[Sporadic Inclusion Body Myositis].

Sporadic inclusion body myositis (sIBM) is an intractable and progressive skeletal muscle disease of unknown etiology. Muscle biopsy typically reveals endomysial inflammation, invasion of mononuclear cells into non-necrotic fibers, and rimmed vacuoles, suggesting that inflammation and degeneration co-exist in the pathomechanism. According to a nationwide survey conducted by a research team of the Ministry of Health, Labor, and Welfare, the number of patients is increasing in Japan as well. The clinical progression shows a slow and chronic deterioration. sIBM is usually diagnosed five years after onset. Muscle weakness and atrophy in the quadriceps, wrist flexors, and finger flexors are typical neurological findings of sIBM. Dysphagia and asymmetric weakness are often found. Serum creatine kinase is usually below 2,000 IU/L. sIBM is generally refractory to current therapy, such as steroids or immunosuppressants. Understanding the pathomechanism of sIBM is crucial for developing effective therapeutic strategies.

Phenotypic spectrum of inclusion body myositis.

Inclusion body myositis (IBM) is a progressive, debilitating muscle disease commonly encountered in patients over the age of 50. IBM typically presents with asymmetric, painless, progressive weakness and atrophy of deep finger flexors and/or quadriceps muscle. Many patients with IBM develop dysphagia. However, atypical presentations of IBM with isolated dysphagia, asymptomatic hyper-CKemia, foot drop, proximal weakness, axial weakness, and facial diplegia have been reported. Other acquired and some inherited disorders may present similar to IBM, and this list gets more expansive when considering atypical presentations. In general, disease progression of IBM leads to loss of hand function and impaired ambulation, and most IBM patients become wheelchair dependent within 13-15 years of disease onset. Hence, IBM impacts negatively patients' quality of life and reduces longevity compared to the general population. Acknowledging the complete clinical spectrum of IBM presentation and excluding mimics would shorten the time to diagnosis, lead to prompt initiation of supportive management and avoid unproven therapy. Ongoing advanced phase studies in IBM provide hope that a therapy may soon be available. Therefore, an added potential benefit of early diagnosis would be prompt initiation of disease-modifying therapy once available.

Paraneoplastic myopathies.

This chapter reviews the association between cancer and the idiopathic inflammatory myopathies (IIM), which includes dermatomyositis (DM), antisynthetase syndrome (ASyS), immune-mediated necrotizing myopathy (IMNM), and inclusion body myositis (IBM). Accumulating evidence shows that the risk of a coexisting malignancy is high in patients with DM, especially among those with anti-Tif1γ autoantibodies. Patients with IMNM and no defined autoantibodies also have an increased risk of malignancy. Recent evidence demonstrates that many IBM patients have increased numbers of circulating CD57+ CD8+ T cells, consistent with a diagnosis of large granular lymphocytic leukemia. In contrast, IMNM patients with anti-SRP or anti-HMGCR autoantibodies as well as patients with ASyS syndrome do not have a definitively increased risk of cancer. Patients who have a cancer treated with one of the immune checkpoint inhibitors can develop myositis (ICI-myositis), sometimes along with myasthenia gravis and/or myocarditis.

Frequency of EMG abnormalities in idiopathic inflammatory myopathies under the EULAR/ACR classification criteria.

The European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria for idiopathic inflammatory myopathies (IIM) have been widely used in recent times. However, no studies have focused on electromyography (EMG) findings of IIM, considering the criteria. This study aimed to elucidate the frequency of EMG abnormalities, particularly fibrillation potentials and positive sharp waves (Fib/PSW), the most objective EMG findings of IIM. Clinical and EMG records of adult patients who were clinically diagnosed with polymyositis (PM), dermatomyositis (DM), amyopathic DM (ADM), or inclusion body myositis (IBM) were retrospectively reviewed and classified according to the EULAR/ACR classification criteria. The frequency of Fib/PSW in EMG was investigated in the recruited cases. Seventy-nine patients with clinically diagnosed IIM (44 with PM, 17 with DM, 7 with ADM, and 11 with IBM) were recruited. After classification using EULAR/ACR, 75 satisfied definite or probable IIM (61 and 14, respectively), and the frequency of Fib/PSW in this group was 95%. Furthermore, the remaining 4 patients with insufficient IIM probability also showed Fib/PSW. Fib/PSW may also be seen in cases with insufficient IIM probability not satisfying the criteria. EMG may help detect muscle involvement in these cases through Fib/PSW.

