Diagnosis of Chiari I malformation and related syringomyelia: radiological and neurophysiological studies.

INTRODUCTION: The diagnosis of Chiari I malformation relies mainly on the anatomical demonstration of the abnormal position of the cerebellar tonsils below the foramen magnum, and of the associated bony anomalies of the posterior cranial fossa and craniocervical junction, as well as of the eventually-associated spinal cord cavitations. Consequently, the neuroradiological work-up plays a fundamental role in the definition of the malformation and in the follow-up of operated patients. REVIEW: The authors review the pertinent literature on the neuroradiology of the Chiari I malformation, with special regard to MRI, with the aim of providing the reader with an updated instrument for its diagnosis.