What imaging is needed for a patient with sudden lockjaw after a fall, accompanied by a wound on the lower chin?

Imaging for Sudden Lockjaw After Fall with Chin Wound

CT maxillofacial without contrast is the essential imaging modality needed for this patient with lockjaw (trismus) following trauma, as it provides nearly 100% sensitivity for detecting mandibular fractures, including subtle condylar and subcondylar fractures that commonly cause trismus. 1

Primary Imaging Recommendation

• CT maxillofacial is superior to all other modalities for evaluating mandibular trauma, offering multiplanar and 3-D reconstructions critical for detecting comminution, displacement, and complex fractures that alter surgical management 1
• CT is particularly essential for evaluating condylar and ramus fractures, where displacement can be subtle but is the most common cause of post-traumatic trismus 1
• The imaging allows faster acquisition than radiography or MRI and is less dependent on patient positioning—important when a patient cannot open their mouth 1

Critical Associated Injuries to Screen For

Cervical spine imaging must be obtained given the mechanism of fall, as 11% of patients with mandibular fractures have concomitant cervical spine injuries 1

• Falls with loss of consciousness result in more severe maxillofacial injuries and higher risk of associated injuries 2
• High-velocity trauma mechanisms (falls to floor) are associated with both mandibular and cervical spine fractures 1

Alternative Imaging (Lower Priority)

Panoramic radiograph (OPG) may be considered only if clinical suspicion is low, but has significant limitations:

• Sensitivity of 92% for simple fractures but misses condylar fractures, subcondylar fractures with anterior displacement, and nondisplaced anterior fractures 1
• Cannot adequately assess the degree of displacement or comminution—both critical for surgical planning 1
• Complex fractures may be mistaken for isolated fractures 1
• Use of plain radiography has become less favorable in emergency trauma settings 1

Regarding Your Treatment Plan

Your antibiotic and tetanus prophylaxis approach is appropriate for the chin wound, but the imaging must be completed before definitive management:

• Mefenamic acid (NSAID) for pain control is reasonable
• Cefuroxime provides adequate coverage for facial wound contamination
• ATS (anti-tetanus serum) and TAT (tetanus antitoxin) are appropriate for wound prophylaxis

Critical Clinical Pitfalls

• Do not assume lockjaw is only muscular spasm—it frequently indicates condylar or subcondylar fracture requiring surgical evaluation 1
• Airway assessment is paramount before imaging, as maxillofacial trauma can lead to airway-compromising edema, though this develops gradually rather than suddenly 3
• If cervical spine injury is suspected, use jaw thrust maneuver rather than head tilt-chin lift for airway management, as it produces significantly less motion at unstable cervical segments 4
• Temporomandibular joint injury can develop inflammatory and degenerative changes after facial trauma, requiring long-term follow-up 5

Imaging Protocol Summary

1. CT maxillofacial without IV contrast (primary study) 1
2. CT cervical spine (given fall mechanism and mandibular injury) 1
3. Consider CT head if any loss of consciousness or neurological symptoms 6