The Chiari ("kee-are-ee") malformation is a disorder
of the brain where the cerebellum is herniated through the
foramen magnum and into the spinal canal. The foramen magnum
is the hole in your skull that the brainstem and spinal cord
exit, and is illustrated with the dotted-line from "A"
to "B" in the diagram to the left. Part "C"
is the herniated cerebellum, or the Chiari malformation.
This
herniation causes two things to happen: first, symptoms result
as the herniated cerebellum pushes against the brainstem.
Second, the flow of cerebrospinal fluid (CSF) is disturbed
and a syrinx, or syringomyelia may form (but not always).
Remember that the CSF is what keeps your brain and spinal
cord "buoyant" and serves as a cushion that protects
them from unexpected trauma. For a more detailed look at cerebrospinal
fluid, and its importance in your body, make sure you check
out our "CSF dynamics"
section.
Please see our section "Syringomyelia"
for more information on how this syrinx can form and its various
symptoms.
The MRI shown below demonstrates a classic chiari malformation.
The malformation is circled in white.
