INCIDENCE OF POSTLAMINECTOMY KYPHOSIS AFTER CHIARI DECOMPRESSION

Study Design. In this retrospective study, a 5-year series of a pediat ric population undergoing Chiari decompressions is reviewed. Objective s. To review the experience with children treated with suboccipital cr aniectomy and uni- or multilevel cervical laminectomy for Chiari malfo rmation, to determine the incidence of kyphosis and to identify factor s predictive of cervical instability. Summary of Background Informatio n. Upper cervical laminectomy in the pediatric population has a signif icant risk of Postoperative kyphosis. To decrease the incidence of thi s complication, a concerted effort was made to avoid violation of the facet joint during cervical laminectomy, Methods. Thirty-two patients (mean age 4.9 years, range 1 day to 18 years) had surgical decompressi on of Chiari I or II malformations throughout a 5-year period (1989-19 94). Radiographs and operative records were analyzed to determine the number of cervical levels decompressed and extent of laminectomy. Resu lts. Mean follow-up was 3.7 years (range 9 months to 7 years). Only on e patient had clinical and radiographic evidence of kyphosis and requi red C2-C3 fusion. Two others had radiographic signs of mild cervical k yphosis but remained asymptomatic. These three patients had two-level complete laminectomies. Twenty-nine patients had no clinical or radiog raphic evidence of cervical instability. A mean of three cervical leve ls were decompressed (range 0-4), including partial laminectomies, com plete laminectomies, and one osteoplastic laminotomy to drain a lower cervical syrinx. The overall frequency of kyphosis in this series (9%) was substantially lower than in previous reports. Although the number of cervical levels decompressed did not correlate with cervical insta bility, the one patient with clinical instability had inadvertent viol ation of the facet joint, suggesting that overaggressive laminectomy m ay be a critical factor that predisposes patients to postoperative kyp hosis. Conclusion. Cervical kyphosis after Chiari decompression is a r ecognized complication of cervical laminectomy in children, the freque ncy of which may be decreased by careful attention to operative techni que.