COVID-19 vaccine-related myositis

Abstract

A 56-year-old non-diabetic woman with no evidence of prior SARS-CoV-2 infection presented with profound left upper arm pain, soreness and curtailed movement. Because of disabling pain she could hardly carry her handbag. The patient reported no unaccustomed or vigorous exercise or heavy manual labor prior to the onset of symptoms. Pain had developed 8 days after a second dose of COVID-19 vaccine into her deltoid muscle and produced decreased range of motion and progressive weakness. She had no systemic symptoms as malaise and fever. Upon physical examination, there were no signs of skin erythema or swelling. There was tenderness over the deltoid muscle, guarding and decreased abduction of the shoulder and arm. Serologic testing yielded increased serum creatine kinase concentration suggesting skeletal muscle damage. Urine analysis excluded myoglobinuria. At MRI for investigation of muscle pain and dysfunction, middle head of the deltoid muscle appeared severely edematous, with no apparent tearing or abscess (Figure Deltoid muscle architecture was preserved and edema appeared to track along the muscle fascicles. On contrast-enhanced MR images, affected muscle exhibited prominent enhancement indicating inflammation (myositis) (Figure Management consisted of rest, cryotherapy, compression and NSAIDs to decrease subjective pain. Symptoms resolved over the course of 6 weeks with no residual loss of function. Interestingly, MR findings persisted almost 2 months past resolution of symptoms.