TBI

• For people with a head injury and a GCS score of 12 or less consider giving tranexamic acid:

  • 2g IV bolus
• For people with a GCS score of 8 or less, ensure early involvement of an appropriately trained clinician to provide advanced airway management
• Criteria for doing CT head within 1 hour:

  • GCS of 12 or less on initial assessment
  • GCS score of less than 15 at 2 hours after the injury
  • Suspected open or depressed skull fracture
  • Any sign of basal skull fracture - hemotympanum, racoon eyes, CSF leak, battle's sign
  • Post traumatic seizure
  • Focal neurological deficit
  • More than 1 episode of vomiting
• CT head scan within 8 hours (or within 1 hour if presenting after 8 hours) if they have had some loss of consciousness or amnesia since the injury and any one of:

  • Aged 65 or over
  • Any current bleeding or clotting disorders (or on anticoagulants)
  • Dangerous mechanism of injury
  • More than 30 minutes retrograde amnesia
• Traumatic brain injury = evidence of damage to the brain as a result from trauma to the head, represented with a reduced GCS or presence of a focal neurological deficit
• Classification:

  Minimal = GCS 15 with no LOC

  Mild = GCS 13-15 (concussion)

  Moderate = GCS 9-12

  Severe = GCS 3-8
• Clinical features of raised ICP:

  • Nausea and vomiting
  • Restlessness, agitation or drowsiness
  • Slow slurred speech
  • Papilloedema
  • Sluggish dilated pupil which then becomes fixed (blown)
  • Cranial nerve palsy e.g. CN III with down and out pupil
  • Seizures
  • Reduced GCS
  • Decoricate posturing - abnormal flexion of the arms and extension of legs
• Cushing's reflex:

  • Physiological response to raised ICP which attempts to improve perfusion
  • Leads to Cushing's triad:
  • Bradycardia
  • Hypertension
  • Irregular respirations
• Cerebral Perfusion Pressure (CPP)

  • CPP = Mean Arterial Pressure (MAP) – ICP
  • A rise in ICP will reduce CPP. If CPP drops too low for a significant amount of time, ischaemia occurs.
• Herniation:

  • Defined as movement of brain structures from one cranial compartment to another
  • Herniation of the cerebellar tonsils through the foramen magnum leads to compression of the brainstem and respiratory arrest - referred to as coning
  • Herniation of the uncus of the temporal lobe through the tentorial notch often leads to compression of CN III = blown pupil
• Primary brain injury:

  • Initial injury causes to brain tissue from the forces of the traumatic event itself
  • Focal - skull fractures, blood vessel injury and haematoma formation
  • Diffuse - contusion (bruising) - frequently associated with oedema and especially likely to cause raised ICP
• Secondary brain injury:

  • Indirect damage to brain tissue that occurs after the primary insult, worsening to original injury, common causes:
  • Inadequate perfusion causing cerebral hypoxia
  • Acidosis
  • Hypoglycaemia
  • Cerebral oedema leading to raised ICP
• Interventions for cerebral oedema and raised ICP:

  • Avoid tight C-spine collars
  • Position patient at 30 degrees to aid venous drainage
  • Mannitol or hypertonic saline to reduce ICP - hypertonic saline has a high concentration of sodium which draws out water
  • Intubation and hyperventilation - hypocapnia causes vasoconstriction in the cerebral arterioles and thus reduces cerebral blood flow
• Expanding haematoma interventions:

  • Reverse clotting abnormalities
  • Consider tranexamic acid if less than 3 hours since injury
  • Neurosurgical intervention
• Diffuse axonal injury:

  • Type of TBI that results from brain sudden acceleration against the skull - shearing of the axonal tracts of the white matter
  • RTI most common cause
  • Shaken baby syndrome
  • Patients will have loss of consciousness at the time of injury with a prolonged post-traumatic coma