Ipsilateral Hypertrophy of the Mastoid Process in Surgical Cases of Congenital Muscular Torticollis.

OBJECTIVE

This study was to investigate ipsilateral hypertrophy of the mastoid process in the patients with congenital muscular torticollis (CMT).

DESIGN

Retrospective cross-sectional study.

PATIENTS: Children with CMT.

METHODS

A total of 212 surgical cases of patients with CMT (age: 50.9 ± 44.3 months) and 212 age- and gender-matched controls (age: 50.4 ± 44.2 months) were included. The mastoid process volume was calculated and compared for both groups on the computed tomography axial images. A linear regression analysis was performed between the age and the intrasubject volume difference in the mastoid process.

RESULTS

The volume of the mastoid process in the CMT side was significantly larger than that of the non-CMT side in the CMT group (32.2 ± 30.3 cm3 vs 21.9 ± 22.8 cm3; P < .001). In the control group, there was no significant difference between the volume of the right and left mastoid process (21.6 ± 24.6 cm3 vs 21.2 ± 23.8 cm3; P = .472). The intrasubject volume difference in the mastoid process in the CMT group showed a linear increase with the age (adjusted R2 = 0.286; P < .001), and the volumetric asymmetry of the mastoid process became more severe over age compared to the control group.

CONCLUSION

We showed ipsilateral hypertrophy of the mastoid process in patients with CMT and demonstrated that the volumetric asymmetry increased with age.