Quantifying the Effect of the Cross-Facial Nerve Graft on the Nonparalyzed Side.

Objective: The cross-facial nerve graft (CFNG) is employed in facial reanimation surgery to restore neural connectivity from the nonparalyzed side of the face to the paralyzed side, facilitating spontaneous smiling. Typically, the sural nerve, due to its length, serves as the donor graft. Implantation involves functional facial branch transection to provide graft input. However, impact of this transection on a patient's smile has not been conclusively quantified.

Study setting & design: Tertiary Care Academic Medical Center; retrospective chart review.

Methods: In a chart review of patients from 2018 to 2022, 15 patients with unilateral flaccid facial paralysis who underwent CFNG were identified. Demographic and clinical data were collated including medical history and operative details. Emotrics software was used to compare preoperative and postoperative photographs by measuring smile parameters. Percent change was analyzed via Student's T-test.

Results: A zygomatic branch was sacrificed in 8/15 (53%) surgeries and a buccal branch in 4/15 (27%) surgeries. When evaluating smile angle, dental show, upper lip height deviation, and commissure excursion for open and closed smiles, the average relative change for the nonparalyzed side was 3.4%, 2.8 mm, 12.5%, 3.0 mm, and 1.9% respectively. When comparing these metrics preoperatively and postoperatively in the functional side, there was no statistically significant difference (P = .13, P = .65, P = .33, P = .36, P = .64).

Conclusion: There was no significant difference in our assessment of smile after facial branch transection in CFNG, suggesting the impact on a patient's smile may be negligible. Additional studies are needed to characterize qualitative impact on patients and result generalizability.