From the Guidelines
Sporadic Inclusion Body Myositis is the most common inflammatory myopathy in adults over 50 years of age. This condition is characterized by symmetric or asymmetric weakness of insidious onset involving the proximal and/or distal muscles, with a male to female ratio of 3:1, as noted in a study published in the Mayo Clinic Proceedings 1. Key features of this condition include:
- Atrophy of the forearm flexors, finger flexors, and quadriceps muscles
- Dysphagia as a prominent feature, leading to poor outcomes such as feeding tube placement or recurrent aspiration pneumonia
- Minimally elevated muscle enzyme levels, such as the CK level
- A muscle biopsy revealing an inflammatory mononuclear cell infiltrate with rimmed vacuoles and congophilic deposits, as described in the study 1. The management of Sporadic Inclusion Body Myositis focuses on addressing complications and maintaining function and independence, rather than relying on immunosuppressive therapies which have been shown to be ineffective in this condition.
From the Research
Inflammatory Myopathies in Adults over 50
- The most common inflammatory myopathy in adults over 50 is inclusion body myositis (IBM) 2, 3.
- IBM is characterized by an insidious onset, progressive indolent course, and is generally felt to be refractory to standard therapy for myositis 4.
- The diagnosis of IBM is based on the clinical presentation and the histopathological findings in muscle biopsy, however increasing evidence on genetics and paraclinical biomarkers has recently come to light giving new insights on the pathogenesis, the diagnosis and the potential treatment of the disease 3.
Clinical Presentation and Diagnosis
- Symptoms of IBM include proximal leg and distal arm weakness, and most commonly patients present early slowly progressive quadriceps weakness which leads to falls and to difficulties in climbing stairs 3.
- The aetiopathogenesis of the disease remains unclear and despite some preliminary promising results, to the day there is no effective treatment 3.
- Muscle biopsy is an important tool in the diagnosis of IBM, and the presence of active inflammation at entry into the therapeutic protocol may be associated with clinical improvement 5.
Treatment and Management
- Various immunosuppressive and immunomodulatory agents have been used to treat IBM, but the efficacy of these treatments is still uncertain 4, 5, 6.
- Some studies have reported modest benefit from therapies such as prednisone, methotrexate, and azathioprine, but the response to treatment is often variable and unpredictable 4, 5.
- More research is needed to determine the most effective treatment strategies for IBM, and to develop standardized outcome measures for clinical trials 6.