There is presently no efficient therapy available in progressive MS, especially if there is no clear evidence of active inflammatory lesions or exacerbations as part of the disease. There are, however, evidence that some treatment protocols using cytotoxic drugs may to some extent slow down the progressive course. One specific feature of long-standing MS is that inflammatory cells accumulate in the central nervous system(CNS) compartment in the subarachnoid and perivascular spaces and may therefore be hard to reach via standard drug delivery through systemic administration. Administration of substances via the Intrathecal (IT) route, however, have shown to efficiently distribute in the subarachnoid spaces and may therefore be an attractive route of drug delivery