The Evolution of Intra-Operative Facial Nerve Identification: A Review of the Literature

Abstract

Background:

Iatrogenic facial nerve injury is a feared complication of craniomaxillofacial surgery, particularly when the parotid gland is instrumented or the Superficial Musculoaponeurotic System (SMAS) is violated. Facial palsy can have devastating psychosocial consequences for the patient, prompting decades of research to refine techniques of intraoperative facial nerve identification and preservation to avoid this outcome. The objective of this literature review is to trace the evolution of techniques for intraoperative facial nerve identification and describe ongoing advances in the field.

Methods:

PubMed and Google Scholar were queried to identify publications describing both historical and conventional understandings of facial nerve anatomy and intraoperative facial nerve identification technique. Keywords included “facial nerve identification,” “facial nerve monitoring,” “facial nerve anatomy,” “facial nerve landmarks,” and “iatrogenic facial nerve injury.” Articles were screened for the following exclusion criteria: non-English language, full text unavailable, single-subject case reports, examination of peripheral nerves other than the facial nerve, non-mammalian animal models, and studies focusing on identification of the facial nerve at its pontine origin. Data was extracted and organized by year of publication, study type, study population, surgical context, method of facial nerve identification, key findings, advantages, limitations, and level of evidence.

Results:

Forty-two publications, published between 1954 and 2025, were included. Our review details both historical and conventional techniques of facial nerve identification including use of anatomic landmarks, electrical nerve stimulation, magnification and microscopy, and enhanced optical techniques including fluorescence-guided surgery.

Conclusions:

Intraoperative facial nerve identification is crucial to prevent iatrogenic facial nerve injury; however, there is limited consensus on the precise identification technique. Facial nerve identification techniques continue to evolve, with fluorescence-guided surgery likely to be the next frontier in advancement of the safety and efficacy of these techniques.