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

Abstract

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.

Keywords: Electromyogram; Guillain-Barré syndrome; Myopathy; Nerve conduction; SARS-CoV2.

Fig. 1

Nerve conduction study, electromyogram, and disease trajectory. (a) Motor and sensory nerve conduction was normal despite severe muscle weakness. Compound muscle action potential (CMAP) amplitudes are measured in millivolts (mV); 2 mV per division for all motor study traces. DML, distal motor latency in ms. MCV1, motor conduction velocity in millisecond (ms). MCV2, motor conduction velocity in ms. Sensory nerve action potential (SNAP) amplitudes are measured in microvolts (μV); 20 μV per division for all sensory study traces. DSL, distal sensory latency. SCV, sensory conduction velocity. (b) Electromyogram (EMG) showing myopathic motor unit potentials, a full recruitment pattern and spontaneous muscle fiber activity in several sampled muscles. Motor unit potential (MUP) amplitudes are measured in microvolt (μV); 200 μV per division for all EMG traces

Fig. 2

Muscle histopathology and MRI of upper thigh axial sections. (a-d) Muscle histopathology sections sampled from quadriceps femoris muscle stained with hematoxylin and eosin, showed variation in muscle fiber size with predominantly spherical shape myosites and multifocal and discrete myosite degeneration lacking infiltration of inflammatory cells. (e) T2 weighted MRI section of the upper thigh done on day 20, showed marked hyperintensity in both the quadriceps muscles. (f) Repeat T2-weighted MRI of the same section of the thigh muscles done after 48 days of the 1st MRI shows both the quadriceps muscles appear normal