Reconstruction of facial nerve in patients with acoustic neuroma by diffusion tensor imaging

Abstract

Objective To investigate the clinical application value of preoperative facial nerve reconstruction by diffusion tensor imaging (DTI) in operations of acoustic neuroma. Methods We retrospectively collected 38 cases of patients who underwent operations of acoustic neuroma at Department of Neurosurgery, General Hospital of Tianjin Medical University from September 2013 to September 2015. Prior to operations, each patient underwent 3 T magnetic resonance DTI scanning. The facial nerve fiber tractography was made and the tumor was reconstructed with the software of 3D-Slice. Intraoperative electrophysiological monitoring was conducted to assess the degree of resection and facial nerve injury. Results Preoperative DTI reconstruction of the facial nerve was satisfactory in 32 (84.2%) out of 38 cases and clearly revealed the three-dimensional relationship between the facial nerve and the tumor, which was consistent with intraoperative verification. The facial nerve in 6 cases(15.8%)failed to be reconstructed by DTI tracer technique. DTI showed that the facial nerve was located at the ventral anterior inferior part in 10 (31.3%) cases, ventral central part in 16 (50.0%) cases, ventral anterior superior part in 5 (15.6%) cases and lower part of the tumor in 1 (3.1%) case. The facial nerve was anatomical preserved during operation in 36 (94.7%) cases. At 7 days post surgery, the facial nerve function was graded according to the House-Brackmann scale as 10 cases in grade Ⅰ, 20 cases in grade Ⅱ, 3 cases in grade Ⅲ and 5 cases in grade Ⅳ-Ⅴ; and cases with good facial nerve function accounted for 78.9% of all patients. Conclusion Preoperative reconstruction of the facial nerve by DTI could be used to guide resection of the acoustic neuroma and reduce the injury of facial nerve to a certain extent. Key words: Neuroma, acoustic; Facial nerve; Diffusion tensor imaging; Fiber tracking