Label-Free Facial Nerve Identification During Parotidectomy Using Nerve Autofluorescence: An Initial Clinical Series

Facial nerve (FN) dysfunction remains a clinically important complication of parotidectomy, even when recovery is ultimately complete. Traditional nerve identification relies on anatomic dissection, selective stimulation, and, in many cases, intraoperative monitoring (IONM). These approaches may be limited when anatomy is distorted. This study evaluated the feasibility, safety, and utility of autofluorescence-guided FN identification during parotidectomy. A retrospective case series was conducted in 18 patients who underwent superficial or total parotidectomy for parotid gland tumors. All procedures were performed by the same surgical team using standard operative technique and selective electrical nerve stimulation. Near-ultraviolet (NUV) autofluorescence imaging was obtained immediately after FN exposure and before further dissection. Raw grayscale and real-time colored overlay images were acquired. Quantitative image analysis was performed using manually selected regions of interest to measure nerve and background intensities, nerve-to-background ratio, longitudinal signal homogeneity, and apparent branch width. Given the case series design, findings were summarized using descriptive statistics. The cohort included 18 patients, 15 women and 3 men, who underwent superficial or total parotidectomy for parotid neoplasms. Final pathology showed pleomorphic adenoma in 15 cases and carcinoma in 3 cases, with deep lobe involvement in 1 case. Autofluorescence imaging generated clear contrast between the FN and surrounding tissue on grayscale and colored overlay views. Mean native grayscale nerve intensities ranged from 244.3 to 247.4 px, compared with background intensities of 41.7 to 45.8 px, yielding nerve-to-background ratios of 5.40 to 5.86. Colored overlay rendering increased the maximum nerve-to-background ratio to 10.16. Longitudinal signal remained uniform, with coefficients of variation (CVs) ranging from 0.028 to 0.043. No postoperative FN paralysis occurred, and all patients had House-Brackmann grade I function at six months. In this retrospective case series, autofluorescence-guided FN imaging during parotidectomy was feasible and provided consistent visual contrast between nerve and surrounding tissue without identified imaging-related safety concerns. These findings support further study of this approach as a useful adjunct to standard FN identification strategies.