Head trauma (main)

This page is for adult patients. For pediatric patients, see: head trauma (peds)

Background

• Also known as Traumatic Brain Injury (TBI): Impairment in brain function from a mechanical force

TBI Pathophysiology

Primary injury

• Contusions
  • Bruises to brain parenchyma
• Hematomas
  • Epidural hematoma
  • Subdural hematoma
  • Intraparenchymal
  • Intraventricular
  • Subarachnoid hemorrhage
• Diffuse axonal injury
• Direct cellular damage
  • Neurons
  • Axons
• Tearing and shearing of tissues

Secondary injury

Brain swelling causes increased ICP which compresses the tissue causing ischemia with direct compression of the vasculature causing brain tissue herniation and brain death

• Leads to expansion of the original injury (predominantly metabolic insult)
  • Calcium and sodium shifts
  • Mitochondrial damage
  • Production of free radicals
• Ultimately leads to damage to axonal integrity and axonal transport
  • Enzyme activity leads to apoptosis
• Microscopic structural injury is often unidentifiable on CT or MRI

Cerebral Blood Flow and Autoregulation

• vasoconstriction
  • HTN, Hypocarbia, alkalosis
• No good way to measure cerebral blood flow
  • Use CPP as surrogate
    • CPP is amount of pressure needed to perfuse the brain
    • CPP=MAP-ICP
      • When ICP elevates, CPP decreases
      • Normal ICP
        • 15 in adults
        • <10 to 15 in children
        • 1.5 to 6.0 in infants
• Autoregulation allows the body to control the cerebral blood flow
  • Autoregulatory mechanism is damaged in most TBI patients

Clinical Features

• Adult patient with blunt head trauma

Differential Diagnosis

Head trauma

• Traumatic brain injury
  • Intracranial hemorrhage
  • Moderate-to-severe traumatic brain injury
    • Elevated intracranial pressure
  • Mild traumatic brain injury
    • Clinical decision rules for head CT in trauma
    • Post-concussive syndrome
• Orbital trauma
• Maxillofacial trauma
• Scalp laceration
• Skull fracture
  • Basilar skull fracture
  • Skull fracture (peds)
• Pediatric head trauma
  • PECARN head trauma rule

Neck Trauma

• Penetrating neck trauma
• Blunt neck trauma
  • Vertebral and carotid artery dissection
  • Strangulation
  • Whiplash injury
• Cervical injury
  • Cervical fractures and dislocations
  • Cervical injury (peds)
  • Cervical spine clearance
• Neurogenic shock
• Spinal cord injury

Evaluation

Adult GCS

Eye Opening	Verbal	Motor
		6: Obeys commands
	5: Oriented	5: Localizes to pain
4: Spontaneously opens	4: Confused speech	4: Withdraws from pain (normal flexion)
3: Opens to command	3:Inappropriate words	3: Decorticate posturing (abnormal flexion)
2: Opens to pain	2: Incomprehensible sounds	2: Decerebrate posturing (extension)
1: Does not open	1: No response	1: No response

• 14-15: Mild
• 9-13: Moderate
• 3-8: Severe

Workup

Workup is dependent on GCS severity, see:

• Mild traumatic brain injury (GCS 14-15)
  • Clinical decision rules for head CT in trauma
• Moderate-to-severe traumatic brain injury (GCS <14)

Management & Disposition

Dependent on underlying diagnosis, see:

• Intracranial hemorrhage
• Moderate-to-severe traumatic brain injury
  • Elevated intracranial pressure
• Mild traumatic brain injury
• Post-concussive syndrome

See Also

• Pediatric head trauma
• Coup contrecoup injury