Regression of Degenerative Retro-Odontoid Pseudotumour Treated in a Collar
Bibliographic record
Abstract
Degenerative retro-odontoid pseudotumour is an uncommon condition that is thought to be a manifestation of biomechanical stressors at the cranio-cervical junction.It is frequently attributed to atlanto-axial instability (AAI), 1 although it has also been identified in patients with adjacent segment ankylosis, or ossification of the anterior or posterior longitudinal ligaments.2 The histopathology of reported cases is consistent in that this entity comprises benign, fibrous tissue suspected to be a reactive process secondary to chronic mechanical stress of the posterior ligamentous complex.1,2 Treatment aims to stabilise this segment of the spine, and surgical instrumentation is the dominant strategy in the literature, comprising case reports and small series.[3][4][5] Managing AAI in a collar is not novel, although it has not been well described in the treatment of degenerative pseudotumour.Our case demonstrates collar treatment of retro-odontoid pseudotumour presenting with myelopathy, resulting in mass regression and clinical improvement.The context is in a poor surgical candidate with a sizeable lesion, and no evidence of underlying inflammatory pathology.An 80-year-old woman presented with a 4-month history of neck pain, decreased dexterity, and extremity paresthesias.She could ambulate with a walker, and had no bowel and bladder dysfunction.Review of systems was non-contributory-no history of trauma, infection, malignancy, or other rheumatologic sequelae.Notable examination findings included upper-extremity hyper-reflexia.Plantar and Hoffmann's reflexes were negative.Patchy, non-dermatomal sensory loss was noted in the upper and lower extremities.Cervical spine MRI revealed a retro-odontoid soft tissue mass, peripherally enhancing and mixed in signal intensity, measuring 1.5 × 2.2 × 1.2 cm (Figure 1).There was severe compression of the thecal sac at the level of the mass with local T2-hyperintense cord changes.Degenerative changes were present throughout the cervical spine.No atlanto-axial erosion was noted to suggest rheumatologic pannus or depositional arthropathy, nor was there surrounding bony destruction or enhancement to suggest malignancy.There was no widening of the atlanto-dental interval appreciated on these initial studies.These findings were corroborated with computed tomography for high-resolution bony visualisation.In summary, this patient presented with progressive cervical myelopathy in the context of a retro-odontoid mass.She was admitted for further testing, including rheumatologic bloodwork and consultation and work-up for primary malignancy, which was negative.As such the working diagnosis was degenerative pseudotumour, and treatment was initiated with a rigid cervical collar.Surgery was considered, although ultimately opted against owing to risks associated with the patient's osteopaenic bone quality, small stature, and vertebral artery anatomy.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.004 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".