In 1926, Roussy and Lévy described a hitherto undescribed entity which they called "dystasie aréflexique héréditaire." Thus far, no patient has come to postmortem examination, and the nosology of this disease has been a matter of controversy. The finding of numerous onion bulbs in the nerve biopsy specimen from one of Roussy and Lévy's original patients demonstrates that this entity is a form of hypertrophic neuritis.