I have PN in my face too. I had it more in my face & head than anywhere else. My MRI was clean and so were 2 CT scans. It may not be the cranial nerves per se, as there are tons of peripheral nerves that are also in the same area.

The brain and spinal cord are the CNS, not the peripheral system. Do you have problems with smell,taste,eye movement issues? I didn't. So my neuro said no cranial nerve involvement, but I'm not 100% convinced as I have eye twitching,heightened sense of smell,and pain in my head and cheeks.

As far as CNS involvement, hard to determine,but upper body involvement and face/head often signify some CNS involvement, but not always.