I had to figure out the workings of both the A & C nerves on my own after seeing 4 Neurologists ( who of course Rx d Gabapentin , NG ) tried Capzasin HP , Benadryl , 1 jerk PA had me using a Topical Anti Bacterial , I saw 10 other Drs. , Lidocaine , Lyrica , MRI $$$$$$$$$$ Jackpot for them . I got tired of it after 14 months , took matters into my own hands and surmised I had some Myelin Sheath disruption / damage , Axons , Transmitters , Receptors ( signals ) all in the T5 upper branch . All of that figured out on this keyboard and I quit high school in the 11th. grade to eat lunch . Finally I figured it out , found the right medication for less than $15 . Some Post Herpetic Neuralgia difficulty thanks to not 1 dr. ever bothering to examine my scalp or behind / above the eyebrow . SAD