Assessment of Facial Nerve Function Following Acoustic Neuroma Surgery: Facial Nerve Grading Systems

Abstract

A number of grading systems for assessment of facial nerve function using gross or regional scales have been proposed internationally. At the Consensus Meeting of Acoustic Neuroma, the discussants agreed that the House-Brackmann scale was used most widely throughout the world, the Yanagihara system was always used in Japan and in some other countries, and other systems were used only by small groups. In view of the current situation, this chapter reviews the House-Brackmann scale and the Yanagihara system and describes the advantages and disadvantages of each system. The House-Brackmann grading scale is a representative gross scale that is useful for clinical purposes in general. However, all of the discussants agreed that the House-Brackmann scale needed to be modified to make it more relevant and reliable for assessing facial nerve function after acoustic neuroma surgery. The modification and its rationale are described. The Yanagihara system developed in Japan is a representative regional scale. The chart for obtaining the paralysis score is presented. The score provides accurate information on the grade of facial dysfunction to assess the course of recovery and to predict the outcome of the palsy. Conversion between the House-Brackmann scale and the Yanagihara paralysis score is described.