Does a patient with a history of loss of consciousness (LOC), nausea, disorientation, initial inability to feel arms, and current numbness after a 50-pound package fell on their head, and an unremarkable computed tomography (CT) scan, require a magnetic resonance imaging (MRI) of the neck and brain?

MRI of Neck and Brain is Indicated for This Patient

Yes, this patient should undergo MRI of both the neck and brain despite the unremarkable CT scan. The combination of head trauma, loss of consciousness, neurological symptoms (numbness and inability to feel arms), and persistent symptoms with a normal CT scan strongly indicates the need for more sensitive imaging 1.

Rationale for MRI Imaging

Brain MRI Indication

• The patient experienced loss of consciousness and disorientation after significant head trauma (50 lb package)
• Persistent neurological symptoms (numbness) despite normal CT
• According to ACR Appropriateness Criteria, MRI is more sensitive than CT for:
  • Small white matter lesions in traumatic axonal injury 1
  • Subtle findings adjacent to the calvarium or skull base 1
  • Detecting acute ischemic changes 1

Neck MRI Indication

• Initial inability to feel arms and persistent numbness strongly suggests potential cervical spine involvement
• There is a well-established association between maxillofacial/head trauma and cervical spine injuries 1
• MRI can detect soft tissue injuries of the cervical spine that CT cannot identify 1

Clinical Decision Algorithm

1. Initial presentation: Head trauma + LOC + neurological symptoms (arm numbness)
2. Initial CT scan: Unremarkable
3. Decision point: Persistent neurological symptoms despite normal CT
   • If symptoms resolved completely → observation may be appropriate
   • If symptoms persist (as in this case) → proceed with MRI

Evidence Supporting This Approach

The ACR Appropriateness Criteria for Head Trauma states that "MRI is more sensitive than CT for acute infarct" and "Brain MRI may be indicated as a second-line study when there are persistent neurologic deficits that remain unexplained after the head CT" 1.

Studies have shown that approximately 27% of patients with mild traumatic brain injury and normal CT scans show abnormalities on early MRI, including small cortical contusions or hemorrhagic axonal injury 1. These findings can be clinically relevant for predicting outcomes.

For cervical spine evaluation, MRI can detect soft-tissue injuries in 5% to 24% of trauma patients with negative cervical spine CT 1. The presence of neurological symptoms (arm numbness) significantly increases the likelihood of cervical spine involvement.

Important Considerations and Pitfalls

• Don't rely solely on normal CT: CT has limited sensitivity for detecting subtle brain injuries and spinal cord pathology
• Don't dismiss persistent neurological symptoms: Arm numbness after head trauma strongly suggests cervical spine involvement that requires evaluation
• Don't delay imaging: Persistent neurological symptoms after trauma require prompt and thorough evaluation
• Don't overlook the cervical spine: There is a 7-11% association between facial/head fractures and cervical spine injuries 1

MRI without contrast would be the appropriate initial study for both brain and cervical spine, with contrast added if there is suspicion for vascular injury or other pathology requiring contrast enhancement.