Brockmeyer Douglas L, Brockmeyer Meghan M, Bragg Taryn
Department of Neurosurgery, University of Utah, Salt Lake City, Utah 84132, USA.
J Neurosurg Pediatr. 2011 Oct;8(4):357-62. doi: 10.3171/2011.7.PEDS1138.
Congenital craniovertebral anomalies are relatively common, but anomalies leading to overt craniocervical instability may be difficult to recognize and treat. The authors present a series of patients with atlantal hemi-rings, a disorder resulting in congenital craniovertebral instability. Presentation, treatment, imaging, and follow-up data obtained in patients with atlantal hemi-rings were assessed to identify factors relevant to craniocervical instability.
Nineteen patients were identified with atlantal hemi-rings, defined as a bony discontinuity of the C-1 ring in conjunction with lateral displacement of the C-1 lateral masses (as seen on coronal CT scans). Clinical and radiological characteristics were analyzed, including patient age at presentation, extent of occipitocervical motion, amount of C-1 lateral mass displacement, associated craniocervical anomalies, integrity of the transverse ligament, and neurological status.
The mean patient age at presentation was 22 months (range birth to 9 years). The mean amount of occipitocervical translation seen on dynamic imaging was 9 mm (range 2-20 mm). Four patients required occipitocervical fusion at presentation. The remaining 15 patients were monitored for a mean of 20 months, and 9 ultimately underwent fusion. Surgery was also recommended for 4 of the remaining 6 children.
This report describes the radiological and clinical characteristics of patients with atlantal hemirings and craniocervical instability. The authors believe that this anomaly is the underlying cause of progressive instability in a significant proportion of patients with craniocervical abnormalities. The presence of atlantal hemi-rings should prompt immediate and thorough neurosurgical evaluation.
先天性颅颈交界区异常相对常见，但导致明显颅颈交界区不稳定的异常可能难以识别和治疗。作者报告了一系列患有寰椎半环的患者，这是一种导致先天性颅颈交界区不稳定的疾病。对寰椎半环患者的临床表现、治疗、影像学及随访数据进行评估，以确定与颅颈交界区不稳定相关的因素。
确定19例患有寰椎半环的患者，其定义为C1环的骨质连续性中断并伴有C1侧块的侧向移位（如在冠状位CT扫描上所见）。分析临床和放射学特征，包括患者就诊时的年龄、枕颈活动范围、C1侧块移位量、相关的颅颈交界区异常、横韧带的完整性及神经状态。
患者就诊时的平均年龄为22个月（范围从出生至9岁）。动态影像学检查显示枕颈平移的平均量为9mm（范围2 - 20mm）。4例患者就诊时即需行枕颈融合术。其余15例患者平均随访20个月，其中9例最终接受了融合术。其余6例儿童中有4例也建议行手术治疗。
本报告描述了寰椎半环合并颅颈交界区不稳定患者的放射学和临床特征。作者认为，这种异常是相当一部分颅颈交界区异常患者渐进性不稳定的根本原因。寰椎半环的存在应促使立即进行全面的神经外科评估。
