Deterioration of weakness despite the discontinuation of atorvastatin argues against statin myotoxicity. However, autoimmune  / necrotizing myopathy may develop in patients exposed to statins, manifesting by progressive weakness and persistet elevation of CK despite discontinuation of statin.  Seropositivity for autoantibodies targeting 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), the pharmacologic target of statins, is now commercially available to assess for statin induced autoimmune myopathy¹. Celiac disease could result in proximal weakness and pain in association with rickets and vitamin D deficiency, mainly in children ². The presence of monoclonal gammopathy raises the possibility of amyloid myopathy and late onset nemaline rod myopathy. The finding of mixed myopathic and neurogenic findings in the EMG is non-specific, but suggests chronic myositis, inclusion body myositis and nemaline rod myopathy. A muscle biopsy (quadriceps) was done as the next diagnostic step.

References:

1.         Mohassel P, Mammen AL. Statin-associated autoimmune myopathy and anti-HMGCR autoantibodies. Muscle & nerve 2013;48:477-483.

2.         Suthar R, Sankhyan N, Thapa BR, Singhi P. Proximal Myopathy: A Rare Presentation of Celiac Disease. Journal of child neurology 2013;28:1485-1488.