Ataxia is a term that describes abnormality in the coordination of movement. Manifestations commonly include a wide-based unsteady gait and poor coordination of the extremities. There can be associated abnormality in ocular motility and poor coordination of speech. Each of these alterations can relate to abnormal motor trajectory or placement during active movement (dysmetria), and/or to errors in the sequence and speed of motor activity. Abnormality in the rate, force,  direction, and/or path of movement results in motion that is imprecise and dysfunctional. Purposeful, rapid alternating motion rates of muscle groups become slower and less fluid (dysdiadochokinesis), and the motion may have
diminished rhythm (dysrhythmokinesis) . Early in the course of an ataxia-causing disease process there may be decreased resistance to passive movement (hypotonia), and muscle stretch reflexes (DTRs) may demonstrate a
“pendular” response. Intention tremor may be present when initiating or performing an activity, especially when the ataxia is of cerebellar origin. Ocular nystagmus, skew deviation, disconjugate saccades, and altered ocular
pursuit movements can also be seen as components of ataxia. As an anatomic localizing sign, a wide-based stance, with feet several inches apart, is the most
common, but not specific, clinical sign of cerebellardisease. Truncal instability and rhythmic tremor of the body or head (titubation)  occur especially, but not
exclusively, in association with disorders that involve the cerebellar midline. Physical findings associated with ataxia and the utility of these findings relative to anatomic localization have been reviewed.