Adolescent-onset multisystem proteinopathy due to a novel VCP variant.

Valosin-containing protein (VCP) pathogenic variants are the most common cause of multisystem proteinopathy presenting with inclusion body myopathy, amyotrophic lateral sclerosis/frontotemporal dementia, and Paget disease of bone in isolation or in combination. We report a patient manifesting with adolescent-onset myopathy caused by a novel heterozygous VCP variant (c.467G > T, p.Gly156Val). The myopathy manifested asymmetrically in lower limbs and extended to proximal, axial, and upper limb muscles, with loss of ambulation at age 35. Creatine kinase value was normal. Alkaline phosphatase was elevated. Electromyography detected mixed low amplitude, short duration and high amplitude, long duration motor unit potentials. Muscle biopsy showed features of inclusion body myopathy, which in combination with newly diagnosed Paget disease of bone, supported the VCP variant pathogenicity. In conclusion, VCP-multisystem proteinopathy is not only a disease of adulthood but can have a pediatric onset and should be considered in differential diagnosis of neuromuscular weakness in the pediatric population.

Inclusion body myositis-health-related quality of life and care situation during phases of the "patience journey" in Germany: results from a qualitative study.

BACKGROUND: To understand the health-related quality of life (HRQoL) in inclusion body myositis (IBM) from a holistic perspective on the background of a complex care situation. The focus was on how the patient journey may be structured over the course of this rare disease. METHODS: An exploratory qualitative study was performed via in-depth semi-structured interviews. Seven patients (males n = 5) with 2011 European Neuromuscular Centre (ENMC) IBM criteria from the German IBM patient registry were interviewed for this study. The dynamic network approach of resilience and the throughput-model of health services research were used to structure the qualitative analysis. RESULTS: Our results suggest that IBM patients experience the holistic HRQoL and care situation typically in four phases: (1) uncertainty about physical vulnerability until diagnosis, (2) promising treatment approaches, (3) self-management and dyadic coping, (4) weak body, busy mind and caregiver burden. The homophonous in-vivo code "patience journey" describes the frequently reported emotional perspective of the patient journey. Although the overarching theme of perceived social support varied throughout these phases, a reliable patient-partner-dyad may lead to improved HRQoL in the long-term. CONCLUSIONS: New hypotheses for future quantitative research were generated to better understand the IBM patients' burden in the long term. The identified relevance of social support emphasizes the patients' need to handle IBM as manageable in medical settings. During exhausting phases of IBM progression, more effective care elements for patients and their partners could disclose varying needs. Strengthening multi-professional healthcare services via individualised informational, practical, or emotional support could improve HRQoL, especially since there is no curative treatment available so far.

Update on the evaluation and management of dysphagia in sporadic inclusion body myositis.

PURPOSE OF REVIEW: Dysphagia is a common symptom of sporadic inclusion body myositis (IBM), affecting disease trajectory and patient quality-of-life. Despite this, it is considerably understudied. The purpose of this review is to summarize current evidence related to the evaluation and management of dysphagia in IBM. We highlight a patient case involving a multidisciplinary management approach, and we encourage continued exploration of exercises for delaying progression and improving impairments in patients with IBM and dysphagia. RECENT FINDINGS: Recent investigations confirm that dysphagia in IBM is a debilitating and complex symptom that warrants timely evaluation and management. Further, they highlight the lack of validation of standardized swallowing-related metrics specifically for IBM and the limited evidence supporting a consensus of management approaches. Small scale research and clinical anecdotal data support a multidisciplinary and multipronged patient-centered approach, including rehabilitative exercise protocols, for dysphagia management in IBM. SUMMARY: A paucity exists in the literature to effectively guide clinical decision-making for patients with IBM and dysphagia. Given this, it is our belief that a careful multidisciplinary and multipronged patient-centered approach is critical for dysphagia management in IBM. Prospective, longitudinal research on the underlying mechanisms of swallowing dysfunction using advanced and validated swallowing-related outcome measures is urgently needed.

Autoimmune inflammatory myopathies.

