The elbow: MR features of nerve disorders

Muscle interconnections in the anterior and posterior arm compartment: a cadaveric case series with possible clinical implications

PURPOSE

The report describes four cases of accessory bundles (ABs) or fibers connecting the muscles of the anterior with the posterior arm compartment. The ABs morphology (pure muscular or musculofascial or musculoaponeurotic) is described emphasizing their attachment points, characterized as muscles' interconnections.

MATERIALS AND METHODS

Four formalin-embalmed donated male cadavers were dissected.

RESULTS

The muscles' interconnections were unilaterally identified. In the first case, the two ABs originated from the coracobrachialis muscle (CB), received fibers from the biceps brachii (BB), and were inserted into the triceps brachii (TB) medial head. The ABs created an arch over the brachial vessels and the median nerve (MN). In the second case, an accessory musculoaponeurotic structure was identified between CB and TB medial head and extended over the brachial vessels. In the third case, the myofascial ABs between the BB short head and the upper arm fascia, coursed anterior to the MN, the brachial artery, and the ulnar nerve, with direction to the TB medial head. In the fourth case, the three muscular ABs originating from the CB superficial and deep heads, in common with the BB short head, joined the upper arm fascia and the TB medial head and possibly entrapped the musculocutaneous nerve, the MN, and the brachial artery.

CONCLUSION

ABs or musculoaponeurotic extensions may predispose to complications due to their potential compression on nerves and vessels. Clinicians should consider the possible existence of such bridging variants between muscles, in the differential diagnosis of a patient presenting with ischemia, edema, or MN palsy symptoms.

Magnetic resonance imaging evaluation of patients with clinically diagnosed medial Epicondylitis

OBJECTIVE

We evaluated magnetic resonance imaging (MRI) findings in patients with clinically diagnosed medial epicondylitis (ME) and determined whether any of the MRI findings correlated with the follow-up pain level after nonoperative treatment.

MATERIALS AND METHODS

We retrospectively reviewed 83 patients who had undergone elbow MRI examinations for clinically diagnosed ME and who were followed-up for more than 6 months. Five categories of MRI findings were selected for qualitative grading: common flexor tendon (CFT) origin signal changes, ulnar collateral ligament (UCL) insufficiency, ulnar neuritis, bony changes of the medial epicondyle, and calcification. The mean follow-up after MRI examination was 21 months. We performed multivariate regression analysis to analyze whether any of these MRI findings were associated with the follow-up pain level after nonoperative treatment.

RESULTS

Positive MRI findings included CFT origin signal changes (66%), ulnar neuritis (40%), UCL insufficiency (30%), calcification (27%), and bony changes (18%). Multivariate analysis indicated that CFT origin signal changes were independently associated with the follow-up pain level (β = 3.387; p = 0.004).

CONCLUSION

In patients with clinically diagnosed ME, MRI demonstrated diverse abnormal findings in the CFT origin, ulnar collateral ligament, ulnar nerve, and bone. Among the findings, the severity CFT origin signal changes, which indicates the severity of tendon degeneration in ME, was associated with the follow-up pain level. This information can be helpful in consulting on the prognosis of nonoperative treatment in patients with clinically diagnosed ME.

Ultrasound biomechanical anatomy of the soft structures in relation to the ulnar nerve in the cubital tunnel of the elbow

BACKGROUND

Chronic ulnar nerve entrapment worsened by elbow flexion is the most common injury, but rare painful conditions may also be related to ulnar nerve instability. The posterior bundle of the medial collateral ligament (pMCL) and the retinaculum, respectively form a soft floor and a ceiling for the cubital tunnel. The aim of our study was to dynamically assess these soft structures of the cubital tunnel focusing on those involved in the biomechanics of the ulnar nerve.

METHODS

Forty healthy volunteers had a bilateral ultrasonography of the cubital tunnel. Elbows were scanned in full extension, 45° and 90°, and maximal passive flexion. Morphological changes of the nerve and related structures were dynamically assessed on transverse views.

