Three cases of acute myositis in adults following influenza-like illness during the H1N1 pandemic
A 25-year-old male presented with four days of progressive weakness and muscle pain. Initially he noticed myalgias in his chest and biceps. Two days prior to presentation he noticed forearm pain and hand weakness. One day prior to presentation he noticed lower extremity weakness and pain, limiting his ability to ambulate. Two weeks prior to presentation he had been prescribed amoxicillin for a sore throat and fever, however he was not tested for streptococcus or influenza at that time. He denied prior medical problems, trauma, routine medication use or recent strenuous exercise.\nVital signs and general examination were normal. He had no rashes or joint pain. Bilateral arm and forearm muscles were tight and tender. Strength was decreased bilaterally in upper and lower extremities, including wrist extension and flexion (4/5), grip strength (4-/5), hip flexion (3/5), hip extension (5-/5), knee flexion (4-/5) and knee extension (5-/5). His reflexes and sensation were normal.\nLaboratory values were generally unremarkable with the exception of a CK of 3,575 ng/ml. Pertinent negative virologic tests included CSF bacterial culture, HIV, Influenza A by DFA, Influenza B by DFA, and CSF Influenza by PCR. An MRI of the cervical spine was normal.\nHe was given IV fluids and ibuprofen. The day following presentation his weakness continued to progress and involved truncal weakness. Needle EMG study (distal, proximal and paraspinal muscles) showed only one run of positive waves in the thoracic paraspinal muscles. Two days after presentation he had dramatic improvement. His strength returned to 5/5 except in his left upper extremity strength, which improved to 4+/5 in wrist flexion, wrist extension and finger extension. The swelling and tenderness also improved. His CK decreased to 975 ng/ml and serum creatinine remained stable and within normal limits.