Also known as Arnold-Chiari Malformation or ACM, this is an ucommon structural condition affecting the cerebellum. Essentially there is extra cerebellum crowding the outlet of the brainstem/spinal cord from the skull on its way to the spinal canal. This crowding will commonly lead to severe headaches, neck pain, loss of balance, tingling in the arms and/or legs, stiffness, and less often will cause problems such as chronic coughing, difficulties with swallowing, and choking. Often the symptoms are made worse with straining.
Untreated, the chronic crowding of the brainstem and spinal cord can lead to very serious consequences including paralysis. In addition they can lead to the development of syrinxes which may further injure the patients spinal cord and function. When the diagnosis is suspected the study of choice is an MRI scan. These malformations are very difficult to see on CT scans and impossible to see on plain x-rays.
There are many ways to treat Chiari malformations, but all require surgery. The basic operation is one of uncrowding the area at the base of the cerebellum where it is pushing against the brainstem and spinal cord. This is done by removing a portion of bone at the base of the skull deep to the neck muscles as well as often removing a part of the back of the first and occasionally additional spinal column segments.