What Is Parkinsonism?

Parkinsonism is any condition that causes symptoms similar to those of Parkinson's disease. Any condition that affects the basal ganglia can cause these symptoms. Parkinsonism may be a side effect of certain drugs, especially antipsychotic drugs. These drugs interfere with or block the action of dopamine, the main chemical messenger (neurotransmitter) in the basal ganglia. Disorders that can cause parkinsonism include other degenerative brain disorders, viral encephalitis (a rare disorder that follows a flu-like infection), brain tumors, strokes, and head injury (particularly the repeated injury that occurs in boxing).

Levodopa, which can often cause people with Parkinson's disease to improve dramatically, is often less helpful to people who have parkinsonism.