Patients with an myofascial trigger point (MTrP) in their upper trapezius will be divided into three groups: Group A receiving MTrP injection with normal saline (control group), Group B with hypo-osmolar dextrose (5% dextrose), and Group C with hyper-osmolar dextrose (15% dextrose). Clinical outcomes and morphological changes will be measured before the injection, one hour after, one week after, two weeks after, and one month after the injection to delineate the therapeutic effects of dextrose injection for an MTrP.

This experiment is designed to evaluate the therapeutic effects of dextrose injection on an myofascial trigger point (MTrP). Patients with an MTrP in their upper trapezius will be recruited and be divided into three groups: Group A receiving MTrP injection with normal saline (control group), Group B with hypo-osmolar dextrose (5% dextrose), and Group C with hyper-osmolar dextrose (15% dextrose). Clinical outcomes (visual analog scale, pressure pain threshold, range of motion, neck disability index) will be measured before the injection, one hour after, one week after, two weeks after, and one month after the injection. Morphological changes of an MTrP before, and after the injection will also be evaluated by sonography. Through this study, the definite therapeutic effects, and the better osmolality of dextrose injection for the treatment of an MTrP will be delineated.

Inclusion Criteria:

• 1). Patients should be 20 years of age or older;

• 2). They are able to communicate freely;

• 3). Patients have the diagnosis of myofascial pain syndrome (MPS) with a definite myofascial trigger point (MTrP) in the neck base and upper back regions (the upper trapezius muscle). The MTrP is identified based on the following criteria, as recommended by Simons [Simons et al., 1999]:

  • (a). a localized tender spot in a palpable taut band of muscle fibers,
  • (b). recognized pain (as the usual clinical complaint) when the tender spot is compressed,
  • (c). characteristic and consistent referred pain.

• 4). Symptoms of MPS should be more than 3 weeks.

Exclusion Criteria:

• (1). acute or serious medical problems;
• (2). cognitive impairment or psychiatric disorder;
• (3). coagulopathy or any other bleeding disorder;
• (4). taking medication of anticoagulation or antithrombolytics;
• (5). sensory deficiency over the body part where MTrPs located;
• (6). serum hepatitis B or acquired immunodeficiency syndrome;
• (7). malignancy;
• (8). pregnant or likely to be pregnant.
• (9). diabetes mellitus