Pain Somatoform Disorder 

According to the Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV), somatoform disorders are characterized by "the occurrence of one or more physical complaints for which appropriate medical evaluation reveals no explanatory physical pathology or pathophysiologic mechanism, or, when pathology is present, the physical complaints or resulting impairment are grossly in excess of what would be expected from the physical findings."^[1] Pain disorder is one of the somatoform disorders.

The main clinical feature of this disorder is pain that cannot be fully attributed to a known medical disorder in at least one anatomic site. The pain causes clinically significant distress, impairment, or both in social, academic, occupational, or other areas of functioning. Psychological factors are judged to play an important role in the onset, severity, exacerbation, or maintenance of the pain.^[2] The pain is not intentionally produced and is not under the patient's voluntary control. A somatoform disorder cannot be better accounted for by a mood disorder, anxiety disorder, or psychotic disorder.

Pain disorder can be divided into 2 categories.

• Pain disorder associated with psychological factors and no identifiable general medical condition: Psychological factors play a major role in the onset, severity, exacerbation, or maintenance of the pain.
• Pain disorder associated with psychological factors and a general medical condition: Both the psychological factors and the general medical condition have important roles in the onset, severity, exacerbation, or maintenance of the pain.

Pain, as defined by the International Association for the Study of Pain, is an "unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage." Pain has a neurophysiologic sensory component, which signals that tissue insult is occurring, and a perceptual psychological component, which affects the subjective experience of pain.

The following factors may modify the experience and expression of pain:

• A heightened awareness of bodily sensations (ie, somatosensory amplification) characterizes a personality style.
• Attentional bias towards imminent physical stimuli may be observed.
• Affective states, such as anxiety and depression, may increase a subjective sense of suffering.
• A signal of severe tissue damage is how pain is interpreted.
• Although pain threshold is similar in males and females, with increasing age, girls report pain and more readily seek relief.
• Pain catastrophizing by the child or parent increases pain intensity, disability, and school absenteeism.^[3]
• Cultural and ethnic groups differ in the acceptability of expressing discomfort and in the value placed on pain tolerance.
• Developmental stage plays a role because children experience pain no less intensely than adults, but children younger than 8 years express more overt distress.
• Family influences affect the degree of disability caused by pain (ie, dysfunction due to pain is more pronounced in some families as a result of modeling and positive reinforcement of the sick role).

Frequency

United States

Medically unexplained headache or abdominal pain occurs at least once a week in 10-30% of children and adolescents. Prevalence has increased over the past decade. The diagnosis of pain disorder rests not only on the physician's inability to fully explain the pain on an organic basis but also on the clinical implication of the role of psychological factors.

International

Psychosomatic symptoms are more frequent among school-children in Japan than in Sweden.^[4] In both countries, an increase in frequency has been noted over the past decade in parallel with other psychological symptoms and suicide rates.

Mortality/Morbidity

Psychological stress may result in numerous physical effects, including the following:

• Stress affects immune responses through the hypothalamus-pituitary-adrenal axis and the sympathetic nervous system. Neuropeptides and neurotransmitters are released, triggering various GI responses, such as gut dysmotility. In recurrent abdominal pain, nonspecific inflammatory changes can be found on biopsy specimens at all levels of the GI tract, suggesting that immunomodulation plays a role in the pathogenesis of the symptom.
• Emotional distress can cause muscular pains and headaches through increased muscular tension.
• Psychologically induced changes in behavior, such as compulsive activity or prolonged bed rest, lead to secondary physiologic changes and attendant symptoms.

Race

Ethnic groups may differ in the acceptability of expressing discomfort and in the value placed on pain tolerance.

Sex

Medically unexplained somatic symptoms are more frequent in girls than in boys, and the difference is more marked in adolescence. Differences in pain threshold have not been noted, but girls more readily report pain and seek relief.

Age

Children experience pain no less intensely than adults; however, children younger than 8 years express more overt distress. Medically unexplained pains occur more frequently with increasing age. Younger prepubertal children with pain disorder are usually monosymptomatic; recurrent abdominal pain is the most frequent symptom, followed by headaches. With increasing age, more children report symptoms from various locations. Adolescents with pain disorder are often polysymptomatic, with increasing frequency of headaches, limb pain, and chest pain in the same individual.