MRI of myositis and other urgent muscle-related disorders

Imaging spectrum of atraumatic muscle disorders: a radiologist's guide

Atraumatic muscle disorders comprise a very wide range of skeletal muscle diseases, including metabolic, inflammatory, autoimmune, infectious, ischemic, and neoplastic involvement of the muscles. Therefore, one must take clinical and laboratory data into consideration to elucidate the differential diagnoses, as well as the distribution of the muscle compromise along the body-whether isolated or distributed along the body in a symmetric or asymmetrical fashion. Assessment of muscular disorders often requires imaging investigation before image-guided biopsy or more invasive procedures; therefore, radiologists should understand the advantages and limitations of imaging methods for proper lesion evaluation and be aware of the imaging features of such disorders, thus contributing to proper decision-making and good patient outcomes. In this review, we propose a systematic approach for the assessment of muscle disorders based on their main imaging presentation, dividing them into patterns that can be easily recognized.

Myositis and Its Mimics: Guideline Updates, MRI Characteristics, and New Horizons

Myositis is defined as inflammation within skeletal muscle and is a subcategory of myopathy, which is more broadly defined as any disorder affecting skeletal muscle. Myositis may be encountered as a component of autoimmune and connective tissue disease, where it is described as idiopathic inflammatory myopathy. Myositis can also be caused by infections, as well as toxins and drugs, including newer classes of medications. MRI plays an important role in the diagnosis and evaluation of patients with suspected myositis, but many entities may have imaging features similar to myositis and can be considered myositis mimics. These include muscular dystrophies, denervation, deep venous thrombosis, diabetic myonecrosis, muscle injury, heterotopic ossification, and even neoplasms. In patients with suspected myositis, definitive diagnosis may require integrated analysis of imaging findings with clinical, laboratory, and pathology data. The objectives of this article are to review the fundamental features of myositis, including recent updates in terminology and consensus guidelines for idiopathic inflammatory myopathies, the most important MRI differential diagnostic considerations for myositis (i.e., myositis mimics), and new horizons, including the potential importance of artificial intelligence and multimodal integrated diagnostics in the evaluation of patients with muscle disorders.

Autoimmune diseases of the spine and spinal cord

Magnetic resonance imaging (MRI) and clinicopathological tools have led to the identification of a wide spectrum of autoimmune entities that involve the spine. A clearer understanding of the unique imaging features of these disorders, along with their clinical presentations, will prove invaluable to clinicians and potentially limit the need for more invasive procedures such as tissue biopsies. Here, we review various autoimmune diseases affecting the spine and highlight salient imaging features that distinguish them radiologically from other disease entities.

Lower extremity infections: Essential anatomy and multimodality imaging findings

In modern practice, imaging plays an integral role in the diagnosis, evaluation of extent, and treatment planning for lower extremity infections. This review will illustrate the relevant compartment anatomy of the lower extremities and highlight the role of plain radiographs, CT, US, MRI, and nuclear medicine in the diagnostic workup. The imaging features of cellulitis, abscess and phlegmon, necrotizing soft tissue infection, pyomyositis, infectious tenosynovitis, septic arthritis, and osteomyelitis are reviewed. Differentiating features from noninfectious causes of swelling and edema are discussed.

Rhabdomyolysis: a review of imaging features across modalities

This review illustrates the imaging features of rhabdomyolysis across multiple modalities and in a variety of clinical scenarios. Rhabdomyolysis is the rapid breakdown of striated muscle following severe or prolonged insult resulting in the release of myocyte constituents into circulation. In turn, patients develop characteristically elevated serum creatine kinase, positive urine myoglobin, and other serum and urine laboratory derangements. While there is a spectrum of clinical symptoms, the classic presentation has been described as muscular pain, weakness, and dark urine. This triad, however, is only seen in about 10% of patients. Thus, when there is a high clinical suspicion, imaging can be valuable in evaluating the extent of muscular involvement, subsequent complications such as myonecrosis and muscular atrophy, and other etiologies or concurrent injuries causing musculoskeletal swelling and pain, especially in the setting of trauma. Sequela of rhabdomyolysis can be limb or life-threatening including compartment syndrome, renal failure, and disseminated intravascular coagulation. MRI, CT, ultrasound, and 18-FDG PET/CT are useful modalities in the evaluation of rhabdomyolysis.