The autoimmune inflammatory myopathies constitute a heterogeneous group of acquired myopathies that have in common the presence of endomysial inflammation and moderate to severe muscle weakness. Based on currently evolved distinct clinical, histologic, immunopathologic, and autoantibody features, these disorders can be best classified as dermatomyositis, necrotizing autoimmune myositis, antisynthetase syndrome-overlap myositis, and inclusion body myositis. Although polymyositis is no longer considered a distinct subset but rather an extinct entity, it is herein described because its clinicopathologic information has provided over many years fundamental information on T-cell-mediated myocytotoxicity, especially in reference to inclusion body myositis. Each inflammatory myopathy subset has distinct immunopathogenesis, prognosis, and response to immunotherapies, necessitating the need to correctly diagnose each subtype from the outset and avoid disease mimics. The paper describes the main clinical characteristics that aid in the diagnosis of each myositis subtype, highlights the distinct features on muscle morphology and immunopathology, elaborates on the potential role of autoantibodies in pathogenesis or diagnosis , and clarifies common uncertainties in reference to putative triggering factors such as statins and viruses including the 2019-coronavirus-2 pandemic. It extensively describes the main autoimmune markers related to autoinvasive myocytotoxic T-cells, activated B-cells, complement, cytokines, and the possible role of innate immunity. The concomitant myodegenerative features seen in inclusion body myositis along with their interrelationship between inflammation and degeneration are specifically emphasized. Finally, practical guidelines on the best therapeutic approaches are summarized based on up-to-date knowledge and controlled studies, highlighting the prospects of future immunotherapies and ongoing controversies.

Exploring challenges in the management and treatment of inclusion body myositis.

PURPOSE OF REVIEW: This review provides an overview of the management and treatment landscape of inclusion body myositis (IBM), while highlighting the current challenges and future directions. RECENT FINDINGS: IBM is a slowly progressive myopathy that predominantly affects patients over the age of 40, leading to increased morbidity and mortality. Unfortunately, a definitive cure for IBM remains elusive. Various clinical trials targeting inflammatory and some of the noninflammatory pathways have failed. The search for effective disease-modifying treatments faces numerous hurdles including variability in presentation, diagnostic challenges, poor understanding of pathogenesis, scarcity of disease models, a lack of validated outcome measures, and challenges related to clinical trial design. Close monitoring of swallowing and respiratory function, adapting an exercise routine, and addressing mobility issues are the mainstay of management at this time. SUMMARY: Addressing the obstacles encountered by patients with IBM and the medical community presents a multitude of challenges. Effectively surmounting these hurdles requires embracing cutting-edge research strategies aimed at enhancing the management and treatment of IBM, while elevating the quality of life for those affected.

Inclusion body myositis with early onset: a population-based study.

INTRODUCTION: Inclusion body myositis (IBM), an inflammatory myopathy with progressive weakness without efficient treatment, typically presents after 45 years of age and younger patients are sparsely studied. METHODS: In a population-based study during a 33-year period, 142 patients with IBM were identified in western Sweden. Six patients fell outside the European Neuromuscular Centre 2011 criteria for IBM due to young age at symptom onset, verified by a muscle biopsy < 50 years of age. These were defined as early-onset IBM and included in this study. Medical records, muscle strength, comorbidities, muscle biopsies, and nuclear- and mitochondrial DNA were examined and compared with patients with IBM and age matched controls from the same population. RESULTS: The median age at symptom onset was 36 (range 34-45) years and at diagnosis 43 (range 38-58) years. Four patients were deceased at a median age of 59 (range 50-75) years. The median survival from diagnosis was 14 (range 10-18) years. The prevalence December 31 2017 was 1.2 per million inhabitants and the mean incidence 0.12 patients per million inhabitants and year. The mean decline in quadriceps strength ± 1 standard deviation was 1.21 ± 0.2 Newton or 0.91 ± 0.2% per month and correlated to time from diagnosis (p < 0.001). Five patients had swallowing difficulties. All patients displayed mitochondrial changes in muscle including cytochrome c oxidase deficiency and the mitochondrial DNA mutation load was high. CONCLUSIONS: Early-onset IBM is a severe disease, causing progressive muscle weakness, high muscle mitochondrial DNA mutation load and a reduced cumulative survival in young and middle-aged individuals.

[Sporadic Inclusion Body Myositis].

