Infraspinatus muscle atrophy: implications?

PURPOSE: To evaluate associated findings in patients who exhibited atrophy of infraspinatus muscle at magnetic resonance (MR) examination of their shoulders to clarify implications of this abnormality. MATERIALS AND METHODS: With an electronic database search, cases of advanced infraspinatus muscle atrophy in patients who underwent MR imaging during a 1-year period for evaluation of shoulder pain or dysfunction were identified. The analysis was restricted to cases interpreted by one reader who applied a standardized method of reporting. Associated MR imaging findings in these cases were tabulated. RESULTS: Advanced infraspinatus muscle atrophy was encountered in 51 (4.3%) of 1,191 MR examinations of the shoulder. Tears of the infraspinatus tendon were present in only 27 (53%) of 51 cases. In 46 (90%) of 51 cases, a full-thickness tear was present in the anterior portion of the rotator cuff. In 10 (20%) of 51 cases with infraspinatus muscle atrophy, cuff muscle atrophy was confined to the infraspinatus muscle. Cuff muscle atrophy was isolated to the infraspinatus muscle in four (17%) of 24 cases in which atrophy of the infraspinatus muscle was present despite an intact tendon. In none of the 51 cases was there a mass in the suprascapular or sphenoglenoid notch. CONCLUSION: Infraspinatus muscle atrophy typically occurs with tendon tears in the anterior aspect of the rotator cuff. Concomitant atrophy in the supraspinatus muscle often is present, but infraspinatus muscle atrophy can occur in isolation, and this finding does not imply that the infraspinatus tendon is ruptured.     

Der Karpaltunnel der Schulter / The Carpal Tunnel of the Shoulder: Die arthroskopische Dekompression des N. suprascapularis

Pain in the posterior area of the shoulder can be caused by pathologies of the suprascapular nerve. Pain may be due to neural entrapment while the nerve is passing through the suprascapular notch. A tear of the rotator cuff may cause traction, resulting in shoulder pain. This might be one of the reasons for persisting pain after successful rotator cuff repair. Neurological and clinical examinations are the most important elements of diagnosis while ultrasound or fluoroscopic diagnostic infiltration remains the current gold standard. Arthroscopic decompression in the area of the suprascapular notch is a safe and reliable procedure of releasing the nerve from entrapment. Various studies show an improvement of muscular function and pain relief after this procedure.     

Suprascapular nerve entrapment at the spinoglenoid notch in a professional baseball pitcher

Suprascapular nerve injuries at the spinoglenoid notch are uncommon. The true incidence of this lesion is unknown; however, it appears to be more common in athletes who participate in sports involving overhead activities. When a patient is being evaluated for posterior shoulder pain and infraspinatus muscle weakness, electrodiagnostic studies are an essential part of the evaluation. Electromyography will identify an injury to the suprascapular nerve as well as assist in localizing the site of injury. In addition, imaging studies are also indicated to help exclude other diagnoses that can mimic a suprascapular nerve injury. The initial management should consist of cessation of the aggravating activity along with an organized shoulder rehabilitation program. If the patient fails to improve with 6 months to 1 year of nonoperative management, surgical exploration of the suprascapular nerve should be considered. Release of the spinoglenoid ligament with resultant suprascapular nerve decompression may result in relief of pain and a return of normal shoulder function.     

MR imaging evaluation of suprascapular nerve entrapment

The aim of this study was to assess the significance of muscular edema, atrophy, and fatty changes in the diagnosis of suprascapular nerve entrapment (SSNE), and to confirm muscular edema as the most significant sign of neuropathy. A retrospective study of 18 patients with suprascapular nerve entrapment was performed. All patients underwent electromyographic studies and MR imaging with a 1.5-T Echo Speed system (General Electric, Milwaukee, Wis.). The diagnosis of muscle edema was reached when muscles presented a high signal on T2-weighted fast spin-echo (SE) fat-suppressed images. Muscular trophicity and fatty changes were analyzed on a sagittal oblique cut using SE T1-weighted images. Intra- and inter-observer reproducibility using kappa test, sensitivity, and specificity were analyzed, together with negative and positive predictive value of each criterion. The topographic diagnosis was correct as edema affected the infraspinatus muscle alone when the suprascapular nerve was entrapped at the spinoglenoid notch. Both the supraspinatus and infraspinatus muscles were affected when nerve was compressed at the suprascapular notch. Sensitivity and specificity of muscular edema were, respectively, 94.5 and 100%. Muscular atrophy sensitivity and specificity were 81 and 80%, respectively. Fatty changes sensitivity and specificity were 25 and 96%, respectively. Muscular edema seems to be a more sensitive sign of SSNE than muscle atrophy and fatty changes when compared with EMG results. Magnetic resonance imaging can reach a positive, topographic, and etiologic diagnosis of SSNE.     

