1998 Volume 12 Issue 2 Pages 169-176
The pressure dissociation between the ICP and spinal canal pressure caused by the disturbance in CSF flow at the level of foramen magnum region is believed to be responsible for the development and expansion of the syringomyelic cavity that is associated with Chiari type I malfomation. The purpose of this article is to record observations concerning the changes of CSF hydrodynamics in the spinal canal before and after surgery for foramen magnum decompression (FMD), and to evaluate the effect of FMD on syringomyelia from the hydrodynamic point of view. Thirteen syringomyelia patients with the mean age of 42.5, who underwent FMD with dural plasty in our institute from 1994 to 1997, agreed to be measured for the pressure volume index (PVI) and CSF outflow resistance (Ro) by the bolus lumbar intrathecal injection method that was previously descibed by Marmarou in terms of the various neck positions. PVI in neutral, extened and flexed position were improved by 74.8%, 104.4% and 54.3% respectively. Ro in neutral, extended and flexed postion were improved by 34.6%, 27.2% and 40.5% respectively. Mean values of PVI and Ro in any neck positions were improved by 77.8% and 34.1% respectively. The authors concluded that FMD is effective in the correction of the CSF dynamics in syringomyelia associated with Chiari type I malformation. From the hydrodynamic point of view, this is thought to relate with craniospinal CSF pressure dissociation.
