Is electrode-modiolus distance a prognostic factor for hearing performances after cochlear implant surgery?

The aim of this study was to evaluate electrode array position in relation to cochlear anatomy and its influence on hearing performance in cochlear implantees. Twenty-two patients (25 ears) with Med-El cochlear implants were included in this retrospective study. A negative correlation was observed between electrode-modiolus distance (EMD) at the cochlear base and monosyllabic word discrimination 6 months after implantation. We found no correlation between EMD and hearing outcome at 12 months. The insertion depth/cochlear perimeter ratio appeared to negatively influence the EMD at the base. Indeed, deep insertions in small cochleae appeared to yield smaller EMD and better hearing performance. This observation supports the idea of preplanning the surgery by adapting the electrode array to the length of the available scala tympani.

Do facial nerve displacement pattern and tumor adhesion influence the facial nerve outcome in vestibular schwannoma surgery?

OBJECTIVE: To assess the nerve facial displacement by a vestibular schwannoma and nerve adhesion to tumor as predictive factors of facial function outcome. STUDY DESIGN: A prospective cohort study. SETTING: Tertiary referral center. PATIENTS: Ninety-six patients undergoing a solitary vestibular schwannoma surgery during 2005 were included. Data concerning tumor size (Stage 1, intracanalicular; Stage 2, < or =15 mm in the cerebellopontine angle [CPA]; Stage 3, 15-30 mm in the CPA; and Stage 4, >30 mm in the CPA), intraoperative facial nerve displacement (Type 1, anterior to the tumor; Type 2, anterior and superior to the tumor and separated from the cochlear nerve; Type 3, superior to the tumor; and Type 4, posterior to the tumor), degree of tumor adhesion (weak, intermediate, and strong) and postoperative facial function according to the House and Brackmann classification at days 10, 30, 90 and 180 were collected. RESULTS: A good facial function (Grade 1 or 2) was reported in 73% at postoperative Day 180. Univariate analysis showed that facial outcome was better in small tumors, in displacement Types 1 and 2 (Type 1, 46%; Type 2, 34%; and Type 3, 20%), and in tumors with weak and intermediate adhesion (weak, 10%; intermediate, 38%; and strong, 52%). Facial nerve displacement and adhesion were related to tumor stage. The combination of tumor stage, adhesion, and nerve displacement in a logistic regression model was highly predictive of postoperative facial function. CONCLUSION: Facial nerve displacement and nerve adhesion to tumor are significant predictive factors of facial function outcome after vestibular schwannoma surgery in addition to tumor size.