T2-WEIGHTED 3-DIMENSIONAL FAST SPIN-ECHO MR IN INFLAMMATORY PERIPHERAL FACIAL-NERVE PALSY

PURPOSE: Our objective was to identify histologically and intraoperati vely verified focal nerve thickening of the distal intrameatal segment on three-dimensional fast spin-echo (FSE) T2-weighted MR images as a new diagnostic criterion in patients with inflammatory peripheral faci al nerve palsy, METHODS: Twenty-two patients with clinically diagnosed unilateral (n = 20) or bilateral (n = 2) inflammatory peripheral faci al nerve palsy were examined on a 1,5-T MR imager using noncontrast an d contrast-enhanced T1-weighted SE sequences and 3-D T2-weighted FSE s equences with secondary reformations. Abnormal contrast enhancement an d possible focal nerve thickening of the distal intrameatal segment, l abyrinthine nerve segment, and geniculate ganglion region were analyze d prospectively, RESULTS: In all patients, the T1-weighted postcontras t SE images showed characteristic smooth, linear, abnormally intense c ontrast enhancement of the distal intrameatal segment, indicating peri pheral inflammatory nerve palsy, In 23 nerves (96%) a focal bulbous ne rve thickening of the distal intrameatal segment was observed on 3-D T 2-weighted FSE images, In 100% of patients with peripheral inflammator y facial nerve palsy, postcontrast T1-weighted SE images showed a smoo th, linear, and abnormally intense contrast enhancement of the distal intrameatal segment; reformatted very thin 3-D T2-weighted FSE images showed a focal bulbous nerve thickening of the distal intrameatal segm ent in 96% of patients, These findings corresponded to intraoperative and histologic findings, CONCLUSION: Three-dimensional T2-weighted FSE sequences are fast and cheap compared with T1-weighted postcontrast i mages, but secondary reformations are time-consuming and require exact anatomic knowledge for careful analysis of the different nerve segmen ts.