Computed tomographic features of the proximal petrous facial nerve canal in recurrent Bell's palsy

Abstract

Objectives The primary objective was to determine whether the narrowest dimensions of the labyrinthine facial nerve (LFN) canal on the symptomatic side in patients with unilateral recurrent Bell's palsy (BP) differ from those on the contralateral side or in asymptomatic, age‐ and gender‐matched controls on computed tomography (CT). The secondary objectives were to assess the extent of bony covering at the geniculate ganglion and to record inter‐observer reliability of the CT measurements. Methods The dimensions of the LFN canal at its narrowest point perpendicular to the long axis and the extent of bony covering at the geniculate ganglion were assessed by two radiologists. Statistical analysis was performed using the Wilcoxon signed‐rank and Mann‐Whitney U tests (LFN canal dimensions) and the Chi‐squared test (bony covering at the geniculate ganglion). Inter‐observer reliability was evaluated using Intra‐Class Correlation (ICC) and Cohen's kappa. Results The study included 21 patients with unilateral recurrent BP and 21 asymptomatic controls. There was no significant difference in the narrowest dimensions of the ipsilateral LFN canal when compared to the contralateral side or controls (P = .43‐.94). Similarly, there was no significant difference in the extent of bony covering at the geniculate ganglion when compared to either group (P = .19‐.8). Good inter‐observer reliability was observed for LFN measurements (ICC = 0.75‐0.88) but not for the bony covering at the geniculate ganglion (Cohen's kappa = 0.53). Conclusion The narrowest dimensions of the LFN canal and the extent of bony covering at the geniculate ganglion do not differ in unilateral recurrent BP, casting doubt over their etiological significance. Level of Evidence Level IV.