Iatrogenic facial nerve injury: the role of facial nerve monitoring.

Intraoperative facial nerve monitoring has emerged as a powerful tool for facilitation of surgery involving the facial nerve. This tool must be properly applied and maintained, however, in order to avoid untoward results and to maximize its potential benefits. Facial nerve monitoring is best suited for prevention of iatrogenic injury. Once injury has become established, its value may be severely limited, especially for moderate to severe injury, in which visual assessment of injury is still the most effective means to determine the need for repair. The most valuable derivative of facial nerve monitoring is enhanced awareness of the edge of the facial nerve contour. This allows strategic alterations in surgical technique for improved facial nerve functional preservation. Although facial nerve monitoring appears to have already had a favorable influence on facial nerve preservation, further improvement seems likely over time through an ongoing process of trial and error.