Predicting postoperative outcomes in adults with Chiari I malformation clinically presenting with atypical headache by means of brainstem fractional anisotropy values: a prognostic test accuracy study

Abstract

BACKGROUND: There is no clear consensus about the precise algorithm for the management of Chiari I malformation (CIM), specially, in patients presenting clinically an atypical headache. The brainstem is one of the most compromised areas in CIM due to the compression exerted by tonsillar migration. Posterior fossa decompression (PFD) leads to an increase in space and the alleviation of pressure on the spinal cord. Hence, our question is whether measuring fractional anisotropy (FA) values in the brainstem could predict surgical response in patients with CIM presenting an atypical headache. OBJECTIVES: To evaluate the sensitivity of having higher brainstem fractional anisotropy values as a predictor of good surgical outcomesin patients with CIM clinically presenting with atypical headache. DESIGN AND METHODS: The research is designed as a non-experimental longitudinal study, observing brainstem FA results of patients with CIM presenting atypical headache. Presurgical and postsurgical pain evaluation will be measured with the visual analogue scale (VAS) and the respective results will be compared to assess improvement or not. The sensitivity of having higher brainstem FA results to predict good surgical outcome will be evaluated along with other measurements: specificity, positive and negative predictive values, ROC curve, likelihood ratio and the diagnostic accuracy. STUDY PARTICIPANTS: 39 patients with CIM suffering from an atypical headache will be recruited from the presurgical consultation in Hospital Universitari Josep Trueta (Girona), Hospital Unversitari Germans Trias i Pujol (Badalona) and Hospital Universitari Arnau de Vilanova (Lleida)