Recurrent Temporal Infections: The Link to Systemic Lupus Erythematosus

BACKGROUND Systemic lupus erythematosus (SLE) is an autoimmune disease with diverse manifestations. The involvement of the musculoskeletal system is very common, and infection is one of the manifestations, which can involve any part of the body. We report a case of a middle-aged woman with recurrent episodes of infection of her left temple. CASE REPORT A 51-year old woman was referred to our clinic following failures to eradicate infection on her left temple for 9 months. Examination revealed facial asymmetry, with diffuse non-tender swelling involving her left temple area, which extended to her cheek. Computed tomography and magnetic resonance imaging (MRI) showed a periosteal reaction of the zygomatic bone. Left temporalis muscle thickening and residual osteomyelitis of the zygomatic bone were also shown by MRI. In view of the unresolved infection with incision and drainage and antibiotics, further blood investigations led to the discovery of SLE. The antinuclear antibody and anti-double-stranded DNA were positive. In addition, low nephelometry markers, C3 (26.7 mg/dL) and C4 (8.24 mg/dL), were observed. This patient was treated with 200 mg of oral hydrochloroquine once daily and 5 mg of oral prednisolone once daily. After 6 months of treatment, the infection subsided, and the structures involved showed remarkable healing. The patient is still taking the same dose and frequency of both drugs at the present time. CONCLUSIONS Temporalis pyomyositis and osteomyelitis of the zygomatic bone could be manifestation of SLE disease; however, the involvement of infection cannot be ruled out.

Nontuberculous mycobacterial myositis in dermatomyositis with long-term use of immunosuppressant: a case report

Inflammatory myopathies, such as polymyositis and dermatomyositis, are systemic inflammatory disorders that affect skeletal muscles and internal organs. The treatment of inflammatory myopathies usually involves long-term use of high doses of steroids and/or immunosuppressants, making patients susceptible to opportunistic infections. Unfortunately, infections are a leading cause of morbidity and mortality in patients with inflammatory myopathies. Musculoskeletal nontuberculous mycobacterial infections are rare. Nontuberculous mycobacterial infections are easily overlooked owing to their rarity, leading to delayed diagnosis and treatment, indolent clinical course, and difficulty isolating the pathogen. Nontuberculous mycobacterial infections are a growing health concern because of their increasing incidence and the need for prolonged treatment. In patients with connective tissue diseases, immunosuppressant use may lead to an increased risk of nontuberculous mycobacterial infection with a poor prognosis, which highlights the need for early diagnosis and treatment. Herein, we report the case of a 59-year-old man diagnosed with dermatomyositis, who had prolonged use of immunosuppressants and developed a disseminated soft tissue infection in both thighs caused by Mycobacterium abscessus. Multimodal images were obtained using magnetic resonance imaging, ultrasonography, and computed tomography. A strong suspicion of possible combined opportunistic infections and appropriate staining is essential in diagnosing nontuberculous mycobacterial myositis.

Clinical applications of skeletal muscle diffusion tensor imaging

Diffusion tensor imaging (DTI) may allow the determination of new threshold values, based on water anisotropy, to differentiate between healthy muscle and various pathological processes. Additionally, it may quantify treatment monitoring or training effects. Most current studies have evaluated the potential of DTI of skeletal muscle to assess sports-related injuries or therapy, and training monitoring. Another critical area of application of this technique is the characterization and monitoring of primary and secondary myopathies. In this manuscript, we review the application of DTI in the evaluation of skeletal muscle in these and other novel clinical scenarios, with emphasis on the use of quantitative imaging-derived biomarkers. Finally, the main limitations of the introduction of DTI in the clinical setting and potential areas of future use are discussed.

