Traumatic brain injury Flashcards
What is a TBI?
Is an acquired brain injury due to damage to the brain as a result of the sudden application of mechanical energy from external physical forces
What is a penetrating TBI?
Foreign object penetrates the brain, the trauma is where the object is
What is a closed TBI?
Head suddenly and with force comes into contact with a stationary object and the brain is compressed against the inner surface of the skull, more common type of brain injury (brain slams against the inner surface of the skull), get lots of lesions from the acceleration and decelleration and parts of brain move independently of each other, causes diffuse lesions, outcome is worse than open brain injury
What are the causes of TBI?
Mechanism of injury: Fall, Transport-related accident, Assault, Other (Non-intentional e.g., sports injury)
* Children, and adults > 45 years – falls
* Adolescents and young adults – violence and motor vehicle accidents
* TBI occurs more often in: lower socioeconomic classes, unemployed, substance abuse, poor academic performance
What is the neuropathology of TBIs?
A traumatic brain injury can occur due to both:
* Contact forces to the head
* Acceleration/deceleration head movements
- Linear Forces
- Angular Rotation
Head moves within the skull and ricochets off the internal surface of the skull and bc the brain is made of tissues of diff densities they move relative to one another so there are lots of diffuse white matter lesions
Brain effects of contact and acceleration/deceleration are usually described in terms of primary/immediate, secondary and tertiary processes
What are the 6 primary neuropathological effects of TBI?
- Injury to scalp
- Fractures to skull
- Surface brain contusions (bruising) and cerebral lacerations (tearing from the bony underside of the skull)
- Intracranial haematoma (bleeding)
- Diffuse axonal injury
- Diffuse vascular injury
What are scalp injuries?
- A head injury is not necessarily a brain injury
- External injuries to the face, scalp:
- scalp laceration, bruising, abrasion
- Skull fractures
What is contusion, coup and contre coup?
Bruising of the brain
Contusion occurs where the brain comes in contact with bony areas of the skull.
Coup/Contrecoup injury are associated with contusion
* Coup contusion occurs site of impact/ contact, lesion of brain underneath the pt of impact
* Contrecoup usually associated with translational (linear) acceleration, opposite the pt of impact
* Coup and contrecoup can occur individually and together
What are intracranial bleeds (5 types)?
*Are due to haemorrhage and haematoma through tearing of blood vessels - can occur immediately or over hours/days
*Types
* Extradural (bleed between skull and dura mater)
* Intradural
* Subdural
* Subarachnoid
* Discrete intracerebral or intracerebellar haematoma not in continuity with surface of the brain
What are diffuse axonal/diffuse vascular injuries? (10)
- Early work documented extensive white matter lesions, and shearing strain/injury, described as diffuse axonal injury
- DAI replaced by term, Traumatic Axonal Injury (TAI; damaged axons are grouped, not strictly diffuse)
- TAI principal pathological substrate producing neurological impairment; M changes, slowing of processing, attentional and executive deficits
Cog impairment depends on severity of the BI and esp the severity of TAI - Classical view is that axons are torn at injury but this primarily occurs in moderate to severe TBI
Neuropsych tests measure the severity of TAI - Diffuse vascular injury is frequent in severe TBI
In mild TBI, axons are just stretched so better change of recovering but are torn in severe TBI so dont recover as well - Petechial haemorrhages (tearing of capillaries) like TAI are the result of rapid acceleration-deceleration forces
- Petechial haemorrhages may coalesce into larger lesions with progressive secondary haemorrhage
What is the neuropathology of mild TBI? (2)
- Very mild concussion may produce no permanent damage to cells
- Axons have a capacity for stretch without axotomy occurring
What is the neuropathology of moderate to severe TBI? (7)
- Macroscopic haemorrhages in midline structure (including brain stem) which over time shrink to sunken cystic scars
External force can impact the brain by compression and distorsion or bleeding inside the brain - Microscopic axonal injuries
- Days –numerous axonal swellings and axonal bulbs in deep
- Months to years – small healed superficial contusions, extensive white matter degeneration, relatively intact grey matter, enlarged ventricles
The degree of TAI is proportional to the severity of TBI
Do neuropsych assessment to see how an injury will affect a specific person (their life)
What are 4 secondary neuropathological effects of TBI (moderate to severe)?
- Ischemia (reduced blood supply to brain tissues)
- Hypoxia (lack of oxygen)
- Swelling (oedema)
- Raised intra-cranial pressure (ICP)
Each of these negatively affect outcome
The more patho effects going on, the worse the outcome
What are 4 delayed effects of TBI (moderate to severe)?
- Ongoing atrophy (degeneration) of white matter over time
- Hydrocephalus – occurs due to problems of reabsorption of CSF (e.g., from subarachnoid haemorrhage, oedema); in ventricles compress the brain and give rise to neurological disorders
- Meningitis and brain abscess – most common following depressed or base of skull fractures, surgery
- Post-traumatic epilepsy – incidence around 5%
What are the 2 parameters measured when measuring the severity of TBI?
Two parameters measured:
- Level of coma/impaired consciousness
* Glasgow Coma Scale
- Post-traumatic amnesia
* Westmead Post-traumatic Amnesia Scale
* Abbreviated-Westmead PTA Scale