Elucidation of neurnal mechanism in electroacupuncture at myofascial trigger points for musculoskeletal pain

INTERVENTION: Electro acupuncture with 2000 Hz at trigger point Electro acupuncture with 250 Hz at trigger point Electro acupuncture with 5Hz at trigger point Electro acupuncture with 2000 Hz at non‐trigger point Electro acupuncture with 250 Hz at non‐trigger point Electro acupuncture with 5 Hz at non‐trigger point CONDITION: Neck pain PRIMARY OUTCOME: Subjective feeling of pain score (Visual analog Scale) SECONDARY OUTCOME: Cerebral hemodynamics; Pressure Pain threshold INCLUSION CRITERIA: 1) Subjects who complain of neck pain. 2) Subjects who had myofascial trigger point located in their trapezius muscle.