Clinical Characteristics of 118 Pediatric Patients With Acute Benign Myositis Associated With Influenza A Virus Infection.

OBJECTIVE: The objective of this study was to investigate the clinical and laboratory features of acute benign myositis associated with influenza A virus infection in children. METHODS: A retrospective analysis was performed on the clinical data of 118 children with acute benign myositis associated with influenza A virus infection who were admitted to the Children's Hospital of Chongqing Medical University during the epidemic period of influenza A from February 2023 to May 2023. RESULTS: (1) Most of the 118 children were preschool- or school-age. The most common symptom was sudden lower limb pain after fever, and bilateral calf myalgia was more common. The muscle enzyme spectrum ranged from 187.21 to 32191.00 µg/L (median: 3053 µg/L). Creatine kinase isoenzymes ranged from 5.15 to 749.7 µg/L (median 41.82 µg/L). Myoglobin ranged from 102.79 to 1200 µg/L (median 674.9 µg/L). (3) Examination: electromyography, muscle color Doppler ultrasound, radiograph and cardiac color Doppler ultrasound in Benign acute childhood myositis in children were rarely positive. (4) Treatment and prognosis: besides bed rest and a reduction of physical activity, oseltamivir treatment, drugs to improve energy metabolism, fluid replacement and alkalinization of symptomatic treatment. All children had a good prognosis without sequelae. CONCLUSIONS: This study summarized and analyzed the clinical characteristics of acute benign myositis associated with influenza A infection in children with the aim of allowing rapid and early diagnosis of the disease and reducing unnecessary diagnostic tests and treatments. Closely monitoring myalgia and the muscle enzyme spectrum is recommended to exclude other neuromuscular and metabolic diseases.

Immune-mediated necrotizing myopathy (NAM) related to SARS-Cov-2 infection: a case report.

BACKGROUND: There is a growing body of evidence that severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) or COVID-19 infection is associated with the development of autoimmune diseases. A recent systematic review reported that the new-onset autoimmune disorders during or after COVID-19 infection included inflammatory myopathies such as immune-mediated necrotizing myopathies. CASE PRESENTATION: We described a 60-year-old man diagnosed with COVID-19 infection and later presented with a two-week history of myalgia, progressive limb weakness, and dysphagia. He had a Creatinine Kinase (CK) level of more than 10,000 U/L, was strongly positive for anti-signal recognition particle (SRP) and anti-Ro52 antibody, and a muscle biopsy revealed a paucity-inflammation necrotizing myopathy with randomly distributed necrotic fibers, which was consistent with necrotizing autoimmune myositis (NAM). He responded well clinically and biochemically to intravenous immunoglobulin, steroids and immunosuppressant and he was able to resume to his baseline. CONCLUSION: SARS-CoV-2 may be associated with late-onset necrotizing myositis, mimicking autoimmune inflammatory myositis.

Miositis por SARS-CoV-2 / SARS-CoV-2-associated myositis

Se describe el caso de una paciente de 9 años que presenta, durante el seguimiento por infección por SARS-CoV-2, incapacidad para la deambulación por dolor de extremidades inferiores. Ante una clínica y exploración compatible con miositis, se realiza analítica sanguínea en la que se observa una elevación de creatinfosfoquinasa (CPK). La paciente presenta buena evolución con tratamiento sintomático. A propósito del caso se realiza una revisión bibliográfica de los casos pediátricos de miositis asociados a la infección por SARS-CoV-2 (AU)

We describe the case of a 9-year-old patient who presented with inability to walk due to lower extremity pain in the follow-up of infection by SARS-CoV-2. Since the manifestations and findings of the examination were compatible with myositis, a blood test was performed that evinced elevation of creatine phosphokinase. The patient had a favourable outcome with symptomatic treatment. In the context of this case, we conducted a literature review of paediatric cases of myositis associated with SARS-CoV-2 infection. (AU)

Interleukin-17 contributes to Ross River virus-induced arthritis and myositis.

Arthritogenic alphaviruses are mosquito-borne viruses that are a major cause of infectious arthropathies worldwide, and recent outbreaks of chikungunya virus and Ross River virus (RRV) infections highlight the need for robust intervention strategies. Alphaviral arthritis can persist for months after the initial acute disease, and is mediated by cellular immune responses. A common strategy to limit inflammation and pathology is to dampen the overwhelming inflammatory responses by modulating proinflammatory cytokine pathways. Here, we investigate the contribution of interleukin-17 (IL-17), a cytokine involved in arthropathies such as rheumatoid arthritis, in the development RRV-induced arthritis and myositis. IL-17 was quantified in serum from RRV-infected patients, and mice were infected with RRV and joints and muscle tissues collected to analyse cellular infiltrates, tissue mRNA, cytokine expression, and joint and muscle histopathology. IL-17 expression was increased in musculoskeletal tissues and serum of RRV-infected mice and humans, respectively. IL-17-producing T cells and neutrophils contributed to the cellular infiltrate in the joint and muscle tissue during acute RRV disease in mice. Blockade of IL-17A/F using a monoclonal antibody (mAb) reduced disease severity in RRV-infected mice and led to decreased proinflammatory proteins, cellular infiltration in synovial tissues and cartilage damage, without affecting viral titers in inflamed tissues. IL-17A/F blockade triggered a shift in transcriptional profile of both leukocyte infiltrates and musculoskeletal stromal cells by downregulating proinflammatory genes. This study highlights a previously uncharacterized role for an effector cytokine in alphaviral pathology and points towards potential therapeutic benefit in targeting IL-17 to treat patients presenting with RRV-induced arthropathy.

