Tension-type headache: classification and diagnosis.

Tension-type headache (TTH) is the most prevalent form of primary headache in the general population. In this article, the diagnostic challenges of TTH are discussed. The classification of these headaches according to the second edition of the International Classification of Headache Disorders (ICHD-2) and the main differences between the ICHD-2 and the first edition of the classification (ICHD-1, 1988) are discussed. The typical features of TTH also are highlighted. Finally, the differential diagnosis of episodic and chronic TTH, emphasizing the situations more likely to raise doubts, is discussed. The wide clinical spectrum of TTH frequently challenges the physician's diagnostic acumen. A structured approach to the patient and a better comprehension of this variability of presentation should translate into better quality of care and a more specific diagnosis for TTH sufferers.