Head Injuries

• can involve skull fractures, hemorrhage and edema, or direct injury to brain tissue
• full range of degree of damage
• bone fragments from skull can cause severe damage
• inability of skull to expand increasing intracranial pressure (pressure within the skull)

• may be closed or open injuries
• fractures may be linear, comminuted, compound, depressed, basilar (at base of skull)
• contrecoup injury, usually causing minor damage, can occur contralateral to site of injury (opposite side of the skull)
  

concussions

• reversible dysfunction from mild blow
• usually full recovery in 24 hrs
  

contusion

• bruising of brain tissue
• possibility of residual damage

Hematoma (internal bleeding) can occur as a result of head trauma:

epidural hematoma

• bleeding between dura and skull
  

subdural hematoma

• bleeding between dura and arachnoid

subarachnoid hemorrhage

• space between arachnoid and pia

intracerebral hematoma

• may develop days after injury

Signs and symptoms of head trauma:

• seizures (focal and general)
• cranial nerve impairment
• particularly with basilar fractures
• otorrhea, rhinorrhea (leaking CSF from ears, nose)
• fever (hypothalamic/cranial)
  

Herniation syndromes

• Cingulate (Subfalcine) Herniation
  • The distal anterior cerebral artery (supplies motor cortex of leg) can be compressed causing contralateral leg weakness
• Uncal (Unilateral Transtentorial) Herniation
• Unilateral mass forces the ipsilateral (same side) temporal lobe through the tentorium cerebelli
  • Contralateral upper motor neuron signs
• Ipsilateral third nerve compression
  • dilated pupil
• Contralateral Upper Brainstem compressed
  • Ipsilateral hemiplegia
• Cerebrospinal Fluid (CSF) flow interrupted
• Abnormal respirations
  • Cheyne-Stokes
  • Erratic
• Central Herniation
  • Supratentorial lesion forces the diencephalon centrally through the tentorium cerebelli
  • Compresses the upper midbrain, lateral pons and medulla
  • Early:
    • erratic respirations
    • small reactive pupils
    • increased limb tone
    • Babinski sign
    • Decorticate rigidity (loss of higher motor control; flexion due to rubrospinal system intact)
    • Decerebrate posturing (later) - dysfunction at red nucleus, extension due to reticulo- & vestibulospinal tracts intact
    • Fixed and dilated pupils
• Tonsillar Herniation
  • If posterior fossa pressure is high, the cerebellar tonsils can herniate through the foramen magnum of the skull.
  • Loss of consciousness, as well as compromised cardiovascular and respiratory centres leading to labile BP and ireegular breathing.

Cushing Reflex

• The classical Cushing's reflex is a late event and often occurs pre-mortem
• Relative brain ischemia, causing systemic hypertension due to sympathetic outflow activation, and thereby producing bradycardia by feedback from the carotid baroreceptors