Yuan Joyce T, Teng Edward, Heller Justin B, Kawamoto Henry K, Bradley James P
Department of Plastic and Reconstructive Surgery, UCLA Geffen School of Medicine, Los Angeles, California, USA.
J Craniofac Surg. 2012 Sep;23(5):1421-4. doi: 10.1097/SCS.0b013e31825b3bc7.
The etiology of Angle class III malocclusion with facial asymmetry has not been fully elucidated. To investigate the etiology, patients with asymmetric prognathism (n = 30) from a single institution were assessed for previously undiagnosed torticollis and cranial base asymmetry. Presence of torticollis was determined by measuring restricted head movement when turning the head against a wall and cranial base tilt with upward gaze. Cranial base asymmetry was evaluated by preoperative three-dimensional computed tomography scans. Thirty-one percent of patients with prognathism presented with concurrent facial asymmetry. In patients with asymmetric prognathism, cranial base tilt was present on upward gaze in all patients; mean angle between head and wall was 31 degrees greater than that in control patients, and a 22% to 36% difference in the angle was present when comparing one side with the other. Based on these findings, all patients with asymmetric prognathism were found to be affected by torticollis. By computed tomography scan, 85% of these torticollis patients showed slight anteromedial displacement of the glenoid fossa ipsilateral to torticollis, and 73% demonstrated temporal fossa shift of 4 mm or greater. The current study demonstrates a strong association between asymmetric class III malocclusion, torticollis, and cranial base asymmetry. We conclude that undiagnosed torticollis is a likely etiology for otherwise idiopathic cranial base asymmetry and that cranial base asymmetry in turn causes facial asymmetry and malocclusion. This study highlights the importance of evaluating cranial base asymmetry and torticollis in patients with class III malocclusion to allow for earlier treatment and improved outcomes.
安氏III类错牙合伴面部不对称的病因尚未完全阐明。为了探究病因，对来自单一机构的30例不对称前突患者进行了评估，以确定是否存在先前未诊断出的斜颈和颅底不对称。通过测量头部靠墙转动时的受限运动以及向上注视时的颅底倾斜度来确定斜颈的存在。通过术前三维计算机断层扫描评估颅底不对称情况。31%的前突患者同时存在面部不对称。在不对称前突患者中，所有患者向上注视时均存在颅底倾斜；头部与墙壁之间的平均角度比对照组患者大31度，两侧比较时角度差异为22%至36%。基于这些发现，所有不对称前突患者均被发现患有斜颈。通过计算机断层扫描，这些斜颈患者中有85%显示斜颈同侧关节盂有轻微的前内侧移位，73%显示颞窝移位4毫米或更大。当前研究表明，不对称III类错牙合、斜颈和颅底不对称之间存在密切关联。我们得出结论，未诊断出的斜颈可能是导致特发性颅底不对称的病因，而颅底不对称反过来又会导致面部不对称和错牙合。本研究强调了评估III类错牙合患者颅底不对称和斜颈的重要性，以便能更早进行治疗并改善治疗效果。
