--is used as a diagnostic category by doctors for insurance purposes, but it is descriptive only; the term doesn't indicate cause, just symptom pattern.

You probably should expect to do more digging--maybe even into possible hereditary neuropathy syndromes, if you've had troubles for a long time, even back into childhood.

And yes, gluten sensitivity/celiac can be a cause of neuropathy. The Cornell Weill and Johns Hopkins medical centers, along with a number of European researchers, have been at the forefront of research into this. A positive anti-gliadin test does indicate you are making antibodies to gluten proteins. You should probably look at database known as The Gluten File:

https://sites.google.com/site/jccglutenfree/

It's unlikely a CT scan would show MS lesions of the brain and spinal cord; MRI is better for imaging soft tissues such as those. And sometimes clues to MS can be found in analysis of spinal fluid, or as the result of evoked potential testing. It wouldn't be a bad idea to have MRI's of brain and spinal cord done on sensitive MRI machines if you haven't already.