SNUBBYFAN,
IF you have a diagnosis of ALS/MMN, the doctor will happily put that into a letter and this would qualify you for fast track handling of social security, Medicare, and Veterans benefits (if you are a veteran). Don't delay. This is significant money, backdated to the date you applied. And eventually, if not soon, you will need all the money help you can get. We've all been through this, and it is important to do as soon as you have a diagnosis.
If, in the rare chance that your doctor won't say "this is ALS," then just get him to write the key phrase is: "is more likely than not indicative of ALS." Good luck.
Also, think about your dependents: request to max out your life insurance policy immediately, today, prior to getting the diagnosis in writing if possible.