Myofascial trigger points and sensitization: an updated pain model for tension-type headache

Area of Science:

• Pain research
• Neurology
• Musculoskeletal medicine

Background:

• Current tension-type headache models implicate peripheral nociceptive inputs and central sensitization.
• Previous models suggested tender muscles release algogenic substances, but recent findings challenge this.
• The source of peripheral chemical mediator release in chronic tension-type headache (CTTH) remained unclear.

Purpose of the Study:

• To update the pain model for CTTH by investigating the role of myofascial trigger points (TrPs).
• To identify the primary hyperalgesic zones responsible for central sensitization in CTTH.

Main Methods:

• Review of existing clinical and experimental data on pain mechanisms in CTTH.
• Comparison of algogenic substance levels and pH in active myofascial TrPs versus control tender points.
• Analysis of referred pain patterns elicited by head and neck muscles.

Main Results:

• Active myofascial TrPs exhibit higher algogenic substance levels and lower pH compared to non-specific tender points.
• Referred pain from head and neck muscles is a significant contributor to CTTH pain patterns.
• TrPs are identified as potential primary hyperalgesic zones driving central sensitization.

Conclusions:

• An updated pain model for CTTH proposes that referred pain from myofascial TrPs in specific head, neck, and shoulder muscles plays a key role.
• Myofascial TrPs are suggested as the primary hyperalgesic zones responsible for central sensitization in CTTH.
• This model offers a new perspective on the pathophysiology of chronic tension-type headaches.