Persistent neuromuscular dysfunction in long COVID: A quantitative and single fiber EMG follow-up study

Area of Science:

• Neurology
• Infectious Diseases
• Rehabilitation Medicine

Background:

• Persistent symptoms after SARS-CoV-2 infection, known as long COVID, represent a significant ongoing health concern.
• Previous studies indicated electromyography (EMG) and single-fiber EMG (SFEMG) abnormalities in long COVID patients.
• This research focuses on the long-term neuromuscular consequences of SARS-CoV-2 infection.

Purpose of the Study:

• To evaluate the long-term neuromuscular manifestations in patients with long COVID.
• To assess changes in myopathic findings and SFEMG abnormalities over time.
• To investigate the persistence of neuromuscular dysfunction in long COVID.

Main Methods:

• A follow-up study involving 50 long COVID patients with prior myopathic EMG/SFEMG findings.
• Quantitative EMG (qEMG) and SFEMG were performed at baseline and after a mean follow-up of 1.38 years.
• Comparison of EMG, SFEMG, and clinical scores using statistical tests.

Main Results:

• Motor unit potential amplitudes and durations increased in specific muscles (BB, TA, VM), while polyphasic potentials remained unchanged.
• SFEMG findings in TA and EDC showed no significant changes over the follow-up period.
• Myopathic qEMG decreased from 78% to 18%, while abnormal SFEMG remained prevalent (54% to 56%).

Conclusions:

• Myopathic changes on qEMG diminished over time in long COVID patients.
• SFEMG abnormalities and clinical fatigue scores persisted, indicating ongoing neuromuscular dysfunction.
• These findings suggest that while some neuromuscular changes improve, other mechanisms contribute to persistent long COVID symptoms.