The Psychophysiological Etiology of Muscle‐Contraction Headache

SYNOPSIS Although numerous pharmacological and behavioral treatments of muscle‐contraction headache have been introduced, the psychophysiological mechanisms underlying this pain disorder have not been identified. This paper reviews and critiques laboratory and treatment studies which add to our understanding of the psychophysiological factors involved in muscle‐contraction headache. The results of a number of studies are consistent with a hypothesized muscle‐contraction or vasomotor etiology. However, other studies have reported results inconsistent with these traditional etiological hypotheses. Interpretation of results is hindered by numerous methodological problems, particularly inconsistent and unreliable diagnostic procedures and insufficient controls for alternative etiological explanations. Although causal inferences are difficult to draw, it is evident that significant individual differences exist in the degree to which muscle‐contraction headaches are associated with elevated cephalic muscle tension and that muscle tension alone is insufficient to account for the occurrence of muscle‐contraction headache. The role of additional possible causative factors is discussed.