Autonomic dysfunction in long-COVID syndrome: a neurophysiological and neurosonology study - Papadopoulou, Marianna; Bakola, Eleni; Papapostolou, Apostolos; Stefanou, Maria-Ioanna; Gaga, Mina; Zouvelou, Vasiliki; Michopoulos, Ioannis; Tsivgoulis, Georgios (Journal of neurology, 2022)