Functional neurological symptom disorder, previously known as conversion disorder, consists of neurologic symptoms or deficits that develop unconsciously and nonvolitionally and usually involve motor or sensory function. The manifestations are incompatible with known pathophysiologic mechanisms or anatomic pathways. Onset, exacerbation, or maintenance of conversion symptoms is commonly attributed to mental factors, such as stress or trauma. Diagnosis is based on history after excluding physical disorders as the cause. Treatment begins by establishing a consistent, supportive physician-patient relationship; psychotherapy can help, as may hypnosis and physical therapy.
(See also Overview of Somatization.)
Functional neurological symptom disorder is a form of somatization—the expression of mental phenomena as physical (somatic) symptoms.
The disorder tends to develop during late childhood to early adulthood but may occur at any age. It is more common among women.
Symptoms and Signs
Symptoms of this disorder often develop abruptly, and onset can sometimes follow a stressful event. Typically, symptoms involve apparent deficits in voluntary motor or sensory function but sometimes include shaking movements and impaired consciousness (suggesting seizures) and abnormal limb posturing (suggesting another neurologic or general physical disorder). For example, patients may present with impaired coordination or balance, weakness, paralysis of an arm or a leg, loss of sensation in a body part, seizures, unresponsiveness, blindness, double vision, deafness, aphonia, difficulty swallowing, sensation of a lump in the throat, or urinary retention.
Patients may have a single episode or sporadic repeated ones; symptoms may become chronic. Typically, episodes are brief.
Diagnosis
Clinical evaluation
The diagnosis of functional neurological symptom disorder is considered only after a comprehensive medical examination and tests to rule out neurologic or general medical disorders that can fully account for the symptoms and their effects. An important characteristic is that the symptoms and signs are not consistent with neurologic disease. For example, they may not follow anatomic distributions (eg, sensory deficits that involve parts of multiple nerve roots), or findings may vary at different examinations or when assessed in different ways, as in the following:
A patient may have marked weakness of plantar flexion when tested in bed but can walk normally on tiptoes.
In a supine patient, the examiner's hand under the heel of a "paralyzed" leg detects downward pressure when the patient lifts the unaffected leg against resistance (Hoover sign).
Tremor changes or disappears when the patient is distracted (eg, by having the patient copy a rhythmic movement with the unaffected hand).
Resistance to eye opening is detected during an apparent seizure.
A visual field deficit is tubular (tunnel vision).
Also, to meet criteria for being a disorder, the symptoms must be severe enough to cause significant distress or impair social, occupational, or other important areas of functioning.
Treatment
Sometimes hypnosis or cognitive-behavioral therapy
A consistently trustful and supportive physician-patient relationship is essential. Collaborative treatment that involves a psychiatrist and a physician from another field (eg, neurologist, internist) seems most helpful. After the physician has excluded a general medical disorder and reassured patients that the symptoms do not indicate a serious underlying disorder, patients may begin to feel better, and symptoms may fade.
The following treatments may help:
Hypnosis may help by enabling patients to control the effects of stress and their mental state on their bodily functions.
Narcoanalysis is a rarely used procedure similar to hypnosis except that patients are given a sedative to induce a state of semisleep.
Psychotherapy, including cognitive-behavioral therapy, is effective for some people.
Physical therapy can help some people.
Any coexisting psychiatric disorders (eg, depression) should be treated.