Suprascapular nerve entrapment: evaluation with MR imaging.

Entrapment of the suprascapular nerve is frequently overlooked in the differential diagnosis of shoulder pain. The diagnosis is typically not considered until patients develop severe weakness secondary to atrophy of the spinatus (spinous) musculature that the nerve supplies. Twenty-seven masses were identified adjacent to the suprascapular nerve on magnetic resonance (MR) images of the shoulder; there were 21 ganglion cysts, two synovial sarcomas, one Ewing sarcoma, one chondrosarcoma, one metastatic renal cell carcinoma, and one hematoma associated with a fracture. Atrophy of both the supraspinatus and infraspinatus muscles was seen in association with anteriorly located masses and proximal entrapment of the nerve in 11 cases (40%); isolated atrophy of the infraspinatus muscle was seen in association with posteriorly located masses and distal entrapment of the nerve in nine cases (33%). MR imaging may facilitate the diagnosis of suprascapular nerve entrapment in patients with shoulder pain of unclear origin when perineural masses and atrophy of the spinatus musculature are present.     

Suprascapular neuropathy: diagnosis and management

Although historically considered a diagnosis of exclusion, suprascapular neuropathy may be more common than once believed, as more recent reports are describing the condition as a cause of substantial pain and weakness in patients with and without concomitant shoulder pathology. The etiology is traction or compression of the suprascapular nerve. This can result from a space-occupying lesion, such as a ganglion cyst, or a traction injury as a result of repetitive overhead activities. More recent studies have cited cases of traction injuries occurring with retraction of a large rotator cuff tear. Atrophy of the infraspinatus and/or supraspinatus rotator cuff muscles with resultant weakness in forward flexion and/or external rotation of the shoulder on physical examination may be demonstrated. Magnetic resonance imaging (MRI) is the preferred modality to assess atrophy of the rotator cuff muscles as well as assess potential causes of suprascapular nerve compression. Electromyography and nerve conduction velocity studies remain the gold standard for confirmation of the diagnosis of suprascapular neuropathy; however, nerve pain may occur even in the setting of a negative electromyography. Initial management is usually nonoperative, consisting of activity modification, physical therapy, and nonsteroidal anti-inflammatory drugs. Surgical intervention is considered for patients with nerve compression by an external source or for symptoms refractory to conservative measures. Decompression of the suprascapular nerve may be accomplished through an open approach, although arthroscopic surgical approaches have become more common in the past several years.     

Surgically repaired massive rotator cuff tears: MRI of tendon integrity, muscle fatty degeneration, and muscle atrophy correlated with intraoperative and clinical findings

OBJECTIVE: Our goal in this study was to evaluate by means of MRI the clinical significance of tendon integrity, muscle fatty degeneration, and muscle atrophy in surgically repaired massive rotator cuff tears and to correlate these and other prognostic factors with intraoperative and clinical findings. MATERIALS AND METHODS: Twenty-eight surgically proven massive rotator cuff tears were retrospectively included in the study. Twenty-two patients underwent complete repair, and six patients underwent partial repair. Preoperative and postoperative clinical assessment was performed by using the University of California at Los Angeles score. Preoperative and postoperative MRI studies were evaluated for the presence and extent of rotator cuff tear and for the degree of fatty degeneration and atrophy of the rotator cuff muscles. RESULTS: At a mean 44.4 months' follow-up, 20 patients (71.4%) had a favorable result. A total of 25 patients (89.2%) showed postoperative full-thickness rotator cuff tear, 19 of which were reruptures. A sagittal preoperative rotator cuff tear of less than or equal to 34 mm showed a specificity of 100% for predicting a favorable outcome. A coronal postoperative rotator cuff tear of less than or equal to 34 mm showed a specificity of 85.7% and a positive predictive value of 92.9% for predicting a favorable outcome. A postoperative fatty degeneration of infraspinatus muscle less than or equal to 2 had a specificity of 87.5% and a positive predictive value of 90.9% for predicting a favorable outcome. CONCLUSION: Open repair of massive rotator cuff tears may reach a favorable outcome in a significant proportion of patients, despite a high rate of recurrent or residual tears. Oblique coronal sizes of the recurrent or residual tear of less than or equal to 34 mm and postoperative fatty degenerations of infraspinatus muscle of less than or equal to 2 may allow a favorable outcome.     

