“…22) Pseudotumor occurring secondarily in the area of the odontoid process in rheumatoid arthritis patients is also regarded as having the same cause. 23) Juxtafacet cysts occurring as a result of postoperative instability following cervical spine or lumbar spine surgery have also been reported, 22) as have cases in which a cyst has spontaneously disappeared after only posterior fusion or wearing a Philadelphia collar, 6,23,26) providing evidence supporting the hypothesis of microtrauma due to instability as the cause. However, no history of trauma, rheumatism, facet degeneration, spondylolisthesis, or resultant instability was evident in most of the reported cases of juxtafacet cyst at the level of the odontoid process, including the present case, meaning that the microtrauma hypothesis is implausible.…”