A 9 year-old boy presented with worsening neck and head pain associated with dizziness.

This malformation is know as a Chiari malformation, type I. There are several types of Chiari malformations. In Type I, the malformation is limited to descent of the cerebellar tonsils and medulla into the spinal canal. This malformation is often asymptomatic. Some cases are associated with syringomyelia and/or syringobulbia. When symptomatic, patients typically develop posterior headaches and dizziness. In more severe cases, patients may develop vertical nystagmus and other cranial nerve abnormalities.