Atraumatic atlantoaxial subluxation in pediatric enthesitis-related juvenile idiopathic arthritis: illustrative case

Abstract

Background: Juvenile idiopathic arthritis (JIA) is the most common pediatric rheumatological disease, yet cervical spine involvement remains an underrecognized but potentially devastating manifestation. Atlantoaxial subluxation (AAS) arises from inflammatory changes causing ligamentous laxity and instability.

Observations: A 13-year-old female presented with progressive neck pain. Imaging revealed a 10-mm atlantodental interval on CT, along with hyperintensity and stretching of the transverse atlantal ligament on MRI. She underwent a posterior C1-2 open reduction and fusion. Subsequent rheumatological workup confirmed enthesitis-related JIA, based on polyarticular arthritis, HLA-B27 positivity, and elevated inflammatory markers. To contextualize this case, the authors performed a systematic review and meta-analysis of JIA-related AAS across 21 studies. The pooled incidence of AAS was 14%, with a mean age at JIA onset of 8.47 years and a female predominance of 62%. Enthesitis-related arthritis emerged as the most frequently reported subtype, and 94.4% of patients with AAS improved posttreatment.

Lessons: This case and supporting literature underscore the importance of early detection and multidisciplinary management of AAS in pediatric patients with JIA. Timely neurosurgical stabilization, combined with optimized immunosuppressive therapy, can prevent neurological compromise. Future research should focus on standardized diagnostic thresholds and outcome measures to guide best practices. https://thejns.org/doi/10.3171/CASE25121.

Keywords: atlantoaxial subluxation; cervical spine fusion; enthesitis-related arthritis; juvenile idiopathic arthritis; pediatric spine instability.

FIG. 1.

Abnormal widening of the C1–2 joint space with anterior displacement of C1 relative to C2, measuring 10 mm (red arrows in panels A and B), resulting in mild narrowing of the thecal sac to 8 mm anteroposteriorly in the supine position. A: Sagittal cervical spine soft tissue image. B: Sagittal 3D anatomical reconstruction. No associated fracture is observed. C and D: T2-weighted (C) and T1-weighted (D) cervical spine images revealing abnormal widening of the anterior C1–2 interval, along with posterior displacement of the dens relative to C1 and the skull base. This led to mild thecal sac narrowing and near-complete effacement of the CSF (red arrows). The abnormal soft tissue within the C1–2 space exhibits postcontrast enhancement and T2 hyperintensity, suggestive of inflammatory soft tissue, with a differential diagnosis including pannus related to JIA.

FIG. 2.

Six-month follow-up lateral (A) and anteroposterior (B) radiographs of the cervical spine, showing C1 laminectomy and posterior fusion of C1–2 with stable hardware alignment (red arrows). No paravertebral lucency is observed, cervical lordosis remains straightened, and the previously noted C1–2 widening has been corrected.

FIG. 3.

PRISMA flow diagram showing the methodology employed in conducting the systemic review.