Psychogenic movement disorders.

Psychogenic movement disorders are common, but the diagnosis may be difficult. Visual appearance alone is typically not sufficient to make a diagnosis, but such information is certainly important. That a movement is bizarre can be helpful, but still must be considered thoughtfully since organic movement disorders can have endless variety. The diagnosis should rest on positive findings such as paroxysmal nature, maximum severity at or near onset, variability of tremor direction, frequency and amplitude, entrainment of tremor, distractability and suggestibility, and wildly swaying gait and balance problems with no falling. Psychogenic parkinsonism often poses a problem because of the relatively high frequency of overlap of psychogenic and organic disease. In regard to psychogenic parkinsonism, there are special features to look for. There might be tremor with kinetic movement as well as rest and posture, and finger tremor might be absent. With sequential movements, the sequence effect is typically lacking. Extreme slowness and grunting with great effort may be seen. Improvement in arm swing while running, a feature of organic parkinsonism, may not be seen.