Measurement of Pain Threshold and Superficial Hyperalgesia in Diseases of the Skin

Abstract

Clinicians have long noted that in the presence of certain dermatoses the sensitivity of the skin is altered. Qualitative estimations of these changes in sensation have been made through the use of various methods of thermal and tactile stimulation. However, not until recently has it been possible to investigate quantitatively the effect on sensation of various dermatoses. Ollendorif (1) made a systematic study of the sensibility of the skin of patients with syphilis and other pathologic conditions. In testing normal and abnormal areas of skin she used such methods as stroking with a hair, pin prick, pressure with a probe, and heat. She found that in patients with inflammatory and infiltrative diseases and in the papules of secondary syphilis the sensitivity of the skin was increased. The hyperalgesia demonstrated in the papules of secondary syphilis was so constant and characteristic that she advocated it as a diagnostic measure. Mayr's (2) study of 311 patients with syphilis, in which he used a water manometer to exert pressure on the lesions, showed that the florid secondary eruptions were more sensitive than normal skin. Since the introduction of the thermal radiation method of measuring pain thresholds on the skin, by Hardy et al (3), studies of pain thresholds on normal skin have been numerous. Schumacher et al (4) studied a group of 200 subjects of both sexes between the ages of ten and eighty and reported an average pain threshold of 220 millicalories per second per square centimeter, with a standard deviation of me/see/cm2. The series of 200 subjects studied by Chapman and Jones (5) were found to have much higher and more variable pain thresholds, although their more recent publications describe results more in keeping with those of Schumacher (4). Pfeiffer (6) measured the pain threshold on the pad of the fingertip and on the nail. By blocking the stellate ganglion he separated superficial pain into what he terms sympain and supain, the former being deep pain and the latter bright, burning pain. Bigelow, Wolff and Goodell (7) demonstrated two pain thresholds on the hand following anoxia of thirty-five minutes duration. As one of the pains was elicited a few seconds after the other they suggested that the noxious impulses were mediated by slow and fast fibers (8). A recent study by Bishop (9) of the pain endings in the skin indicates that increasingly intense stimuli applied to one sensory spot will give rise to touch, itch and pain. He attributes the difference in the qualities of the sensations to