title: Effect of craniocervical decompression on peak CSF velocities in symptomatic patients with Chiari I malformation.
abstract: OBJECTIVE
  Peak CSF velocities detected in individual voxels in the subarachnoid space in patients with Chiari I malformations exceed those in similar locations in the subarachnoid space in healthy subjects. The purpose of this study was to test the hypothesis that the peak voxel velocities are decreased by craniocervical decompression.
  
  
  METHODS
  A consecutive series of patients with symptomatic Chiari I malformations was studied before and after craniocervical decompression with cardiac-gated, phase contrast MR imaging. Velocities were calculated for each voxel within the foramen magnum at 14 time points throughout the cardiac cycle. The greatest velocities measured in a voxel during the cephalad and caudad phases of CSF flow through the foramen magnum were tabulated for each patient before and after surgery. The differences in these velocities between the preoperative and postoperative studies were tested for statistical significance by using a single-tailed Student's t test of paired samples.
  
  
  RESULTS
  Eight patients with a Chiari I malformation, including four with a syrinx, were studied. Peak caudad velocity diminished after craniocervical decompression in six of the eight patients, and the average diminished significantly from 3.4 cm/s preoperatively to 2.4 cm/s postoperatively (P =.01). Peak cephalad velocity diminished in six of the eight cases. The average diminished from 6.9 cm/s preoperatively to 3.9 cm/s postoperatively, a change that nearly reached the significance level of.05 (P =.055).
  
  
  CONCLUSIONS
  Craniocervical decompression in patients with Chiari I malformations decreases peak CSF velocities in the foramen magnum. The study supports the hypothesis that successful treatment of the Chiari I malformation is associated with improvement in CSF flow patterns.
authors.affiliation: Department of Radiology, University of Wisconsin, Madison, WI, USA.
authors.forename: Maria T
authors.initials: MT
authors.lastname: Dolar
authors.forename: Victor M
authors.initials: VM
authors.lastname: Haughton
authors.forename: Bermans J
authors.initials: BJ
authors.lastname: Iskandar
authors.forename: Mark
authors.initials: M
authors.lastname: Quigley
mesh_terms: D001099:Arachnoid / Q000503:physiopathology / Q000601:surgery; D001139:Arnold-Chiari Malformation / Q000134:cerebrospinal fluid* / Q000503:physiopathology / Q000601:surgery*; D015170:Cerebrospinal Fluid Pressure / Q000502:physiology*; D003389:Cranial Nerve Diseases / Q000134:cerebrospinal fluid / Q000503:physiopathology / Q000601:surgery; D003399:Craniotomy; D019299:Decompression, Surgical; D005500:Follow-Up Studies; D005539:Foramen Magnum / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging; D012189:Retrospective Studies; D013595:Syringomyelia / Q000134:cerebrospinal fluid / Q000503:physiopathology / Q000601:surgery; D016896:Treatment Outcome