Statin-Induced Immune-Mediated Necrotizing Myopathy Does Not Always Present With Immediate or Severe Symptoms.

Abstract

Statins are 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) inhibitors that can cause myalgia or muscle weakness due to their myotoxic effect. These symptoms usually occur within a few weeks of statin initiation. 1-3 Immune-mediated necrotizing myopathy (IMNM) is characterized by severe muscle weakness and marked elevation of creatine kinase (CK), with anti-signal recognition particle or anti-HMGCR antibodies in 88%–90% of patients. 4 Some IMNM subtypes, particularly anti-HMGCR-positive IMNM, can be triggered by statins. 4 We report a case of statin-induced IMNM with an unusually mild presentation and delayed symptom onset that responded well to steroid monotherapy. 68-year-old of proximal both upper and lower extremities and CK U/L. med-ication our not his muscle A neurological examination revealed slight weakness in shoulder abduction (Medical Re-search Council [MRC] grade 4+) and hip flexion (MRC grade 4) but no other abnormal findings, including for the sensory system, deep tendon reflexes, and coordination. Serum 440 U/L (normal range <190 U/L), the findings of other routine labo-ratory tests normal, of thyroid function. Autoimmune profiling for various negative. Anti-HMGCR antibody a line immunoassay positive at 106 U (positive >10 U). Nerve conduc-tion studies and needle electromyography revealed polyphasic motor-unit po-tentials with