Spontaneous myonecrosis with pyomyositis in a young male with type 2 diabetes mellitus: A case report

Diabetic myonecrosis is a rare complication of poorly controlled diabetes mellitus which commonly affects the thigh and is managed conservatively. Spontaneous ischemic necrosis of muscle is noted without a reduction in vascular supply. Pyomyositis caused by Staphylococcus aureus infection is another rare complication. Atypical presentation of myonecrosis and pyomyositis can occur in the form of simultaneous or sequential involvement of multiple muscle groups. We present a rare case of myonecrosis with pyomyositis in a 39-year-old male patient with a background of type 2 diabetes mellitus who presented with a 5-day history of worsening pain of the right thigh radiating to the right ankle, associated with groin swelling and fever. It is important for clinicians to have a low threshold of suspicion of this rare condition due to the other diverse and similar diagnoses, as well as to prevent further complications and morbidity.

Imaging of Musculoskeletal Soft-Tissue Infections in Clinical Practice: A Comprehensive Updated Review

Musculoskeletal soft-tissue infections include a wide range of clinical conditions that are commonly encountered in both emergency departments and non-emergency clinical settings. Since clinical signs, symptoms, and even laboratory tests can be unremarkable or non-specific, imaging plays a key role in many cases. MRI is considered the most comprehensive and sensitive imaging tool available for the assessment of musculoskeletal infections. Ultrasound is a fundamental tool, especially for the evaluation of superficially located diseases and for US-guided interventional procedures, such as biopsy, needle-aspiration, and drainage. Conventional radiographs can be very helpful, especially for the detection of foreign bodies and in cases of infections with delayed diagnosis displaying bone involvement. This review article aims to provide a comprehensive overview of the radiological tools available and the imaging features of the most common musculoskeletal soft-tissue infections, including cellulitis, necrotizing and non-necrotizing fasciitis, foreign bodies, abscess, pyomyositis, infectious tenosynovitis, and bursitis.

Post-COVID-19 Myositis Based on Magnetic Resonance Imaging: A Case Report

The severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) causes COVID-19, which is known to cause fever, dry cough, exhaustion, headache, and loss of taste and smell. Although fever, sore throat, and cough have historically been the utmost characteristic symptoms of the illness, published case reports have recently started to emphasize additional uncommon and unusual presentations of infection with the coronavirus. In COVID, the musculoskeletal system is seldomly involved. In addition to reviewing the causes and imaging characteristics of COVID-19-related illnesses of the musculoskeletal system, we elaborate on a case of a middle-aged man who developed myositis as sequelae to the COVID-19 infection.

The Musculoskeletal Manifestations of COVID-19: A Narrative Review Article

The coronavirus pandemic has caused a devastating impact across the planet. Millions of lives lost and economic structures are struggling to remain afloat. Clinical effects of SARS CoV-2 virus include tiredness, fatigue, headache, cough, loss of appetite, fever, loss of sensations of taste, and smell as well as other respiratory difficulties. Pulmonary complications of coronavirus infections result in severe pneumonia with the final sequelae being sepsis, and end-stage respiratory failure. Further cardiovascular, neurological, hematological, and gastrointestinal complications build up to cause the demise of the immune system ultimately leading to death of the affected individual. The attack of the virus and the resultant reaction of the epithelial cells lining the respiratory tract have been in the limelight of most studies pertaining to the pandemic. However, a lesser number of studies have detailed the muscular and osseous pathologies that appear post-coronavirus infection. Inflammation post-infection, across the organ systems, may appear as a link to bone and joint pathology. Myalgia is a typical COVID-19 infection symptom. On the contrary, other musculoskeletal signs have very seldom been reported. Multimodality imaging techniques stand a chance at showing the diagnosis and the degree of follow-up after evaluation. Apart from myalgia, there are cases of arthralgia, myopathies, and neuropathies. According to numerous reports, there is the possibility of a link between the current drug regimen used to treat the SARS-CoV-2 infection and the musculoskeletal manifestations observed. In this study, we aim to shed light on the coronavirus pandemic and its association to various musculoskeletal manifestations, provide a different perspective of the infected patients, and address the major points that a clinician must take care while administering care to the patient. We will also address the present treatment in line with the various musculoskeletal symptoms observed.

