In 2 cases of infants with the Chiari II malformation, a prepontine cyst pr
esented in association with the hindbrain abnormalities characteristic of t
he Chiari ii syndrome. Both infants presented with bulbar dysfunction and h
ad poor outcome despite decompression of the cerebellar tonsillar herniatio
n and drainage of the prepontine cysts. No such association between prepont
ine lesions and Chiari II has been described previously. Copyright(C)2000 S
. Karger AG, Basel.