1. Department of Internal Medicine, Division of Pulmonary, Critical Care and Sleep Medicine, Saint Louis University School of Medicine, 3635 Vista Avenue, St. Louis, MO 63110-0250, U.S.A.
2. Department of Clinical and Experimental Medicine and Pharmacology, University of Messina, Messina, Italy
3. IRCCS (Istituti di Ricovero e Cura a Carattere Scientifico) Centro Neurolesi ‘Bonino-Pulejo’, Messina, Italy