I'd get a second opinion (on ANYTHING before having surgery for the issue). But it sounds like you may be at the point where surgery is the best or only life-saving option.

There ARE risks to surgery and my experience is that doctors tend to downplay risk in general; stroke is one (death is another, of course). That's not to warn you away from surgery: EVERYTHING, no exceptions, has risk. NOT having surgery in your situation has risks.

Some things might help improve your situation WITHOUT surgery, or provide better chances of a good outcome following surgery. Here's one example:

Nattokinase (from https://www.lifeextension.com/protocols/heart-circulatory/stroke-cerebrovascular-disease)

Nattokinase is an enzyme extracted from fermented soybeans. Research generally supports nattokinase supplementation as safe and promising for cardiovascular disease risk reduction162 and functional protection after stroke.163,164 In preclinical and clinical studies, nattokinase has been shown to break down the protein fibrinogen, which contributes to blood viscosity and clotting. It has also demonstrated lipid- and blood pressure-lowering activity, as well as neuroprotective effects.163 In a randomized controlled trial published in 2008, individuals who received 2,000 fibrinolytic units (FU) of nattokinase per day for eight weeks experienced reductions in systolic and diastolic blood pressure of about 5.5 mm Hg and 3 mm Hg, respectively.165 In an open-label trial in 45 subjects, supplementation with 4,000 FU of nattokinase daily for two months resulted in decreased levels of blood clotting factors, including fibrinogen, factor VII, and factor VIII.166

And speaking of risk:

Safety note: Cerebral hemorrhaging was reported in a patient concomitantly using aspirin and nattokinase for secondary stroke prevention.167 Therefore, a risk assessment by a healthcare provider is warranted before individuals taking an antithrombotic agent initiate nattokinase supplementation.

There are many things that can improve the odds of surviving surgery (or stroke, for that matter) with less damage than otherwise. I'd look into PQQ, CoQ10, Vitamin C, and a whole raft of other things. You'd naturally want to talk to your doctors about this -- especially about anything taken shortly before surgery, or that might conflict with medications you're taking or would be given during or after surgery -- and I would also talk to medical and medical-adjacent people who FOCUS on nutrition and supplements, given that many MDs are largely ignorant and/or biased about anything non-Rx.

You've been working hard for a long time at keeping yourself healthy -- most don't, of course -- so I believe you can make the most of the information out there and chose the best path for your particular case.

Best wishes, BerlinWallCrosser.