RESULTS

Both the pMCL and the retinaculum tightened with flexion. During elbow flexion, the tightening of the pMCL superficially moved the ulnar nerve remote from the osseous floor of the retroepicondylar groove. A retinaculum was visible in all 69 tunnels with stable nerves (86.3%), tightened in flexion, but absent in 11 tunnels with unstable nerves (13.7%). The retinaculum was fibrous in 60 elbows and muscular in nine, the nine muscular variants did not significantly influence the biomechanics of stable nerves. Stable nerves flattened in late flexion between the tightened pMCL and retinaculum, whereas unstable nerves transiently flattened when translating against the anterior osseous edge of the groove.

CONCLUSION

The retinaculum and the pMCL are key structures in the biomechanics of the ulnar nerve in the cubital tunnel of the elbow.

[Post-traumatic ulnar nerve instability at the elbow: about 5 cases and review of the literature]

At the elbow, the ulnar nerve has a peculiar anatomic location which explains its high vulnerability. We here report five cases of post-traumatic ulnar nerve instability with complete nerve dislocation in front of the epitrochlea. In the light of our experience and review of the literature, the pathogenic, diagnostic and therapeutic aspects of this pathology are reviewed.

Elbow Imaging in Sport: Sports Imaging Series

Elbow pain is a frequent presenting symptom in athletes, particularly athletes who throw. The elbow can be injured as a result of acute trauma, such as a direct blow or a fall onto an outstretched hand or from chronic microtrauma. In particular, valgus extension overload during the throwing motion can precipitate a cascade of chronic injuries that can be debilitating for both casual and high-performance athletes. Prompt imaging evaluation facilitates accurate diagnosis and appropriate targeted interventions.

The Ulnar Nerve at Elbow Extension and Flexion: Assessment of Position and Signal Intensity on MR Images

Purpose To assess the position and signal intensity of the ulnar nerve at elbow extension and flexion by using magnetic resonance imaging. Materials and Methods Institutional review board approval and written informed consent were obtained. Transverse T2-weighted images were obtained perpendicular to the upper arm in 100 healthy elbows of 50 volunteers (23 men, 27 women; age range, 21-57 years) and nine elbows with ulnar neuropathy (five men, four women; age range, 24-59 years) with extension and 130° of flexion. Ulnar nerve position was classified into three types: no dislocation, subluxation, or dislocation. One-way analysis of variance, paired t tests, Student t tests, and multiple regression analysis were used to analyze correlations between ulnar nerve movement angle during flexion and age, sex, presence of the anconeus epitrochlearis muscle, and ulnar neuropathy and to compare the contrast-to-noise ratio of nerve to muscle between extension and flexion. Results Nerve positions in healthy elbows were as follows: All had no dislocation at extension, and at flexion, 51 of 100 elbows (51.0%) had no dislocation, 30 of 100 elbows (30.0%) had subluxation, and 19 of 100 elbows (19.0%) had dislocation. Nerve movement angle was smaller in elbows with the anconeus epitrochlearis muscle than in those without the muscle (P = .045, .015). Presence of the muscle was the only significant factor associated with nerve movement angle (P = .047, .013). Only dominant elbows with nerve movement angle of less than 15° and nondominant elbows with nerve movement angle of less than 10° showed contrast-to-noise ratio increase at flexion (P = .021-.030). Conclusion Ulnar nerve movement during flexion was apparent in approximately half of healthy elbows and was similar between healthy elbows and elbows with ulnar neuropathy. Nerve signal intensity increased during flexion only in elbows without apparent nerve movement. (©) RSNA, 2016 Online supplemental material is available for this article.

Accuracy of MRI in diagnosing peripheral nerve disease: a systematic review of the literature

OBJECTIVE

MRI is increasingly being used to evaluate extracranial peripheral nerve disease in clinical practice. The objective of this study was to systematically review the accuracy of MRI in distinguishing normal from abnormal extracranial peripheral nerves.

