Muscle Triggers as a Possible Source of Pain in a Subgroup of Tension-type Headache Patients?

OBJECTIVES:Tension-type headache (TTH) is a common condition but the underlying etiology is not understood. Episodic TTH may develop into chronic TTH, and some possible triggers may be involved in generation and maintenance. Nociceptive generators and hyperexcitable spots in neck and shoulder regions may to some degree contribute to TTH. The current paper highlights some of the possible triggers and associated pain mechanisms involved in TTH and discusses whether inhibition of these possible triggers may provide new treatment options. RESULTS:This paper presents possible pathophysiological factors in TTH, the role of muscle pain, and how referred pain from triggers can contribute to development, maintenance of sensitization, or both. Referred pain patterns from trigger points and associated muscle hyperalgesia seem to be clinically important factors. Damping the nociceptive peripheral drive may not only reduce the number of TTH attacks but may also prevent, delay the transition from episodic into more chronic TTH, or both. The role of muscle triggers in driving TTH is debated as the pathogenesis of such triggers is not fully understood. Furthermore, inhibiting the drive from the triggers does not consistently modulate TTH. DISCUSSION:Understanding the possible triggers in TTH, muscle hyperalgesia, and widespread pain sensitization, may help to develop better management regimes and possibly prevent TTH from developing into more chronic conditions. Currently, there is a striking difference between the clinical observational studies favoring the role of muscle triggers in TTH and the intervention studies generally not supporting the role of muscle triggers in TTH.