Persistent neuromuscular disorders associated with changes in tibialis anterior and gastrocnemius lateralis muscle architecture in long-covid: an observational longitudinal study

Long COVID-19 causes complications, affecting quality of life and work capacity. However, its long-term impact on lower limb neuromuscular function remains unclear. To evaluate neuromuscular electrophysiological disorders (NEDs) and muscle architecture of the tibialis anterior (TA) and triceps surae (TS) in individuals with moderate or severe COVID-19 compared to control group over 12 months. Seventy participants were divided into moderate-COVID (n = 22), severe-COVID (n = 18), and control (n = 30) groups. COVID groups underwent four assessments over one year. NEDs in the TA and gastrocnemius lateralis (GL) were assessed via stimulus electrodiagnostic testing, while TA and TS muscle architecture was evaluated using ultrasound. Participants with severe-COVID exhibited significantly higher chronaxie (p < 0.001) in the TA at the first assessment, NEDs were observed in 55.55%, 33.33%, and 16.66% of participants across the first three assessments. GL showed 5.55% prevalence of NEDs. Echogenicity increased in TA and GL muscles in the severe-COVID group (p < 0.001). An association was found between TA chronaxie and echogenicity in the COVID groups during the short-term assessment (p < 0.001). Severe COVID-19 is associated with higher prevalence of NEDs in the TA muscle and persistent echogenicity increases, suggesting polyneuromyopathy in the TA and widespread echogenicity abnormalities in long COVID patients.