Correlation of Functional Outcome and Natural History With Clinicoradiological Factors in Surgically Managed Pediatric Chiari I Malformation

BACKGROUND: Chiari I malformation occurs because of an underdeveloped posterior fossa with reduced volume that cannot accommodate the normally developed hindbrain. OBJECTIVE: To study the clinical presentation and surgical outcome of pediatric Chiari I malformation and to correlate outcome with demographic and clinical factors and radiological changes in the syrinx, spinal cord, and preoperative intracranial, posterior fossa, and foramen magnum dimensions. METHODS: This retrospective study spanning 9 years included 20 symptomatic patients who underwent foramen magnum decompression, shrinkage of tonsils, and duraplasty. Improvement at follow-up was assessed with a modified Asgari scoring system. Mean differences in the dimensions of the syrinx and cord, foramen magnum morphometry, and intracranial and posterior fossa for 2 groups (with or without improvement) were analyzed with the independent-sample Student t test. Correlation of outcome in relation to change in radiological factors and influence of variables such as age, type and duration of symptoms, and presence of syrinx were evaluated with the Pearson chi(2) test. RESULTS: Sixty percent of patients showed functional improvement at follow-up. Of various demographic and radiological factors assessed, there was significant difference in mean values of change in cord diameter for the entire cohort (P = .05) and for the subgroup with preoperative syringes (P = .03). There was no correlation between change in any of these factors and functional improvement (chi(2) range, 0-4.673; P > .05). CONCLUSION: More than half the pediatric patients with Chiari I malformation improve after surgery. The age at presentation, duration and type of symptoms, cranial and foramen magnum morphometry, and syrinx-related changes have no bearing on outcome at short-term follow-up. The spinal cord diameter differs significantly in patients with and without functional improvement.