Inclusion body myositis (IBM) is an idiopathic inflammatory muscle disease that predominantly affects elderly men over the age of 50 years, and the number of patients is rapidly increasing in Japan. Generally, muscle weakness and atrophy occur asymmetrically in the flexor muscles of the fingers and wrists and the quadriceps muscles. Invasive muscle biopsy is essential for the diagnosis of IBM. Although its pathogenesis is not yet understood, both inflammatory as well as degenerative mechanisms are postulated to be involved. In particular, degeneration of the IBM muscle may be associated with the IFN-II secretion by highly differentiated CD8+ T lymphocytes. Cytoplasmic 5'-nucleotidase 1A (cN1A) antibody has been detected in the blood samples of approximately half of the patients with IBM. While there are positive opinions about the diagnostic significance of the antibody, its usefulness for the diagnosis of IBM is limited. The results of passive immunization support its etiologic significance; however, more detailed verification, including active immunization, is needed in the future.

Exploring hand and upper limb function in patients with inclusion body myositis (IBM).

Inclusion body myositis (IBM) is an inflammatory myopathy characterized by progressive weakness of knee extensors and finger flexors. Many patients lose independence with fine motor tasks; however, a gap remains as to how these deficits correlate with performance on functional outcome measures. We describe functional hand impairments as measured by performance-based outcome measures in a cross-sectional sample of 74 patients with IBM. Subjects completed a series of outcome measures (Functional Dexterity Test (FDT), Performance of the Upper Limb (PUL), and Sollerman Hand Function Test (SHFT)) alongside a collection of patient reported outcomes (PROs). Assessments were compared to standard IBM measurements, including grip strength and IBM Functional Rating Scale (IBMFRS). FDT and SHFT demonstrated significant correlations to grip (p<0.001; Spearman correlations r=0.48-0.70). Significant correlation was found between all functional outcome measures and IBMFRS (p<0.001; Spearman correlations r=0.51-0.77), as well as PRO Upper Extremity Scale for IBM (IBM-PRO) (p<0.05; Spearman correlations r=0.55-0.73). Non-ambulatory patients demonstrated significantly weaker grip (p<0.001), resulting in lower PUL scores and increased FDT completion times (p<0.001). Collectively, these assessments may provide insight to understanding functional limitations of the hands and potentially allow for more inclusive clinical trials with future validation of hand assessments in IBM.

Clinical pearls and promising therapies in myositis.

INTRODUCTION: Idiopathic inflammatory myopathies (IIMs) represent a diverse group of systemic autoimmune disorders with variable clinical manifestations and disease course. Currently, the challenges of IIMs are multifold, including difficulties in timely diagnosis owing to clinical heterogeneity, limited insights into disease pathogenesis, as well as a restricted number of available therapies. However, advances utilizing myositis-specific autoantibodies have facilitated the definition of subgroups as well as the prediction of clinical phenotypes, disease course, and response to treatment. AREAS COVERED: Herein we provide an overview of the clinical presentations of dermatomyositis, anti-synthetase syndrome, immune-mediated necrotizing myopathy, and inclusion body myositis. We then provide an updated review of available and promising therapies for each of these disease groups. We synthesize current treatment recommendations in the context of case-based construct to facilitate application to patient care. Finally, we provide high-yield, clinical pearls relevant to each of the subgroups that can be incorporated into clinical reasoning. EXPERT OPINION: There are many exciting developments on the horizon for IIM. As insights into pathogenesis evolve, the therapeutic armamentarium is expanding with many novel therapies in development, holding promise for more targeted treatment approaches.

Myasthenia gravis with inclusion body myositis: A case report.

We present the case of a 75-year-old man diagnosed with myasthenia gravis (MG) based on lower leg weakness and ptosis for the past 2 months before admission to our hospital. The patient was anti-acetylcholine receptor antibody-positive at admission. He was treated with pyridostigmine bromide and prednisolone, which improved the ptosis, but the lower leg muscle weakness remained. An additional lower leg magnetic resonance imaging examination suggested myositis. Inclusion body myositis (IBM) was diagnosed after a subsequent muscle biopsy. Although MG is often associated with inflammatory myopathy, IBM is rare. There is no effective treatment for IBM, but various treatment possibilities have recently been proposed. This case emphasises that myositis complications, including IBM, should be considered when elevated creatine kinase levels are observed and conventional treatments do not address chronic muscle weakness.