Enlarged spinoglenoid notch veins causing suprascapular nerve compression

OBJECTIVE: To report the magnetic resonance (MR) imaging findings of enlarged veins in the spinoglenoid notch as a cause of suprascapular nerve compression. DESIGN AND PATIENTS: Six patients presented to MR imaging for evaluation of chronic shoulder pain. Clinical information and MR imaging studies were reviewed. The spinoglenoid notch vascular structures were compared with measurements made in 10 age-matched controls. RESULTS: Spinoglenoid notch vascular structures measured in 10 asymptomatic age-matched control patients ranged from 1 to 4 mm in diameter with an average of 2.2 mm. The six study patients had vascular structures that ranged from 6 to 10 mm in diameter with an average of 8.4 mm. Atrophy and fatty infiltration of the infraspinatus muscle was noted as an associated finding at MR imaging in all six patients. Surgery was performed in three of the six patients, at which time a venous varix was identified in the spinoglenoid notch in all three patients. CONCLUSION: We describe distended veins in the spinoglenoid notch. These may be readily apparent at MR imaging and should be distinguished from paralabral ganglion cysts compressing the suprascapular nerve in the absence of labral tears, especially if percutaneous aspiration of a ganglion cyst is entertained.     

Compression of the suprascapular nerve by a ganglion cyst of the spinoglenoid notch: the arthroscopic solution

We evaluated an all arthroscopic technique for treating suprascapular nerve entrapment by cyst formation in the spinoglenoid notch. Eight patients showed positive MRI and EMG findings with clinical sign of weakness and pain and with atrophy of the muscle. All patients underwent an all-arthroscopic procedure. The patients were evaluated preoperatively and 6 weeks and 3 months postoperatively and for the latest follow-up by clinical examination, MRI, and EMG. All patients improved in terms of pain, strength, and function. We found six superior labrum anterior and posterior (SLAP) lesions. In these patients the cyst was drained, and the SLAP lesion was repaired. In two patients there was no communication between the joint and the cyst, and therefore capsulotomy was performed and left open. The results of our study show that arthroscopic decompression of the suprascapular nerve can be achieved by an all arthroscopic technique if the cyst formation is located at the spinoglenoid notch.     

Posterior Shoulder Pain and Arthroscopic Decompression of the Suprascapular Nerve at the Spinoglenoid Notch

Suprascapular nerve compression is a disease entity not easily recognized or well understood by many surgeons. Posterior shoulder pain, muscle weakness, and muscle atrophy can result from compression of the nerve at either the transverse scapular ligament or the spinoglenoid ligament in many young adults. Compression at the spinoglenoid ligament, although thought to be rare, is often the result of repetitive overhead activities in either athletes or laborers and results in weakness and atrophy of the infraspinatus muscle. More recently, compression at this site occurs in patients with a massive rotator cuff tear. While this diagnosis is complex and other diagnoses must be considered and ruled out, early intervention is important to successfully manage this patient and return them to their desired activities to avoid permanent muscle atrophy. This paper will discuss the detailed physical examination, adjunct diagnostic procedures, and appropriate arthroscopic surgical treatment of this disease entity to provide the expected outcome with great satisfaction.     

