[Problem of the preservation of hearing in acoustic neuroma. Value of the mixed supra petrous and retrosigmoid approach].

The authors described their experience of the possibilities of preservation of hearing on the basis of a series including approximately 180 acoustic neurinomas. Whilst the initial experimental approach involving the use of a sub-occipital approach in seated position was abandoned, in view of the risk of complications inherent to the use of this approach, the authors progressively developed the possibility of the preservation of hearing by a retro-sigmoid approach in horizontal position as described in France by Bremond, Magnand and Garcin, and taken up subsequently by Sterkers. Currently, a retro-sigmoid approach is used combined with a classical supra petral approach which can be used in all cases to assess the tumour at the base of the internal auditory meatus and identify the position of the facial nerve. This surgery by mixed approach can safeguard hearing in small tumours (grades I, II and IIIa) in approximately 75% of cases. Functional hearing should nevertheless be differentiated (approximately one case out of two) in other cases where only residual auditory tissue remains. It is highly likely that improvement in radiological techniques (leading to earlier diagnosis) as well as surgical techniques will lead to the safeguard of hearing in even more cases, and hence the importance of evaluation of these techniques in terms of their relative indication in comparison with the translabyrinthine approach which the authors consider to remain the approach of choice in large tumours (grades IIIb and IV).