Even though I don't like to do this, I'll do some basic statistics. For simplicity, I'll assume that all involved variables are independent (they are dependant of course, but to reduce the involved dependencies, I'll increase the values of variables).

1. Let's assume that the incidence of ALS is 3/100 000=0,00003 (as I said, I started to exaggerate a little).

2. Assume that the patent's only symptom is twitching and that she/he had a clean clinical exam. I'll use the Eisen's famous 6.7% (this percentage is probably even lower, because most of us don't have frequent cramps on weird places). So we get a number of 0,00000201 (6 zeros).

3. Also assume that you had a clean EMG after several months of twitching. Many neuros will say that EMG is more than 90% reliable with respect to LMN abnormalities, so if I use 10%=(100-90)%, we get 0,000000201 (7 zeros).

If the numbers from this site http://www.lightningsafety.noaa.gov/odds.htm are correct, you can see that the odds of being struck by lightning in a given year is 1/1,190,000=0,000008403 (6 zeros). How many of you are afraid to be struck by lightning in the year 2015?

4. Moreover, if you are younger than 40, you have even more than 90% less chance of developing ALS at your present age... So, as I already said in my previous post, the chances are indeed astronomically low.