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. (Figure 1)

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).

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, read our article on The Importance of Your Cerebrospinal Fluid.

Chiari Malformation

The Chiari malformation is one of the leading cause of syringomyelia. There are also many other causes such as trauma. Many theories exist as to what causes the syrinx to form, however, none have conclusively been proven or universally accepted. Most surgeons agree that the flow of CSF around the herniated tonsils must be restored in order to see the syrinx resolve, or collapse.

Syringomyelia

Syringomyelia ("sear-ing-go-my-EEL-ya") is simply a fluid-filled cavity of cerebrospinal fluid (CSF) in the spinal cord. This fluid filled sac, or cavity, is also known as a syrinx. This cavitation of the spinal cord is usually progressive and can cause neurological deterioration over time. In other words, until the underlying cause of the syrinx is fixed, it will continue to get larger and cause progressive damage to the nerves of the spinal cord.

The MRI (figure 2) demonstrates a classic Chiari malformation. The malformation is circled in white.




Content provided by UW Medicine Neurological Surgery, Seattle, Washington

Many theories exist as to what causes the syrinx to form, however, none have conclusively been proven or universally accepted. Incidents of trauma can also cause the syrinx to form.

This cavitation of the spinal cord is usually progressive and can cause neurological deterioration over time. In other words, until the underlying cause of the syrinx is fixed, it will continue to get larger and cause progressive damage to the nerves of the spinal cord.

Most surgeons agree that the flow of cerebrospinal fluid (CSF) around the herniated tonsils must be restored in order to see the syrinx resolve, or collapse. The nature of syringomyelia is progressive, and so treatment to fix the cause of the syrinx is absolutely vital as soon as possible.

Otherwise, the patient will continue to get worse as the damage becomes more and more permanent. Therefore, early treatment is important because some of the nerve damage can be permanent.

An MRI is the only way to confirm and properly diagnose this disorder. It is very important to get surgical treatment before you start to experience muscle weakness. This is usually not seen until the syrnix acvity becomes very large.

Once a syrinx reaches a persons brainstem it is known as syringobulbia. If you or someone you know has a syrinx that reaches the brainstem area, surgical treatment must be seriously considered! Many of your systems that keep you alive are all located in the brainstem, and you certainly don't want pressure from a syrinx to be put on those structures.