Traumatic brain injury Flashcards
(30 cards)
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
How do we measure consciousness? (5)
*Glasgow Coma Scale
* presence, duration and depth of impaired consciousness and coma
* used to describe altered consciousness from a mild confusional state to deep coma
If are confused, there was an alteration of consciousness
* 3 aspects measured: verbal responses, motor responses and eye opening
* highly reliable when used by trained persons
What is the total coma score? (5)
Total coma score: E+M+V = 15 (range 3-15)
* Persons with a GCS of 15 can still be in post-traumatic amnesia
* A GCS of 8 is the critical score
8 > =unconsciousness
A GCS 15 can still have a TBI but they’re conscious (has amnesia)
* 90% are in coma if GCS ≤8 (e.g., 1 on eye opening, 5 on motor response and 2 on verbal response)
* A score of 3-deepest level of coma (no movements, sounds or eye opening) is associated with a greater likelihood of death
The worse the GCS and the longer the amnesia = worse TBI
What is coma defined as?
- Coma is defined as:
- Not opening eyes
- Not obeying commands
- Not uttering understandable words
What is post traumatic amnesia? (5)
- An acute but temporary period following coma/impaired consciousness during which the patient is confused, disorientated
- Hallmark of PTA is amnesia: where the patient is unable to record events in memory in a continuous or connected way
Patients will often have islands of M but no continuous recall - By definition the patient must be amnesic for a period
- Measured from the time of injury and includes the period of unconsciousness
- Post-traumatic amnesia (PTA) is also characterised by intellectual and behavioural disturbances
What is the importance of PTA? (3)
- PTA is used as an index of TBI severity
Correlates most strongly with outcome (longer PTA = worse TBI) - PTA duration is one of the best predictors of recovery and outcome following TBI (more so than the GCS)
- Best predictor of atrophy were scores on the Westmead PTA scale
How do we measure PTA?
Standardised prospective measurement of PTA:
- Moderate to Severe TBI
* Westmead PTA Scale (WPTAS)
- TBI/Concussion
* Abbreviated-Westmead PTA Scale
What is the Westmead Post-traumatic Amnesia Scale? (5)
*Testing begins when:
* Patient communicates intelligibly
* Is able to follow commands (i.e. GCS motor score = 6)
*Testing stops:
* Operational definition: Person is out of PTA if they can achieve a perfect score of 12/12 on the Westmead PTA Scale for 3 consecutive days. PTA is judged to have ended on the first of the 3 consecutive days of perfect recall
- Administered daily generally by Occupational Therapists; Registered nurses on weekends.
Someone who has daily contact with the patient - 7 orientation questions: (age, dob, month, time of day, day, year, place)
- 5 memory questions: (examiner’s name and face, 3 picture cards)
What is the Abbreviated-Westmead PTA Scale? (9)
When someone has a GCS between 13 and 15
* Administered hourly for up to 4 hours
* Mandatory for use within Emergency Departments in NSW, and can be given by ambulance staff at the scene
* Can be administered at any time within 24 hours of injury
* Patient is out of PTA on the first score of 18/18
- Orientation items:
*If a patient’s response is incorrect they are immediately presented with the correct answer.
*If a patient responds with “I don’t know” or does not respond spontaneously they are presented with a multiple choice.
- Picture cards:
*At the second and every consecutive assessment, if one or more of the picture cards are not recalled spontaneously a choice is given from the 3 target pictures and six distractor items.
Patient is given 4 tries to score 18/18, testing stops as soon as they do, if not they’re given the Westmead
What is an additional parameter in determining TBI severity? (5)
- Retrograde Amnesia (RA)
- Failure to recall events prior to the TBI
- More remote memories are spared
- Usually RA is of much shorter duration than PTA
Decribe a M close in time to the accident
More severe TBI = longer RA - RA may shrink over time as the individual recovers from PTA
PTA Ms will never be recovered but RA Ms may be recovered over t - Length of RA associated with TBI severity (e.g., in mild TBI, RA may be minutes to seconds)
