Two of my dogs have been MRI'd for suspected SM. Oz has the malformation but no syrinxes yet, while Riley has SM and had surgery last June. Oz bounced back from it like he had never been sedated and was a wild man right away (He was 11 months old). Riley however, had problems recovering from the anesthesia and needed to stay overnight so they could monitor her. I think she is definitely the exception rather than the rule though.
If she is diagnosed with SM, I would just be sure you are clear on your options. With Riley I was told by two different neurology groups that she needed surgery and was not a candidate for long-term medical management. See if you can find out how large the syrinxes are - I think how wide they are is the more important measurement and how much of the spinal column is affected. Just be sure you understand the dosing of any medications and side effects. Also, talk about what kind of effects you should see from medication even if she is a candidate for surgery. That way, you will have some idea if the medication is doing what it should be doing. Both Jen and Linda had some great suggestions for questions also. Regarding the microchip - my dog's neurologist said that the MRI can sometimes disrupt the microchip and I should have it read by the vet's office afterwards. Both dog's chips worked just fine.
This is not a journey any of us want to take, but unfortunately too many of us have been down this road. I'm sorry you have this worry. If you get an SM diagnosis, use the support we can all give you. Believe me, it's helped me through some rough patches.