Severe TBI

FACTS

  • Most likely age groups to suffere TBI:
    • 0-4
    • 15-19
    • 65+

HPI

universal ROS
+ detailed trauma history

PHYSICAL EXAM

GCS
universal neuro exam

IMAGING

CT without contrast:
  • loss-of gray-white differentiation (indicates severe swelling / hypoxic injury)
  • effacement of sulci
  • slit vents
  • scattered petechial hemorrhage in corpus callosum indicative of
MRI Brain without contrast
  • evaluate SWAN hits based on Adams DAI classificaiton
Adams Diffuse Axonal Injury Classification
  • Grade 1: A mild diffuse axonal injury with microscopic white matter changes in the cerebral cortex, corpus callosum, and brainstem
  • Grade 2: A moderate diffuse axonal injury with gross focal lesions in the corpus callosum
  • Grade 3: A severe diffuse axonal injury with finding as Grade 2 and additional focal lesions in the brainstem
A/P
Following TBI, the general principles of resuscitation are reducing ICP, maintaining CPP (MAP - ICP), evacuating space-occupying lesions, avoiding cerebral hypoxia
 
EVD/Bolt
  • CPP ideally 60-70
  • PBO2 > 20%
 
Critical care:
  • Na+ at least normonatremia, do not drive up unless needed (do not want to desensitize brain to HTS for no reason)
  • Cooling: prevent fever (which increases CMRO2)

Severe TBI Protocol
- cEEG: non-convulsive status epilepticus is highly associated (22%) with hypoxic brain injury
- EVD + Bolt (protocol)
- Day 4:
- Day 5: d/c bolt and get MRI without contrast w/ SWAN
- Day 11: SSEPs if still not following commands

Other
- pituitary labs (endocrinopathy common) 
 

Pedatric TBI

  • after moderate-severe TBI, GH deficiency most common in children (10-40% dysfunction)

Cerebral Perfusion Pressure (CPP)

  • Brain Trauma Foundation guidelines currently recommend 60-70 mmHg
  • > 70 increases ARDs risk

cerebral metabolic rate of oxygen (CMRO2)

  • definition: CMRO2 = CBF / (AV oxygen difference), typicall 3-3.5 mL/100/g/min
  • decreases: sedatives
  • increases: fever
  • does not directly affect: oxygen

Cerebral Blood Flow (CBF)

  • CBF estimated ~50 mL/100g/min

Brain tissue oxygenation

  • PbO2 < 20 is hypoxia

Hypothermia

  • not proven to improve survival/long-term functional outcomes
  • mechanism: decreased excitatory NTs --> ↓ cerebral metabolic rate
  • risks: infection, coagulation abnormalities, MI, afib

Prognostication

MRI Brain without contrast
SSEPs
  • N20 = negative deflection of signal recorded from scalp in area of central sulcus approximately 20 ms after each stimulus, averaged
    • represnts post-synaptic activity related to sensory stimulation
    • absence = poor prognosticator