Diagnosing Chiari malformation
A complete medical history and physical examination, followed by a complete neurological evaluation to assess symptoms and neurological function, are required to begin the diagnostic process. Some patients may have problems with coordination, balance, eye movement, sensation, and strength. The reflexes may be overactive or underactive. Reflexes that are present only when the spinal cord is not functioning properly may also be detected. It is also entirely possible that none of the preceding problems will be present and that the patient will have an entirely normal examination. This can make it extremely difficult to determine whether Chiari malformation is the problem. In that case, an experienced neurosurgeon’s judgment is vital. If the neurological examination is abnormal, a neurosurgeon may detect a pattern of abnormal findings that make it possible to pinpoint the problem in the cervical spinal cord and brain stem.
MRI is the most valuable resource for diagnosing Chiari malformation. It provides detailed images about the anatomy of the areas at the base of the brain. The longtime standard for diagnosing Chiari malformation is a measurement of five millimeters of protrusion of the cerebellum into the spinal column; if this is detected, the doctor may be able to confidently make the diagnosis. However, in some cases, the measurement is less – and this can cause patients to go undiagnosed and untreated.
Advances in detecting Chiari malformation using MRI and other diagnostic tools have been reported by various sources. The Wisconsin Chiari Center (www.wichiaricenter.org), for example, reports having developed MRI imaging strategies designed to demonstrate brain stem compression more clearly. These strategies involve using three-dimensional imaging and cine imaging, which essentially makes a movie of the brain, to determine if the brain stem is being compressed. Others have reported on the use of spinal taps as a diagnostic tool (www.chiarione.org).