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 preo perative hearing and whose tumor does not reach the brain stem or exte nd to the lateral third of the internal auditory canal. This report pr esents the surgical technique and results for 15 acoustic neuromas rem oved by members of the House Ear Clinic between 1986 and 1991 using th is approach. The technique differs importantly from the standard suboc cipital approach. A mastoidectomy with decompression of the sigmoid si nus allows forward retraction of the sigmoid sinus, enabling tumor rem oval without cerebellar retraction. Also, replacement of the craniotom y flap prevents adherence of the dura to 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 hearin g (less than or equal to 30 db SRT and greater than or equal to 70% sp eech discrimination) postoperatively, and 57% retained at least measur able 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 of the internal auditor y canal, the authors will continue to use the retrosigmoid approach fo r tumor removal.