Thinking beyond pannus: a review of retro-odontoid pseudotumor due to rheumatoid and non-rheumatoid etiologies

Prevalence of likely retro-odontoid pseudotumor in patients receiving dental CBCT examinations

OBJECTIVES

We calculated the prevalence of unsuspected retro-odontoid pseudotumor (ROP) as detected in cone beam computed tomography (CBCT) examinations. Additionally, we examined patient age, sex, and presence and severity of cervical osteoarthritis (OA) as potential risk factors for ROP.

STUDY DESIGN

We retrospectively analyzed de-identified CBCT scans of 455 patients from the Division of Oral and Maxillofacial Radiology at the University of Connecticut School of Dental Medicine. Identification of likely ROP was completed through a likelihood scoring scale (1-4) due to the lack of magnetic resonance images. Severity of cervical OA was determined using 5 osteoarthritic features. An ordinal logistic regression model was used to link potential risk factors to ROP.

RESULTS

In total, 18 patients (3.9%) were classified with probable (11 patients [2.4%]) or definite (7 patients [1.5%]) likely ROP. Older age and the presence and severity of OA were significantly associated with higher ROP scores (P < .001). There was no significant association of ROP likelihood and patient sex (P = .637). An increase of 1 year of age increased the chance of a patient having a higher ROP likelihood score (P < .001). The age-adjusted chance of having a more severe ROP increased with moderate to severe OA (P ≤ .017).

CONCLUSIONS

Prevalence of likely ROP increases with age and OA but is not associated with sex. Individuals with moderate or severe OA are more likely to have ROP.

Acute abducens nerve palsy from a complex retro-odontoid pseudotumor with a protrusion: A case report

Retro-ondontoid pseudotumors represent soft tissue proliferation surrounding the transverse ligament of the atlas, which most commonly results in cervical neck pain or myelopathy due to impingement upon the cervicomedullary junction. The causes of retro-odontoid pseudotumor formation are varied and include metabolic, inflammatory, degenerative, and post-traumatic etiologies. To the best of our knowledge, an abducens nerve palsy as a result of a complex retro-odontoid pseudotumor has never been reported. We discuss a case of a 90-year-old woman who presents with acute lateral gaze palsy with multimodality imaging demonstrating a retro-odontoid pseudotumor with an unusual protrusion which courses superolaterally to the level of the pons and compresses the abducens nerve root entry zone.

Transdural Approach for Resection of Craniovertebral Junction Cysts: Case Series

BACKGROUND

Craniovertebral junction (CVJ) cysts, including retro-odontoid pseudotumors, are challenging pathologies to treat and manage effectively. Surgical intervention is indicated when these lesions result in progressive myelopathy, intractable pain, or instability.

OBJECTIVE

To present a case series of older patients who underwent successful resection retro-odontoid lesions using transdural approach.

METHODS

A single-center, retrospective observation study of older patients who underwent transdural resection of CVJ cysts at a single institution was performed. Summary demographic information, clinical presentation, perioperative and intraoperative imaging, and Nurick scores were collected and analyzed.

RESULTS

Eight patients were included (mean age [±SD] 75.88 ± 9.09 years). All patients presented with retro-odontoid lesions resulting in severe cervical stenosis, cord compression, and myelopathy. The mean duration of surgery was 226 ± 83.7 minutes. The average intraoperative blood loss was 181.2 cc. The average hospital stay was 4.5 days ± 1.3 (range, 3-7 days). The average follow-up time was 12.5 ± 9.5 months. No intraoperative complications were encountered. The Nurick classification score for myelopathy improved at the final postoperative examination (2.38 ± 1.06 vs 1 ± 1.07). Three patients demonstrated a pre-existing deformity prompting an instrumented fusion. Both computed tomography and MRI evidence of complete regression of retro-odontoid cyst were noted in all patients on the final follow-up.

CONCLUSION

Posterior cervical transdural approach for ventral lesions at the CVJ is a safe and effective means of treating older patients with progressive myelopathy. This technique provides immediate spinal cord decompression while limiting neurological complications commonly associated with open or endoscopic anterior transpharyngeal approaches.

