Now, the second type is called secondary progressive multiple sclerosis or SPMS which initially is pretty similar to the relapse-remitting type, but over time the immune attack becomes constant which causes a steady progression of disability.

第二种是继发进展型MS（SPMS）：发病一开始和复发缓解型MS很相似，但是一段时间后免疫攻击持续，导致残疾持续进展。