Psychophysiology of pain.

The recent literature on pain states shows: pain thresholds are relatively constant for an individual, but pain tolerance is influenced by psychological state; the expression of pain is a function partly of ethnic membership and degree of extroversion; pain complaints are determined as well by cultural and extroversive factors, and also degree of neuroticism. Studies of pain patients reveals that those with acute pain tend to show normal personality profiles, but the degree of pain experienced is related to the degree of anxiety present. Most chronic pain patients, like those with psychogenic pain, show somatic preoccupations and reactive depression. The treatment and/or rehabilitation of pain patients has developed in three areas. In cases of peripheral neuropathy and some spinal cord lesions, electrical stimulation with "neural pacemakers" can often "close the gate" to pain signals and provide significant reduction or abolition of pain. Psychotropic medications, particularly the tricyclic antidepressants, sometimes in combination with phenothiazines and antihistamines, are effective in many instances of central pain, and help increase the pain tolerance and decrease the need for narcotics in other pain states. Operant conditioning, including the use of biofeedback, extinguishes pain behavior and increases pain-incompatible behaviors, with good long-term results.