--dietary lapses or other stress activations NECESSARILY implicate autoimmune processes, although they certainly CAN. But plenty of people notice symptom exacerbations with dietary lapses and other stressors (and not just with neuropathy, either).

Stress has a lot of biochemical effects that are still not greatly understood, though perpetuation of inflammatory responses is certainly among them, and that, of course, can lead to a whole host of symptoms.

And, as you can well imagine, many people with clear cut cases of, say, Type II diabetic neuropathy can have symptoms exacerbations if they eat a lot of carbs suddenly, or if they consume alcohol in some quantity. Not everyone necessarily experiences this, and the amounts that produce a reaction may vary greatly. But I don't think it's bad advice for anyone with neurologic symptoms, however idiopathic, to treat themselves as if they are diabetic/gluten sensitive/alcohol sensitive/vitamin deficient and live accordingly. Many do have better days if they limit carbs, gluten, and alcohol, and supplement reasonably. Nerves are very sensitive to stressors, and the fewer of these, and the more available good nutrients are, the better off they'll be.