Hearing preservation in retrosigmoid approach of small vestibular schwannomas: prognostic value of the degree of internal auditory canal filling.

OBJECTIVES

To assess the contribution of preoperative radiologic appearance of vestibular schwannoma (VS) on the magnetic resonance imaging in constructive interference in steady-state sequences and demonstrate if the degree of the internal auditory canal (IAC) filling is correlated with hearing and facial preservation.

PATIENTS: A group of 278 patients who underwent VS surgery in a tertiary referral center.

INTERVENTION: Retrosigmoid approach surgery.

MAIN OUTCOME MEASURES: Patients were classified in 4 groups according to the percentage of IAC filling on the preoperative magnetic resonance imaging as Group IAC 1(IAC empty or filled <25% and with free fundus), Group IAC 2 (IAC filled from 25% to 50% with free fundus), Group IAC 3 (IAC filled from 50% to 75% with free fundus), and Group IAC 4 (complete filling of the IAC without fundus obliteration).

RESULTS

A good correlation was observed between the IAC classification and the rate of hearing and facial preservation. The global rate of postoperative facial palsy was 10.4%. The global rate of hearing preservation in 213 patients with preoperative hearing class A and B was 40.8%. Regression analysis showed that the degree of lateral extension of the VS in the IAC was a strong predictor of hearing preservation ( p < 0.04).

CONCLUSION

The retrosigmoid approach yields good facial outcomes in selected patients with possible hearing preservation. In case of patient with small tumor and IAC empty or filled less than 75% and with free fundus, surgery is the treatment of choice for patients with serviceable hearing and the desire to retain it.