Retro-odontoid pseudotumor: a potentially serious cervical spine incidental finding on cone beam computed tomography

Retro-odontoid pseudotumor (ROP) is a benign proliferation of soft tissues posterior to the odontoid process. It can be associated with both inflammatory and noninflammatory arthritis. Altered biomechanics and atlantoaxial instability are the major contributing factors. There are no characteristic clinical findings. In the majority of cases, ROP is detected as an incidental finding in imaging. Early diagnosis of the lesion is important because of its proximity to the spinal canal and spinal cord. Clinical signs and symptoms range from pain to paralysis depending on the presence and level of spinal cord compression. In very rare cases, the lesion might cause sudden death of the patient. We report a case of ROP detected as an incidental finding in cone beam computed tomography of a patient examined for implant treatment planning.

Changes in retro-odontoid mass after upper cervical spine surgery

A non-neoplastic mass posterior to the dens is termed a retro-odontoid mass (R-OM). This retrospective study evaluated radiographic and clinical outcomes and R-OM changes after upper cervical spine surgery. This study included 69 patients who underwent upper cervical spine surgery, including atlantoaxial fusion, occipitocervical fusion, or decompression. All patients underwent preoperative magnetic resonance imaging (MRI). Six-month follow-up MRI examinations were performed in 30 patients who had preoperative R-OMs. Radiographic outcomes of the anterior and posterior atlantodental intervals were measured using X-rays and computed tomography. The R-OM and space available for the cord (SAC) were measured using MRI. Clinical outcomes were evaluated using neck and arm pain visual analog scales, the Japanese Orthopedic Association score, the neck disability index, and the patient-reported subjective improvement rate. The anterior atlantodental interval decreased, while the posterior atlantodental interval and SAC increased postoperatively. Among the clinical outcomes, the neck and arm pain and the neck disability index decreased postoperatively, while the Japanese Orthopedic Association score increased. All clinical and radiographic outcomes improved postoperatively. The R-OM either decreased in size or disappeared after fusion surgery in all cases, except in one patient who underwent decompression surgery. In conclusion, stabilization through fusion surgery is essential for treating R-OM.

Atlantoaxial Intradural Synovial Cyst Mimicking an Extradural Lesion Adjacent to a Retro-odontoid Pseudotumor: A Case Report

Atlantoaxial synovial cysts can very rarely penetrate the dura mater into the thecal sac and cause direct neural compression. Several case reports have been available on "intradural synovial cysts" (IDSCs). In this study, we report on a case with an atlantoaxial IDSC mimicking an extradural lesion. A 90-year-old man was diagnosed with a cystic lesion located laterally to the atlantoaxial joint adjacent to the retro-odontoid pseudotumor (ROP) causing cervical spinal cord compression. Thus, surgical removal was planned. On preoperative examination, the cyst, which had a two-layer structure showing a T2-isointense small mass inside a T2-hyperintense lesion, was thought to be located in the extradural region. However, operative findings showed that the cyst was located inside the dura mater. Histopathological examination suggested a synovial cyst. No recurrence of the cyst was observed until the latest follow-up after 3 years, and the ROP decreased in size. Almost all IDSCs reported previously were observed in the medial site of the atlantoaxial joint. In our case, however, the cyst was observed adjacent to the posteromedial site of the right atlantoaxial joint and the ROP, mimicking an extradural lesion. We had no knowledge regarding the IDSC before the surgery and assumed an extradural lesion. Albeit rare, the existence of such a condition should be considered.

Factors Associated with Retro-Odontoid Pseudotumor in Long-Term Hemodialysis Patients

OBJECTIVE

Hemodialysis has been reported to be associated with retro-odontoid pseudotumor (ROP), but its clinical characteristics have not been well described. The purpose of the present study was to investigate the factors associated with ROP in hemodialysis patients.

METHODS

A retrospective clinical study of hemodialysis patients was conducted with the evaluation of computed tomography and magnetic resonance imaging of cervical spinal lesions at a single institution from 2012 to 2020. The patients' characteristics and radiographic findings were assessed. A case-control analysis was performed between patients with ROP (ROP group) and patients without ROP (control group).

RESULTS

We analyzed 46 patients. The mean duration of hemodialysis (± standard deviation) was 21.5 ± 11.8 years. The mean retro-odontoid soft tissue thickness was 4.3 ± 0.3 mm and was correlated with the duration of hemodialysis (r = 0.46, P < 0.01). Thirty patients (65.2%) were included in the ROP group. The ROP group showed a significantly longer duration of hemodialysis (24.9 ± 11.2 years vs. 15.2 ± 10.3 years, P < 0.01) and a higher incidence of osteolytic lesions in the atlantoaxial joint compared with the control group (60.0% vs. 18.8%, P < 0.01). Logistic regression analysis revealed the atlantoaxial osteolytic lesions are associated with retro-odontoid pseudotumor in hemodialysis patients (odds ratio, 5.1; 95% confidence interval, 1.1-24.2; P = 0.04).

