Clinical and laboratory characteristics of secondary progressive MS.
Secondary progressive (SP) MS follows on from but is distinct in its clinical picture from relapsing remitting (RR) MS. Diagnosis is usually straightforward except during the transitional stage when the two phenotypes merge. It is clear that most patients that start with relapsing remitting MS will develop SP disease, although the underlying pathogenesis that causes this change is subject to much debate. Clinical features such as pattern and site of symptoms, and age of onset, in the relapsing remitting stage versus progressive disease, suggests a difference in the pathophysiology. Laboratory markers may give insight into the disease mechanisms. Measures of urinary and CSF myelin basic protein-like material (MBPLM) indicate demyelination and subsequent oligodendrocyte and axonal loss. Tertiary neutralising antibodies to MBP antibodies could attenuate remission and lead to continuous progression, and neuronal antibodies found in SP disease may contribute to the axonal loss. In addition, differences in nitric oxide and other inflammatory cytokine patterns might either be secondary to or causative of the pathological mechanisms.Greater understanding of progressive MS is a priority considering permanent disability results almost entirely from this stage of the disease.