A high-dose inoculum size results in persistent viral infection and arthritis in mice infected with chikungunya virus.

Chikungunya virus (CHIKV) is an emerging mosquito-transmitted alphavirus that leads to acute fever and chronic debilitating polyarthralgia. To date, the mechanism underlying chronic recurrent arthralgia is unknown. In the present study, newborn wild-type C57BL/6 mice were infected with CHIKV, and the virological and pathological features of CHIKV infection were analyzed over a period of 50 days. Acute viral infection was readily established by footpad inoculation of CHIKV at doses ranging from 10 plaque forming unit (PFU) to 106 PFU, during which inoculation dose-dependent viral RNA and skeletal muscle damage were detected in the foot tissues. However, persistent CHIKV was observed only when the mice were infected with a high dose of 106 PFU of CHIKV, in which low copy numbers (103-104) of viral positive strand RNA were continuously detectable in the feet from 29 to 50 dpi, along with a low level and progressive reduction in virus-specific CD8+ T cell responses. In contrast, viral negative strand RNA was detected at 50 dpi but not at 29 dpi and was accompanied by significant local skeletal muscle damage at 50 dpi when mild synovial hyperplasia appeared in the foot joints, although the damage was briefly repaired at 29 dpi. These results demonstrated that a high viral inoculation dose leads to viral persistence and progression to chronic tissue damage after recovery from acute infection. Taken together, these results provide a useful tool for elucidating the pathogenesis of persistent CHIKV infection and viral relapse-associated chronic arthritis.

COVID-19 IgG-related autoimmune inflammatory necrotizing myositis.

The COVID-19 pandemic caused by the SARS-CoV-2 virus has affected millions of people around the globe. The most common presentation of COVID-19 is fever and upper and lower respiratory tract infection. Myalgia is fairly common in the prodromal phase of the viral illness which self-resolves. There is very scant literature on autoimmune myositis triggered by COVID-19 infection. We report a case of SARS-CoV-2 infection, who presented with progressive muscle weakness with rhabdomyolysis and necrotizing autoimmune myopathy on muscle biopsy. This case report imposes awareness of musculoskeletal autoimmune processes triggered by COVID-19 which requires clinical suspicion for early diagnosis and initiation of treatment.

Rare complication of four extremity compartment syndrome requiring fasciotomy from influenza A viral myositis.

Influenza A and B commonly cause benign respiratory disease in humans, but can cause more severe illness in high-risk populations. We report an unusual case of a previously healthy adult patient who presented with myositis and severe rhabdomyolysis secondary to influenza A infection that resulted in atraumatic compartment syndrome of all four extremities, each requiring emergent fasciotomy. The patient was subsequently managed with delayed primary closure and skin grafting in the operating room. Prompt recognition of this rare complication by the team resulted in no limb amputations. On his first follow-up appointment, 1 month after discharge, he had regained full functionality in both his hands and his feet were both close to 50% of baseline and improving with physical therapy.

Concurrent acute myositis and Guillain-Barre syndrome in Cytomegalovirus infection - a rare case report.

BACKGROUND: Cytomegalovirus (CMV) is a double stranded DNA virus and ubiquitous in nature. Association of Guillain-Barre syndrome (GBS) and CMV is well known but CMV acute myositis is a rare condition. Restriction of movements of limbs due to severe pain in myositis may obscure the diagnosis of GBS and this may easily miss. CASE PRESENTATION: Here we describe a 29-year-old male presenting with pain and swelling of bilateral lower limbs which progressed rapidly with increasing serum creatine kinase levels with positive IgM CMV antibodies. In view of no improvement in clinical condition, patient was further evaluated and found to have concurrent GBS. He was treated with plasmapheresis and improved. CONCLUSION: Cytomegalovirus infection presenting as acute myositis is a uncommon and further association with GBS is a rare occurrence.

COVID-19 and the nervous system.

