Convergence Nystagmus Associated With Arnold-Chiari Malformation-Reply

In Reply.  —We are pleased that your correspondents agree with our description of the abnormalities and of the implications drawn from them and that disagreement is confirmed to our categorization of the patient as a Chiari type I malformation.It is true that in Chiari's original description of the type I malformation only the cerebellar tonsils are displaced inferiorly, and it is therefore historically correct to include only cases of pure cerebellar ectopia in the Chiari type I category. However, one is then left with a large majority of patients in whom depression of the cerebellar tonsils is associated with varying degrees of depression of the medulla. In some of these cases there is a typical cervicomedullary kink at the level of the depressed dorsal column nuclei. Syrinx formation is commonly present. If these are not to be classified as Chiari type I malformations, what is the correct terminology? They