Inclusion body myositis: a case of bilateral extremity weakness

Inflammatory myopathy is a common cause of bilateral muscular weakness in adults. Although not as common as polymyositis, inclusion body myositis (IBM) is a form of inflammatory myopathy characterized by chronic progressive muscle inflammation and often goes undiagnosed and untreated. IBM patients most commonly present with proximal lower extremity weakness and may have normal creatine kinase (CK) levels. A high level of clinical suspicion is required for prompt and accurate diagnosis of IBM, which is diagnosed definitively with a muscle biopsy. The patient described in this case report is a 68-year-old man who initially presented with both bilateral symmetric proximal lower extremity and distal upper extremity weakness. IBM was suspected through history, electromyography, and definitively diagnosed with muscle biopsy. The patient was subsequently initiated on prednisone therapy and physical therapy, with improvement in muscular strength after 2 months. In patients presenting with bilateral extremity weakness and normal CK level, the diagnosis of IBM should be included in the differential diagnosis and muscle biopsy performed for appropriate cases.