Chiari I malformation in children-the natural history.

To review the natural history of asymptomatic and symptomatic pediatric Chiari I malformations with and without syringomyelia. We reviewed the literature for case reports and case series describing the natural history of asymptomatic and symptomatic children with Chiari I malformations with and without syringomyelia. Our review included approximately 700 asymptomatic children without syringomyelia, 100 symptomatic children without syringomyelia, 22 asymptomatic children with syringomyelia, and 11 symptomatic children with syringomyelia. Symptomatic and imaging outcomes at the point of last reported follow-up were noted to describe the natural history of Chiari I malformations in children. Our review of about 700 asymptomatic children with CM-I without syrinx revealed that most children do not exhibit new-onset symptoms (5-6%) or syrinx (2-3%). The nearly 100 published cases of symptomatic CM-I without syrinx suggest that about half of children report symptomatic improvement (48%) and few report symptomatic worsening (7%). New-onset syrinx is rarely observed (2%). Few cases have been published about asymptomatic and symptomatic CM-I with syrinx as syringomyelia are generally regarded to be an indication for surgical intervention. Nevertheless, all 22 children with asymptomatic CM-I with syringomyelia included in this study were asymptomatic at follow-up, with syrinx resolution observed in 18 children and tonsillar herniation improvement observed in 16 children. Overall, our review of asymptomatic pediatric CM-I with or without syringomyelia suggests that its natural history is much more favorable than previously acknowledged and that the literature generally favors conservative management of these cases. Our review of asymptomatic pediatric CM-I with or without syringomyelia suggests that its natural history is much more favorable than previously acknowledged and that the literature generally favors conservative management of these cases. Further study of symptomatic pediatric CM-I is necessary to better understand its natural history.