JSUR Journal

Introduction

To date, the operative treatment is separated into fusion and decompression. The latter is also subdivided into anterior, composed of ventral decompression, which is performed endoscopically via transoral approach, and posterior procedures; dorsal decompression is widespread and can lead to regression of the retro-odontoid mass without resection. Fusion procedures are more recently advocated based on the pathophysiology of cervical instability, considering that the resolution of such alteration leads to mass reduction without resection. It involves Occipital-cervical Fusion, usually performed in cases where the retro-odontoid mass is compressing the medulla, avoiding the growth of the mass, and C1-C2 fusion, which is a less restrictive procedure. However, there has yet to be a consensus in the literature regarding which procedure is the standard for hypertrophic dens. Thus, our study aims to provide a better view of whether fusion or decompression is a better treatment option regarding site accessibility and surgeon skills. This study describes a case while presenting a literature review of the physiopathology and treatment of hypertrophic dens, also discussing the concepts involving upper cervical spine stability. 

Case Report

A 61-year-old male patient presented with cervical pain associated with progressive limb weakness. He started complaining of cervical pain and difficulty walking, evolving with dropping objects, especially with the right hand, and finally restricted to a wheelchair. Upon physical examination, the patient presented a muscle strength of grade 2 on the right side of the body, including right foot drop and grade 3 force on the left side. There was also global loss of sensation from the neck down, pain and temperature worst on the left side, but vibration worst on the right side. Pathological hyperreflexia, with increased reflex area, was also present, in addition to bilateral positive Hoffmann’s sign. Indeed, he also had sphincter dysfunction, reporting difficulty in initiating urination. An MRI scan showed a hypertrophic growth of the soft tissue behind the dens, reducing the spinal canal at C1/C2 level and compressing the cervical spine (Figure 1). The patient was operated on with a C1/C2 posterior decompression and fixation using the Harms technique without any attempt to remove the anterior mass. The patient recovered well, with important pain relief, sphincter function restored and strength improvement, and walking again. The comparison between pre-op and post-op sizes is shown in Figure 2.

Figure 1: This image shows the ROP in pre-operation.

Figure 2: Comparison between ROP size in pre operation (A), immediate post operative (B) and a week of postoperative (C).

Methods

A PubMed search adhering to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines was performed. The search for publications using the following descriptors: retroodontoid Pseudotumor, retro-odontoid pseudotumor, periodontoid mass, retro odontoid soft mass or odontoid pannus AND treatment, according to database algorithm. The search encompassed all available articles in English and Portuguese, published between 2012 and 2022. The inclusion criteria were: treatment description, post-operative description and non-tumor patient. The following characteristics were used to exclude studies: literature reviews, animal studies, correspondence or letters, articles not available in full text and articles with incomplete information. Titles and abstracts were analysed to screen articles with positive exclusion criteria. From eligible articles the data were obtained, which included: 1) Patients, 2) Age, 3) Sex, 4) Etiology, 5) Surgery, 6) Follow Up, 7) Regression in C1-C2 fusion, 7) Size Pre-op, 8) Size Post Op.

Results

The literature search yielded 99 articles. The title and abstract of 99 articles were screened and based on exclusion criteria, 77 articles were eliminated. After this initial screening, 16 articles were assessed for eligibility, of which 9 were excluded because of the type of treatment not adhering to the inclusion criteria. Works that were duplicated and whose content was not within the context studied were excluded. Therefore, 7 studies (Table 1) were eligible for analysis.

OO (Os Odontoideum); RA (Rheumatoid Arthritis); DA (Degenerative Arthritis); OALL (Ossification of Anterior Longitudinal Ligament); AAS (Atlantoaxial Subluxation); NI (Non Identified); NA (Not Available); M (Male); F (Female); m (months).

Discussion

Types and Classifications of Pannus

Usually, the Retro-Odontoid Pseudotumor (ROP) is classified either as rheumatoid or non-rheumatoid. On the occasion that it is linked with rheumatoid arthritis, leading to inflammation, it is denominated as pannus. In this way, histopathologically, the pannus can be hypervascular, hypovascular, and fibrous [2]. Moreover, retro-odontoid pseudotumor is associated with Atlantoaxial Instability (AAI), Dish Syndrome, ossification of the posterior longitudinal ligament, and trauma. Also, calcium and amyloid depositions may lead to pseudotumor. The AAI has been considered a fundamental part of the pathophysiology of the ROP once the hypermobility of the joint results in the tearing of the ligaments and deposition of inflammatory tissue or abnormal substances in the posterior aspect of the dens, leading to a mass formation [2]. This idea is supported by the fact that mass reduction was observed in cases treated with stabilization alone [6], which means that the stabilization interrupts the deposition process, culminating in mass reduction due to the resolution of the inflammatory mechanism. It’s a noticeable historical trend in using smaller surgeries with stabilization instead of larger surgeries for mass resection [12]. This trend results from the development of new methods and parameters using MRI imaging to assess the integrity of ligament structures. Therefore, evaluating AAI is central to the treatment choice and may help differentiate cases that need decompression (mass resection or laminectomy) or stabilization alone.