Retro-odontoid Pseudotumor Without Radiological Atlanto-axial Instability: a Systematic Review.

BACKGROUND: Retro-odontoid pseudotumor (RP) can be caused by several pathologies, especially rheumatoid arthritis, and is usually associated with the presence of atlanto-axial instability (AAI). On the other hand, a different group of patients has been identified in whom RP is observed without radiological findings of AAI. The pathophysiology, clinical characteristics, and prognosis of these latter group of patients are not well described in the literature.

METHODS: A PubMed and Scopus search adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was performed to include studies reporting patients with RP without radiological instability (RPWRI). The data gathered from this review was analyzed to characterize RPWRI.

RESULTS: The search yielded 36 articles with a total of 62 patients. All studies were case reports and small case series. Different characteristics of RPWRI are described, including causes, pathophysiology, and treatment.

CONCLUSIONS: The results of this review show that RPWRI has different etiologies such as hypermobility, deposition of substances and perhaps disc herniation. Depending on the cause of RPWRI, the pathophysiological mechanism is different. Treatment should be tailored based on the primary cause of RP and the degree of compression of the cervicomedullary junction. Different degrees of improvement are usually observed after surgical treatment in these patients regardless of the treatment used, but a higher rate of mass regression was observed in those patients in whom the atlanto-axial (AA) joint was stabilized.