Traumatic Brain Injury Flashcards
What are the conditions causing brain injury?
- Trauma
- Tumor
- Stroke
- Metabolic derangements
- Degenerative disorders
What are the manifestations of traumatic brain injury?
- Changes in LOC (may fluctuate depending on extent & level of injury/damage - RAS dependent)
- confusion ^ mild
drowsy
obtundation
stupor
coma v extreme
- confusion ^ mild
- Alteration in sensory & motor functions
- Posturing: decorticate and decerebrate
- Cranial nerve reflexes
A) Pupil reflex (function of brainstem + CN II & III)
- indicator of brain herniation
- increased IVP may impair eye movements controlled by CN III, IV & VI
B) Oculovestibular reflex
- sign of brainstem dysfunction
- 2 tests to do:
I. Caloric ice water test (invasive)
> ice water is injected into ear canal
> normal = conjugate eye movement (both eyes move together towards direction of water entering)
> abnormal = dysconjugate/asymmetric eye movement
> absent = no eye movement
II. Doll’s eye test (non-invasive)
> Oculocephalic head turning test (absent response)
> indicate brainstem damage
> normal = eyes turn in direction oop of head rotation
> abnormal = eyes stay midline & don’t turn when head is rotated
C) Corneal reflex
- absence of blink response
- indicator of severely impaired brain function
Who is more likely to get traumatic brain injury?
- Males
- People of lower SES
- 21-60 years old
- Young and active
How many types of brain injuries are there?
Primary/Direct
- caused by impact/initial insult
- include diffuse axonal injury & focal lesions of laceration, contusion and haemorrhage
- types:
1. Focal/coup injury
> localised at site of impact of skull
2. Polar - coup/countercoup injury
> occur as a result of brain shifting within skull and meninges during course of acceleration/deceleration movement = cause local injury in two separate poles of brain
3. Diffuse
> movement of brain within cranial cavity causing wide neuronal damage
4. Intracranial haematomas
> epidural, subdural and subarachnoid
Secondary (*TBI often initiates mechanism of secondary injury - ischaemia, increased ICP and altered vascular regulation)
- progressive damage from physiologic response to an initial insult
- damage results from
1. Subsequent brain swelling
2. Infection
3. Cerebral hypoxia
- often diffuse/multifocal, including:
1. Concussion
2. Infection
3. Hypoxia brain injury
What are the causes of traumatic brain injury?
- Motor vehicle collisions
- Industrial accidents
- Minor HI
- Criminal assault
What are the different types of skull fractures?
Linear, Depressed and Basal skull fractures
*fractures of cranial vault is obvious on skull xray
*2/3 of skull fractures are associated with intracranial lesions (but intracranial lesions can also occur without skull fractures/external injuries - need to do hx/pe TRO HI)
What can you see on linear skull fractures?
- Lucent xray = brain separation
- Dense xray = brain overlap
- Cause rupture of meningeal vessels
What are depressed fractures and what do they indicate?
Depressed fractures are open fractures associated with infection
- Stellate (multiple fractures radiating from a single point): impact from blunt object ; underlying brain injury
- Egg shell = child abuse
What is a basal skull fracture and how to detect one?
- most important/critical case
- difficult to detect in X-rays due to irregular and dense bones
- other soft tissue injuries may give clue:
- Haemotympanum (blood in middle ear)
- CSF rhinorrhoea/otorrhoea
- Periauricular/retoauricular ecchymoses (bruise behind ear) - Battle’s sign
- Periorbital ecchymoses (bruise ard eyes) - Racoon’s eyes
- often associated with CN injuries (CN are located at base of skull)
1. Anosmia
2. Partial loss of vision
3. Facial palsy
4. Vertigo
5. Nystagmus
*indications of HI include: scalp wound, fracture, swelling/bruising, LOC, nasal discharge and stiff neck
What are the types of intracranial lesions?
- Concussion
- Contusion
- Epidural/Extradural haematoma
- Acute subdural haematoma
- Chronic subdural haematoma
- Subarachnoid haemorrhage
- Intracerebral haemorrhage
What is a concussion?
It is an immediate transient LOC (dazed/star struck)
What are the causes of concussion?
- Rotation of cerebral hemisphere to relatively fixed brainstem
- Electro-physiological dysfunction of RAS
- No structural lesion & residual sequelae
What are the signs and symptoms of concussion?
- Retrograde amnesia (before events; indicate severity of lesion)
- Antegrade amnesia (after events, very brief)
What is a contusion?
A head injury resulting in haemorrhage into brain tissue
What are the causes of contusion?
- Deceleration of brain against skul = rupture surface of brain
- Frontal and occipital pole affected
- Coup injury - directly under point of impact
- Countercoup - at point opposite point of impact
What are the signs and symptoms of contusion?
- Hemiparesis/gaze paralysis (frontal injuries)
- Visual defect - occipital lobe
- CN dysfunction - commonly olfactory
- Cerebral oedema, decorticate, decerebrate = more severe injury
- Coma - if bilateral cerebral lesions
What is an extradural/epidural haematoma
*shows convex on xray
It is a haemorrhage between skull and dura mater
- due to direct trauma causing fracture to temporal bone and damage to middle meninges
- as there’s an arterial bleed = condition will worsen rapidly (fast blood leak)
What is the symptom of extradural/epidural haematoma?
Brief LOC -> short lucid interval -> coma/other signs of deteriorating LOC (*depend on whether patient is herniating/progress of neurological deterioration due to herniation)
*carries a bad prognosis for severe extradural haematoma
What treatment does extradural/epidural haematoma require?
Immediate surgical evacuation to drain bleed
What if extradural/epidural haematoma do not get treated?
It will cause decerebrate rigidity, coma then death
What is an acute subdural haematoma?
*shows concave (look like a cave) on xray
It is a haemorrhage between dura mater and arachnoid membrane (bleed through veins)
- may not be associated with any surface injuries on scalp
- follows severe HI due to change in velocity
- due to rupture of surface cerebral veins that join dural venous sinuses
- twice as common as epidural haematomas
What are the symptoms of acute subdural haematoma?
Brief LOC due to concussion -> relatively longer lucid interval (few mths to years) -> coma (progressive neurological deterioration due to herniation)
*bad prognosis if accompanied with cerebral injury due to high velocity
What is the treatment for acute subdural haematoma?
Surgical evacuation
What happens if acute subdural haematoma is not treated?
It will cause decerebrate rigidity, coma then death
