Grade |
Zone involved |
Zonal anatomy |
PN 1 |
Clinical PNI imaging zone 1 |
V1: Up to superior orbital fissure, V2: Up to foramen rotundum, V3: Up to foramen ovale and VII: Up to stylomastoid bell or foramen |
PN 2 |
Clinical PNI imaging zone 2 |
V1, V2 and V3: From zone 1 to Gasserian ganglion. VII: Zone 1 to lateral end of IAC including geniculate ganglion and labyrinthine segment of facial nerve |
PN 3 |
Clinical PNI imaging zone 3 |
All nerves proximal to ganglion into the cisterns or into the brain stem |