PHTY303 Lecture 4: PHTY303 Week 4 DIL continued
PHTY303 Week 4 DIL: An introduction to TBI
Describe TBI in terms of its:
• Epidemiology
• Aetiology
• Pathophysiology
• Classification Systems
• Clinical Course/Prognosis
2. Defining TBI
- Acquired Brain Injury (ABI) is a loosely defined term referring to an umbrella or
overarching term applied to describe insults to the brain that are not congenital or perinatal in
nature.
- It usually encompasses single-event pathology of traumatic and non traumatic origin, and
may include a variety of aetiologies such as malignancy, infectious diseases, haemorrhages,
aneurysms, cerebral contusions/concussions/abscesses, trauma, or other 'acquired'
problems (eg stroke). In some instances this term will encompass brain injury acquired from
progressive neurological conditions (eg MS) as symptomatology can be similar, but other
authors will exclude this group from their definition.
- Traumatic Brain Injury (TBI) results from mechanical energy to the head from external
physical forces. It may involve altered level of consciousness, post-traumatic amnesia, and
other neurological signs, seizues and is not due to drugs, alcohol, medication, systemic
issues, or psychological trauma. It may involve rapid forward and backward motion or a
blunt/penetrating force
3. Epidemiology
- Variability in ABI/TBI definition can lead to incomplete capture of epidemiology data. However,
it is clear it is a major socio-economic issue and burden around the world
- The Australian Institute of Health and Welfare (2007) Disability in Australia:
ABI. (Bulletin no. 55 AUS 96. Canberra. AIHW) report local ABI prevalence rates
- for people aged under 65 years as (these authors defined ABI as any damage to
the brain that occurred after birth):
- Almost 3/4 of people with abi and almost all who have brain injury as their main
disabling condition are under 65 years .....
- Two thirds are under 25 with a strong peak for males 15-24
4. Fast facts & Epidemiology and Aetiology
TBI:
- is a major cause of hospitalisation, disability and death in Australia and has a high
incidence.
- in 2004-05 was responsible for at least 22,700 hospitalisations, about 980 deaths in
hospital, and estimated direct hospital care costs of $184 million
- causes high societal costs – loss of productive life and need for long term and often
lifelong services (care, housing, equipment), particularly considering advances in
emergency, ICU and neurosurgery practices as people are surviving catastrophic injuries
when previously they may not.
- Health care costs reduce over first 6 years but accommodation and care costs usually
increase
- has rates for males two and a half times for females
- has low mortality rates for those patients only seen in ED (the majority) but high mortality
rates are seen in those hospitilsed
- aetiology is most commonly caused by falls (9,233 or over 40%), transport accident
injuries (7,153 or over 31%) and assault (3,105 or nearly 14%).
- other causes include: gunshot, pushbike, sport
- 1 in 45 Australians have an ABI with activity limitations or participation restrictions
Pathphysiology
- Make sure you remember the role of the various parts of the CNS to understand
what occurs when they are damaged including:
• Arterial supply including Anterior, Middle, Posterior Cerebral Artery and
Cerebellar Arteries
• Lobes of the Brain including Frontal, Occipital, Parietal, Temporal,
• The Brainstem and cranial nerves
• Cerebellum and Basil Ganglia
• Right and Left differences
• Broca's and Wernicke's area
Classification Systems
(1) Closed head injury: acceleration / deceleration injury or blow to head and skull remains intact
e.g. car accident
(2) Open head injury: skull is fractured and brain coverings (dura) are torn exposing the brain
e.g. penetrating injury
Two types of Injuries can occur with TBI
1. Primary Damage: mechanical injuries - the direct result of damage and may be focal or
diffuse.
2. Secondary Damage: due to cerebral ichaemia and the resulting cascade of biochemical
changes occurring seconds, hours or days after trauma
Primary Damage - may include
• Cerebral contusions (bruises due to blunt trauma; may be coup/countercoup)
• Cerebral lacerations - traumatic tears of the cortical surface of the brain
• Penetrating injuries
• Intracranial haemorrhages
• Extradural (usually associated with #'s of temporal/parietal bone; often needs urgent
evacuation)
