The term “parkinsonism” refers to a group of problems with movement, including (1) slowness of movement, (2) a specific type of tremor, (3) stiffness in the limbs, and (4) unsteadiness. Many diseases can cause one or more of these symptoms. The most common is idiopathic Parkinson’s disease, which is often treated with medications. Aside from idiopathic Parkinson’s disease, there are several other diseases that can exhibit one or more parkinsonian features. In some cases, it is difficult to tell these diseases apart, but the value of distinguishing them from one another is that their treatments may be different. Neurologists specializing in movement disorders have expertise in diagnosing treating parkinsonian disorders.