What investigations should be done for a patient with a traumatic brain injury?

Investigations for Traumatic Brain Injury

Non-contrast CT (NCCT) is the first-line imaging test for all patients with traumatic brain injury, with high sensitivity for detecting clinically significant injuries requiring neurosurgical intervention. 1

Initial Imaging Selection

Non-contrast CT (NCCT)

• NCCT is the initial triaging diagnostic imaging test of choice for all TBI patients (Class I recommendation) 1
• NCCT effectively detects intracranial hemorrhage, extra-axial fluid collections, skull fractures, cerebral edema, and signs of herniation 1
• Advantages include widespread availability, rapid acquisition time, and minimal contraindications 1
• NCCT has high negative predictive value for excluding neurosurgical intervention in mild TBI 1

Clinical Decision Rules for CT in Mild TBI

Three validated prediction rules can help identify which mild TBI patients require NCCT:

• New Orleans Criteria (NOC): For patients with GCS 15 only 1
• Canadian CT Head Rule (CCHR): For patients with GCS 13-15 with blunt trauma 1
• NEXUS-II: Broader inclusion criteria 1

These rules have sensitivity of 97-100% for identifying patients who can safely avoid NCCT 1

MRI Indications

• MRI is not indicated as a primary evaluation tool for acute TBI 1
• MRI is recommended when NCCT is normal but unexplained neurologic findings persist (Class I recommendation) 1, 2
• MRI is more sensitive than NCCT for detecting:
  • Nonhemorrhagic axonal injury 1, 2
  • Hypoxic ischemic encephalopathy 1
  • Brain stem injuries 1
  • Small subdural hematomas 1
  • Brain contusions 1

Specialized MRI Sequences

• T2 GRE and SWI*: Most sensitive for detecting hemorrhagic axonal injuries (Class IIa recommendation) 2, 3
• DWI: Sensitive for acute parenchymal contusions and axonal injuries 1
• T2W FLAIR: More sensitive than NCCT for subarachnoid hemorrhage and brain contusions 1

Follow-up Imaging

Repeat NCCT Indications

• Indicated for patients with neurologic deterioration (Class I recommendation) 1
• Recommended for moderate to severe TBI (evidence level II) 1
• Indicated for anticoagulated patients with abnormalities on initial NCCT 1
• Not routinely recommended for mild TBI with negative initial CT (Class III recommendation) 1, 2

Follow-up MRI Indications

• Recommended for persistent, new-onset, progressive, or worsening symptoms (Class I recommendation) 1, 2
• Approximately 27% of patients with mild TBI and normal CT show abnormalities on MRI that may predict outcomes 2

Special Considerations

Pediatric Patients

• Clinical observation before NCCT decision is effective in reducing unnecessary radiation exposure (Class IIa recommendation) 1
• Each additional hour of ED observation is associated with decreased CT rates without delaying diagnosis of significant TBI 1
• In suspected non-accidental trauma, MRI may identify multiple injuries of varying age 1

Prognostic Tools

• Marshall and Rotterdam scores on NCCT are validated prediction tools for clinical outcomes in moderate to severe TBI 1
• Rotterdam score predicts 6-month mortality based on NCCT findings 1

Common Pitfalls

• Negative NCCT does not exclude diffuse axonal injury, as more than 80% of these lesions are not associated with macroscopic hemorrhage 2
• Approximately 15% of patients with mild TBI and normal CT scans will have persistent neurocognitive sequelae at 1 year 2
• Negative imaging studies, including brain MRI, do not accurately predict which patients will remain symptomatic with post-concussive symptoms 1
• Patients with neurologic abnormalities should be observed closely despite negative NCCT results 1

Summary of Recommendations

1. NCCT is the first-line imaging test for all TBI patients (Class I) 1
2. Use validated clinical decision rules to determine which mild TBI patients need NCCT 1
3. MRI is indicated when NCCT is normal but unexplained neurologic findings persist 1, 2
4. Repeat NCCT is indicated for neurologic deterioration, not routinely for mild TBI 1
5. Specialized MRI sequences (T2* GRE, SWI, DWI) provide highest sensitivity for detecting axonal injury 1, 2, 3