CONCLUSION

There is significant heterogeneity between studies investigating the accuracy of MRI. Studies have shown that nerve T2-weighted or STIR hyperintensity, nerve enlargement, and nerve flattening are associated with peripheral nerve disease.

Magnetic resonance imaging of the elbow: a structured approach

CONTEXT

The elbow is a complex joint and commonly injured in athletes. Evaluation of the elbow by magnetic resonance imaging (MRI) is an important adjunct to the physical examination. To facilitate accurate diagnosis, a concise structured approach to evaluation of the elbow by MRI is presented.

EVIDENCE ACQUISITION

A PubMed search was performed using the terms elbow and MR imaging. No limits were set on the range of years searched. Articles were reviewed for relevance with an emphasis of the MRI appearance of normal anatomy and common pathology of the elbow.

RESULTS

The spectrum of common elbow disorders varies from obvious acute fractures to chronic overuse injuries whose imaging manifestations can be subtle. MRI evaluation should include bones; lateral, medial, anterior, and posterior muscle groups; the ulnar and radial collateral ligaments; as well as nerves, synovium, and bursae. Special attention should be paid to the valgus extension overload syndrome and the MRI appearance of associated injuries when evaluating throwing athletes.

CONCLUSION

MRI evaluation of the elbow should follow a structured approach to facilitate thoroughness, accuracy, and speed. Such an approach should cover bone, cartilage, muscle, tendons, ligaments, synovium, bursae, and nerves.

Throwing injuries of the upper extremity

The overhead throwing motion is a complex sequence of maneuvers that requires coordinated muscle activity in the upper and lower extremities. The shoulder and elbow are subject to multidirectional forces and are particularly vulnerable to injury during specific phases of the overhead throwing motion. Ligamentous, tendinous, neural, and osseous pathology that may occur in the shoulder or elbow of an overhead-throwing athlete will be discussed, with an emphasis on the role of MR imaging and MR arthrography.

DIFFUSION-WEIGHTED MAGNETIC RESONANCE IMAGING OF THE ULNAR NERVE IN CUBITAL TUNNEL SYNDROME

Diffusion-weighted images based on magnetic resonance reveal the microstructure of tissues by monitoring the random movement of water molecules. In this study, we investigated whether this new technique could visualize pathologic lesions on ulnar nerve in cubital tunnel. Six elbows in six healthy males without any symptoms and eleven elbows in ten patients with cubital tunnel syndrome underwent on diffusion-weighted MRI. No signal from the ulnar nerve was detected in normal subjects. Diffusion-weighted MRI revealed positive signals from the ulnar nerve in all of the eleven elbows with cubital tunnel syndrome. In contrast, conventional T2W-MRI revealed high signal intensity in eight elbows and low signal intensity in three elbows. Three elbows with low signal MRI showed normal nerve conduction velocity of the ulnar nerve. Diffusion-weighted MRI appears to be an attractive technique for diagnosis of cubital tunnel syndrome in its early stages which show normal electrophysiological and conventional MRI studies.

What's new in common upper extremity entrapment neuropathies

Upper extremity entrapment neuropathies are common and disabling, and correct diagnosis is essential for proper management. This article is a review of the recent developments related to diagnosis and treatment of common upper extremity nerve entrapments, including novel treatment strategies for suprascapular, median, ulnar, and radial nerve entrapments. When combined with classic peripheral nerve examination techniques, innovations in imaging modalities have led to more reliable diagnoses. Innovations in surgical techniques, such as endoscopic approaches, have been controversial as to their effects on patient outcome, but recent randomized controlled trials have provided important information regarding common operative techniques, particularly with regard to carpal tunnel surgery and ulnar nerve transpositions.

