Cervical spondylotic myelopathy caused by single-level vertebral spontaneous fusion.

PURPOSE: To evaluate the clinical features, imaging 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 who underwent anterior surgery were included in this study and 38 patients with CSM caused by spinal degeneration were enrolled as a control group. Demographic features, clinical presentations, imaging characteristics, surgery strategy, Nurick grade, Japanese Orthopedic Association (JOA) score, neck disability index (NDI), and complications were evaluated.

RESULTS

There were significant differences between the two groups in the mean age and the average duration of neck pain. There was no significant difference between the two groups in length of cervical spine. In the SLVSF group, 13 patients had upper segment translational instability and none had rotational instability. Pre- and postoperative Nurick grades were 2.94±0.77 and 2.19±0.54 in the SLVSF group, and 2.97±0.72 and 2.16±0.64 in the control group. Pre- and postoperative JOA scores were 9.25±2.02 and 11.69±1.62 in the SLVSF group, and 9.87±2.58 and 12.53±2.69 in the control group. Pre- and postoperative NDI values were 28.5±7.75 and 15.56±5.51 in the SLVSF group, and 16±6.13 and 11.29±4.58 in the control group.

CONCLUSIONS

Patients with SLVSF have necks of normal lengths, which can be used to distinguish this disorder from Klippel-Feil syndrome. There are three main features of SLVSF: (1) hypoplasia at both of the spontaneously fused vertebral bodies; (2) a major pathological feature of translational instability of the upper vertebra to the fused level; and (3) severe neck pain. Anterior surgery has a good therapeutic effect for patients with cervical SLVSF.