Congenital Chiari malformations.

Chiari malformation is the commonest anomaly of the craniovertebral junction involving both the skeletal as well as the neural structures. This entity has rapidly evolved over the past decade with newer visualization techniques, thus posing new challenges to diagnosis and management. This review includes the developmental theories, the latest nomenclature and existing treatment modalities of this interesting anomaly. Five theories tried to explain the malformation of the hindbrain and the neuraxis but no single theory completes the development of embryonic defects. Several atypical presentations have been reported with either incidental/asymptomatic features resulting in further classifications. The new magnetic resonance imaging flow techniques attempt to substantiate the clinical presentations and correlate with the abnormality which can be subtle in correlation. Surgical correction to improve the cranial volume, decrease the hydrocephalus and improve flow across the foramen magnum is the mainstay but needs to be tailored to a given type of malformation. Further clinical and imageological studies, especially longitudinal natural history, might improve our understanding of the atypical/asymptomatic presentations and the management that is currently available.