Ulnar nerve compression in the cubital tunnel by an epineural ganglion: a case report

Epineural ganglia are considered to be a usual cause of peripheral nerve compression. In this report, we present a rare case of ulnar nerve compression by an epineural ganglion in the cubital tunnel. A 28-year-old right-handed female secretary developed progressive pain, numbness, and weakness in her right elbow, forearm, and hand for 6 months. Atrophy of the adductor pollicis and the first dorsal interosseous muscles was apparent. Clinical examination revealed a cystic mass at the posterior side of the elbow. Magnetic resonance imaging identified a ganglion while electrophysiologic studies revealed a severe conduction block of the ulnar nerve at the elbow. During surgery a 2-cm diameter epineural ganglion was identified compressing the ulnar nerve and was excised using microsurgery techniques. Two months postoperatively, the clinical recovery of the patient was very satisfactory, although the postoperative electrophysiologic studies demonstrated a less dramatic improvement.

Peripheral Neuropathies of the Median, Radial, and Ulnar Nerves: MR Imaging Features

The median, radial, and ulnar nerves of the upper limbs may be affected by various peripheral neuropathies, each of which may be categorized according to its cause, as either an entrapment or a nonentrapment neuropathy. Entrapment neuropathies, also referred to as nerve compression syndromes, include the supracondylar process syndrome, pronator syndrome, anterior interosseous nerve syndrome, carpal tunnel syndrome, posterior interosseous nerve syndrome, cubital tunnel syndrome, and Guyon canal syndrome. Nonentrapment neuropathies include traumatic nerve injuries, infectious and inflammatory conditions, polyneuropathies, and mass lesions at anatomic locations where entrapment syndromes typically do not occur. Although clinical examination and electrophysiologic testing are the cornerstone of the diagnostic work-up, in certain cases magnetic resonance (MR) imaging may provide key information about the exact anatomic location of a lesion or may help narrow the differential diagnosis. In patients with a diagnosis of peripheral neuropathy, MR imaging may help establish the cause of the condition and provide information crucial for conservative management or surgical planning. In addition, knowledge of the normal anatomy and of the possible causes, typical clinical findings, and MR imaging features of peripheral neuropathies that affect the median, radial, and ulnar nerves allows greater confidence in the diagnosis.

Entrapment neuropathies of the shoulder and elbow in the athlete

MRI is a useful diagnostic method for evaluating nerve disease at the shoulder and elbow. MRI can depict the normal anatomy of the nerves, confirm and identify the cause of the neuropathy, identify the site of entrapment based on muscle denervation patterns, and detect unsuspected space-occupying lesions. MRI can also narrow down the differential diagnosis of nerve disease, such as in the case of suprascapular nerve syndrome versus Parsonage-Turner syndrome, or radial tunnel syndrome versus lateral epicondylitis. Large prospective studies with surgical correlation, however, are still necessary to better elucidate MRI's exact role in the assessment of entrapment neuropathies of the upper extremity.

Sports-related injuries of the elbow: an approach to MRI interpretation

MRI is a valuable tool for evaluating the athlete with elbow pain, particularly in those with nonlocalizable pain. MRI also is helpful in sorting out the cause of pain in athletes who may have acute trauma superimposed on tendinopathy or other chronic injuries from repetitive microtrauma. Even in athletes in whom the cause of pain confidently can be diagnosed clinically, MRI can document the injury severity, which can be helpful for estimating recovery time or in preoperative planning. By contributing to an accurate early diagnosis, MRI also can help minimize the time that athletes are away from their sports. The authors describe their approach to the MRI interpretation of elbow injuries in athletes, including osteochondral lesions, epicondylitis, and tears of the medial collateral ligament.

Magnetic resonance imaging findings in patients with medial epicondylitis

OBJECTIVE

To compare the MR imaging findings of 13 patients with clinically diagnosed medial epicondylitis with the MR imaging findings of 26 patients of similar age with no clinical evidence of medial epicondylitis.

DESIGN AND PATIENTS

The study group consisted of 13 patients with clinically diagnosed medial epicondylitis. The control group consisted of 26 patients of similar age with no clinical evidence of medial epicondylitis. The medical records and MR imaging findings of these patients were retrospectively reviewed by two fellowship-trained musculoskeletal radiologists.

