Pediatric Chiari malformation type I: long-term outcomes following small-bone-window posterior fossa decompression with autologous-fascia duraplasty.

Chiari malformation type I (CM-I) is a common hindbrain disorder that is associated with deformity and elongation of the cerebellar tonsils. Although CM-I occurs in both pediatric and adult patients, its prevalence, clinical features and management in the pediatric population are not well defined. The current study evaluated a consecutive case series of 92 children (38 females and 54 males) who were diagnosed with congenital CM-I. All patients underwent small-bone-window posterior fossa decompression with autologous-fascia duraplasty. Clinical and radiological features were analyzed and long-term follow-up data were recorded. Risk factors associated with clinical outcomes were investigated using comprehensive statistical methods. Out of the 92 children, 11 (12.0%) were asymptomatic. Associated ventricular dilation was observed in 24 children (26.1%) and concomitant syringomyelia was observed in 72 children (78.3%). A total of 44 children (47.8%) showed scoliosis on plain films. Follow-up data (mean duration, 88.6 months) were available for all patients. Syringomyelia was absent or markedly reduced in 56 patients (77.8%). Symptoms were alleviated in 66 patients, remained unchanged in 12 patients and progressed in 3 patients. Statistical analysis indicated that the cerebellar tonsillar descent (CTD) grade, basilar invagination and platybasia influenced the clinical outcome (P<0.05). In conclusion, early recognition and surgical treatment of CM-I in pediatric patients can lead to good outcomes. The current results suggested that small-bone-window posterior fossa decompression with autologous-fascia duraplasty was an effective safe treatment option with a low complication rate. High CTD grade, basilar invagination and platybasia were indicated to be predictors of poor clinical prognosis.