@birdman518 It must feel good to have some answers. With spinal cord compression at C3, this can generate other symptoms in your body, so it may be related to your arm pain, but there are no tests that would confirm it. When you have stenosis in the foramen at the nerve roots, that produces specific pain where those nerves go and that will follow a dermatome map. I had pain all over my body from spinal cord compression at C5/C6, and I did not have nerve root compression. My stenosis was labeled "moderate" and that was enough to cause an uneven gait, muscle spasms in my legs, tingling and numbness, and I was loosing coordination in my arms. I lost some muscle due to atrophy and not all came back, even though my MRI did not show spinal cord damage. Mild myelopathy may not show on the MRI. Trust your gut about your symptoms. I knew that my all over pain was caused by the cord compression because I had tracked my symptoms over time, and for a while, I could turn pain on and off simply by turning my head or bending my neck. My surgeon couldn't promise that the surgery would fix my pain, but it did.
A good surgeon does not pressure a patient for a decision, and will help the patient make an informed decision by explaining the risks and benefits, so it is good your surgeon took time and did this. One question I would ask would be about the materials in the implants and if there are different choices on hardware or no hardware. I was worried about foreign materials, and my surgeon told me that a fusion heals best with just a bone graft. A metal plate on the front on the spine ads stability and gives the surgeon some peace of mind, but it is not always necessary. Before plates were invented, a patient just stayed in a hard collar until fused. I made that choice and did that because I had some concerns about a potential immune reactions to metals because I developed problems wearing pierced earrings. There are lots of implants that screw in at an angle so no anterior plate is needed. If an immune reaction happens, it may not be possible to remove a "cage" that has bone fused around it. My hunch turned out to be right because after I broke my ankle, I could not avoid having titanium plates and screws, and I developed chronic hives and pain a few months after the surgery. Another issue was that after having metal placed in my body, my asthma got worse and I had trouble getting my lungs clear. I made the decision to remove the ankle hardware a couple months ago, and my health improved and my breathing improved again. That may not be an issue for you. I am glad that I chose a fusion with no hardware and I was in a neck brace for 3 months by choice. Bone also has a very slight bit of flexion to it and when you screw rigid hardware to it, that changes. Plate length can also influence adjacent segment disease. The longer the plate, the greater the risk and if it is too long, it can rub on an adjacent disc. A bone graft fusion shrinks a little bit as a fusion heals. Perhaps that is the reason your surgeon suggested a metal cage, but that might be something to ask questions about.
You may want another opinion. Surgeons have different choices in spine hardware and tend to use the companies that they are familiar with, so you may get a different option with another surgeon. I wasn't really clear about which 3 levels you mentioned as you mentioned C3/C4 and C5/C6. You have been living with symptoms a long time, and things can always get worse. Did your surgeon explain how things would progress without surgery? My opinion really doesn't matter, what matters is what you think is the right path for you.