Cervical spondylotic myelopathy caused by single-level vertebral spontaneous fusion

YAN Ning; YU Shunzhi; ZHAO Shan; ZHANG Chen; HOU Tiesheng; HE Shisheng

doi:10.3969/j.issn.1674-666X.2014.05.04

Abstract：Objective To evaluate the clinical features, radiological characteristics, surgical options and clinical outcomes of patients with cervical spondylotic myelopathy (CSM) caused by single-level vertebral spontaneous fusion (SLVSF). Methods Sixteen consecutive patients with SLVSF (SLVSF group) treated in Shanghai 10th People's Hospital from July 2002 to June 2012 were included in this study, and they all underwent anterior sugery. Of these patients, 11 were categorized as type Ⅰ (fusion of the vertebral bodies, the lamina and the spinous processes) and 5 were categorized as type Ⅱ (the vertebral bodies and the lamina were fused, but the spinous processes remained independent). Clinical features, imaging presentations, surgical strategy, functional scores and complications were recorded, and at the same time, the clinical data of those patients were compared with another group of 38 patients who suffered from CSM caused by cevical spinal degeneration as control. Results There were significant differences between two groups in the mean age and the average duration of neck pain (P <0.05), while there was no statistical difference in length of cervical spine (P >0.05). In SLVSF group, 13 patients had translational instability of the upper vertebra at the fused segment, but no one had rotational instability. Vertebral index at fused segment was bigger than the index at any other segment, the difference had statistical significance (P <0.05). Preoperative Nurick grades and Japanese Orthopaedic Association scores between two groups had no statistical differences (P >0.05); while neck disability index in SLVSF group was higher than that in degeneration group, the difference between two groups had statistical significance (P <0.05). The neurological function scores one year after the surgery were all improved compared with preoperative ones (P <0.05). Conclusions Neck length of patients with SLVSF is normal, which can be used to distinguish this disorder from Klippel-Feil syndrome. The main features of SLVSF are: hypoplasia at both of the spontaneously fused vertebral bodies and local discs, a major pathological feature of translational instability of the upper vertebra at the fused level, as well as severe neck pain. Anterior surgery could achieve good therapeutic results, and the extent of subtotal vertebrectomy should be mentioned.