Posterior Shoulder Pain and Arthroscopic Decompression of the Suprascapular Nerve at the Transverse Scapular Ligament

The etiology of posterior shoulder pain can be elusive for the treating physician. Compression of the suprascapular nerve at either the transverse scapular ligament or the spinoglenoid ligament can lead to resultant posterior shoulder pain, muscle weakness, and permanent muscle atrophy. Compression at the transverse scapular ligament, the more common finding than realized in the past in patients, can often result in weakness and atrophy of both the supraspinatus and infraspinatus muscles as compression occurs at the suprascapular notch prior to the nerve giving off motor branches to each of these muscles. Patients with this pathology often have a long-standing disease course of missed diagnoses and even wrong surgical procedures. This paper will discuss the anatomy, pathophysiology, and presentation of symptoms in patients. A thorough discussion of the physical examination as well as appropriate adjunct diagnostic procedures will follow to aid the clinician in making a correct diagnosis with detailed recommendations for appropriate arthroscopic decompression allowing the athlete and patient to return to activities of daily living with a short recuperation period.     

Suprascapular neuropathy in pitchers

The clinical features and preoperative and postoperative electrodiagnostic studies were reviewed in two professional pitchers with a suprascapular neuropathy. These studies demonstrate that denervation of the infraspinatus and/or supraspinatus muscle is not always due to entrapment of the nerve at the suprascapular or spinoglenoid notches, as is often proposed. Similar studies in healthy pitchers during spring training and again at midseason demonstrate that slowing of suprascapular nerve conduction is detectable in some cases as the season progresses. Sagittal sections of a cadaver with the arm fixed in the acceleration phase of the pitching motion demonstrate five possible sites of trauma to the suprascapular nerve. Mechanisms proposed to explain these progressive, but potentially reversible, changes include consideration of biomechanical factors as well as anatomical features. An alternative hypothesis to nerve trauma that explains this symptom complex is intimal damage to the axillary or suprascapular artery and subsequent production of microemboli which become trapped in the suprascapular nerve vasa nervorum.     

Suprascapular neuropathy in volleyball players

BACKGROUND: Suprascapular nerve entrapment with isolated paralysis of the infraspinatus muscle is uncommon. However, this pathology has been reported in volleyball players. Despite a lack of scientific evidence, excessive strain on the nerve is often cited as a possible cause of this syndrome. Previous research has shown a close association between shoulder range of motion and strain on the suprascapular nerve. No clinical studies have so far been designed to examine the association between excessive shoulder mobility and the presence of this pathology. AIM: To study the possible association between the range of motion of the shoulder joint and the presence of suprascapular neuropathy by clinically examining the Belgian male volleyball team with respect to several parameters. METHODS: An electromyographic investigation, a clinical shoulder examination, shoulder range of motion measurements, and an isokinetic concentric peak torque shoulder internal/external rotation strength test were performed in 16 professional players. RESULTS: The electrodiagnostic study showed a severe suprascapular neuropathy in four players which affected only the infraspinatus muscle. In each of these four players, suprascapular nerve entrapment was present on the dominant side. Except for the hypotrophy of the infraspinatus muscle, no significant differences between the affected and non-affected players were observed on clinical examination. Significant differences between the affected and non-affected players were found for range of motion measurements of external rotation, horizontal flexion and forward flexion, and for flexion of the shoulder girdle (protraction); all were found to be higher in the affected players than the non-affected players. CONCLUSIONS: This study suggests an association between increased range of motion of the shoulder joint and the presence of isolated paralysis of the infraspinatus muscle in volleyball players. However, the small number of patients in this study prevents definite conclusions from being drawn.     

Greater tuberosity notch: an important indicator of articular-side partial rotator cuff tears in the shoulders of throwing athletes.

We examined the location of rotator cuff tears, associated labral injuries, and notches on the greater tuberosity of the humeral head in shoulders of throwing athletes. Arthroscopic findings (rotator cuff tear, labral condition, and greater tuberosity notch) as well as other factors (duration of playing baseball, range of motion, and joint laxity) of 61 baseball players were retrospectively studied. The presence of a greater tuberosity notch was also evaluated for by plain radiographs. Forty patients had articular-side partial rotator cuff tears, most of which occurred in the interval between the supraspinatus and infraspinatus tendons. The existence of a rotator cuff tear was not related to the range of motion, joint laxity, the detachment of the superior glenoid labrum, or posterosuperior labral injury. Greater tuberosity notches were recognized in 38 shoulders by arthroscopy and most were detected on plain radiographs. The presence of a notch was significantly related to the existence of a rotator cuff tear, while the size of the notch was significantly related to the depth and width of the tear. The greater tuberosity notch seems to be one of the most important diagnostic indicators for a rotator cuff tear in throwing athletes.     

