At the crossroads between tension-type headache and fibromyalgia.

Fibromyalgia syndrome and tension-type headache have multiple clinical features in common, and pathogenic mechanisms partly overlap. Significant differences need to be recognized as well. Studying the correlations of these often comorbid conditions represents a unique opportunity to gain insight into their pathophysiology and that of other chronic pain syndromes, to increase the accuracy of their diagnosis, and to improve the therapeutic armamentarium.