No one can predict 100 per cent who will get better or how much they will improve after surgery. In the case of your condition (called cervical compression myelopathy (CCM)) the chances are very good that you will get significant improvement with cervical fusion.
Many studies done show up to 80 per cent of patients with CCM get pain relief and improved function with this treatment. The neck and arm pain, numbness and tingling, and arm weakness get better and so does function.
Scientists have tried to figure out what makes the difference between someone who gets better with surgery and someone who does not. Is it age? Severity of symptoms? Length of time the symptoms were present before surgery? Curvature of the spine?
A recent study to look at predictive factors found that it wasn't any of those things. Just having the fusion was enough to bring about the good results. One way to test how much benefit you might get from a fusion is to try wearing a neck brace or cervical collar for two or three days.
Get a firm neck collar (not the soft foam kind). Try one that really restricts your motion. Keep in mind that a cervical fusion will only stop motion at the level that's been fused, not the entire neck. Since muscles atrophy quickly and motion is important for overall function, don't try this for more than the two or three days suggested.
If you experience improvement, you may want to consider having the operation sooner than later. This is not a foolproof method of prediction. No studies have been done comparing patients before and after fusion who used this test to predict results.