For evaluation of facial nerve function, Yanagihara's 40 points grading system (Yanagihara's system) has widely been used in Japan, while House and Brackmann's facial nerve grading system (House andBrackmann's system) has been generally used in the United States and Europe.
In order to investigate the relationship of the results of facial nerve function test between these twosystems, we conducted a total of68evaluations of postoperative facial nerve function simultaneously usingthese two systems in36cases of surgically proven unilateral acoustic neuroma, and the results werecompared.
The results obtained were as follows;
1) Although the method of evaluation of the motor function of the eyes and mouth apparently differsbetween these two systems, a highly positive correlation was found between facial nerve functionregarding the movements of eye and mouth evaluation.
2) There was a highly positive correlation between total points in Yanagihara's system and the evaluationgrade in House and Brackmann's system.
3) Some of long-lasting cases without hypoglossal-facial anastomosis were evaluated to be in grade III orgrade IV in House and Brackmann's system because of the presence of secondary defects although theyshowed the relatively excellent postoperative recovery in more than 30 points in Yanagihara's system.However, in the cases with hypoglossal-facial anastomosis, the presence of secondary defects did notapparently affect on the relationship between the results obtained by these two systems because of therelatively poor recovery of postoperative facial nerve function.
4) Based upon these results, it was concluded that the facial nerve function evaluated by these twosystems can be speculated from each other although there is a discrepancy between them in some caseswith secondary defects.
