Disclosures: Aaron M. Krueger, MD: Nothing to disclose

Case Description: The patient presented to Neurology clinic with a chief complaint of walking difficulty and diffuse bilateral hand weakness. Past medical history was significant for obesity and hyperlipidemia. The patient was taking Simvastatin. Over the last 4 months the patient progressed to needing a cane for ambulation followed by a walker with accompanying grip weakness over 2 years. Physical exam revealed 4/5 hand and 3/5 strength in her lower extremities bilaterally. Bilateral foot drop was noted. NCS/EMG studies revealed proximal myopathic pathology with active denervating features suggesting a chronic moderate axonal sensorimotor polyneuropathy. The patient declined, requiring inpatient admission to the Neuro ICU for respiratory failure, dysphagia, and severe delirium.

Setting: Initial clinic presentation subsequently requiring Neuro-ICU care.

Patient: A 71-year-old female.

Assessment/Results: In the Neuro-ICU a CT-head, MRI brain, lumbar puncture, and autoimmune panel assay could not pathologically describe the patient’s symptoms. A left deltoid muscle biopsy showing necrotizing myopathy with rare lymphocytic inflammatory cell infiltrates confirmed the diagnosis of necrotizing autoimmune myositis (NAM). Marker testing for Anti-HMGCR and Anti-SRP antibodies was found to be seronegative for both markers. Simvastatin was discontinued, prednisone initiated, and two failed attempts at IVIG treatment were made but were limited by respiratory distress. The patient was placed on hospice and expired shortly thereafter.

Discussion: NAM is a rare form of myositis comprising only 16% of 1 of every 100,000 cases of idiopathic inflammatory myopathies annually. Our patient presented with a very rare form of NAM that was dual seronegative for both Anti-HMGCR and Anti-SRP IgG antibody levels, markers used to help diagnose NAM.

Conclusion: NAM is a rare disease affecting muscle tissues that is mildly associated with statin use. This is a rare case of NAM presenting as hand and lower extremity weakness found to be dual seronegative for Anti-SRP and Anti-HMGCR antibodies.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/hand-and-lower-extremity-weakness-in-dual-seronegative-3-hydroxy-3-methylglutaryl-coenzyme-a-reductase-and-signal-recognition-particle-antibody-necrotizing-autoimmune-myositis-a-case-report/