CONCLUSIONS

The existence of ROP in hemodialysis patients was associated with osteolytic lesions in the atlantoaxial joint. The finding of atlantoaxial erosive lesions in long-term hemodialysis patients requires spine surgeons to carefully evaluate the presence of ROP.

Imaging Characterization of Non-Rheumatoid Retro-Odontoid Pseudotumors: Comparison with Atlantoaxial Manifestation of Rheumatoid Arthritis

Backgroundand Objectives: To date, imaging characterization of non-rheumatic retro-odontoid pseudotumors (NRROPs) has been lacking; therefore, NRROPs have been confused with atlantoaxial joint involvement of rheumatoid arthritis (RA). It is important to differentiate these two disease because the treatment strategies may differ. The purpose of this study is to characterize imaging findings of NRROPs and compare them with those of RA. Material and Methods: From January 2015 to December 2019, 27 patients (14 women and 13 men) with NRROPs and 19 patients (15 women and 4 men) with RA were enrolled in this study. We evaluated various imaging findings, including atlantoaxial instability (AAI), and measured the maximum diameter of preodontoid and retro-odontoid spaces with magnetic resonance imaging (MRI) and computed tomography (CT). Results: Statistical significance was considered for p < 0.05. AAI was detected in eight patients with NRROPs and in all patients with RA (p < 0.0001). Seventeen patients with NRROPs and six patients with RA showed spinal cord compression (p = 0.047). Compressive myelopathy was observed in 14 patients with NRROPs and in 4 patients with RA (p = 0.048). Subaxial degeneration was observed in 25 patients with NRROPs and in 9 patients with RA (p = 0.001). Moreover, C2-3 disc abnormalities were observed in 11 patients with NRROPs and in 2 patients with RA (p = 0.02). Axial and longitudinal diameter of retro-odontoid soft tissue and preodontoid and retro-odontoid spaces showed significant differences between NRROP and RA patients (p < 0.0001). Furthermore, CT AAI measurements were differed significantly between NRROP and RA patients (p < 0.05). Conclusions: NRROPs showed prominent retro-odontoid soft tissue thickening, causing compressive myelopathy and a high frequency of subaxial and C2-3 degeneration without AAI.

Cervical amyloidoma of transthyretin type: a case report and review of literature

Background

Amyloidoma is a rare clinical entity characterized by the focal aggregation of amyloid protein within the body, void of systemic involvement. To our knowledge, there have only been 26 reports of cervical amyloidoma to date. Amyloid light chain and beta-2-microglobulin are the most common types, with only three previous reports of transthyretin (ATTR) Amyloidoma.

Case presentation

We report a case of a 71-year-old male who presented with worsening strength and coordination of his upper extremities, right upper-leg pain, unsteady gait, and a reduced range of motion of his neck in all planes. Magnetic resonance imaging revealed a solitary mass compressing the spinal cord at C1-C2. Treatment consisted of cervical decompression and stabilization. Pathological examination confirmed solitary amyloid deposition of ATTR. Postoperative neurological assessment revealed improved balance, gait, hand function, and grip strength. Investigational imaging was ordered 8 months postoperatively revealing no evidence of systemic involvement, confirming the diagnosis of cervical ATTR amyloidoma. A discussion is provided surrounding the published literature of ATTR amyloidoma with description of the typical presentation, management, and outcomes of this rare pathology.

Conclusion

Previous cases and studies indicate clinical signs such as ligamentum of flavum hypertrophy and carpal tunnel syndrome may precede focal ATTR spinal disposition. Outcomes for amyloidoma are generally favourable, as tumour resection prevents irreversible deficits. Patients have a low rate of recurrence with an overall excellent prognosis following resection and stabilization.

Update on imaging of the cervical spine in rheumatoid arthritis

Rheumatoid arthritis is a multisystem, autoimmune, inflammatory disorder with numerous musculoskeletal manifestations. Involvement of the cervical spine is common and may result in severe complications due to synovitis, erosions, pannus formation, spinal instability and ankylosis. The purpose of this article is to review the current role of imaging in the rheumatoid spine, with emphasis on radiographs and MRI.

Headache Attributed to Disorder of the Cranium and Base of the Skull

The article describes the approach to imaging that clinicians should adopt in cases of headaches suspected to be secondary to cranial vault or skull-base disorder. As a rule, computed tomography (CT) is superior to MRI for most of the osseous lesions, and lesions of the middle and external ear. MRI provides a complimentary role to CT and is the modality of choice in a few conditions such as extraosseous neoplasms of the skull base.

