Speech deficits in multiple sclerosis: a narrative review of the existing literature oleh Panagiotis Plotas, Vasiliki Nanousi, Anastasios Kantanis, Eirini Tsiamaki, Angelos Papadopoulos, Angeliki Tsapara, Aggeliki Glyka, Efraimia Mani, Fay Roumelioti, Georgia Strataki, Georgia Fragkou, Konstantina Mavreli, Natalia Ziouli, Nikolaos Trimmis