Imaging of Craniovertebral Junction Instability, Fixation, and Stenosis in Children.

Craniovertebral junction (CVJ) instability, fixation, and stenosis in children are closely related conditions that are often challenging to diagnose and are associated with significant morbidity. Groups at higher risk for CVJ abnormalities include children with trisomy 21, juvenile idiopathic arthritis, upper respiratory infection or other inflammatory conditions of the head and neck, and certain skeletal dysplasias. Radiography, CT, and MRI play complementary roles in the evaluation of pathologic conditions of the CVJ. CVJ morphometry is helpful in characterizing osseous relationships and suggesting potential instability and/or neural compression. CT with multiplanar and three-dimensional volume-rendered reconstructions may be helpful in identifying (a) congenital anomalies associated with instability and/or neural canal narrowing; (b) disorders predisposing to atlantoaxial rotatory fixation (AARF), such as retropharyngeal inflammation in Grisel syndrome; and (c) acquired osseous abnormalities associated with irreducibility in children with chronic AARF (eg, facet deformity or new bone formation). Dynamic CT is particularly helpful for evaluating children with persistent torticollis that is refractory to initial conservative therapy. Early diagnosis and treatment of AARF are essential in reducing the likelihood of progression to chronic AARF. Performing CT angiography before C1-C2 fixation may help identify vascular variations that increase surgical risk and provide an opportunity for modification of the surgical plan. MRI is preferred for assessment of the hindbrain; upper cervical spinal cord; and nonossified structures such as cartilage, ligaments, and paravertebral soft tissues. The authors discuss normal development and anatomy, imaging evaluation, and disorders associated with CVJ instability, fixation, and stenosis in children. Imaging-related treatment considerations are also discussed. ^©RSNA, 2025 Supplemental material is available for this article.