TBI and Spinal Cord Injury Flashcards
Direct TBI
Occurs when the head is directly struck or its motion suddenly arrested by motion.
Indirect TBI
Cranial content are set into motion by forces other than direct contact. Eg. coup and counter coup
Primary TBI
Mechanical damage that occurs at the time of head trauma.
Eg. brain lacerations, haemorrhages, contusions, avulsions
Secondary TBI
- A facade if events proceeding primary TBI at the cellular and molecular level that continues for hours to days after the primary injury.
- Contributes to further brain injury including hypoxia, hypotension, hyperpyrexia, hyper/hypocarbia and anaemia.
Pathophysiology of brain injury
- brain injury as a result of trauma, cerebral oedema, hydrocephalus, space occupying lesion,
spontaneous bleed > increased ICP > decreased cerebral perfusion = hypoxia > ATP production > Na+/K+ pump fail > Na+ retained in cells causes cell swelling and cerebral oedema = further increase in ICP - brain needs O2 therefore patient needs increased ventilation and perfusion pressure but increased ventilation leads to decreased CO2 which causes vasoconstriction = decreased CPP > hypoxia develops > increased CO2 > increased ICP = further damage to brain
Patient presentation of TBI
- N/V
- Lacerations/contusion/haematomas to scalp
- Visible fractures or indentations to skull
- Racoon eyes
- CSF in nose/ears
- Unresponsiveness
- Confusion/disorientation
- Unequal puipls/fixed dilated
- Amnesia
- Combativeness/aggression
- numbness/tingling in extremities
- Loss of sensation/motor function
- Seizure
- Dizziness
- Visual disturbances
- Decorticate/decerebrate
- Cushings triad
Preventing secondary head injury
- Maintain SpO2 >94% using non-rebreather
- EtCO2 35-40mmHg
- Maintain MAP >80mmHg for cerebral perfusion
- Head tilt 30 degrees
- Pain management (fentanyl)
- Antiemetic
- Seizure management
- Prevention of hypothermia
Diffuse axonal injury
Axonal stretching leading to axolemmal disruption, ionic flux, neurofilament compaction, and microtubule disassembly, resulting in formation of retraction balls, axonal swelling and disconnection.
Cerebral herniation
Occurs with increased ICP due to increased volume overwhelming neuronal compensatory mechanisms of the CNS.
- Cushings triad
Other symptoms:
- sluggish pupils/fixed or dilated, bounding HR, altered LOC.
Cushings triad
- Hypertension or widening pulse pressure
- Bradycardia
- Irregular respiratory pattern (chyene-stokes) - alternating between hyperventilation and apnoea
Monroe-Kelly Hypothesis
- A pressure-volume relation between ICP and CCP regarding skull contents: CSF, brain and blood.
In case of injury where haemorrhage occurs, increasing fixed space within cranium, ICP is raised and CPP decreased. Arteries constrict to decrease intracranial volume = decreased perfusion and increased CO2 causes vasodilation. Further increase in ICP, compressed venous circulation, poor cerebral perfusion, increased swelling = brain tissue displacement and compression of brian stem.
Decorticate posturing
- Injury above midbrain
- Flextion of upper extremities and extension of lower extremities
Decerebrate posturing
- Arms extend abnormally and become adducted
- Clenched teeth
- Legs internally rotated
TBI Signs and symptoms (MIND CRUSHED)
- Mental status change
- Irregular breathing
- Nerve changes to optic/occular motor (pupils)
- Decorticate/decrebrate posturing
- Cushings triad
- Reflex sensitivity
- Unconscious
- Seizures
- Headache
- Emesis
- Deteriorating motor function
Intracranial pressure (ICP)
- Normal 5-15mmHg
- Influencing factors: CO2, O2, temp, body posturing, arterial.venous pressure