Cervical spine instability following cervical laminectomies for Chiari II malformation: a retrospective cohort study.

Objective: The treatment of symptomatic Chiari II malformations typically involves multilevel cervical laminectomies in very young children. These patients are at significant risk of cervical instability. The purpose of this study was to determine the incidence and significance of cervical instability after multilevel cervical laminectomies in a cohort of patients decompressed for Chiari II malformation.

Methods: Postoperative dynamic lateral cervical spine radiographs were obtained on pediatric patients who had multilevel cervical laminectomies for symptomatic Chiari II malformations. Postoperative cervical spine instability was determined radiographically using published criteria. Clinical instability and need for cervical fusion were also assessed.

Results: Nine patients met inclusion criteria for the study. Five of the nine patients (56%) showed evidence of radiographic instability of their cervical spines following surgery for their Chiari II malformations, according to the criteria used. No patient showed evidence of clinical instability or required cervical fusion.

Conclusion: Radiographic evidence of cervical spine instability following multilevel cervical laminectomies for Chiari II is common but may be of minimal clinical significance. The reason for the lack of clinical instability in what might be considered high-risk patients is not understood.