Musculoskeletal Trauma and Infection

MR is often the most definitive imaging for assessment of musculoskeletal trauma and infection. Although it is not possible to address all the intricacies of these complex topics in a single article, this review will attempt to provide a useful toolbox of skills by discussing several common clinical scenarios faced by emergency radiologists in interpretation of adult trauma and infection. These scenarios include MR assessment of hip and pelvic fracture, traumatic soft tissue injuries, septic arthritis, soft tissue infection, and osteomyelitis.

The Musculoskeletal Involvement After Mild to Moderate COVID-19 Infection

COVID-19, a disease caused by the novel coronavirus SARS-CoV-2, has been drastically affecting the daily lives of millions of people. COVID-19 is described as a multiorgan disease that affects not only the respiratory tract of infected individuals, but it has considerable effects on the musculoskeletal system, causing excessive fatigue, myalgia, arthralgia, muscle weakness and skeletal muscle damage. These symptoms can persist for months, decreasing the quality of life of numerous individuals. Curiously, most studies in the scientific literature focus on patients who were hospitalized due to SARS-CoV-2 infection and little is known about the mechanism of action of COVID-19 on skeletal muscles, especially of individuals who had the mild to moderate forms of the disease (non-hospitalized patients). In this review, we focus on the current knowledge about the musculoskeletal system in COVID-19, highlighting the lack of researches investigating the mild to moderate cases of infection and pointing out why it is essential to care for these patients. Also, we will comment about the need of more experimental data to assess the musculoskeletal manifestations on COVID-19-positive individuals.

Clinical features and diagnostic tools in idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIMs) are rare autoimmune disorders affecting primarily muscles, but other organs can be involved. This review describes the clinical features, diagnosis and treatment for IIMs, namely polymyositis (PM), dermatomyositis (DM), sporadic inclusion body myositis (sIBM), immune-mediated necrotizing myopathy (IMNM), and myositis associated with antisynthetase syndrome (ASS). The diagnostic approach has been updated recently based on the discovery of circulating autoantibodies, which has enhanced the management of patients. Currently, validated classification criteria for IIMs allow clinical studies with well-defined sets of patients but diagnostic criteria to guide the care of individual patients in routine clinical practice are still missing. This review analyzes the clinical manifestations and laboratory findings of IIMs, discusses the efficiency of modern and standard methods employed in their workup, and delineates optimal practice for clinical care. Α multidisciplinary diagnostic approach that combines clinical, neurologic and rheumatologic examination, evaluation of electrophysiologic and morphologic muscle characteristics, and assessment of autoantibody immunoassays has been determined to be the preferred approach for effective management of patients with suspected IIMs.

MRI and muscle enzymes do not support the diagnosis of local anesthetic myotoxicity: a descriptive case series

BACKGROUND

The presence of thigh muscle edema as characterized by increased signal intensity on MRI has been used to support the diagnosis of presumed local anesthetic-induced myotoxicity reported after total knee arthroplasty (TKA) with continuous adductor canal block (CACB). However, neither postoperative baseline imaging appearance nor muscle enzyme values have been described in conjunction with this clinical scenario. Thus, the usefulness of MRI or enzymatic biomarkers of muscle injury for supporting the diagnosis of local anesthetic myotoxicity is unknown.

METHODS

This descriptive case series documents postoperative MRI appearance of the ipsilateral upper leg, plus preoperative and postoperative creatine phosphokinase and aldolase values in volunteer patients who underwent uncomplicated TKA with CACB.

RESULTS

In 27 volunteer patients with no postsurgical evidence of clinically relevant myotoxicity, anterior thigh muscle edema was universally evident on imaging (n=12) and muscle enzyme values (n=19) were normal or only slightly elevated.

CONCLUSIONS

The non-specificity of these findings suggests that MRI and near normal muscle enzyme levels are of limited diagnostic value when there is clinical suspicion of local anesthetic myotoxicity in the setting of TKA with CACB.

TRIAL REGISTRATION NUMBER

NCT04821245.