Proposed criteria for the diagnosis of CBS.

To satisfy the diagnostic criteria, patients had to have an insidiously progressive disorder, which was unresponsive to levodopa treatment, two of three major criteria (in italics), and two minor criteria. *Criteria in italics are major criteria, and the rest are minor criteria. †The response of the parkinsonism to levodopa therapy should be tested with at least 25/250 mg of carbidopa/levodopa administered three times a day for at least 2 months. The response to levodopa is considered poor when the extrapyramidal features fail to show marked improvement, or the therapeutic effect is transient (i.e., lasts less than a year). ‡Includes aphasia, dysarthria and dysgraphia. §Includes frontal release signs reduced verbal fluency and other abnormal tests of frontal functions.