Hello paper_bats and welcome to NeuroTalk.

The EMG is used in the diagnostic process for many things, but is not part of the diagnostic criteria (McDonald Criteria) for Multiple Sclerosis.

If the EMG is abnormal then Multiple Sclerosis is ruled out as the cause for your symptoms and will give your Dr. an idea of what should be looked at for a possible cause.

Multiple Sclerosis is a disease of the Central Nervous System(CNS) which includes the brain, spinal cord and optic nerves. Your Dr. is looking to rule in/out peripheral nerve involvement which is not MS.

Spine problems (degenerative disc disease, herniated/bulging disc, stenosis and more) can cause neurological problems but this would not be related to Multiple Sclerosis.

Below are two links the first one explains the criteria for diagnosing MS and the second link explains those other conditions that cause symptoms similar to MS.

http://www.nationalmssociety.org/Sym.../Diagnosing-MS

http://www.nationalmssociety.org/Sym...ns-to-Rule-Out