Chiari's description of cerebellar ectopy (1891). With a summary of Cleland's and Arnold's contributions and some early observations on neural-tube defects.

One hundred years ago, Chiari published his first paper on cerebellar ectopy. The contribution of his paper and those of Cleland (1883) and Arnold (1894) to the development of the knowledge of craniocervical abnormalities is discussed. Some early contributions (those of Tulp and Ollivier d'Angers) to the subject of neural-tube defects were also studied and it is concluded that Chiari's name should be connected with the different types of cerebellar ectopy.