By the time my mother saw a neurosurgeon, the doctor told me that she suspected ALS based on the tests she did in the office. We did not get a definite dianosis until she had the EMG and Nerve Conduction tests. The day she had the tests, I asked the doctor that did them if there was any sensory problems showing. He wouldn't give me an answer in front of her. Instead, after my father was pushing her wheelchair out of the exam room, he took me aside and told me that there was no sensory problems showing in the nerve conduction studies. I had already researched ALS and knew a lot of what was to come. I had read that nerve conduction studies showing motor problems with no sensory problems pointed to ALS. I knew she had ALS the day we walked out of that office. The official diagnosis came 3 weeks later when the test results came back.
You have to realize, She was playing softball with the grandkids in April 2007. She developed a dropfoot in May 2007. She wasn't diagnosed until Feb. 2008. By that time, she was using a cane and/or in a wheelchair when she would have to walk longer distances. She was affected all over to some degree from May 2007 through Feb 2008. In nine short months she went from running to barely able to go using a walker. From Feb to October 2008, she lost her voice, got a peg , then eating ability was lost. She hasn't ate since late October 2008. She had been bedridden Since late November 2008. She is now on neurontin, oxycodone, and morphine for pain. The one thing she doesn't have is a bi-pap machine. She refused it at the outset. She has good days and bad days (for her). There have been times when we were sure she was leaving us....only to have her bounce back.
With that history stated, I do believe a neurologist can diagnose ALS, if you are affected to the same degree my mother was, without actual testing. However, I do not believe any neurologist will diagnose ALS without standardized testing. As for ruling it out without testing, I would say that in the really early stages, most doctors, including neurologists, would not go into depth testing for it. Remember, the doctors attempt to rule out everything else it could be before giving such a sad diagnosis.
My advice to you is to live your life to the fullest now.....if you have ALS, you will be glad you did what you could do while you could do it. If, it turns out you don't have ALS, you will have had a full life when your time does come. Either way...... no regrets!