Secondary Cervicothoracic Scoliosis in Congenital Muscular Torticollis

Abstract

Background: Although secondary cervicothoracic scoliosis frequently occurs in patients with congenital muscular torticollis (CMT), the relationship between scoliosis and CMT has not been evaluated. This study aims to evaluate the effects of surgical release of sternocleidomastoid (SCM) muscle on secondary cervicothoracic scoliosis in patients with CMT and determine factors affecting the improvement of scoliosis after surgical release of SCM muscle.

Methods: Eighty-seven of the 106 patients, confirmed as having secondary cervicothoracic scoliosis with CMT with a minimum 1-year follow-up, were included in this study. Preoperative and last follow-up radiologic outcomes were assessed for the cervicomandibular angle (CMA), Cobb angle of the cervicothoracic scoliosis, and direction of convexity in the scoliosis curve. Patients were divided into two groups to assess the improvement of Cobb angle according to residual growth potential; age ≤ 15 years and > 15 years. The improvement of Cobb angle after surgical release was compared in the two groups. Correlation analysis and multivariable regression analysis were performed to determine the factors affecting the improvement of scoliosis.

Results: All the radiologic parameters, such as the Cobb angle and CMA, improved significantly after surgical release (p < 0.001). The improvement of Cobb angle was significantly higher in age ≤ 15 years than in age > 15 years (p < 0.001). The improvement of Cobb angle was significantly correlated with age (r = -0.474, p < 0.001) and the preoperative Cobb angle (r = 0.221, p = 0.036). In multivariable regression analysis, age and preoperative Cobb angle were shown to be predisposing factors affecting the improvement of scoliosis.

Conclusions: The results showed that SCM release can be a beneficial treatment for secondary cervicothoracic scoliosis. The improvement of scoliosis was greater when the SCM release was performed before the patient reached the end of growth.

Keywords: Cervicomandibular angle; Cobb angle; Congenital muscular torticollis; Secondary scoliosis; Sternocleidomastoid release.

Fig. 1. (A) The cervicomandibular angle (CMA) was measured on the anteroposterior radiograph of the cervical spine to quantify the degree of head tilt. The CMA was defined as the angle between a line connecting the lower margins of the mandibular angles (upper line) and a line drawn along the upper border of the C7 vertebral body (lower line). (B) Cobb angle was measured on the posteroanterior (PA) radiograph of the whole spine to quantify the magnitude of scoliosis. The Cobb angle was defined as the angle formed by two perpendicular lines between the superior endplate (upper line) of the proximal end vertebra and the inferior endplate of the distal end vertebra (lower line).

Fig. 2. An anteroposterior radiograph of the cervical spine was attached to a posteroanterior radiograph of the whole spine to show the coronal deformity of the axial skeletal structure not only with scoliosis but also with head tilt. (A, B) A 9-year-old girl presented with congenital muscular torticollis. (A) The preoperative plain radiograph shows a 16° cervicomandibular angle (CMA) and a 15.1° Cobb angle. The direction of head tilt was identical to the direction of the convexity of the curvature. (B) Twenty months after unipolar sternocleidomastoid (SCM) muscle release, the patient showed improvement of the head tilt and scoliosis. Her CMA improved to 1° and her Cobb angle decreased to 1°. (C, D) A 30-year-old woman presented with neglected congenital muscular torticollis. (C) The preoperative plain radiograph shows a 30° CMA and a 23° Cobb angle. The direction of head tilt was identical to the direction of the convexity of the curvature. (D) Thirty-one months after bipolar SCM muscle release, the patient showed improvement of the head tilt and scoliosis. Her CMA improved to 1.4° and her Cobb angle decreased to only 18°.