I'm not a doctor but if you've ever had to deal with nerve pain or neurological conditions in general, there's a ton of stuff we don't know. Doctors will readily admit this. Not sure that the question of whether we've "tried hard" to understand it is a productive one but there's a ton of stuff where we have only a vague idea of what is going on, we prescribe drugs that sort of work but we don't know how they work, conditions that they can't even nail down a diagnosis for, etc. It's probably one of the least well understood areas of medicine.