"Trigger points" are small areas of localized sensitivity and pain found in muscles and connective tissue.1 They may be produced by acute trauma, chronic inflammation, or ischema, or they may be developed as a result of stress from daily activities or postural habits. Although the pain and sensitivity are localized, reports in the literature suggest that the discomfort may be referred to other parts of the body ("referred pain") through the autonomic nervous system.
These areas may be located by palpation, with the aid of the eraser end of a pencil, or by means of electrical currents. It has been suggested that the combination of electrical stimulation and ultrasound is beneficial in both locating and treating the involved areas. A tetanizing current within the comfortable intensity range of the patient is normally used for both location and treatment, offering "massage-like" contraction to the muscles to which it is applied.2
Illustrations are from Mettler Electronics Corporation, Anaheim, California, with permission.
PG: Trigger points: Diagnosis and management. Am Fam Physician
SH: The myofascial genesis of pain. Postgrad Med. II(5): May 1952.