Head injury
FM Brett
MD FRCPath

2. At the end of this lecture you should be able to:
Know basic facts about the incidence of head injury
Know the difference between focal and diffuse injury
Know the difference between missile and non-missile head injury
Be able to classify ICH
Know the difference between traumatic and spontaneous SAH
Be able to list the complications of Raised ICP

3. Head Injury - Facts Whether accidental, criminal or suicidal
leading cause of death < 45
Accounts 1% of all deaths, 30% traumatic
deaths and 50% of RTA deaths
Severity assessed by GCS

4. GCS 9-12- moderate H I 8 or less – severe H I
1. Best eye response - (max 4)
2. Best verbal response - (max 5)
3. Best motor response - (max 6)
GCS- 13+ mild H I
9-12- moderate H I
8 or less – severe H I

5. HI Longer unconscious and deeper coma >
May result in LOC
Longer unconscious and deeper coma >
likelihood that pt has suffered severe HI
60% good recovery
Based on US, UK and Netherland figures
for every 100 HI, 5 VS, 15 severely disabled, 20 minor problems, 60 full recovery

6. Nature of lesions in HI
Non - missile- RTA
Missile
Distribution of lesions
Focal
Diffuse

7. TIME COURSE Immediate Delayed Primary damage Secondary damage ischemia
scalp laceration
skull fracture
cerebral contusions
ICH
DAI
TIME COURSE
Immediate
Delayed
Secondary damage
ischemia
hypoxia
cerebral oedema
infection

8. Pattern of damage in non -missile HI
Focal
Scalp- contusion, laceration
Skull - fracture
Meninges - haemorrhage, infection
Brain - contusions, laceration, infection
Diffuse damage
Brain, DAI, DVI, HIE, Cerebral oedema

9. ICH is a complication of 66% of cases of non-missile head injury

10. Haemorrhage May be EXTRADURAL INTRADURAL - subdural, subarachnoid
intracerebral

11. EDH Found in 2% HI Usually associated with skull fracture
Peak yrs
Rare < 2 and >60
Arterial bleed -
usually meningeal
vessels

12. Subdural haemorrhage
Usually venous
Rupture of bridging
veins

13. Subdural haematoma: classification
48-72 hours – acute composed of clotted blood
3-20 dys – subacute – mixture of clotted and
fluid blood
3 weeks + - chronic encapsulated haematoma

14. SAH
Berry aneurysm
Traumatic
Infectious
Fusiform aneurysm
AVM
CAA

15. CIRCLE OF WILLIS

16. Berry aneurysms Congenital Risk of bleeding inc; Hypertension AVM
systemic vascular
disease
defects collagen
polcystic renal disease

17. Traumatic SAH may result from severe contusions
Fracture of skull can rupture vessels
IVH may enter SAS
RULE OUT ANEURYSM

18. Cerebral contusions Superficial bruises of the brain
Frequent but not inevitable after
head injury

19. Various types of surface contusions and
lacerations
~ Coup – at point of impact
~ Contrecoup- diametrically opposite point
of impact
~ Herniation – at point of impact between
hernia
~ Fracture related to # of skull

21. Sites of cerebral contusions
Frontal poles
Orbital surfaces of the frontal
poles
Temporal poles
lateral and inferior surfaces of
occipital poles
cortex adjacent to sylvian fissure

23. Uncommon types of focal brain damage
Ischaemic brain damage due to traumatic
dissection and thrombosis of vertebral or carotid
arteries by hyperextension of the neck
Infarction of pituitary - due to transection
of pituitary stalk
pontomedullary rent

24. Infection complication of skull fracture Open HI
Incidence is increased even after closed
HI as devitalised tissue prone to infection

25. Diffuse brain injury – term coined by
clinicans to describe head-injured patients
who have global disruption of neurological
function without a lesion on CT scan that
would account for their clinical state
Implies widespread structural damage
which neuropathologically is likely to be
traumatic or hypoxic/ischaemic in origin

26. Diffuse damage DAI - widespread damage to axons in the
CNS due to acceleration/deceleration of the
head
Pts usually unconscious from moment of
impact
Lesser degrees compatible with recovery of
consciousness

27. Primary axotomy - almost immediate
Pathogenesis of DAI
Primary axotomy - almost immediate
Large axolemmal tears- influx of CA++
- activation of calcium activated proteases
- severe cytoskeletal disruption- disconnection

28. Secondary axotomy Ca++ activated proteases focally damage the
the axonal BUT immediate disconnection does
not occur
Failure of cellular repair mechanisms or
secondary neuronal damage results in axonal
disconnection
Axoplasmic transport continues and results in
proximal axonal swelling

29. Diffuse vascular injury
Multiple petechial haemorrhages in
the white matter of the frontal and
temporal lobes
Probably results from traction and shearing
of parenchymal BV

30. Brain swelling and raised ICP Results from:
cerebral vasodilation - inc cerebral blood vol
damage to BV - escape of fluid through BBB
inc water content of neurones and glia- cytotoxic
cerebral oedema

32. Three patterns of brain swelling in HI
Swelling adjacent to contusions
Diffuse swelling of one cerebral hemisphere
e.g evacuation of ASDH
Diffuse swelling both hemispheres

33. ICH Herniation Subfalcine herniation Tentorial herniation
Tonsillar herniation

35. End result of herniation is compression and Duret
haemorrhages as seen in the pons

36. Ischemic damage - likely if:
clinically evident hypoxia
hypotension with systolic < 80mmHg
for at least 15 mins
episodes of inc BP i.e > 30 mm Hg

37. MISSILE HEAD INJURY Caused by objects propelled through air
Injury may be:
Depressed
Penetrating
Perforating

38. Traumatic spinal cord injury
Nature of lesions - Indirect/direct
Distribution % cervical,
25% thoracic, 6-15% lumbar.
Fractures C1/2, C4-7, T11-L2

39. Principal causes of spinal cord compression
~ Lesions in vertebral column- prolapsed disc,
kyphoscoliosis, #,
Metastatic tumour
~ Spinal extradural lesions – metastatic carcinoma,
lymphoma, myeloma,
abscess
~ Intradural extramedullary lesions –
Meningioma, Schwannoma
~ Intramedullary lesions - Astrocytoma, ependymoma, cyst formation

40. CONCLUSIONS ~ Can be missile or non-missile.
~ HI – leading cause of death under age of 45
~ Can be missile or non-missile.
~ Distribution of lesions – focal or diffuse.
~ ICH may be extradural or intradural
~ SAH may be traumatic or spontaneous
~ Main complication of HI is raised ICP.