RESULTS

Eleven of the 13 patients in the study group had thickening and increased signal intensity of the common flexor tendon on both T1-weighted and T2-weighted images. The remaining two patients in the study group had soft tissue edema around a normal-appearing common flexor tendon. Twenty-one of the 26 patients in the control group had a normal-appearing common flexor tendon on MR imaging. Three patients in the control group had a thickened common flexor tendon which was of intermediate signal intensity on T1-weighted images but of uniform low signal intensity on T2-weighted images. Two patients in the control group had a thickened common flexor tendon which was of intermediate signal intensity on both T1-weighted and T2-weighted images. None of the patients in the control group had soft tissue edema around the common flexor tendon.

CONCLUSION

MR imaging findings of patients with clinically diagnosed medial epicondylitis included thickening and increased T1 and T2 signal intensity of the common flexor tendon and soft tissue edema around the common flexor tendon. The presence of intermediate to high T2 signal intensity or high T2 signal intensity within the common flexor tendon and the presence of paratendinous soft tissue edema were the most specific findings of medial epicondylitis on MR imaging.

Magnetic resonance imaging of the elbow. Part II: Abnormalities of the ligaments, tendons, and nerves

Part II of this comprehensive review on magnetic resonance imaging of the elbow discusses the role of magnetic resonance imaging in evaluating patients with abnormalities of the ligaments, tendons, and nerves of the elbow. Magnetic resonance imaging can yield high-quality multiplanar images which are useful in evaluating the soft tissue structures of the elbow. Magnetic resonance imaging can detect tears of the ulnar collateral ligament and lateral collateral ligament of the elbow with high sensitivity and specificity. Magnetic resonance imaging can determine the extent of tendon pathology in patients with medial epicondylitis and lateral epicondylitis. Magnetic resonance imaging can detect tears of the biceps tendon and triceps tendon and can distinguishing between partial and complete tendon rupture. Magnetic resonance imaging is also helpful in evaluating patients with nerve disorders at the elbow.

MR imaging of entrapment neuropathies at the elbow

MR imaging has a valuable role in the evaluation of compressive neuropathies at the elbow. Specific MR signs in association with clinical findings can supply an accurate diagnosis. A review of normal anatomy, clinical features, and MR assessment of nerve entrapment syndromes at the elbow is presented.

Nerves in a pinch: imaging of nerve compression syndromes

Nerve compression is a common entity that can result in considerable disability. Early diagnosis is important to institute prompt treatment and to minimize potential injury. Although the appropriate diagnosis is often determined by clinical examination, the diagnosis may be more difficult when the presentation is atypical, or when anatomic and technical limitations intervene. In these instances, imaging can have an important role in helping to define the site and etiology of nerve compression or in establishing an alternative diagnosis. MR imaging and ultrasound provide direct visualization of the nerve and surrounding abnormalities. For both modalities, the use of high-resolution techniques is important. Bony abnormalities contributing to nerve compression are best assessed by radiographs or CT. For the radiologist, knowledge of the anatomy of the fibro-osseous tunnels, familiarity with the causes of nerve compression, and an understanding of specialized imaging techniques are important for successful diagnosis of nerve compression.

Compression of the ulnar nerve at the elbow by an intraneural ganglion

A rare cause of ulnar nerve compression at the elbow is presented in this report. A 42 year old right-handed mechanic developed subacute, progressive numbness, tingling and weakness in his right hand. Electrophysiologic studies demonstrated a severe conduction block affecting the ulnar nerve in the retrotrochlear groove but without any sign of major axonal loss. His hand functions were carefully studied prior to surgery. While fine motor tasks were not affected, the hand strength was markedly diminished. At surgery, a 1-cm diameter intraneural ganglion at the site of the conduction block was found and excised. The patient made a dramatic recovery within 6 weeks post-surgery. The conduction block completely resolved and the hand functions also returned to normal. This and other reported cases point to the importance of early diagnosis and intervention.

