Psychogenic movement is an unwanted muscle movement such as a spasm or tremor that is caused by an underlying psychological condition.
Psychogenic movement can involve any part of the body and resemble the same muscle movements that occur with a biological condition or structural abnormality. Most psychogenic movement is involuntary—done without being consciously initiated by the individual. Psychogenic movement may develop as part of a conversion disorder (in which a psychological event causes physical symptoms with no known medical cause). It also may result from a somatoform disorder (characterized predominantly by multi-system symptoms that are associated with distress and/or dysfunction), factitious disorder (an illness that simulates symptoms for psychological reasons), or malingering (not characterized as a psychiatric disorder but where illness is pretended as a way to achieve a secondary goal such as the acquisition of drugs or disability benefits).
Unlike movement disorders caused by biological or structural conditions, psychogenic movement disorders commonly develop suddenly, progress rapidly to maximum severity, may increase in intensity, and come and go with complete or partial remissions. The movement may be less when the person is distracted, and the severity of symptoms varies among individuals. The course of the psychological condition may be short-lived or lead to chronic disability.
Psychogenic movement is uncommon before the age of 10 years. In children, the dominant limb is most often affected, while adults most frequently see movement in the nondominant limb.
Psychogenic movement disorders include:
Psychogenic tremor (also called functional tremor) can appear as any form of tremor movement. Characteristics may vary but generally include sudden onset and remission, increased incidence with stress, change in tremor direction and/or body part affected, and greatly decreased or disappearing tremor activity when the person is being distracted. Many individuals with psychogenic tremor have a conversion disorder.
Psychogenic dystonia involves involuntary muscle contractions that cause slow, repetitive movements or abnormal postures that are often severely painful. Onset may be abrupt or appear as part of a recurring attack. Psychogenic dystonia typically involves fixed postures, particularly from the start, whereas dystonia caused by a muscle or structural abnormality tends to involve more mobility and be action induced.
Psychogenic myoclonus refers to sudden, involuntary muscle contractions (twitches) or jerking of a muscle or group of muscles that are caused by a psychological condition. Myoclonic jerks may occur alone or in sequence, in a pattern or without pattern. Increased startle or startle-like movements are frequent. Psychogenic myoclonus may occur spontaneously or be generated by an action or reflex. The twitching cannot be controlled by the person experiencing it.
Psychogenic parkinsonism involves rigid movements that are extremely slow and often associated with a great sense of effort and rapid onset of severe fatigue. Individuals with psychogenic parkinsonism may also have tremor. Symptoms are usually seen on both sides of the body.
Psychogenic gait disturbances feature unusual patterns of stance and gait. Individuals may stagger or veer from side to side when walking and appear to be losing their balance, but only rarely fall. Sudden knee buckling without falling is common.
No single test can confirm psychogenic movement, which can prove difficult to diagnose. Physicians must rule out co-existing conditions and other recognizable movement disorders. There may be fluctuations during a neurological exam—particularly an increase of movement following attention and suggestion (an external influence on the will of the patient), and a decrease when the person is distracted.
Electromyography (EMG) may be used to measure bursts of electrical activity from the brain and/or spinal cord to a peripheral nerve root (found in the arms and legs) that controls muscles during contraction and at rest. Electroencephalography (EEG) can correlate the movement and detect any changes in electrical activity patterns produced by the brain.
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