Psychogenic (functional) parkinsonism.

Psychogenic parkinsonism (PP), although often quite disabling, is one of the least commonly reported subtypes of psychogenic movement disorders. There are certain features that help distinguish PP from idiopathic Parkinson's disease, such as abrupt onset, early disability, bilateral shaking and slowness, nondecremental slowness when performing repetitive movements, voluntary resistance against passive movement without cogwheel rigidity, distractibility, "give-way" weakness, stuttering speech, bizarre gait, and a variety of behavioral symptoms. While the diagnosis of PP is clinical, functional imaging evaluating the integrity of nigrostriatal pathways can help distinguish PP from other types of parkinsonism. PP can coexist in patients with organic parkinsonism, adding to the challenge of making a diagnosis of PP. Being cognizant of the clinical signs of psychogenic movement disorders, including PP, will lead to earlier diagnosis and hopefully improved outcomes.