Critical illness myopathy: Glucocorticoids revisited?

Severe acute myopathy following SARS-CoV-2 infection: a case report and review of recent literature

Background

SARS-CoV2 virus could be potentially myopathic. Serum creatinine phosphokinase (CPK) is frequently found elevated in severe SARS-CoV2 infection, which indicates skeletal muscle damage precipitating limb weakness or even ventilatory failure.

Case presentation

We addressed such a patient in his forties presented with features of severe SARS-CoV2 pneumonia and high serum CPK. He developed severe sepsis and acute respiratory distress syndrome (ARDS) and received intravenous high dose corticosteroid and tocilizumab to counter SARS-CoV2 associated cytokine surge. After 10 days of mechanical ventilation (MV), weaning was unsuccessful albeit apparently clear lung fields, having additionally severe and symmetric limb muscle weakness. Ancillary investigations in addition with serum CPK, including electromyogram, muscle biopsy, and muscle magnetic resonance imaging (MRI) suggested acute myopathy possibly due to skeletal myositis.

Conclusion

We wish to stress that myopathogenic medication in SARS-CoV2 pneumonia should be used with caution. Additionally, serum CPK could be a potential marker to predict respiratory failure in SARS-CoV2 pneumonia as skeletal myopathy affecting chest muscles may contribute ventilatory failure on top of oxygenation failure due to SARS-CoV2 pneumonia.

Intensive Care Unit-Acquired Weakness: Neuropathology

There is extensive evidence in the literature that both peripheral nerve fibers and muscle fibers are affected in the course of intensive care unit-acquired weakness. Peripheral nerve lesion is characterized by axonal degeneration, without inflammatory changes. Muscle fiber involvement is characterized by muscle fiber atrophy and loss of thick filaments, predominantly involving type 2 fibers, but myonecrosis ("acute necrotizing myopathy of intensive care") has also been reported. Steroids can precipitate thick myofilament damage, probably to some extent also triggered by immobilization and neuromuscular junction blockade. Sepsis and a systemic inflammatory response cause muscle fiber injury because of the release of cytokines and chemokines that modulate enzymatic reactions related to proteolysis. Regarding axonal injury, hyperglycemia, hypoalbuminemia, inflammatory response, and hypoperfusion are accepted risk factors. Nerve and muscle biopsy are the best methods for detection of structural abnormalities, but these are invasive investigations; although not suitable for repeated studies, in selected cases, biopsies may have a role in diagnosis.