Figure 1.

Images of a 9-year-old boy. (a) Sagittal computed tomography scan shows basilar invagination, assimilation of atlas, and C2–C3 fusion. (b) T2-weighted magnetic resonance imaging shows neural compression. External syringomyelia and external syringobulbia can be seen. (c) Coronal computed tomography scan shows marked craniovertebral junction deformity. (d) Sagittal scan shows Goel Type 1 atlantoaxial instability. (e) Postoperative computed tomography scan shows reduction of basilar invagination and craniovertebral fixation. (f) Computed tomography showing the implant. (g) Coronal computed tomography scan showing the implant. (h) Preoperative clinical image. (i) Postoperative clinical image showing reduction of torticollis