Chiari I malformation is a congenital condition characterized by the lowest part of the cerebellum (the cerebellar tonsils) extending below its usual position inside the skull to down in the spinal canal.   If this condition is symptomatic there is surgery which can accomadate the abnormal position of the cerebellar tonsils and thus lead to a decrease in symptoms.  No two patients with Chiari have exactly the same symptoms, but there are trends.  Much is available on line.  The American Association of Neurosurgeons is one of those sites.  Google AANS-Chiari for the link.  There is an opportunity to upload your story once you have undergone your surgery.  Other organizations specifically for the Chiari patient are available.  Conquer Chiari, ASAP, and Chiari International have good information.  Several universities also have "Chiari Institutions" that have a prescribed battery of tests with expedient assignment to the first available neurosurgeon.  The Mayfield Clinic in Cincinnati has such a program  Most important is to find a neurosurgeon who has performed many of the operations and with whom you are comfortable.

The operation involves giving more room to the cerebellum at the foramen magnum (the hole in the base of the skull through which the spinal cord passes). This always involves removing some of the skull, a craniectiomy and usually part of the first and second cervical vertebrae.  Rarely the tonsils extend further down into the spinal canal.  One of my patients went all the way to the fifth cervical vertebrae.  One neurosurgeon reported not opening the lining of the brain and spinal canal, the dura.  Using that technique he reported a twenty percent failure rate with the operation.  Most neurosurgeons open the dura and sew a patch to the opening to give the brain more room.  Some even coagulate the tonsils and open the inner lining, the arachnoid.  A few even open up the lower fluid cavity, the fourth ventricle, and plug a potential hole letting fluid get into the spinal cord.  This maneuver is not necessary.  The choice of patch also varies widely from artificial materials to animal tissues or cadaver tissue.  I most often use fascia taken from the patients leg, though I have used animal tissue derived membranes, though they do not seem to work as well as one's own tissue.  I also try to not open the arachnoid, the inner lining.  This is a somewhat tricky maneuver and does not always work.  When it does work the patient has a much shorter hospital stay.  The arachnoid membrane is very thin and is a barrier but not restrictive in the same way as the dura.  Have a thorough conversation with your neurosurgeon about choice of material to sew into your body as well as details of what is planned during the operation.

In the office I save some appointments every week just for Chiari patients to expedite reviewing symptoms and studies to determine if and what operation may help relieve symptoms.