Ataxia is derived from the Greek word for “disorderly.” Originally a general term that was applied to a number of different medical disorders of heartbeat, gait, and movement, “ataxia” is now used more specifically to mean the incoordination of movement following damage of the sensory or cerebellar system. The purpose of this update is to review the causes and possible mechanisms of ataxia. A better understanding of the possible mechanisms of ataxia could lead to improved treatment strategies for this challenging group of patients. Neural Structures Associated With Ataxia Ataxia can result from damage to several different motor or sensory regions of the central nervous system, as well as from peripheral nerve pathology.1 One of the most common causes of ataxia is damage to the cerebellum, often caused by stroke, disease, or tumor.1