In order to investigate whether the long-term prognosis of postoperative facial nerve function might bepredicted by the precise analysis of facial nerve function in early stage after acoustic neuroma surgery, weconducted the sequential evaluation of facial nerve function as frequently as possible up to60postoperativedays in11cases of unilateral acoustic neuroma (AN). The operation was conducted through the extendedmiddle cranial fossa approach, and the facial nerve function was evaluated by the modified Yanagihara'sgrading system (40points Japanese grading system). Based upon the lowest facial score within5daysafter the operation, all subjects were classified into 4 groups such as Group A (below10points), Group B (over10points, below20points), Group C (over20points, below30points) and Group D (over30points), and the postoperative facial nerve function up to60postoperative days was analyzed in the individual group.
The results obtained were as follows;
1) Three cases in Group A showed a low facial score immediately after the operation and did not showany improvement of the facial score during the follow-up period.
2) One case in Group B showed a deterioration of the facial score from10days after the operation anddid not show any improvement during the follow-up period.
3) Three cases in Group C showed a temporary deterioration of the facial score10to20days after theoperation, however, the facial nerve function improved markedly by the end of the follow-up period.
4) Four.cases in Group D showed a high facial score immediately after the operation and no facial palsywas observed thenafter.
5) Based upon these results, it was concluded that the precise analysis of facial nerve function in earlystage after tumor removal enables us to differentiate the cases with excellent long-term prognosis fromothers, and the precise analysis is very useful in predicting the long-term prognosis of postoperativefacial nerve function in AN natients.
