Computed tomography Scan Size Analysis of stapedius and tensor tympani muscles in middle ear myoclonic tinnitus.

Objectives: To analyze the sizes of the stapedius and tensor tympani (TT) muscles using a temporal bone CT (TBCT) scan in patients with middle ear myoclonic tinnitus (MEMT) and investigate their value for the diagnosis of this rare cause of tinnitus.

Methods: Medical records and TBCT of patients with MEMT or vascular tinnitus (VT) at Seoul St. Mary's Hospital from January 2012 to December 2022 were reviewed. The stapedius and TT muscles were analyzed.

Results: Thirty-eight patients with unilateral MEMT and 39 patients with VT were included. More males were in the MEMT group compared to the VT group (MEMT:  = 24, VT:  = 8,  = .001). The mean age of the MEMT group was younger compared to the VT group (MEMT: 35 ± 12 years, VT: 44 ± 14.3 years,  = .005). The mean BMI for the MEMT group was less than the VT group (MEMT: 22.3 ± 2.5, VT: 24.8 ± 4.36,  = .010). The mean length and width of the stapedius in the MEMT group were larger than those of the VT group ( MEMT: 1.47 ± 0.60 mm, VT: 0.98 ± 0.24 mm,  = .001; MEMT: 0.89 ± 0.32 mm, VT: 0.72 ± 0.19 mm,  = .009). The mean length and width of the TT in the MEMT group were larger than that of the VT group ( MEMT: 3.10 ± 0.50 mm, VT: 2.27 ± 0.42,  = .001; MEMT: 2.02 ± 0.36, VT: 1.75 ± 0.26  = .001).

Conclusion: The mean length and width of the stapedius and TT muscles measured in the MEMT group were longer and wider than the VT group. This suggests the use TBCT scan as a diagnostic tool for MEMT. Further studies with a larger study group to validate the results of this study are recommended.Level of Evidence: 4.