Factors influencing the outcome in symptomatic Chiari I malformation.

Background: To study the clinico-radiological determinants of outcome in patients with Chiari I malformation (CIM).

Materials And Methods: The disability assessment of 48 patients with C I M who underwent posterior decompression was done by modified Klekamp and Samii scoring system. The outcome was regarded as good when the patient was ambulant without any aid with an improvement in the disability score; and, poor when (a) there was postoperative deterioration or lack of improvement; (b) the patient was non-ambulant without aid, irrespective of the improvement in the clinical score; or, (c) there was a perioperative mortality. Patients with hydrocephalus; those who underwent syringo-subarachnoid or syringo-peritoneal shunt as the primary procedure; and, patients with atlanto-axial dislocation were excluded from the study. STATISTICAL METHODS USED: Categorical data were expressed in proportions and analyzed with Chi square test. Analysis of factors predicting clinical outcome at 6 months was done utilizing logistic regression analysis.

Results: The outcome assessed at six months showed that 30 patients (62.5%) had good outcome while 18 patients (37.5%; including two perioperative mortalities) had a poor outcome.

Conclusions: Significant predictors of outcome in patients with CIM include the duration of symptoms (P value=0.006), respiratory distress (P value=0.001), and basilar invagination (P value=0.048). The effect of syringomyelia in predicting the clinical outcome could not be determined due to the differences in the number of patients in the groups with or without syringomyelia.