Which statement best describes the characteristic of ataxia?

• A. Typified by under- or over-shoot of the intended target
• B. Onset of tremor during movement
• C. Difficulty with balance when standing still
• D. Complete paralysis of limbs

Answer: (A)

Ataxia is a lack of coordinated movement arising from cerebellar dysfunction. The most characteristic finding is dysmetria—the tendency to misjudge distance or movement amplitude, which causes an under- or overshoot of the intended target. For example, when trying to reach a finger or touch the nose, the limb may stop short or overshoot the mark. Tremor can occur during purposeful movement (an intention tremor) and balance issues can accompany cerebellar problems, but the defining feature here is the miscalculation of movement extent. Complete paralysis would not be described as ataxia.