Is it necessary to do temporal bone computed tomography of the internal auditory canal in tinnitus with normal hearing?

Radiological Evaluation of Inner Ear with Computed Tomography in Patients with Unilateral Non-Pulsatile Tinnitus

OBJECTIVE

The objective of this research was to investigate the possible relationship between tinnitus and certain bony inner ear structures using computed tomography (CT).

MATERIALS AND METHODS

This was a prospective, controlled, double-blind study. The subjects of the study were divided into the following three groups: group 1 (G1), patients with unilateral sensorineural hearing loss (SNHL) and unilateral non-pulsatile tinnitus in the same ear; group 2 (G2), patients with normal hearing and unilateral non-pulsatile tinnitus; and group 3 (G3), healthy volunteers with neither tinnitus nor hearing loss. The basal turn length, internal acoustic canal (IAC) width and length, bony cochlear nerve canal (BCNC) width, and IAC diameter at the porus acousticus internus (PAI) were measured.

RESULTS

The mean BCNC width was significantly narrower in G1 and G2 than in the control group (G3) (p<0.001). For patients in G2, BCNC width was significantly narrower in ears with tinnitus (p<0.001) than in ears without tinnitus. The mean IAC diameter at PAI was also narrower in the G1 patients (p=0.007) compared with the other groups.

CONCLUSION

The results of this study suggest that CT evaluation of the inner ear structures is important in patients with tinnitus. According to the results, a narrow BCNC may cause phantom sensations and be related to cochlear nerve dysfunction. Therefore, it is recommended that clinicians evaluate BCNC carefully while assessing such patients.

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.