Bezuidenhout AF, et al. - An exploratory study using real-time MRI was performed to correlate disease severity in symptomatic patients with Chiari I malformation with cough-associated changes in CSF flow. For the purpose of this investigation, 13 symptomatic subjects with Chiari I malformation (tonsillar herniation of ≥5 mm) were prospectively studied. A significant negative correlation was found between the percentage change in CSF stroke volume and Chiari I malformation disease severity. In patients with Chiari I malformation, assessment of CSF flow response to a coughing challenge has the potential to become a valuable objective noninvasive test for clinical assessment of disease severity.