Chiari and Its Related Disorders
Chiari malformation has always been classified as a “rare” disease and is "officially" reported to occur in less than 1% of the population. The actual occurrence of Chiari malformation in the general population is, in fact, unknown.
First, we do not yet know how to define the problem correctly. Second, many neurosurgeons with extensive experience treating Chiari malformation have come to learn that the current criteria for diagnosing Chiari on MRI scans are much too strict. As a result, many Chiari patients are misdiagnosed.
At the Wisconsin Chiari Center, we have come to view the problem as a result of the compression of the brain stem or spinal cord at the base of the skull. This may occur even if the tonsils of the cerebellum protrude through the foramen magnum (that is, if the base of the brain protrudes through the opening where the spinal cord and brain connect) by as little as one millimeter.
Our studies have shown us that the neurological symptoms of Chiari malformation may also occur because of other disorders such as cervical spinal stenosis, tethered cord syndrome and syringomyelia. These different disorders may occur independently of Chiari malformation but frequently occur in conjunction with Chiari malformation in the same patient.
All these disorders have one thing in common: They result in disturbed function of the spinal cord. Therefore, when we are faced with a patient who complains of the symptoms of Chiari malformation, we attempt to exclude each of these conditions.
We have to prioritize the conditions that we diagnose from the most severe to the least severe. In this manner we can select that treatment that is likely to have the greatest benefit for the patient. Each of these conditions is diagnosed by MRI imaging. Newer imaging techniques, some developed by Dr. Heffez and his radiology colleagues, have improved our ability to recognize brain stem compression and spinal cord compression.