Cross-sectional case-control studies (Blue)
The objective of this study was to explore the spectrum of skeletal muscle and nerve pathology of patients who died following SARS-CoV-2 infection and assess for direct viral invasion of these tissues. Psoas muscle and femoral nerve sampled from 35 consecutive autopsies of patients who died following SARS-CoV-2 infection and 10 SARS-CoV-2-negative controls were examined under light microscopy. Clinical and laboratory data were obtained by chart review. In SARS-CoV-2-positive patients, mean age at death was 67.8 years (range 43-96 years) and the duration of symptom onset to death ranged from 1-49 days. Four patients had neuromuscular symptoms. Peak creatine kinase was elevated in 74% (mean 959 U/L, range 29-8413 U/L). Muscle showed type 2 atrophy in 32 patients, necrotizing myopathy in 9, and myositis in 7. Neuritis was seen in 9. Major histocompatibility complex-1 (MHC-1) expression was observed in all cases of necrotizing myopathy and myositis and 8 additional patients. Abnormal expression of myxovirus resistance protein A (MxA) was present on capillaries in muscle in 9 patients and in nerve in 7. SARS-CoV-2 immunohistochemistry was negative in muscle and nerve in all patients. In the 10 controls, muscle showed type 2 atrophy in all patients, necrotic muscle fibers in 1, MHC-1 expression in non-necrotic/non-regenerating fibers in 3, MxA expression on capillaries in 2, and inflammatory cells in none, and nerves showed no inflammatory cells or MxA expression.The authors concluded that muscle and nerve tissue demonstrated inflammatory/immune-mediated damage likely related to release of cytokines. There was no evidence of direct SARS-CoV-2 invasion of these tissues. This study provides class IV evidence that muscle and nerve biopsies document a variety of pathological changes in patients dying with COVID-19.
Joome Suh, Shibani S. Mukerji, Sarah I. Collens, Robert F. Padera, Geraldine S. Pinkus, Anthony A. Amato, Isaac H. Solomon. Skeletal Muscle and Peripheral Nerve Histopathology in COVID-19. Neurology Jun 2021, 10.1212/WNL.0000000000012344; DOI: 10.1212/WNL.0000000000012344