Injection Technique for Teres Major Syndrome

Indications and Clinical Considerations

The teres major muscle is susceptible to developing myofascial pain syndrome. Prolonged lifting of heavy objects held in front of the body or repetitive activities that require medial rotation of the humerus, such as using a screwdriver, may cause the development of teres major syndrome. The teres major muscle is also susceptible to developing myofascial pain after blunt trauma to the muscle, such as that to the posterolateral chest in motor vehicle accidents or from sports injuries such as spearing injuries in football or falls onto the lateral scapula ( Fig. 39.1 ). Magnetic resonance imaging and ultrasound imaging may help identify traumatic injury to the teres major muscle as well as other pathology that may be responsible for the patient’s pain symptomatology ( Fig. 39.2 ).

Myofascial pain syndrome is a chronic pain syndrome that affects a focal or regional portion of the body. The sine qua non of myofascial pain syndrome is the finding of myofascial trigger points on physical examination. Although these trigger points generally are localized to the regional part of the body affected, the pain of myofascial pain syndrome often is referred to other anatomic areas. This referred pain often is misdiagnosed or attributed to other organ systems, leading to extensive evaluations and ineffective treatment. Patients with myofascial pain syndrome involving the teres major often have referred pain into the ipsilateral shoulder and upper extremity.

The trigger point is the pathognomonic lesion of myofascial pain and is believed to result from microtrauma to the affected muscles. This pathologic lesion is characterized by a local point of exquisite tenderness in affected muscle. Mechanical stimulation of the trigger point by palpation or stretching produces not only intense local pain but also referred pain. In addition to this local and referred pain, there often is an involuntary withdrawal of the stimulated muscle, which is called a “jump sign.” This jump sign is also characteristic of myofascial pain syndrome. Patients with teres major syndrome will exhibit trigger points in the axillary or posterior portion of the muscle ( Fig. 39.3 ).

Taut bands of muscle fibers often are identified when myofascial trigger points are palpated. In spite of this consistent physical finding in patients with myofascial pain syndrome, the pathophysiology of the myofascial trigger point remains elusive, although many theories have been advanced. Common to all of these theories is the belief that trigger points are a result of microtrauma to the affected muscle. This microtrauma may occur as a single injury to the affected muscle or as a result of repetitive microtrauma or chronic deconditioning of the agonist and antagonist muscle unit.

In addition to muscle trauma, a variety of other factors seem to predispose the patient to developing myofascial pain syndrome. The weekend athlete who subjects his or her body to unaccustomed physical activity may develop myofascial pain syndrome. The poor posture of someone sitting at a computer keyboard or watching television has also been implicated as a predisposing factor to the development of myofascial pain syndrome. Previous injuries may result in abnormal muscle function and predispose the patient to the subsequent development of myofascial pain syndrome. All of these predisposing factors may be intensified if the patient also has poor nutritional status or coexisting psychological or behavioral abnormalities, including chronic stress and depression. The teres major muscle seems to be particularly susceptible to stress-induced myofascial pain syndrome.

Stiffness and fatigue often coexist with the pain of myofascial pain syndrome, increasing the functional disability associated with this disease and complicating its treatment. Myofascial pain syndrome may occur as a primary disease state or in conjunction with other painful conditions, including radiculopathy and chronic regional pain syndromes. Psychological or behavioral abnormalities, including depression, frequently coexist with the muscle abnormalities associated with myofascial pain syndrome. Treatment of these psychological and behavioral abnormalities must be an integral part of any successful treatment plan for myofascial pain syndrome.