A pandemic due to novel coronavirus arose in mid-December 2019 in Wuhan, China, and in 3 months' time swept the world. The disease has been referred to as COVID-19, and the causative agent has been labelled SARS-CoV-2 due to its genetic similarities to the virus (SARS-CoV-1) responsible for the severe acute respiratory syndrome (SARS) epidemic nearly 20 years earlier. The spike proteins of both viruses dictate tissue tropism using the angiotensin-converting enzyme type 2 (ACE-2) receptor to bind to cells. The ACE-2 receptor can be found in nervous system tissue and endothelial cells among the tissues of many other organs.Neurological complications have been observed with COVID-19. Myalgia and headache are relatively common, but serious neurological disease appears to be rare. No part of the neuraxis is spared. The neurological disorders occurring with COVID-19 may have many pathophysiological underpinnings. Some appear to be the consequence of direct viral invasion of the nervous system tissue, others arise as a postviral autoimmune process, and still others are the result of metabolic and systemic complications due to the associated critical illness. This review addresses the preliminary observations regarding the neurological disorders reported with COVID-19 to date and describes some of the disorders that are anticipated from prior experience with similar coronaviruses.

Concurrent Guillain-Barré syndrome and myositis complicating dengue fever.

Dengue is an arboviral infection that classically presents with fever, headache, joint pain, skin flush and morbilliform rashes. Neurological manifestations are well recognised but their exact incidence is unknown. Though myalgias are common in dengue virus infection, myositis and/or elevated serum creatine kinase is an uncommon complication. Guillain-Barré syndrome is another rare neurological manifestation associated with dengue fever. Here, we report the case of a 21-year-old man with serologically confirmed dengue fever presenting with severe myalgia, bilateral lower and upper limb weakness with raised creatine kinase, MRI suggestive of myositis and myonecrosis and nerve conduction velocity showing bilateral lower limb and axillary sensory motor neuropathy. He was managed conservatively and made an uneventful recovery.

[Viral myositis, a pediatric case report]. / Miositis viral, reporte de un caso pediátrico.

Acute viral myositis is a complication after a viral infection mainly caused by Influenza A and B viruses. It is characterized as a transitory, sudden, self-limiting and benign inflammatory process. It usually affects preschool and school children presenting bilateral pain and sensitivity in the muscle groups of the lower limbs without alteration in the neurological examination. It can affect the gait or standing. The main complication is rhabdomyolysis, which is why clinical followup and values of creatine phosphokinase must be done. We present the case of a school-age child diagnosed with acute viral myositis. Because it is not a frequent entity and its incidence in Latin America is unknown, we consider important to report the case and review the topic, as its clinical course is benign, easily treated, and its knowledge can avoid unnecessary studies and hospitalizations.

La miositis viral aguda es una complicación posterior a una infección viral causada, principalmente, por virus influenza A y B. Se caracteriza por ser un proceso inflamatorio transitorio, súbito, autolimitado y benigno. Generalmente, afecta a niños preescolares y escolares, que presentan dolor bilateral y sensibilidad en los grupos musculares de los miembros inferiores sin alteración en el examen neurológico. Puede generar alteración de la marcha o de la bipedestación. Su principal complicación es la rabdomiólisis, por lo que se debe hacer un seguimiento clínico y de los valores de la creatinfosfoquinasa. Se presenta el caso de un niño en edad escolar con diagnóstico de miositis viral aguda. Debido a que es poco frecuente y su incidencia en Latinoamérica es desconocida, se considera importante el reporte del caso y la revisión del tema, ya que su curso es benigno, de fácil manejo, y su conocimiento evita estudios y hospitalizaciones innecesarias.

Animal model of arthritis and myositis induced by the Mayaro virus.

BACKGROUND: The Mayaro virus (MAYV) is an endemic arbovirus in South American countries, where it is responsible for sporadic outbreaks of Mayaro fever. Clinical manifestations include fever, headache, ocular pain, rash, myalgia, and debilitating and persistent polyarthralgia. Understanding the mechanisms associated with MAYV-induced arthritis is of great importance due to the potential for its emergence, urbanization and dispersion to other regions. METHODS: 15-day old Balb/c mice were infected by two distinct pathways, below the forelimb and in the rear footpad. Animals were observed for a period of 21 days. During this time, they were monitored every 24 hours for disease signs, such as weight loss and muscle weakness. Histological damage in the muscles and joints was evaluated 3, 7, 10, 15 and 20 days post-infection. The cytokine profile in serum and muscles during MAYV infection was evaluated by flow cytometry at different post-infection times. For pain analysis, the animals were submitted to the von Frey test and titre in different organs was evaluated throughout the study to obtain viral kinetics. FINDINGS: Infection by two distinct pathways, below the forelimb and in the rear footpad, resulted in a homogeneous viral spread and the development of acute disease in animals. Clinical signs were observed such as ruffled fur, hunched posture, eye irritation and slight gait alteration. In the physical test, both groups presented loss of resistance, which was associated with histopathological damage, including myositis, arthritis, tenosynovitis and periostitis. The immune response was characterized by a strong inflammatory response mediated by the cytokines TNF-α, IL-6 and INF-γ and chemokine MCP-1, followed by the action of IL-10 and IL-4 cytokines. INTERPRETATION: The results showed that Balb/c mice represent a promising model to study mechanisms involved in MAYV pathogenesis and for future antiviral testing.

