Is There a Relationship Between Bell's Palsy and Internal Auditory Canal?

In the present study, we evaluated the diameter of internal acoustic canal in patients with Bells palsy to investigate the role of anatomical differences of the temporal bone in etiology of Bell's palsy. Sixty-four patients who were diagnosed as Bells Palsy and temporal bone computed tomography imagings of them were included into the study group (Group 1). The control group (Group 2) was consisted of 35 healthy subjects without Bell's Palsy. All patients had temporal bone computed tomography imaging. The internal auditory canal inlet, mid-canal, outlet and canal lengths were measured at the most distinctive cross-section of the seventh and eighth cranial nerves bifurcation. In the study group, Bells palsy was on the right side in 26 patients (40.6 %) and on the left side in 38 patients (59.4 %). Initial House-Brackmann (HB) score was HB-2 in 29 patients (45.3 %), HB-3 in 18 patients (28.1 %), HB-4 in 13 patients (20.3 %) and HB-5 in 4 patients (6.2 %). At 6-month evaluation, HB-score of the patients were HB-1 in 37 patients (57.8 %), HB-2 in 25 patients (39.1 %) and HB-3 in 2 patients (3.1 %). Internal auditory canal (IAC) measurements of the groups showed that there were no significant differences between the measurements of right-mid canal, right canal length; and left canal outlet and left canal length of the study and control groups. Right inlet and outlet; and left inlet and mid-canal values of the study group (Bell's palsy) were significantly lower than those of the control group. In Bell's palsy group, left inlet, outlet and canal length values were significantly higher than those of the right ones. Correlation analysis showed that there were no significant correlation between paralysis side; initial HB stage; and IAC measurement results. In patients with higher initial HB score, their 6-month later HB-score was also higher. In patients with higher 6-month HB score; R canal inlet, R mid-canal, L-canal inlet, and L-mid canal values were lower. Lower IAC inlet and mid-canal values were detected in patients with Bell's palsy. Therefore narrow IAC inlet and mid-canal values may be one of the risk factors for Bell's palsy.