I think your mayo trained neurologist needs to ask more of her patients if they suffer from fatigue during the day. It may not be a symptom of sfn but it can certainly be a result of sfn. Pain can certainly grind you down, disruption of sleep patterns, taking much more effort to do things than before because of limitations resultant from PN, possible autonomic complications for some of those with sfn, living with uncertainty everyday are just a few reasons i can think of off the top of my head.