Compression at Myofascial Trigger Point on Chronic Neck Pain Provides Pain Relief through the Prefrontal Cortex and Autonomic Nervous System: A Pilot Study

This randomized controlled pilot study investigated the neurological mechanisms by which compression of myofascial trigger points relieves chronic cervical pain. Twenty-one women aged 20-31 years who had suffered from neck pain for more than three months participated, all diagnosed with myofascial pain syndrome by an experienced professional. Participants were randomized into two groups: one receiving ischemic compression at real trigger points in the upper trapezius muscle, and the other receiving compression at control points located 2 cm distant from the trigger points. The protocol consisted of four cycles of 30-second compression each, with rest intervals of 120 seconds.

Throughout the procedure, hemodynamic activity of the prefrontal cortex was monitored using near-infrared spectroscopy (NIRS), while autonomic nervous system activity was assessed through heart rate variability (HRV). Results demonstrated that compression at trigger points produced significant relief of subjective pain compared to the control group. More importantly, HRV analysis revealed that treatment at trigger points significantly increased high-frequency components (HF%), indicators of parasympathetic activity, while decreasing low-frequency components (LF%) and the LF/HF ratio, suggesting reduction of sympathetic activity. Simultaneously, hemodynamic activity in the dorsomedial prefrontal cortex was significantly reduced during compression of trigger points.

Correlation analyses revealed significant relationships between changes in autonomic activity, pain reduction, and changes in brain activity. Specifically, the increase in parasympathetic activity correlated negatively with pain intensity and prefrontal cortex activity, while the decrease in sympathetic activity showed positive correlations with pain relief. These findings suggest that trigger point compression operates through an integrated mechanism involving the central and peripheral nervous systems. The technique appears to modulate the autonomic nervous system response through the prefrontal cortex, a brain region known to regulate both pain perception and autonomic functions.

The reduction of sympathetic activity may contribute to pain relief by decreasing excessive acetylcholine release at motor nerve endings, reducing local vasoconstriction, and facilitating the removal of nociceptive substances. From a clinical standpoint, these results provide scientific evidence for the mechanisms underlying the efficacy of manual therapy at trigger points, a technique widely used in physical therapy and massage practice. The study validates the importance of precise localization of trigger points to obtain optimal therapeutic results, since compression at incorrect locations did not produce the same benefits. Limitations include the relatively small sample size, the homogeneous population (only young women), and the assessment of only one treatment session, not allowing conclusions about long-term effects.