Lateralization of chronic pain.

A number of recent articles have discussed the issue of laterality of chronic pain with inconclusive results. While some authors have found evidence for a preponderance of left-sided pain, others have failed to find such evidence. Unfortunately, none of the studies have clearly explained the rules used for deciding laterality. Consequently, considerable differences exist in the frequency of lateralized versus unlateralized patients in these studies, raising the question of whether variance in results reflects actual differences or different methodologies. In the current study, 101 chronic pain patients were asked to complete a drawing indicating the location and extent of their pain. These drawings were scored for the presence and absence of pain in each of 45 body areas, using a highly reliable rating system. The results suggest that laterality may be normally distributed. The findings are discussed in light of previous research, and suggestions are made for possible uses of the rating system.