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

Background

‘Crowned dens syndrome' (CDS) is a special form of calcium pyrophosphate dihydrate deposition disease which is characterized radiologically by a halo-like or crown-like distribution in the periodontoid region and clinically by cervical pain. Herein, we will describe our experience of posterolateral epidural supra-C2-root approach (PESCA) for biopsy of retro-odontoid lesions in one surgical session after occipitocervical fixation and decompression in a patient with CDS and massive brainstem compression.

Case Presentation

A 70-year-old woman presented to our department with a 4-week history of progressive walking impairment, neck pain, neck rigidity, fever, dizziness, slight palsy of the left hand, and multiple fall episodes. Magnetic resonance imaging (MRI) of the craniovertebral junction (CVJ) and cervical spine revealed a lesion of the odontoid process and the retro-odontoid region with mainly solid components, as well as small cystic components, and brainstem compression and displacement. In first step, fusion surgery of the CVJ C0–C4 was performed with occiptocervical decompression. After fusion and decompression the lower lateral part of the C1 arc and the lateral superior part of the left side of the C2 arc were removed. The entry point was located directly above the superior part of the C2 root. A biopsy of the lateral portions of the lesions was obtained by bioptic forceps under microscope guidance. Pathologic examination of the mass revealed deposition of birefringent crystals compatible with calcium pyrophosphate. In addition to the clinical symptoms (especially neck pain), the diagnosis of CDS was made. Non-steroidal inflammatory drugs (NSAIDs) and colchicine (and later magnesium) were started. At follow-up examination 6 months after surgery, an MRI scan of the cervical spine revealed regression of the pannus and the cyst with replacement of the brainstem, clinical improvement of walking, and increased strength of the left hand.

Conclusions

This study demonstrates that PESCA can be used to obtain tissue for pathological analysis in one surgical sitting after fusion and decompression and that fusion, decompression, and PESCA (in the same session) together with subsequent conservative management could be a good alternative for the treatment of CDS.

Atlantoaxial stenosis after muscle-preserving selective laminectomy

There are few reports of degenerative atlantoaxial stenosis and new stenosis after cervical decompression. We experienced four cases of atlantoaxial stenosis after muscle-preserving selective laminectomy. We compared these four cases with no stenosis cases after long-term follow-up of selective laminectomy, as well as healthy subjects. A total of 1205 patients who underwent muscle-preserving selective laminectomy due to cervical disorders were included in this study. Postoperative atlantoaxial stenosis, which needed decompression, appeared in 4 cases, and 30 patients did not have radiological stenosis for more than 10 years after surgery. Twenty healthy volunteers were also used as controls. The radiographic parameters measured were C2-C7 angle, C2-C7 sagittal vertical axis (SVA), C2 slope, C7 slope, C2-C5 angle, C5-C7 angle, C1-C2 angle, and atlantodental interval (ADI). We measured the anterior-posterior (AP) diameters of the spinal cord (SC) and dural tube (Dura) at C1/C2 with sagittal MRI. In the cases of atlantoaxial stenosis, the AP of SC and Dura at C1/C2 were smaller preoperatively, and the residual space for SC (SAC) was also smaller. The preoperative ADI was significantly higher in patients with atlantoaxial stenosis, suggesting preoperative instability at C1/C2. Analysis of the ROC curve showed that patients with a preoperative SAC of less than 3.6 mm and an ADI of more than 1.35 mm were more likely to develop postoperative atlantoaxial stenosis. When we perform a muscle-preserving selective laminectomy, decompression of C1/C2 is suggested when the SAC at C1/C2 is less than 3.6 mm and the ADI is more than 1.35 mm.

Calcium pyrophosphate dihydrate crystal deposition disease and retro-odontoid pseudotumor rupture managed via posterior occipital cervical instrumented fusion: illustrative case

BACKGROUND

Craniocervical junction and subaxial cervical spinal manifestations of calcium pyrophosphate deposition disease are rarely encountered. The authors presented a severe case of retro-odontoid pseudotumor rupture causing rapid quadriparesis and an acute comatose state with subsequent radiographic and clinical improvement after posterior occipital cervical fusion.