2D SPLASH: a new method to determine the fatty infiltration of the rotator cuff muscles

The objective of this paper is to quantify the fatty degeneration (infiltration) of rotator cuff muscles with a new spectroscopic FLASH (SPLASH) sequence. Before planned surgery (reconstruction or muscle transfer), 20 patients (13 men, 7 women; 35–75 years) with different stages of rotator cuff disease underwent an MR examination in a 1.5-T unit. The protocol consists of imaging sequences and a newly implemented SPLASH, which allows an exact quantification of the fat/water ratio with a high spatial resolution in an arbitrarily shaped region of interest (ROI). The percentages of fat in the rotator cuff muscles were determined. To determine statistically significant differences between the different stages of rotator cuff tear, a Kruskal-Wallis H test was used. Fatty infiltration of the supraspinatus muscle was correlated with cross-sectional area (CSA) measures (Bravais-Pearson). We found significant differences between different stages of rotator cuff disease, the fatty infiltration and the volume loss (determined by the occupation ratio) of the supraspinatus muscle. With the increasing extent of rotator cuff disease, fatty infiltration increases significantly, as does the volume loss of the supraspinatus muscle. Comparing fatty infiltration and the occupation ratio individually, there was only a moderate inverse correlation between fatty infiltration and the occupation ratio, with considerable variation of data. Fatty infiltration of the infraspinatus muscle occurred when the infraspinatus tendon was involved to a lesser extent. The SPLASH sequence allows exact quantification of fatty infiltration in an arbitrarily shaped ROI. The extent of atrophy and fatty infiltration correlates with the size of the tear. Atrophy and fatty infiltration correlate only moderately and should be evaluated separately.     

Cystic changes at supraspinatus and infraspinatus tendon insertion sites: association with age and rotator cuff disorders in 238 patients

PURPOSE: To retrospectively determine the frequency of posterior and anterior cystic abnormalities at rotator cuff insertion site on the greater tuberosity and to determine their relationship to patient age and rotator cuff disorders. MATERIALS AND METHODS: Institutional review board approval was given; informed consent was waived. The study was HIPAA compliant. In 238 patients with rotator cuff diagnoses at surgery, preoperative magnetic resonance (MR) imaging studies were reviewed to localize osseous cystic changes as anterior (supraspinatus insertion site) or posterior (infraspinatus insertion site) on the greater tuberosity. If rotator cuff tear was present, tendon retraction and location of partial tear (articular or bursal surface) were recorded. Two radiologists reached conclusions by consensus. Locations of cysts were correlated to surgical cuff diagnoses: no tear, tendinopathy, partial-thickness tear, and complete tear. Prospective interpretations from original MR reports were compared with surgical results. Statistical analyses included one-way analysis of variance, chi(2), Fisher exact, and Student t tests, as well as logistic regression and receiver operating characteristic curve comparison. RESULTS: There were 238 consecutive patients (150 men, 88 women; mean age, 43 years). Cysts were located at or near footprint of cuff tendon and demonstrated fluid or soft-tissue signal intensities. Posterior cysts occurred in 56.7% of shoulders and showed no statistical correlation to age or cuff diagnosis. Anterior cysts occurred in 22.7% of shoulders and were strongly associated with cuff disorders (P<.001). Controlling for cuff disorders, there was no relationship between anterior cysts and age (P>.50). Anterior cysts were more common in partial-thickness articular (48%) than in bursal (13%) tears (P<.001). CONCLUSION: Posterior cysts were more common than anterior cysts and showed nearly random distribution among patients, regardless of age and cuff diagnosis. Anterior cysts were closely associated with cuff disorders.     

Rim-rent tear of the rotator cuff: a common and easily overlooked partial tear

OBJECTIVE: The purpose of this study was to determine the incidence of rim-rent rotator cuff tears in a population of patients referred for shoulder MRI and to determine the sensitivity of MRI for the detection of these tears. CONCLUSION: Rim-rent tears are a common type of partial-thickness rotator cuff tear, much more commonly present than has been previously reported. In particular, infraspinatus rim-rent tears are more common than previously believed. Rim-rent tears of the infraspinatus tendon and those involving the anterior-most fibers of the supraspinatus tendon are commonly overlooked on MRI, possibly because of failure to appreciate the high incidence of these types of tears and failure to inspect the anterior-most fibers of the rotator cuff.     

