Facial nerve grading systems

Abstract

A comprehensive, accurate, and valid system for reporting results of facial nerve surgery and disease is needed. This study describes and statistically analyzes eight currently available systems for reliability, validity, and ease of use. They are divided into three grading categories: gross scales, regional systems, and specific scales. Botman and Jongkees, May, and Peitersen have proposed five-point gross scales. Janssen, Smith, Adour and Swanson, and Yanagihara have devised regional systems. Stennert has proposed a specific criteria scale. Fifteen otologists experienced with facial nerve problems used modifications of the existing scales to evaluate videotapes of 12 patients representing the complete range of facial function. The observers' responses were translated back to the original scales. Observers also ranked patients from least to most severe, to obtain an accurate assessment of facial function for patients in the study. A follow-up questionnaire examined observers' system preferences. Validity is measured by correlating responses to different scales and by comparing responses to each scale with observers' rankings. All scales have good validity except the scales of Stennert and Yanagihara. Consistency of responses is determined by reliability coefficients. Coefficients for all scales are high except for the gross scale, which is moderately reliable, and the Stennert scale, which is unreliable. Results indicate that all scales succeed in evaluating patients with normal function or total paralysis. The regional scales have the highest reliabilities but they also have wide response ranges. Most also assume a level of precision that is unsubstantiated. Gross scales have smaller ranges, which result in greater agreement of responses but lower reliability. Comparisons to more complex scales show that the simpler gross scales convey similar information about patients. The study concludes that a gross scale is the best type of system and proposes a new scale for international acceptance. This system has six categories, includes secondary defects, is designed to clearly differentiate between moderate degrees of dysfunction, and should facilitate interpretation and communication of facial nerve results.