Is an MRI (Magnetic Resonance Imaging) indicated in the emergency department (ED) for a middle-aged to elderly patient with sudden severe facial pain and a history of multiple sclerosis, stroke, or facial trauma?

MRI in the Emergency Department for Facial Pain

MRI is NOT indicated as the initial imaging modality in the ED for facial trauma, but CT is the gold standard; however, MRI becomes indicated as a supplemental study when cranial nerve deficits are present, CSF leak is suspected, or when evaluating for MS exacerbation in patients with known multiple sclerosis. 1

Initial Imaging Approach in the ED

For Facial Trauma Patients

• CT maxillofacial is the gold standard for initial evaluation of facial trauma in the ED, providing rapid acquisition with superior bone detail and multiplanar reconstructions 1, 2
• CT has replaced radiographs because plain films cannot characterize the full extent of fractures or detect intracranial pathology 1
• Concurrent head CT should be obtained given that 68% of patients with facial fractures have associated head injuries 3, 2

When MRI Becomes Indicated (Supplemental Role)

MRI should be obtained after initial CT when:

• Cranial nerve deficits are present that are not explained or incompletely characterized by CT 1
• CSF leak is suspected from skull base fracture, where MRI's superior soft-tissue contrast and multiplanar capabilities excel 1
• Olfactory nerve injury is suspected in naso-orbital-ethmoid fractures, using high-resolution heavily T2-weighted images 1
• Small foreign bodies like asphalt pieces need detection, where MRI is superior to CT 1
• Skull base herniation requires characterization of herniated contents through bony defects 1

Special Consideration: Multiple Sclerosis Patients

When MS is the Primary Concern

• MRI is the most sensitive method for detecting MS lesions and plays a supportive role in clinical diagnosis 4, 5
• For suspected MS exacerbation presenting as facial pain (trigeminal neuralgia), brain MRI with gadolinium is appropriate to assess for new lesions 6
• The 2024 McDonald criteria now include the optic nerve as a fifth anatomical location, requiring fat-saturated sequences for symptomatic optic nerve lesions 6
• MRI cannot be the sole diagnostic tool for MS—it remains fundamentally a clinical diagnosis with MRI providing supportive evidence 4, 5

MS Diagnostic Criteria on MRI

• Characteristic MS lesions include Dawson Fingers, ovoid lesions, corpus callosum lesions, and asymptomatic spinal cord lesions 4
• Dissemination in space requires lesions in at least 4 of 5 locations: periventricular, juxtacortical/cortical, infratentorial, spinal cord, and optic nerve 6
• T2-weighted imaging detects lesions in 70-100% of clinically definite MS patients 7

Critical Pitfalls to Avoid

Timing and Logistics

• Do not delay stabilization for imaging—airway, breathing, and circulation take absolute priority before any facial evaluation 3, 2
• MRI acquisition time is significantly longer than CT, making it impractical for initial trauma evaluation 1
• MRI is not useful for detecting acute facial fractures—CT detects fractures with higher sensitivity 1

Diagnostic Accuracy

• Persistent gadolinium enhancement >3 months, lesions with mass effect, or meningeal enhancement suggest diagnoses other than MS and require alternative workup 4
• A negative MRI at the time of initial presentation does not rule out MS 4
• In elderly patients (>50 years) with suspected MS, more stringent criteria should be applied to improve specificity, as age-related white matter changes can mimic MS 8

Stroke Considerations

• For acute stroke presenting with facial symptoms, CT/CTA is the appropriate initial ED imaging to assess for large vessel occlusion and determine thrombolytic eligibility
• MRI with diffusion-weighted imaging has higher sensitivity for acute ischemia but is not the standard ED approach due to time constraints and availability