Cerebellar atrophy with Chiari malformation: An example of trans-synaptic degeneration?

A 23-year old man was found to have a Chiari Type 1 malformation and cerebellar atrophy. While this association has previously been described, the remote cerebellar atrophy is difficult to explain. We believe the answer lies with our finding of signal hyperintensity on MR imaging at the level of the inferior olives. This suggest hypertrophic olivary degeneration, caused by trans-synaptic degeneration following disruption to the Guillain-Mollaret triangle. Propagation of this process to the cerebellar Purkinje cells occurs in some cases. We describe a case in support of this hypothesis and review previously published evidence.