I should add one more thing for completeness.

About a full year I really noticed any SFN symptoms, I suffered from an acute onset of a plurality of neurological systems, including severe intermittent headaches (which were nothing like the few migraines or other headaches I've head--these were very localized unilateral pains), sensitivity to bright lights, blurred/difficult vision, difficulty speaking, alcohol intolerance, tinnitus, insomnia, short term memory loss, extreme difficultly concentrating on challenging task, and some loss of fine motor skills (my handwriting suddenly became terrible).

Prior to this acute onset I had been feeling 'off' for a few months, but had none of the above systems.

I went to the doctor a few days after this started and had an EEG and a brain MRI, but everything looked fine.

After a few months of hell, I could appreciate that the symptoms were decreasing and becoming more episodic, and they continued to improve over the next 3 years. They are basically gone as of today, except for some mild tinnitus and insomnia. (neither of which I ever had before this started).

Because of this, there was a concern about neurosarcoidosis--it can cause most of the above systems. However, my brain MRI was normal, as was a chest x-ray.

Obviously this could have no connection to SFN, but I have no idea.