Successful treatment of adult Arnold-Chiari malformation associated with basilar impression and syringomyelia by the transoral anterior approach.

A case of adult type I Arnold-Chiari malformation associated with basilar impression, syringomyelia, atlantoaxial dislocation, and occipitalization of the atlas is reported. Preoperative magnetic resonance imaging clearly revealed evidence of severe anterior compression of the cervicomedullary junction due to basilar impression and a sharp clivoaxial angle. Therefore, transoral anterior decompression and fusion were performed, resulting in an improvement of the patient's neurologic signs and symptoms. Postoperative magnetic resonance imaging showed an obvious reduction of the tonsillar herniation and syringomyelia, as well as an improvement of the cervicomedullary compression.