Proximal lower limb weakness in adult viral myositis: An unusual case presentation

Background. Viral myositis predominantly affects children, manifesting as sudden calf pain. It is rare in adults, where it often presents as myalgia and weakness in the proximal upper and lower limbs, with slow resolution. We report an atypical presentation of post-viral myositis in an adult, characterized by pronounced weakness and minimal tenderness in the proximal lower limbs, which resolved after administration of methylprednisolone. Case report. A 24-year-old male presented with sudden lower extremity weakness, impairing his ability to stand from a squatting position and climb stairs, with minimal thigh pain. Examination revealed minimal tenderness and marked proximal inferior paraparesis. Elevated monocyte counts and creatine kinase (CK) levels were noted. Needle EMG indicated a myogenic lesion. The patient received intravenous methylprednisolone and experienced complete resolution. Conclusions. Viral myositis can occur in adults with atypical presentations dominated by proximal lower limb weakness. Physicians should consider viral myositis in adults with a history of flu-like symptoms and acute limb weakness.