Inclusion body myositis: Update on the diagnostic and therapeutic landscape

Abstract

Inclusion body myositis (IBM) is a progressive muscle disease affecting patients over the age of 40, with distinctive clinical and histopathological features. The typical clinical phenotype is characterized by prominent involvement of deep finger flexors and quadriceps muscles. Less common presentations include isolated dysphagia, asymptomatic hyper-CKemia, and axial or limb weakness beyond the typical pattern. IBM is associated with marked morbidity as majority of patients eventually become wheelchair dependent with limited use of their hands and marked dysphagia. Furthermore, IBM mildly affects longevity with aspiration pneumonia and respiratory complications being the most common cause of death. On muscle biopsy, IBM is characterized by a peculiar combination of endomysial inflammation, rimmed vacuoles, and protein aggregation. These histopathological features are reflective of the complexity of underlying disease mechanisms. No pharmacological treatment is yet available for IBM. Monitoring for swallowing and respiratory complications, exercise, and addressing mobility issues are the mainstay of management. Further research is needed to better understand disease pathogenesis and identify novel therapeutic targets.

Patient-Reported Health-Related Quality of Life, Anxiety and Depression in Patients with Inclusion Body Myositis: A Register-Based Cross-Sectional Study in Germany

“…IBM patients mostly utilize walking aids (walking sticks or crutches) after a few years, and after approximately 10-16 years, they need wheelchairs [12,13]. Nevertheless, IBM per se does not shorten life expectancy, 2 of 18 but thus far, causative therapies are not available [14]. However, high-dose intravenous immunoglobulins can slow down disease progression and are recommended in the German guidelines.…”

Whole-body muscle magnetic resonance imaging in inflammatory myopathy with mitochondrial pathology

“…On the other hand, most patients with IM-Mito in our cohort do not meet the European Neuromuscular Center Criteria for probable or definite IBM. Although the presence of rimmed vacuoles is a classic finding in IBM, there are several descriptions in which this finding may be absent, depending on the muscle biopsied and the stage of the disease ( 33 , 34 ). Therefore, it is not possible to determine whether cases classified in this study as IM-Mito were IBM based only on the absence of rimmed vacuoles in the muscle biopsy.…”

Inclusion body myositis

“…Current auto-antibody tests (anti-NT5C1A) have high specificity (90%) but only moderate sensitivity (40%); results must be interpreted in the clinical context. 3 A muscle biopsy should be performed, which may reveal inflammation, rimmed vacuoles, and congophilic inclusions; interpretation requires expertise in neuromuscular pathology. 4 …”