Relation of skin temperature to pain threshold

Two recent studies have established a very close relationship between environmentally-induced changes in skin temperature and the pain threshold for radiant heat stimuli. The present experiment was designed to verify the relationship by using as pain test area the skin surface of the back of the hand, as the skin temperature here is likely to vary from individual to individual much more than for the forehead.

Subjects were 50 neurotic and depressed patients of both sexes, age range 20-79. Skin temperatures were recorded on the right hand until a steady level was reached, then radiant heat stimuli were applied to a blackened area of the left hand. Results showed a highly significant negative correlation between pain threshold and skin temperature level, while differences due to age and sex were negligible. Drops in skin temperature were a common reaction during pain testing.

The significance of this finding is discussed in terms of the adaptive function of skin temperature changes and their relation to tissue damage. The results are consistent with the view that the pain experience, although having its distinctive sensory components, is intimately related to, and affected by, central factors of autonomic regulation. Some implications for general experimental and clinical research on pain are briefly outlined.