Cerebrospinal Fluid Dynamics Study: A Unique Tool for Management of Chiari 1 Malformation Patients

Background and Aim: Chiari I Malformation (CIM) is defined as the descent of cerebellar tonsils 5 mm or more below the foramen magnum, with or without associated syrinx. The degree of tonsillar descent has a poor correlation with the progression of the disease and clinical presentation of the patients. Abnormal CSF (cerebrospinal fluid) dynamics at the foramen magnum is the main pathophysiological factor responsible for the progression of tonsillar descent, syrinx formation, and hence clinical manifestations of the patients. This study aimed at correlating CSF dynamic changes with the clinicoradiological profile of CIM patients. Methods and Materials/Patients: A prospective longitudinal study was conducted on 25 patients of CIM out of which 24 patients underwent standard midline suboccipital craniectomy with augmented duraplasty and 1 patient had ventriculoperitoneal shunt surgery for hydrocephalus. CSF flow study was done in sagittal as well as in axial sections at the level of foramen magnum using cine flow Magnetic Resonance Imaging (MRI). Clinical and radiological assessments about CSF flow parameters were performed before and after decompression surgery. Results: After suboccipital decompression, 23 out of 24 patients had relief in their symptoms and 1 patient had progressive syringomyelia. Post-operative MRI scan at 3 months showed normalshaped tonsils in all 24 patients. Ten out of 11 patients with syrinx had a reduction in the diameter of the syrinx cavity. Peak CSF flow velocities reduced significantly (P 0.05) in the post-operative period and correlated well with the clinicoradiological improvement. Conclusion: Abnormal CSF flow dynamics are responsible for the progression of the disease and clinical manifestations in CIM patients. Cine flow MRI is a useful tool in the management of CIM patients both for proper selection of surgical candidates and in the post-operative follow-up.