Ataxia describes a lack of muscle coordination during voluntary movements, such as walking or picking up objects. A sign of an underlying condition, ataxia can affect your movements, your speech, your eye movements and your ability to swallow. Persistent ataxia usually results from damage to your cerebellum — the part of your brain that controls muscle coordination. Many conditions may cause ataxia, including alcohol abuse, stroke, tumor, cerebral palsy and multiple sclerosis. It’s also possible to inherit a defective gene that may cause one of many ataxia variants.