OBSERVATIONS

The authors surveyed the literature and outlined multiple described operative management strategies for compressive cervical and craniocervical junction calcium pyrophosphate deposition disease manifestations ranging from neck pain to paresthesia, weakness, myelopathy, quadriparesis, and cranial neuropathies. In this report, radiographic features of cervical and craniocervical junction calcium pyrophosphate deposition disease were explored. Several previously described surgical strategies were compiled, including patient characteristics and outcomes.

LESSONS

With this case report, the authors presented for the first time an isolated posterior occipital cervical fusion for treatment of a compressive retro-odontoid pseudotumor with rupture into the brainstem. They demonstrated rapid clinical and radiographic resolution after stabilization of cranial cervical junction only 12 weeks postsurgery.

Upper Cervical Compression Myelopathy Caused by the Retro-Odontoid Pseudotumor With Degenerative Osteoarthritis and Calcium Pyrophosphate Dihydrate Disease: A Case Report and Literature Review

The retro-odontoid pseudotumor is often concurrent with atlantoaxial subluxation (AAS). Therefore, the pseudotumor is relatively common in rheumatoid arthritis (RA) but rare in primary osteoarthritis (OA). This is a case report of an elderly male patient suffering from neck pain and compression myelopathy caused by the craniocervical pseudotumor with OA but without atlantoaxial instability. He had long-lasting peripheral and spinal pain treated by nonsteroidal anti-inflammatory drugs. Imaging found upper cervical spondylosis without AAS or dynamic instability but with periodontoid calcifications and ossifications, suggesting calcium pyrophosphate dihydrate (CPPD) crystal deposition. Based on a comprehensive literature search and review, CPPD disease around the atlantodental joint is a possible contributor to secondary OA development and retro-odontoid pannus formation through chronic inflammation, which can be enough severe to induce compression myelopathy in non-RA patients without AAS. The global increase in the aged population advises caution regarding more prevalent upper cervical spine disorders associated with OA and CPPD.

Upregulating miR-27a-3p inhibits cell proliferation and inflammation of rheumatoid arthritis synovial fibroblasts through targeting toll-like receptor 5

Rheumatoid arthritis (RA) is a serious chronic inflammatory disease and synovial fibroblasts (SFs) serve a vital role in the pathogenesis and progression of RA. Current studies have demonstrated that dysregulation of microRNAs is involved in RA etiopathogenesis. The present study aimed to investigate the role of microRNA (miR)-27a-3p in RASFs, as well as its molecular mechanism. RASFs were isolated from synovial tissues from patients with RA. Expression of miR-27a-3p and toll-like receptor 5 (TLR5) was detected using reverse transcription-quantitative polymerase chain reaction and western blotting. Cell proliferation, apoptosis and inflammatory response were measured with MTT assay, flow cytometry and ELISA kits, respectively. The target binding between miR-27a-3p and TLR5 was predicted on DIANA TOOLS software, and confirmed by dual-luciferase reporter assay and Biotin-coupled miRNA pull-down assay. Expression of miR-27a-3p was downregulated and TLR5 was upregulated in synovial tissues and RASFs isolated from patients with RA. Functionally, upregulating miR-27a-3p may promote the apoptosis rate of RASFs and suppress cell proliferation and secretions of interleukin (IL)-1β, IL-6 and tumor necrosis factor-α. TLR5 was validated as a downstream target for miR-27a-3p in RASFs, and its expression was negatively regulated by miR-27a-3p. Silencing TLR5 in RASFs may exert similar effects to miR-27a-3p-overexpression; whereas, restoring TLR5 counteracted the suppression of miR-27a-3p-overexpression on RASF proliferation and inflammation, as well as the promotion on apoptosis. miR-27a-3p upregulation may suppress RA progression by inhibiting RASFs proliferation and inflammation through targeting TLR5.

Retro-odontoid pseudotumor with uncommon presentation of cervical spine injury

Background

We report the first case of retro‐odontoid pseudotumor with an isolated symptom of C2–C3 dysesthesia triggered by a traumatic event.

Case Presentation

An 86‐year‐old man, who was a wood craftsman for more than 50 years, presented to the emergency room with sudden‐onset severe posterior head and neck dysesthesia after accidentally falling backward. No neurological impairment of the extremities was noted. Computed tomography revealed a C2–C7 osteophyte formation, mainly in front of the vertebral bodies. Moreover, magnetic resonance imaging showed cervical spinal cord compression by a soft tissue mass posterior to the odontoid process of the axis. Therefore, we diagnosed a cervical spine injury with an isolated symptom of C2–C3 dysesthesia due to a retro‐odontoid pseudotumor. He did not undergo surgical intervention and was transferred to a rehabilitation hospital on day 11 for pain control.

