Retro-Odontoid Pseudotumor Formation in the Context of Various Acquired and Congenital Pathologies of the Craniovertebral Junction and Surgical Techniques

Abstract

Retro-odontoid pseudotumor formation consists of an abnormal growth of granulation tissue typically posterior to the odontoid process, resulting as a manifestation of atlantoaxial instability. This instability can occur as a result of conditions ranging from severe mechanical trauma to metabolic disease or autoimmune conditions such as rheumatoid arthritis. A pseudotumor may impinge on the spinal nerves or even the spinal cord and brainstem, manifesting symptoms from severe neck pain to cervicomedullary compression or myelopathy, and in some cases even sudden death. The objective of this review is to consolidate the findings in published case reports and relevant prior literature reviews regarding the formation of retro-odontoid pseudotumor. We address the pathophysiology involved in acquired and congenital pseudotumor formation, including those associated with rheumatoid arthritis (panni). Additionally, we discuss past and current operative techniques designed to curtail and ultimately regress a retro-odontoid pseudotumor and pannus. Surgical techniques that are addressed include ventral decompression (both transoral and transnasal), dorsal decompression, and indications for posterior instrumentation in pannus formation, particularly in cases that may be sufficiently treated in lieu of an anterior approach. Finally, we will examine the role of external orthoses as both a method of conservative treatment as well as a potential adjunct to the aforementioned surgical procedures.

Measurement of Deformity at the Craniovertebral Junction: Correlation of Triangular Area and Myelopathy

“…It has been well reported by many researchers that the retro-odontoid mass tissue disappeared after fixation of the CVJ. 14,17,18,25 Chang et al 17 observed that the TA decreased immediately after the surgery and continued to decrease until 2 years after surgery. In this study, the ΔTA was 1.18 cm 2 in patients who had combined anterior and posterior decompression surgery.…”

Case Report: Posterolateral Epidural Supra-C2-Root Approach (PESCA) for Biopsy of a Retro-Odontoid Lesions in Same Sitting After Occipitocervical Fixation and Decompression in a Case of Crowned Dens Syndrome With Brainstem Compression and Displacement

“…Even if conservative therapy is indicated in most cases of CDS, surgery is also indicated in a few cases ( 27 ). Fiani et al ( 4 ) concluded that occipital–cervical fusion “is indicated in cases where the panni impinge on the medulla and the upper cervical cord” and that the “goal in occipital surgical fusion is to prevent further progression of the pseudotumor and improve neurological outcomes.” Furthermore, they concluded that “neurological improvements are often noted in patients as soon as 1 week after surgery and complete resolution of the pseudotumor can be visualized on imaging within 1 year of surgical repair.”…”

“…Retro-odontoid pannus may develop in the spinal canal ( 4 ), may cause compression of the brainstem, may result in quadriplegia, or may even lead to sudden death in rare cases ( 5 ).…”

Changes in retro-odontoid mass after upper cervical spine surgery

“…A non-neoplastic soft tissue mass posterior to the dens is termed a retrodental or retro-odontoid mass (R-OM); in other studies, it was also referred to as a retro-odontoid or periodontoid pseudotumor 5 , 10 , 11 . R-OMs are often observed in patients with rheumatoid arthritis, congenital anomalies, os odontoideum, degenerative conditions, or trauma.…”

“…Earlier techniques were often followed by increased complications and failure rates 8 , while modern fixation materials and constructs have resulted in better outcomes. Currently, screw-based constructs provide rigid, short-segment stabilization-which is crucial in achieving successful fusion-thereby preventing aggravation of neurologic morbidity and myelopathy 9 .A non-neoplastic soft tissue mass posterior to the dens is termed a retrodental or retro-odontoid mass (R-OM); in other studies, it was also referred to as a retro-odontoid or periodontoid pseudotumor 5,10,11 . R-OMs are often observed in patients with rheumatoid arthritis, congenital anomalies, os odontoideum, degenerative conditions, or trauma.…”