Estimation of Normal Semi-circular Canal Dimensions on Computed Tomography

To measure and compare length, width and luminal diameters of semi-circular canals (SCC) on Multiplanar reformatted CT images in individuals without any features of vestibular dysfunction.

A prospective, cross sectional, observational study was conducted in a tertiary care hospital in October - November 2021. Multiplanar reformatted CT temporal bone images of 50 participants without features of vestibular dysfunction were used to measure the curved lengths, widths and luminal diameters of the three semi-circular canals. Unpaired t-test was used to ascertain and compare the values obtained.

Fifty participants, 27 women and 23 men (mean age 38.5 years) were included in the study. Mean curved lengths of Superior, posterior and Lateral SCCs were 1.37 cm, 1.33 cm and 1.19 cm respectively. Semi-circular width of Superior SCC (4.8 mm) was significantly larger than Posterior SCC (4.17 mm, p = 0.03) which was significantly larger than Lateral SCC (3.65 mm, p = 0.04). No significant difference was found between mean mid luminal diameters of the three SCCs. Mid luminal diameters were significantly smaller than the diameters at either ends of all SCCs.

The results can potentially serve as reference values for Indians and for further studies on pathophysiology of disequilibrium.