End-to-Side Cross-Face Nerve Graft for Mental Nerve Reconstruction after Segmental Mandibulectomy

Pu JJ, Plastic and Reconstructive Surgery, 2025 (Ideas & Innovations). PMID: 39626201

Key takeaways

• End-to-side cross-face graft restored protective lip–chin sensation in all six patients (≥ S3).

• Two patients achieved full tactile and two-point recovery (S4).

• Average static and moving 2-point discrimination: 12.4 mm and 8.4 mm, respectively.

• No loss of sensation on the donor (contralateral) side.

• Technique allows for reinnervation when proximal stump is absent

Background

Segmental mandibulectomy transects the inferior alveolar nerve, leaving the lower-lip numb. This may hamper eating, speech, and quality of life. Traditional interposition nerve grafts are lengthy and may be impossible if the proximal stump is retracted within the mandible.

Objective

Assess feasibility and early sensory outcomes of an end-to-side cross-face nerve graft from the contralateral mental nerve to reinnervate the distal mental nerve after mandibulectomy.

Methods

• Design: Prospective pilot case series (Level IV).

• Setting: Two tertiary centers; simultaneous fibula free-flap jaw reconstruction.

• Participants: 6 adults (3 M/3 F), mean age 57.2 y; malignant tumors (5 SCC, 1 verrucous).

• Inclusion: Segmental mandibulectomy with mental-nerve loss; ≥ 12 mo follow-up.

• Intervention: 7 cm autologous donor nerve (lateral sural cutaneous or motor branch to FHL harvested from within the fibula donor site) sutured end-to-end to the distal mental stump and end-to-side into an epineural window on the contralateral mental nerve (4 × 9-0 nylon stitches).

• Primary endpoint: Sensory recovery via Mackinnon–Dellon Modified MRC scale.

• Secondary endpoints: Static & moving two-point discrimination; operative time; donor-site morbidity.

• Stats: Descriptive (n too small for inferential testing).

Results

• Graft metrics: Mean length 63.3 mm; neurorrhaphy time 33.5 min.

• Primary outcome: 100 % achieved ≥ S3; 2/6 S4.

• Two-point discrimination: Static 12.4 mm; moving 8.4 mm.

• Follow-up: Mean 14.3 mo (range 12–18 mo).

• Safety: No contralateral sensory deficit; no flap or graft complications; minimal donor-site changes.

Conclusion

End-to-side cross-face grafting reliably restores lower-lip sensation after mandibulectomy while preserving contralateral nerve function, potentially offering a simpler alternative to interposition grafts.

Strengths & limitations

• Strengths:

  • Addresses anatomic situations where proximal IAN is inaccessible.

  • Nerve graft is more out of the way for bony inset and fixation.

• Limitations:

  • Small sample; no control group.

  • Short follow-up; long-term durability unknown.

  • Sensory testing not blinded.

Future directions

Larger, controlled studies comparing this approach to conventional interposition nerve grafts and to processed nerve allografts are warranted.

Clinical relevance

Surgeons reconstructing segmental mandibulectomy defects can consider this technique to provide patients meaningful sensory restoration. It offers surgeons an option for reinnervation when the proximal ipsilateral nerve stump is not available. The authors suggest this approach may require shorter grafts (and thus faster reinnervation), but the average graft length (6.3 cm) was on par with previously reported interposition graft lengths. Limited options still persist for when the distal mental nerve stump has been resected.