Immediate Evaluation and Management of Finger Numbness Following Deep Laceration
A patient with finger numbness after a deep laceration requires immediate assessment for digital nerve injury, with surgical exploration indicated in 87-93% of cases where clinical signs of nerve damage are present. 1, 2
Initial Clinical Assessment
Perform focused examination for:
- Static two-point discrimination testing (abnormal if ≥10 mm), which indicates likely nerve injury requiring exploration 3
- Sensory mapping of the affected finger to determine the specific nerve distribution involved 4
- Motor function testing including intrinsic muscle strength if applicable 4
- Vascular status by checking capillary refill, color, and warmth of the digit 1
Imaging Protocol
Obtain plain radiographs immediately to evaluate for:
- Fracture fragments that may require open reduction and internal fixation 1
- Foreign bodies within the wound that could complicate nerve repair 1
- Standard 3-view hand series (PA, lateral, and oblique) to maximize diagnostic yield for associated injuries 1
Surgical Decision-Making
Proceed with surgical exploration in the following scenarios:
- Abnormal two-point discrimination (≥10 mm) with deep laceration mechanism, as 87-93% will have nerve transection requiring repair 3, 2
- Complete sensory loss in a specific nerve distribution 2
- Presence of fracture fragments requiring fixation 1
Important Clinical Context
Approximately 87-93% of patients with clinical signs of digital nerve injury will have complete nerve transection (neurotmesis) requiring surgical repair 2. However, 7-13% will have traumatic neurapraxia (intact but bruised nerves) that recovers spontaneously over 12 days to 6 months 3, 2. This distinction can only be made definitively at surgical exploration 3.
Timing of Intervention
Perform surgical exploration within 24-48 hours when:
- The patient is hemodynamically stable 1
- No contraindications to anesthesia exist 1
- Adequate surgical expertise is available 1
Delay is acceptable only if the wound is clean, the patient is stable, and definitive repair can be performed within this timeframe 1.
Critical Pitfalls to Avoid
- Do not assume neurapraxia without exploration when two-point discrimination is abnormal, as 87-93% will require nerve repair 2
- Do not perform "watchful waiting" as the initial strategy in deep lacerations with sensory loss, as this delays necessary repair and worsens outcomes 3
- Do not forget to assess for concomitant injuries including flexor tendon damage, vascular injury, and fractures that may require simultaneous repair 1
Patient Counseling
Inform patients that: