Ataxia, defined as impaired coordination of voluntary muscle movement, is a physical finding, not a disease, and the underlying etiology needs to be investigated.

• Ataxia can be the patient’s chief complaint or a component among other presenting symptoms.
• Ataxia is usually caused by cerebellar dysfunction or impaired vestibular or proprioceptive afferent input to the cerebellum .
• Ataxia can have an insidious onset with a chronic and slowly progressive clinical course (eg, spinocerebellar ataxias of genetic origin) or have an acute onset, especially those ataxias resulting from cerebellar infarction, hemorrhage, or infection , which can have a rapid progression with catastrophic effects.
• Ataxia is manifested by a wide-based unsteady gait , errors of extremity trajectory or placement, errors in motor sequence or rhythm and/or by dysarthria. Tone is usually decreased and stretch reflexes may be “pendular.” Nystagmus, skew deviation, disconjugate saccades, and altered ocular pursuit can be present. Truncal instability and tremor of the body or head may occur, especially with cerebellar midline disorders.