What is the first diagnostic test to perform on a patient with a head injury and loss of consciousness after hitting their head on a goal post, with options including Skull x-ray, Electroencephalogram (EEG), Complete Blood Count (CBC), Prothrombin Time/International Normalized Ratio (PT/INR), or Computed Tomography (CT) head scan?

CT Head is the First Diagnostic Test for Head Injury with Loss of Consciousness

A non-contrast CT head scan should be performed immediately as the first diagnostic test for Sarah, who experienced head trauma with loss of consciousness after hitting her head on a goal post.

Rationale for CT Head as First-Line Imaging

Head CT is the gold standard for initial evaluation of traumatic brain injury for several important reasons:

1. High Sensitivity for Acute Injuries: CT is highly sensitive for detecting acute intracranial hemorrhage, fractures, and mass effect that may require immediate intervention 1, 2.

2. Rapid Acquisition Time: CT can be performed quickly, which is critical in the acute trauma setting when timely diagnosis can significantly impact outcomes 2.

3. Guideline-Based Recommendation: The American College of Radiology (ACR) Appropriateness Criteria specifically recommends non-contrast head CT as the first-line neuroimaging test for head trauma with loss of consciousness 1.

4. Clinical Decision Rules Support: Sarah meets criteria for CT imaging according to validated clinical decision rules, including:

   • Loss of consciousness
   • Physical evidence of trauma above the clavicles (hitting head on goal post)
   • Mechanism of injury consistent with significant force 1, 3

Why Other Tests Are Not Appropriate First-Line Options

• Skull X-ray: No longer recommended as first-line imaging for head trauma. The ACR explicitly states there is "no relevant literature to support the use of radiographs in the initial imaging evaluation of acute head trauma" as CT is more sensitive for neurosurgical lesions 1.

• EEG: Not indicated for initial evaluation of traumatic brain injury. EEG evaluates electrical activity of the brain but does not detect structural injuries that require immediate intervention.

• CBC, PT/INR: While these may be ordered as part of the overall trauma workup, they do not diagnose intracranial injuries and should not delay neuroimaging.

Clinical Approach to Sarah's Case

1. Immediate Non-Contrast CT Head: This should be performed without delay due to her loss of consciousness following head trauma 1.

2. CT Findings Will Guide Management:

   • If negative: Close observation may be sufficient
   • If positive: May require neurosurgical consultation or intervention

3. Consider Additional Imaging if indicated by initial CT findings:

   • CT angiography if vascular injury is suspected
   • MRI for better evaluation of parenchymal injuries if CT does not explain clinical status 4

Important Clinical Considerations

• Deterioration Risk: Even with an initially normal CT, patients with head trauma can deteriorate. Close neurological monitoring is essential 5.

• Risk Factors for Significant Injury: Sarah's presentation includes concerning features that warrant immediate imaging:

  • Direct impact to head (against goal post)
  • Loss of consciousness
  • Headache (likely present given mechanism)

• Pitfall to Avoid: Delaying CT imaging in patients with loss of consciousness after head trauma significantly increases morbidity and mortality risk, as early detection of intracranial hemorrhage is critical for timely intervention 1, 2.