Scintigraphy of cubital bursitis

A 50-year-old man with psoriatic arthropathy was examined for a painful mass in the left cubital fossa. The clinical findings indicated a tumor or infection. Computed tomographic scanning and bone scintigraphy also raised the possibility of a malignant lesion. Surgical exploration revealed that the mass was a chronically inflamed bicipitoradial bursa adherent to the biceps tendon. This is a rare condition, with only a handful of cases described in the literature. This is the first scintigraphic case reported. The imaging features of the bursa are discussed in terms of the anatomy.

Emergency MR imaging of orthopedic trauma. Current and future directions

Fast MR imaging protocols pave the way for more widespread use of MR imaging to evaluate emergency room trauma patients. This article reviews technical developments and protocols facilitating rapid imaging, conventional applications of MR imaging to evaluate soft tissue injuries, and newer applications in which MR imaging is used to image both axial and appendicular fractures.

Sonographic appearances of nerve tumors

This article reviews the clinical and sonographic features of neurilemoma, neurofibroma, intraneural ganglion, traumatic neuroma, and Morton's neuroma. The sonographic characteristics and location at typical sites are important diagnostic features for nerve tumors.

Imaging of elbow disorders

Numerous modalities are available for imaging the elbow. Radiographs should be the first imaging procedure performed for evaluation of an elbow abnormality. The use of advanced imaging modalities such as MR imaging, CT, and sonography also is discussed in this article.

MRI of the common peroneal nerve: normal anatomy and evaluation of masses associated with nerve entrapment

The objective of this pictorial essay is to illustrate the MR appearance of the common peroneal nerve and the appearance of masses that have been associated with peroneal nerve entrapment. Four human cadaveric knees underwent axial MRI utilizing a T1-weighted SE sequence. One knee was dissected by an orthopedic surgeon and three knees were transversely sectioned, and the gross morphology of the common peroneal nerve and the perineural structures was evaluated and correlated with the MR images.

Morphologic changes in the ulnar nerve at the elbow with flexion and extension: a magnetic resonance imaging study with 3-dimensional reconstruction

We evaluated the morphology of the ulnar nerve and cubital tunnel with noninvasive magnetic resonance imaging (MRI). We used fresh human cadavers with the elbow in full extension, 90 degrees of flexion, and full flexion. For each elbow, 1-mm slices were imaged interpolated, and reconstructed into 3-dimensional data volumes, and then manually segmented before they were examined with sequential transverse sections, curved sections, and 3-dimensional images. The ulnar nerve follows a tortuous course in full extension, becomes progressively linear with incremental elbow flexion, shifts anteriorly in the cubital tunnel, and flattens against the medial epicondyle. The proximal and midportions of the cubital tunnel also change with flexion from round to elliptical. In addition, successive increases occur in the cross-sectional diameter of the mediolateral plane. The nerve is surrounded by fat throughout the cubital tunnel except adjacent to the medial epicondyle. These observations suggest that the ulnar nerve progressively stretch over the medial epicondyle occurs when the normal elbow is flexed. Direct compression areas of the ulnar nerve were not seen in our study of normal human elbows.

Magnetic resonance imaging of the elbow

Magnetic resonance imaging (MRI) provides useful information regarding the elbow joint. Many abnormalities seen in the elbow are a result of trauma, often from sports such as baseball and tennis. Elbow problems are frequently related to the medial tension-lateral compression phenomenon where repeated valgus stress produces flexor-pronator strain, ulnar collateral ligament sprain, ulnar traction spurring, and ulnar neuropathy. The lateral compression causes osteochondritis dissecans of the capitellum and radial head, degenerative arthritis, and loose bodies. Other elbow abnormalities seen on MRI include radial collateral ligament injuries, biceps and triceps tendon injuries, other nerve entrapment syndromes, loose bodies, osseous and soft tissue trauma, arthritis, and masses, including bursae.

Imaging of the elbow. An update

This article focuses on the use of magnetic resonance in the evaluation of the soft tissue (tendons, ligaments, muscles, and nerves) and osseous structures of the elbow. The need for high quality, high resolution imaging with attention to positioning, sequence selection, and equipment is emphasized. Normal magnetic resonance anatomy and criteria for pathologic change are presented.