Syringomyelia in the brain stem.
Syringobulbia is closely associated with syringomyelia. Both are forms of brain stem neurological disorders that are characterized by a cavity or cyst (syrinx) in the spinal cord. Syringomyelia, which is the more common form, is characterized by cavitation of the central spinal cord and often extends downward along the entire length of the spinal cord. Syringobulbia is characterized by cavitation that appears in the brain stem. These disorders are slowly progressive disorders that are congenital, although there is evidence that syringomyelia and syringobulbia may also be a result of trauma. These disorders are often associated with craniovertebral anomalies (e.g., Arnold-Chiari syndrome).