Overview: except for the case of Parkinsons (incidence of 2/100 for persons > 50 years old), these disorders are rare causes of unsteadiness. All affect the part of the brain called the "basal ganglia". There are also several other categories of neurologically caused unsteadiness including sensory disorders (involving sensation to the feet) and cerebellar disorders. These conditions are not covered here. The information found in these documents is largely written at the medical student level.