Background: To the best of our knowledge, no report on craniovertebral junction (CVJ) abnormalities, except those regarding atlanto-axial rotatory subluxation, in subjects with congenital muscular torticollis (CMT) has been published to date. This study aims to present a variety of concurrent CVJ abnormalities in subjects with CMT and examine the relationship between CVJ abnormalities and the clinical severity of CMT.
Methods: This retrospective cohort study included 48 subjects with CMT who underwent craniofacial computed tomography and neck magnetic resonance imaging. The CVJ was examined in terms of atlanto-occipital rotational angle and atlanto-axial rotational angle and lateral and anterior atlanto-dens intervals for evaluation of rotation of the atlanto-occipital joint, rotation of the atlanto-axial joint, and lateral and anterior shift of the atlanto-axial joint, respectively. We assessed the correlation between degrees of CVJ abnormalities and the clinical severity of CMT. Cervicomandibular angle, cranial vault asymmetry index and ratio of intensity were measured as parameters for clinical severity.
Results: The mean age at the time of imaging study was 75.35±77.56 months in 48 subjects and 41 (85.4%) of them underwent a surgery for CMT. Thirty-one (64.6%) subjects had one or more CVJ abnormalities. Twenty-four (50%) subjects had rotation of the atlanto-axial joint with atlanto-axial rotational angle of more than 6 degrees. Nine (18.8%) subjects had rotation of atlanto-occipital joint with the atlanto-occipital rotational angle of more than 3 degrees. Thirteen (27.1%) subjects had lateral shift of atlanto-axial joint with difference of bilateral lateral ADIs of more than 2mm and no one had instability of the atlanto-axial joint with anterior ADI within normal range. Atlanto-occipital rotational angle and cervico-mandibular angle were positively correlated in 41 subjects who underwent surgery (r=0.32, p<0.05).
Conclusions: This appears to be the first documented study where subjects with CMT also presented with various types of CVJ abnormalities. CVJ abnormalities are common concurrent skeletal deformities in patients with CMT and presence of CVJ abnormalities may indicate the severe severity of CMT. Further prospective studies are required to verify these findings.
