Clinical Application of Trigger Point Acupuncture for Primary Headaches

Abstract

　Trigger points (TrPs) are defined as hypersensitive spots located within taut bands of skeletal muscle fibers, which can elicit local and referred pain upon mechanical stimulation. TrPs in the cervical and masticatory muscles produce referred pain to the head and are considered to be involved in the pathophysiology of primary headaches. In recent years, TrPs have gained attention as a key component of myofascial pain syndrome, and trigger point acupuncture has been widely used as a therapeutic approach for myofascial pain.
　Over the past few years, a Delphi study has been conducted to establish international expert consensus. It suggests that a practical diagnostic criterion for trigger points is the presence of at least two of the following clinical findings: a taut band, a hypersensitive spot, and referred pain.
　Trigger points are also clinically classified into active and latent types. Active trigger points reproduce the patient’s familiar symptoms upon mechanical stimulation, whereas latent trigger points are associated only with local tenderness and do not reproduce the patient’s usual symptoms.
　Trigger point acupuncture has been shown to decrease the amplitude and frequency of endplate noise and endplate spikes, thereby improving abnormal excitability at the neuromuscular junction.
　Reduction of muscle tension is associated with increases in muscle blood flow and oxygen saturation. As a result, biochemicals related to pain and inflammation around trigger points are reduced.
　Furthermore, several studies have reported the effectiveness of trigger point acupuncture in primary headaches, including the treatment of chronic tension-type headache and migraine.
　These findings suggest that active trigger points in the pericranial muscles may be involved in the onset and persistence of primary headache symptoms and that local treatment of these trigger points may help reduce headache symptoms.
　In our clinical experience, relatively favorable effects were observed after three sessions of trigger point acupuncture in patients with lower headache frequency, whereas the effects were limited in those with higher headache frequency.
　These findings indicate that trigger point acupuncture may be more effective when introduced at an earlier stage, before the progression to chronic headache.
　Local treatment of trigger points may be a useful complementary treatment for primary headaches, but further basic and clinical research is needed.