gms | German Medical Science

Objective: Vestibular schwannomas (VS) are surgically challenging tumors. Due to the tumor adherence to the cochlear and the facial nerves, gross total resection is difficult. As the debate regarding the best position used for tumor resection – lateral decubitus vs semi-sitting position – continues, the goal of our study is to compare the outcome results of VS patients with lateral decubitus vs semi-sitting position.

Methods: Data were analyzed form 544 patients with VS who underwent surgical resection in our institution. The majority of patients (77%) had T3 and T4 tumors. The patient cohorts were divided in three decades: 1991-1999 (n=103), 2000-2009 (n=210) and 2010-2019 (n=231). Before 2010, all patients were treated in the lateral decubitus position. After 2010, patients with a patent foramen ovale (n=68) underwent resection in the lateral decubitus, while the semi-sitting position was performed in patients without a patent foramen ovale (n=163). The majority of the latter had a T3 or T4 tumor (n=143). We utilized data analysis with regard to the duration of surgery, intraoperative blood loss and functional outcome of the facial and the cochlear nerves, based on the House-Brackmann Grading System and the Gardner Robertson Scale.

Results: The functional outcome of the facial nerve improved significantly over the three decades (HB 1-2: 59.8%, 78.9%, 81.7%; p<.001; HB 1-3: 81.4% 90.4%, 92.7%). Also, a higher percentage of hearing preservation was achieved (23.3%, 46.8%, 50.5%). For large T3 and T4 tumors, the semi-sitting position was superior to the lateral (HB 1-2: 81.2 vs 74.5%). The same was found for hearing preservation for the whole group (43.3% vs 53.4%). Again for T3 and T4 tumors, the duration of the surgical procedure and blood loss were significantly different (lateral decubitus vs. semi-sitting: 328 vs 286 min (p=.001), 200 vs 150 ml) (p<.001), but not for T1 and T2 tumors. The rates of CSF leakage and wound infections were higher in the semi-sitting position (8.6% vs 2.9%, resp. 4.9% vs 2.9%). Pulmonary embolisms as a major risk for the semi-sitting position occurred in 4.3%. The postop mortality rate was 0.6% (1 patient).

Conclusion: There is a learning curve in VS surgery. The semi-sitting position facilitates surgery since it provides a clean surgical field and allows the preparation with both hands. Operative time and blood loss are significantly reduced; the functional outcome has been further improved. The risk of complications is slightly higher.