Ataxia is caused by disease or injury that damages your spinal cord or nerve cells in your cerebellum, the part of the brain that handles muscle coordination.
People with the condition lose muscle coordination during voluntary movements. Walking, for example, is a voluntary movement as is speaking, both of which can be impacted by ataxia. Blinking your eyes, on the other hand, is an involuntary movement and controlled by a different part of the body.
Head injuries, such as from a car accident, stroke, transient ischemic attack, multiple sclerosis, cerebal palsy, some cancers, tumors and sometimes viruses such as varicella zoster virus (that's the virus that causes chickenpox) may cause ataxia. Sometimes toxic levels of alcohol, drugs and certain medications, as well as lead or mercury poisoning, may be to blame. Ataxia may also run in some families, a genetic condition where the body produces abnormal proteins that eventually cause nerve cells to degenerate. Sometimes, though, ataxia doesn't seem to have a cause, known as sporadic degenerative ataxia -- it's estimated that about 150,000 Americans live with heredity or sporadic types of ataxia [source: National Ataxia Foundation].