The purpose of this study is to determine whether a topical nitroglycerine patch applied daily over a trapezius trigger point can improve patients' symptoms.

If there is improvement, this open label study will help determine the degree of improvement and contribute to the design of a larger double blind placebo controlled trial.

We would consider moving forward to a large randomized trial if:

• The intervention is acceptable to patients (>= 70%) and
• Compliance is satisfactory (>=80%) and
• We find preliminary evidence of efficacy, i.e. average reduction in pain of 20mm on the VAS.

Inclusion Criteria:

• Inclusion criteria include age between 19 and 65 years old, myofascial pain lasting at least 6 months, and a myofascial trigger point point in the trapezius muscle.

Exclusion Criteria:

• Our exclusion criteria include symptomatic disc herniation, symptomatic cervical osteoarthritis, systemic infection, malignancy, collapsed vertebra, thoracic outlet syndrome, temporomandibular joint dysfunction, collagen-vascular disease, or brachial plexopathy. Patients with ongoing litigation regarding their symptoms are not eligible for this study. Also excluded are patients with underlying cardiac disease, hypotension, or medical conditions that may not allow them to tolerate the use of vasodilators, and those who use phosphodiesterase inhibitors.