Detection of Muscle Atrophy on Routine Sonography of the Shoulder

Abstract

Objective. To describe the utility of sonography in visualizing muscle atrophy during routine sonographic examination of the shoulder for evaluation of the rotator cuff tendons. Methods. A retrospective review of 199 shoulder sonographic examinations performed by 2 musculoskeletal radiologists trained in musculoskeletal sonography with knowledge of the typical sonographic findings of muscle atrophy was performed. Reports were reviewed for the presence of muscle atrophy. If atrophy was present, the reports from those examinations were rereviewed for concomitant rotator cuff abnormalities. Results. Forty-five examinations (23%) showed atrophy in at least 1 muscle on the basis of the criteria of increased echogenicity and decreased bulk. There were a total of 81 individual muscles that showed atrophy, with the following distribution: 16% supraspinatus (n = 13), 31% infraspinatus (n = 25), 36% teres minor (n = 29), 2% subscapularis (n = 2), and 6% biceps brachii (n = 5). In 34 of the 45 examinations with muscle atrophy, there were 57 concomitant full-thickness tendon tears: 64% supraspinatus (n = 29), 38% infraspinatus (n = 17), 7% subscapularis (n = 3), 0% teres minor (n = 0), 16% long head of biceps (n = 7), and 2% deltoid (n = 1). Conclusions. Although primary sonographic evaluation of the painful shoulder concentrates on the tendons of the rotator cuff, we suggest that examination of the muscles should become a standard component of the comprehensive shoulder sonographic examination, particularly given the potential clinical implications of muscle atrophy on the outcome of rotator cuff surgery. Key words: atrophy; muscles; rotator cuff; shoulder; sonography. onography has proven to be both sensitive and specific in assessing the integrity of the rotator cuff tendons. 1 Although much has been published on sonographic evaluation of the cuff tendons, there are only a few reports in the imaging literature mentioning the rotator cuff muscles. 2,3The high-resolution capabilities of sonography afford detailed delineation of internal muscle architecture. The normal pennate structure of skeletal muscle, including hypoechoic muscle bundles and hyperechoic investing fibroadipose septa of the perimysium, are easily recognized on sonography.4 Alterations in muscle echo texture and morphologic characteristics can indicate a number of pathologic conditions, both focal, such as tears and hematoma formation, as well as more diffuse processes, including myositis and atrophy. [5][6][7] Although diffuse increased muscle echogenicity may have many etiolo-

Fatty Atrophy of Supraspinatus and Infraspinatus Muscles: Accuracy of US

“…The patients in Sofka et al study (10) and those in our study more commonly had atrophic infraspinatus muscles (25 of 193 in the Sofka et al study; 19 of 65 in our study) than supraspinatus muscles (13 of 193 in the Sofka et al study; nine of 65 in our study). Why atrophy of the infraspinatus muscle can occur with anterior cuff tears while the infraspinatus tendon is intact remains unclear.…”

“…To our knowledge, the favorable results of US in rotator cuff abnormalities have only related to tendon abnormalities. Studies in which muscle quality was addressed are rare (10).…”

“…To our knowledge, authors of only one recently published retrospective study (10) have assessed US with regard to muscle quality by reviewing a large number of US images for the presence of fatty atrophy of the rotator cuff and by relating fatty atrophy to the presence of USdiagnosed tears.…”

Ultrasound findings of teres minor denervation in suspected quadrilateral space syndrome

“…[13][14][15] In a recent study employing sonography, the prevalence of muscle atrophy around the shoulder was described for the first time. 3 However, the authors did not investigate potential causes such as entrapment neuropathies. Teres minor atrophy was seen in 36% of cases of atrophy around the shoulder, and 28% of these cases were seen in isolation with no concomitant rotator cuff tear.…”

“…1 Little has been published on the sonographic examination of the rotator cuff muscles and the potential role of sonography in the investigation of diffuse increased muscle echogenity. 2,3 The present report describes a case of isolated teres minor denervation that was detected during a routine shoulder examination.…”