Nerve at Risk in First Metatarsal Gunshot Wound
The deep peroneal nerve is the primary nerve at risk with a gunshot wound to the first metatarsal with retained foreign bodies.
Anatomical Basis and Clinical Evidence
The deep peroneal nerve is the most commonly injured nerve in lower extremity gunshot wounds, particularly those involving the foot and ankle region 1. In a retrospective review of civilian gunshot wounds to the extremities, the deep peroneal nerve accounted for 38% of all nerve injuries, making it the most frequently damaged nerve in this anatomic region 1.
Mechanism of Injury
Gunshot wounds are high-energy injuries that cause both direct tissue damage along the missile tract and radial injury from kinetic energy transfer 2, 3. This creates a zone of injury extending beyond the visible wound path, placing nearby neurovascular structures at significant risk even without direct transection 4.
- The deep peroneal nerve runs along the dorsum of the foot in close proximity to the metatarsals, making it vulnerable to both direct injury and blast effect from projectiles 5
- Retained foreign bodies (bullet fragments) can cause ongoing nerve compression, scar tissue formation, and delayed neuropathy even after the initial injury 4
- Most gunshot nerve injuries result in neuropraxia or mixed injury patterns rather than complete transection 4
Clinical Presentation
Patients with deep peroneal nerve injury typically present with foot drop and paresthesias in the first web space between the great toe and second toe 4, 5.
- Motor deficits include weakness or inability to dorsiflex the ankle and extend the toes 5
- Sensory loss is limited to the first dorsal web space 5
- Symptoms may be immediate or develop progressively as scar tissue forms around retained fragments 4
Diagnostic Approach
Plain radiographs should be obtained immediately to identify retained foreign bodies and assess for associated fractures 2.
- Lateral and anteroposterior X-rays of the foot are essential to determine bullet fragment location, size, and proximity to neurovascular structures 2
- Ultrasound can identify partial thickness nerve injuries and guide surgical planning 4
- CT imaging may be warranted in hemodynamically stable patients to better characterize the extent of bony and soft tissue injury 2, 3
Management Considerations
Surgical exploration should be considered for patients with clinical evidence of nerve injury and retained foreign bodies causing compression 4, 1.
- Early intervention (within 2-3 months) may prevent dense scar tissue formation that complicates later reconstruction 4
- Nerve decompression and bullet fragment removal can restore function, with successful outcomes reported when performed within one year of injury 5
- Nerve transfer techniques using superficial peroneal or tibial nerve fascicles can restore ankle dorsiflexion in cases of irreparable deep peroneal nerve damage 5
Critical Pitfalls to Avoid
- Do not assume intact nerve function based solely on initial examination, as delayed neuropathy can develop from scar tissue and retained fragments 4
- Fractures around the ankle and foot carry the highest risk for associated nerve injuries and require heightened clinical suspicion 1
- Failure to recognize nerve deficits immediately after injury complicates subsequent management and medicolegal outcomes 6