Background Chiari malformations include a large spectrum of anomalies of hindbrain formation that appear at different stages of development of the central nervous system. Chiari described these malformations as congenital anomalies of the hindbrain characterized by downward elongation of the brain stem and cerebellum into the cervical portion of spinal cord. Much research regarding Chiari malformation I (CMI) has focused on the cerebrospinal fluid (CSF) dynamics rather than the anatomic relationships of the tonsils and brainstem. The aim of the present study was to measure the peak CSF velocity at the foramen magnum and record the changes after foramen magnum decompression in patients with CMI aged Methods A total of 39 patients with CMI were included during a 2-year period and were analyzed for peak CSF flow velocity with respect to surgical intervention using predefined magnetic resonance imaging protocols and surgical technique. Results After foramen magnum decompression, the postoperative mean CSF peak flow velocity showed a statistically significant difference compared with the preoperative value. Conclusion Decompression of the foramen magnum was associated with decreased CSF peak velocity in patients with CMI.
