Cervical juxtafacet cyst with myelopathy due to postoperative instability. Case report.

A 74-year-old man presented with a cervical juxtafacet cyst on the right side of C5-6 and prominent myelopathy. He had been treated with anterior cervical discectomy and fusion at C4-5 as well as anterior foraminotomy of the right C5-6 lesion 20 months previously. The patient underwent complete surgical excision of the lesion. The patient recovered uneventfully, and the myelopathy resolved. Reexamination of the images revealed that we failed to investigate a suspicious minimal cervical juxtafacet cyst on the initial preoperative images and that the degree of subluxation at C5-6 on flexion radiography had increased postoperatively. Therefore, the surgeon should be aware that juxtafacet cyst can be progressive in planning of cervical spinal surgery which can cause or aggravate instability in the presence of an incidental, suspicious juxtafacet cyst on preoperative imaging at the same level, even if the lesion is very small and subclinical.