Scoliosis in children with Chiari I-related syringomyelia

Objective: To study the relationship between scoliosis and Chiari I malformation, with reference to the possible role of cranio-vertebral decompression in preventing the need for scoliosis correction. Material and methods: Out of a total of 36 patients with symptomatic Chiari I, who underwent primary cranio-vertebral decompression by a single paediatric neurosurgeon with an interest in Chiari malformation between 1998 and 2003, 13 had clinically detected scoliosis. Of these, ten had no other structural spine abnormality, which could influence the natural history of scoliosis and were included in this study. Results: In all but one patient, syringomyelia improved significantly after craniovertebral decompression. Of the ten patients, eight had levoscoliosis ( left convexity), all single curves, and two had curves to the right ( both double curves). Six patients did not require corrective scoliosis surgery after cranio-vertebral decompression. The mean Cobb angle for those not requiring scoliosis correction was 29 in contrast to a mean of 76 for those requiring correction [p= 0.001, oneway analysis of variance ( ANOVA)]. The mean age of patients requiring corrective surgery was 158 months against 125 months for those not requiring correction ( p= 0.084, oneway ANOVA). These findings were confirmed by multivariate analysis, which also confirmed that symptom duration, syrinx length and site were not significant in predicting the need for corrective surgery following cranio-vertebral decompression. Conclusions: Cranio-vertebral decompression for Chiari I may prevent the need for corrective scoliosis surgery when performed before the age of ten and below a Cobb angle of 30 degrees.