Arnold-Chiari malformation: a case report

Arnold-Chiari or simply Chiari malformation is the name given to a group of deformities of the posterior fossa and hindbrain (cerebellum, pons and medulla oblongata). Chiari I is the least severe and is often found incidentally. It is characterized by one or two pointed (not round) cerebellar tonsil sprotruding 5 mm below the foramen magnum, measured by a line drawn from the basion to the opisthion (McRaeLine) Headache is the most common presenting symptom (60-70%) in CIM cases. It is typically localized to the occipital and/or upper cervical region. The pain is usually paroxysmal and of short duration following Valsalva maneuvers such as coughing, sneezing, laughing, straining. Syringomyelia is observed in 30-70% of CIM patients due to disruption of CSF dynamics and progressive scoliosis in some of them. Syringomyelia is most commonly found in the cervical region.