A Rare Presentation of Myopathy: Immune-mediated Necrotizing Myositis with Concurrent Cervical Cord Compression – A Case Report

Case Diagnosis: Anti-HMGCoA Reductase Immune-Mediated Myositis

Case Description or Program Description: A 77 year old female with history of statin-induced transaminitis and six months of progressive weakness, presented to the emergency department with significantly elevated creatinine kinase (CK) on outpatient labs. Initial work up and management revealed persistent, brisk elevation of CK and aminotransferases (AST/ALT), despite adequate intravenous fluids (IVF) and steroids. Cervical spine magnetic resonance imaging (MRI) revealed severe spinal canal stenosis at C4-5/C5-6. Neurosurgery could not exclude contribution of cervical myelopathy to her symptoms and performed C4-7 posterior decompression and fusion. Postoperatively, no further work up was pursued as the patient had mild improvements in weakness and lab values with intermittent need for IVF. Physiatry was consulted and the patient was admitted to an inpatient rehabilitation facility (IRF). While at IRF, the patient developed worsening weakness and labs re-demonstrated elevation of CK and AST/ALT. Neurology was consulted and the patient was transferred to the acute hospital for possible immune-mediated necrotizing myopathy (IMNM).

Setting: Inpatient Rehabilitation Facility

Assessment/Results: Neurology confirmed IMNM with positive anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) antibody. Rheumatology, assisted with treatment of four days of intravenous immunoglobulin (IVIG), two weeks of high-dose steroids, methotrexate, and folate. The patient later returned to IRF where she was discharged home.

Discussion (relevance): Clinical suspicion for IMNM should be raised in patients with statin exposure, muscle pain, weakness, and significantly elevated CK (tenfold the upper limit of normal). Hallmarks of treatment include IVIG, high-dose steroids, and often steroid-sparing immunotherapy.

Conclusions: Myopathies have several etiologic considerations. Though rare, consequences of immune mediated myopathies can be devastating with delayed treatment. While many diagnostics are completed prior to IRF, it is critical to recognize the spectrum of myopathies to ensure early involvement of Rheumatology and Neurology to provide appropriate interventions in severe cases.