OBJECTIVES To find out if the ratio of facial nerve to facial canal diameter plays any role in the etiopathogenesis and grade of Bell's palsy. PATIENTS AND METHODS Twenty-nine consecutive patients (16 females, 13 males) diagnosed with unilateral Bell's palsy were enrolled into the study. At admission, 5 patients were grade V, 11 were grade IV, 11 were grade III and 2 were grade II. The grade of Bell's palsy was documented by House-Brackmann facial nerve grading system at admission, 15th day, 1st month and 3th month. Temporal MRI and CT scans were obtained at the time of diagnosis. Diameter of facial nerve and facial canal at the middle of five different segments were measured equidistantly at the same workstation. Both sides of every patient (affected and unaffected) were measured by one radiologist who was not informed about the side of the paralysis. MRI and CT values of each segment were compared between affected and unaffected sides. In addition, FN/FC ratio of affected and non-affected sides was calculated and compared for each segment. We also analyzed if a relationship exists between above-mentioned measurements and the House-Brackmann grade. RESULTS Considering MRI values; statistically significant thickening of facial nerve between affected and unaffected sides was found at labyrinthine (p = 0.012), tympanic (p = 0.023) and geniculate parts (p = 0.04). Considering CT values; statistically significant difference between affected and unaffected sides was not found at any segment. Comparison of FN/FC ratio of both sides revealed statistically significant increment of the affected side at labyrinthine segment (p = 0.015) and geniculate ganglion (p = 0.032). We determined positive correlation between diameter of FN and HB grade at labyrinthine segment (p = 0.03, R = 0.531). On the other hand, we determined negative correlation between diameter of FC and HB grade at labyrinthine segment (p < 0.001, R = -318). A positive correlation between HB grade and FN/FC ratio was found only at the labyrinthine segment (p = 0.003, R = 0.673). CONCLUSION FN/FC ratio of labyrinthine segment and geniculate ganglion was found to be increased in patients with Bell's palsy. In addition, a positive correlation was determined between this ratio and grade of Bell's palsy particularly at labyrinthine segment. Basing the current study, if FN decompression is recommended in Bell's palsy patients with objective findings of bad prognosis, conservative surgery targeting the labyrinthine segment and geniculate ganglion alone might be safer.

中文翻译：

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面神经与面管的比率作为贝尔麻痹的一个指标：CT 和 MRI 的研究

目的 了解面神经与面管直径的比值是否在贝尔麻痹的发病机制和分级中起任何作用。患者和方法 连续 29 名被诊断为单侧贝尔麻痹的患者（16 名女性，13 名男性）被纳入研究。入院时V级5例，IV级11例，III级11例，II级2例。贝尔麻痹的分级在入院时、第 15 天、第 1 个月和第 3 个月由 House-Brackmann 面神经分级系统记录。在诊断时获得了时间 MRI 和 CT 扫描。在同一工作站等距测量五个不同节段中间的面神经和面管直径。每位患者（受影响和未受影响）的两侧都由一位不了解瘫痪一侧的放射科医师测量。比较患侧和未患侧每个节段的MRI和CT值。此外，计算并比较每个段的受影响和未受影响侧的 FN/FC 比率。我们还分析了上述测量值与 House-Brackmann 等级之间是否存在关系。结果 考虑 MRI 值；在迷路 (p = 0.012)、鼓室 (p = 0.023) 和膝状体部分 (p = 0.04) 发现受影响侧和未受影响侧之间面神经的显着增厚。考虑 CT 值；在任何节段均未发现受影响侧和未受影响侧之间的统计学显着差异。两侧 FN/FC 比率的比较显示，在迷路段 (p = 0.015) 和膝状神经节 (p = 0.032) 患侧有统计学意义的增加。我们确定了迷路段 FN 直径与 HB 等级之间的正相关（p = 0.03，R = 0.531）。另一方面，我们确定了迷路段 FC 直径和 HB 等级之间的负相关（p < 0.001，R = -318）。HB 等级和 FN/FC 比率之间的正相关仅在迷路段被发现（p = 0.003，R = 0.673）。结论贝尔麻痹患者迷路段和膝状神经节的FN/FC比值升高。此外，该比率与贝尔麻痹的等级之间存在正相关，特别是在迷路段。根据目前的研究，