Modified retrosigmoid approach: use for selected acoustic tumor removal.

The authors have used a modified retrosigmoid (suboccipital) approach for removal of acoustic tumors in selected patients who have good preoperative hearing and whose tumor does not reach the brain stem or extend to the lateral third of the internal auditory canal. This report presents the surgical technique and results for 15 acoustic neuromas removed by members of the House Ear Clinic between 1986 and 1991 using this approach. The technique differs importantly from the standard suboccipital approach. A mastoidectomy with decompression of the sigmoid sinus allows forward retraction of the sigmoid sinus, enabling tumor removal without cerebellar retraction. Also, replacement of the craniotomy flap prevents adherence to the dura of the scalp, which may prevent postoperative headaches. Tumor size ranged from 0.8 cm to 4.0 cm (mean, 1.9 cm). At 1 year or more postoperative, 13 of the 14 patients with follow-up available had a House-Brackmann (H-B) facial nerve grade I, and one patient had H-B grade II. Three patients retained good hearing ( < or = 30 dB SRT and > or = 70% speech discrimination) postoperatively, and 57% retained at least measurable hearing. For a patient with good preoperative hearing and a tumor that is medially based, involving the cerebellopontine angle but not extending to the brain stem or the lateral end or the internal auditory canal, the authors will continue to use the retrosigmoid approach for tumor removal.