Availability of Latissimus Dorsi Minigraft in Smile Reconstruction for Incomplete Facial Paralysis: Quantitative Assessment Based on the Optical Flow Method

Background: Acute unilateral facial paralysis, such as occurs in Bell palsy and Hunt syndrome, is mostly a benign neurologic morbidity that resolves within a few months. However, incomplete or misdirected return of the affected nerve results in unfavorable cosmetic sequelae in some patients. Although functional problems such as lagophthalmos are rare, facial asymmetry on smiling resulting from a lack of mimetic muscle strength in the cheek is often psychologically annoying to patients. Methods: To obtain a more natural smile, the authors transfer latissimus dorsi muscle to assist in cheek movement. A small, thinned muscle (mini-latissimus dorsi) is sufficient for transplant in this situation. In this study, 96 patients with incomplete facial paralysis who underwent mini-latissimus dorsi transfer were examined. In this series, along with evaluation using the grading scale used in previous reports, preoperative and postoperative videos of 30 patients were analyzed for quantitative assessment using newly developed computer software. Results: Temporary deterioration of paralysis was recognized in three cases but did not last more than a few months. Signs of transferred muscle contraction were recorded after 4 to 12 months among 91 patients. No apparent clinical signs of contraction were recognized in one patient, and four patients could not be followed postoperatively. The synchronized ratio of vertical movement and the symmetrical ratio of horizontal movement both in the cheek and in the lower lip between healthy and paralyzed sides among 30 patients were statistically improved. Conclusions: Statistical analysis using newly developed computer software revealed that a more symmetrical smile can be achieved by muscle transfer among patients with incomplete facial paralysis. Mini-latissimus dorsi transfer can avoid postoperative muscle bulkiness of the cheek and can achieve more natural cheek movement. ( Plast. Reconstr. Surg. 123: 1198, 2009.)