The new insights presented at the 5th Joint Triennial Congress of the European and Americas Committees on Treatment and Research in Multiple Sclerosis (ECTRIMS and ACTRIMS) held in Amsterdam, the Netherlands, 19-22 October 2011, have been summarized at the fourth edition of Post-ECTRIMS meeting held in Madrid in November 2011. Further evidence from epidemiological studies yield a possible relationship between nutrition and alterations of the microbiota that may result in the development of multiple sclerosis (MS) and that may trigger the exacerbation of disease symptoms. Also show the magnitude of impact of comorbidities in multiple sclerosis course as well as the impact of early identification and management. Review of current data on chronic cerebrospinal venous insufficiency and MS sclerosis concludes that there is no role of chronic cerebrospinal venous insufficiency in either multiple sclerosis risk or MS severity. New diagnostic criteria for MS have simplified requirements for demonstrating dissemination of lesions in time. High-field magnetic resonance imaging improves cortical visualization and become a promising tool to detect remyelinization and cortical and medullary lesions, and optical coherence tomography is established as a powerful tool for neuroprotection trials. Diffuse meningeal inflammation through B-cell follicle-like structures is associated with cortical pathology and an accelerated clinical course in secondary progressive MS sclerosis. Systemic inflammation may contribute to neurodegeneration processes in MS, and with regard to grey matter damage recent findings conclude that occurs early in disease course, and correlates with future MS-related disability.