Conclusion

Our report could be useful to emergency physicians dealing with similar cases of cervical symptoms following trauma.

Retro-Odontoid Pseudotumor Without Radiographic Instability with Congenital C1 Assimilation and C2-C3 Fusion: A Case Report

CASE

The authors present a case of retro-odontoid pseudotumor (ROP) with congenital C1 assimilation and C2-C3 block vertebra without radiological instability who presented with cervical myelopathy with spastic quadriparesis. The patient was managed with occipitocervical fusion and C1 laminectomy. She had rapid neurological recovery in 3 months postoperatively and at 2 years had complete resolution of the retro-odontoid mass.

CONCLUSION

C1 assimilation without apparent radiographic instability as a cause of ROP is underappreciated. This case report and review of literature highlight that C1 assimilation and C2-C3 fusion can lead to ROP even in the absence of apparent radiographic instability with posterior atlantoaxial fusion alone providing good results.

Retro-Odontoid and Retro-C2 Body Pseudotumor, Pannus, and/or Cyst. A Study Based on Analysis of 63 Cases

OBJECTIVE

The potential significance of relationship of atlantoaxial instability with retro-odontoid pseudotumor, pannus, and/or cyst (RPC) is analyzed.

METHODS

We searched the database of patients with craniovertebral junction-related instability treated by atlantoaxial fixation from January 2000 to March 2020. We identified 63 patients in whom there was an RPC in the region posterior to the odontoid process or posterior to the posterior aspect of the C2 body.

RESULTS

The RPC was solid in 10 patients, predominantly cystic in 39 patients, and had both solid and cystic components in 14 patients. The vertical dimension of the RPC varied from 4.5 to 10.5 mm (average, 7.9 mm) and the transverse dimension ranged from 2 to 5.2 mm (average, 3.4 mm). In 51 patients, the RPC was in the midline and in 9 patients, it was eccentric in location. In 38 patients, there was erosion of the C2 body adjoining the RPC. Analysis of investigations showed that in 100% of patients, the dome of the RPC was in line with the most susceptible point of potential bone compression of neural structures. The RPC was eccentric in location in 9 patients presenting with torticollis. RPC indicated the presence of atlantoaxial instability even when there were no other positive and validated radiologic indicators. After atlantoaxial stabilization, the RPC spontaneously regressed or disappeared. Direct resection of the RPC was neither performed nor was necessary in any case.

CONCLUSIONS

RPCs are secondary consequences of atlantoaxial instability and need not be primarily addressed by surgical resection. Their location suggests that they might have a neural protective function.

Nonrheumatoid Retro-Odontoid Pseudotumors: Characteristics, Surgical Outcomes, and Time-Dependent Regression After Posterior Fixation

Objective

Although a retro-odontoid pseudotumor associated with rheumatoid arthritis is a well-known clinical entity, little is known about retro-odontoid pseudotumors not associated with rheumatoid arthritis due to their rarity.

Methods

Between 2006 and 2019, consecutive patients with nonrheumatoid pseudotumors were included and retrospectively compared with patients with rheumatoid pseudotumors.

Results

Nineteen patients had nonrheumatoid pseudotumors (mean age, 73 ± 6 years; male, 53%). All had cervical lesions including ossified anterior and posterior longitudinal ligaments with a history of cervical surgery in 5. The mean thickness of the pseudotumors at diagnosis was 8.1 mm (range, 4.2–17.2 mm). Pseudotumor thickness had a significant negative correlation with the atlantodental interval (p = 0.008) and the subaxial range of motion (p = 0.049). In comparison with 7 rheumatoid pseudotumor patients, nonrheumatoid pseudotumor patients were older (p = 0.042), had a higher proportion of males (p = 0.023), had a smaller atlantodental interval (p = 0.007), and had larger pseudotumors at diagnosis (p = 0.030). Of the 19 patients, 18 received posterior fixation with or without C1 laminectomy, while the other received C1 laminectomy alone. The percent pseudotumor thickness at follow-up to those at diagnosis was 91%, 77%, 68%, 46%, 58%, and 49% at 1, 3, 6, 12, 24, and 36 months after surgery, respectively.

Conclusion

This study revealed markedly clinical and radiological differences between nonrheumatoid and rheumatoid pseudotumors. The main etiology for nonrheumatoid pseudotumors was subaxial cervical degeneration and ossified lesions. There were good outcomes following posterior fixation and time-dependent pseudotumor regression within 12 months.

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

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.