First Author: Vatsal Bhatt Clifford Stermer, Vivien Hsu, Ranita Sharma
Necrotizing Autoimmune Myopathy (NAM) associated with 3-hydroxy-3-methylglutaryl-coenzyme A Reductase (HMGCR) antibodies has been described in statin-induced and statin-naive patients. Proximal muscle weakness is the presenting symptom in HMGCR NAM. CK levels can exceed 10x normal values. Statin-induced cases involve two thirds of HMGCR NAM patients and are more likely to respond to immunosuppressive therapy. Muscle biopsy confirms the diagnosis. We report a case with progressive oropharyngeal dysphagia as the presenting complaint with poor response to treatment. To our knowledge, there has been only one previously reported case of statin-exposed HMGCR NAM with a similar presentation.
A 79 year old gentleman presented with four weeks of progressive dysphagia to solids and liquids, a 25lb weight loss and fatigue. He denied odynophagia, vomiting, dyspnea, fevers, skin changes, or arthralgias. No recent vaccinations were administered. Over time he also reported pain with weakness in bilateral lower extremity proximal muscle groups. Increased effort was needed to rise from the sitting position. Once upright he could ambulate. He denied tobacco or alcohol use. He has diabetes treated with metformin, hypertension controlled with medications and hyperlipidemia treated with daily atorvastatin for the past 2 years. Statin was discontinued 2 weeks prior to admission. Age appropriate cancer screening was completed. On exam HR was 96, BP was 137/65 and RR was 18 without hypoxia. He was thin with notable temporal wasting and gargled speech. No neck masses were detected. Cardiopulmonary and abdominal exam were normal. Rashes and edema were absent. Neurological exam revealed intact cranial nerves, no tremors, fasciculations or muscle wasting, no difficulty in raising arms above his head but visible difficulty rising from a chair with a subsequent normal gait, symmetric reflexes and normal cerebellar and sensory testing. Labs included a CPK of 8185, aldolase of 346 (normal < 8), AST/ALT of 176/395 (subsequently normalized), normal renal function, and a hemoglobin of 10. TSH and B12 levels were normal. HIV, T-SPOT, Hepatitis B/C were negative. Vitamin D levels were low. A barium swallow confirmed cricopharyngeal paralysis. MRI brain was normal. Myopathy workup was pursued. Myositis panel antibodies including Jo-1, MI-2, SRP, U2-snRNP, U1-RNP, NXP-2, and TIF1 were all negative. Anti-HMGCR antibodies were markedly elevated at > 200 (normal < 20). Biopsy revealed muscle fiber necrosis, phagocytosis, macrophages and regeneration with minimal inflammation. Despite steroids, IVIG and Rituximab, the patient's clinical condition deteriorated with inability to ambulate and continued need for PEG feeding.
We highlight two variations to the traditional description of statin-induced HMGCR NAM: oropharyngeal dysphagia replacing the classic presentation of proximal muscle weakness and progression of disease despite immunosuppression.