Chikungunya-induced inflammatory myositis: a case report in India.

Chikungunya fever is a benign and self-limiting disease caused by an RNA virus belonging to genus alphavirus and transmitted by infected Aedes mosquitoes. However, a number of atypical presentations involving various systems have been reported. Among the neurological complications, encephalitis, myelitis, Guillain-Barre syndrome and optic neuritis are commonly seen. However, its presentation as isolated inflammatory myositis causing quadriplegia is extremely rare. We report a 35-year-old woman with quadriplegia caused by chikungunya-induced inflammatory myositis. The diagnosis was confirmed with clinical examination, electromyography study, muscle biopsy findings and exclusion of other causes. There have been case reports of inflammatory myositis in association with various infections as well as in association with other neurological presentations in chikungunya. However, this may be the first case report of isolated inflammatory myositis associated with chikungunya fever.

Parechovirus A3 (PeV-A3)-associated myalgia/myositis occurs irrespective of its genetic cluster: a longitudinal molecular epidemiology of PeV-A3 in Yamagata, Japan between 2003 and 2016.

No longitudinal molecular epidemiology of parechovirus A3 (PeV-A3) over a decade is available and PeV-A3-associated myalgia/myositis has been reported only in Japan. Thus, we aimed to clarify the longitudinal molecular epidemiology of PeV-A3 with a major focus on the strains detected from PeV-A3-associated myalgia/myositis cases. We performed sequence and phylogenetic analysis for the VP1 region of PeV-A3 strains in Yamagata, Japan, between 2003 and 2016. The phylogenetic analysis indicated that PeV-A3 strains caused PeV-A3-associated myalgia/myositis as well as a variety of infectious diseases, ranging from mild to severe, in subjects ranging from neonates to adults, irrespective of genetic cluster or variations. PeV-A3 strains are causative agents of a variety of human diseases, irrespective of their genetic cluster. Furthermore, we consider that PeV-A3-associated myalgia/myositis may occur, not only in Japan, but also in other countries, as closely related PeV-A3 strains have been circulating around the world.

[Cytomegalovirus myositis complicated with hemophagocytic lymphohistiocytosis, acute renal failure, and colitis].

A 60-years-old previously healthy man presented with acute renal failure and hemophagocytic lymphohistiocytosis (HLH). Both conditions improved after immunotherapies, but severe limb weakness with elevation of serum CK developed. Needle EMG showed myogenic changes with spontaneous activities and muscle weakness thereafter improved without adding further immunotherapies, suggesting that our patient had viral myositis. After the stabilization of limb weakness, cecal perforation occurred due to cytomegalovirus (CMV) enteritis and temporal significant change of anti-CMV IgG antibody titer was confirmed using paired serum samples. Upregulation of MHC-class I molecule and numerous regenerative muscle fibers were observed in muscle biopsy, but no evidence of direct CMV infection in muscle fibers were seen. Although CMV infection may cause either myositis, acute renal failure, HLH or colitis in individual patient, this is the first case which had been complicated by all these conditions subsequent to CMV infection.

Causation of Acute Flaccid Paralysis by Myelitis and Myositis in Enterovirus-D68 Infected Mice Deficient in Interferon αß/γ Receptor Deficient Mice.

Enterovirus D68 (EV-D68) caused a large outbreak in the summer and fall of 2014 in the United States. It causes serious respiratory disease, but causation of associated paralysis is controversial, because the virus is not routinely identified in cerebrospinal fluid. To establish clinical correlates with human disease, we evaluated EV-D68 infection in non-lethal paralysis mouse models. Ten-day-old mice lacking interferon responses were injected intraperitoneally with the virus. Paralysis developed in hindlimbs. After six weeks of paralysis, the motor neurons were depleted due to viral infection. Hindlimb muscles were also infected and degenerating. Even at the earliest stage of paralysis, muscles were still infected and were degenerating, in addition to presence of virus in the spinal cord. To model natural respiratory infection, five-day-old mice were infected intranasally with EV-D68. Two of the four infected mice developed forelimb paralysis. The affected limbs had muscle disease, but no spinal cord infection was detected. The unique contributions of this study are that EV-D68 causes paralysis in mice, and that causation by muscle disease, with or without spinal cord disease, may help to resolve the controversy that the virus can cause paralysis, even if it cannot be identified in cerebrospinal fluid.