Will be following this with interest as have had steady decline over last couple of years but stable MRI! My neuro is in agreement that I am very possibly SPMS ...BUT doesn't want to label as such because he said once labelled as SPMS there is no going back and only one med in UK - Siponimod I think? When did you last have an MRI? I think it may be worth pushing for an up to date one as that would pretty much show any recent lesions either old ones acting up or new ones. Then once the results of that come in..... move the discussion forwards from there? Just my thoughts and you have my sympathy. I was reading an article by Prof Giovannoni that said even old inflammatory activity can continue to cause damage for many years...he also has an interesting article about Smouldering MS. Might be worth a read for you?

You type of know, you have no break from your symptoms, your disability gets worse, you start walking with a cane in my case , and can't walk distances without a wheelchair. So was not a shock when constant moved me to new treatment for SPMS. And it was Google telling me as constant did not . I did get it confirmed by MS nurse when I asked her. Good luck.