Chiari malformations: diagnosis, treatments and failures.

Chiari malformations refer to abnormalities of the hindbrain originally described by the Austrian pathologist Hans Chiari in the early 1890s. These malformations range from herniation of the cerebellar tonsils through the foramen magnum to complete agenesis of the cerebellum. In this review, we review the different classification schemes of Chiari malformations. We discuss the different signs and symptoms that the two most common malformations present with and diagnostic criteria. We next discuss current treatment paradigms, including the new measure of possible in utero surgery to help decrease the incidence of Chiari type II malformations. There is also a small discussion of treatment failures and salvage procedures in these difficult cases. Chiari malformations are a difficult clinical entity to treat. As more is learned about the genetic and environmental factors relating to their characteristics, it will be interesting if we are able to predict which treatments are better suited for different patients. Similarly, with the evolution of in utero techniques especially for Chiari II malformations, it will be interesting to see if the incidence and practice of treating these difficult patients will change.