Suprascapular nerve entrapment

Shoulder pain in the athlete is a frequent complaint. The common differential diagnoses include a broad list of disorders including, rotator cuff tears and tendonitis, shoulder instability, degenerative disease, and others. Although nerve entrapment syndromes is a relatively uncommon etiology of shoulder pain, they must be considered when the diagnosis is uncertain. Entrapment of the suprascapular nerve can occur at a number of locations along its course. It is imperative that the clinician recognizes the possible areas and anatomical causes of entrapment of the suprascapular nerve. This will ensure an accurate diagnosis and facilitate appropriate and timely treatment.     

Deltoid muscle and tendon tears in patients with chronic rotator cuff tears

Purpose To describe the magnetic resonance imaging (MRI) appearances of tears of the deltoid muscle and tendon in patients with rotator cuff tears and without a prior history of shoulder surgery. Materials and methods Deltoid tears diagnosed on MR examinations were prospectively recorded between February 2003 through June 2004. The images of these patients were then retrospectively reviewed to determine the location of the deltoid tear, the presence of rotator cuff tears, tendon retraction, muscle atrophy, degree of humeral head subluxation, bony erosive changes involving the undersurface of the acromion, and the presence of edema or fluid-like signal intensity in the deltoid muscle and overlying subcutaneous tissues. Results There were 24 (0.3%) patients with deltoid tears; nine men and 15 women. The age range was 54 to 87 (average 73) years. The right side was involved in 20 cases, and the left in four cases. Fifteen patients had full thickness and nine had partial thickness tears of the deltoid. Shoulder pain was the most common presenting symptom. The physical examination revealed a defect in the region of the deltoid in two patients. Nineteen patients had tears in the muscle belly near the musculotendinous junction, and five had avulsion of the tendon from the acromial origin. Full thickness rotator cuff tears were present in all of the patients, and 22 patients had associated muscle atrophy. Subcutaneous edema and fluid-like signal was present in 15 patients. Conclusion Tears of the deltoid muscle or tendon is an unusual finding, but they can be seen in patients with chronic massive rotator cuff tears. Partial thickness tears tend to involve the undersurface of the deltoid muscle and tendon. Associated findings such as intramuscular cyst or ganglion in the deltoid muscle belly and subcutaneous edema or fluid-like signal overlying the deltoid in a patient with a rotator cuff tear should raise the suspicion of a deltoid tear.     

MR evaluation of subscapularis tears.

PURPOSE: The purpose of this work was to describe the MR appearance of tears of the subscapularis tendon and compare the usefulness of different imaging planes as well as note the association of subscapularis tears with other rotator cuff tears and biceps tendon dislocations. METHOD: MR studies at 1.5 T over an 8 year interval were retrospectively assessed for the presence of a rotator cuff tear and/or tear of the subscapularis tendon. Images that showed a subscapularis tear were reviewed for the presence of a visible tear separately on the axial, coronal, and sagittal images. The MR studies were also evaluated for associated tears of the supraspinatus, infraspinatus, and teres minor muscles as well as biceps tendon dislocation and the "naked humerus sign" on coronal images. Last, clinical records and surgical reports were reviewed. RESULTS: Forty-five (2%) of 2,167 rotator cuff tears involved the subscapularis; 27% were partial and 73% were complete tears. Tears were best seen in the sagittal oblique plane. Almost all subscapularis tears were an extension of typical rotator cuff tears: supraspinatus in 35 patients (79%), extending into infraspinatus tears in 25 (56%) and into teres minor tears in 2 patients (4%). Bicipital dislocations were seen in 22 patients (49%), and three complete tears of the biceps (7%) were noted as well. The naked humerus sign was demonstrated in 31 patients (69%). Surgical reports that confirmed the MR findings were available for 15 patients. CONCLUSION: About 2% of rotator cuff tears involve the subscapularis tendon. Most subscapularis tears are extensions of supraspinatus tears and frequently involve the biceps tendon.