I had emg which showed fasciculations and told it was normal. have brisk reflexes whole body muscle soreness and joint tightness. can emg miss als?

Can be tricky: The diagnosis of ALS can be tricky using EMG criteria only. And yes, in the early stages of the disease the test may not even be that sensitive. However, and thankfully, ALS is a relatively rare and unusual disorder for anybody under the age of 50 or 55 to contract. Best evaluation is by a neurologist with experience in neuromuscular disorders and by using both clinical and electrical information.

Unlikely: Emg is the gold standard for diagnosis of als, and is very unlikely to miss it. The exception would be very early disease in als. Fasciculations are normal, and that finding in isolation means nothing. Als typically does not cause whole body muscle soreness or joint tightness.