Table 2. Details of perineural invasion, radiotherapy (RT) for cranial nerves (CNs) and patterns of failure in CNs.

These results summarize clinical (C), radiological(R), and surgical (S) data. Involvement of trigeminal ganglion, auriculotemporal nerve (ATN) and greater superficial petrosal nerve (GSPN) was always identified radiologically.

	Site of primary	Neural target in first RT course to nerves	Site of failure following first RT course to nerves	Site of failure following second RT course to nerves	CN involvement, sequence of events
1	primary not identified	CN V, VII and cavernous sinus	Treated nerves		V2-3(C), VII(C), trigeminal ganglion
2	temple	V2-3 and cavernous sinus	V1 and CN VII		temporal branch of facial nerve(S), V1-3(C), trigeminal ganglion, GSPN, VII(C), III, IV, VI(C)
3	forehead	V1 and cavernous sinus	V3		V1(C), trigeminal ganglion, V2-3(C), VII(C), III, IV, VI (C)
4	medial cheek	V2-3 and cavernous sinus	V1 and CN VII		V2-3(C), GSPN, VII(C), V1 (C), trigeminal ganglion, III, IV, VI (C)
5	lateral eyebrow	V1			V1(S)
6	preauricular	CN VII	ATN and V3		VII(C), V3(C,R)+ATN
7	ear	CN VII	ATN and V3	V2, inferior alveolar verve, cysternal segment of CN V	VII(C), ATN+ V3(R), trigeminal ganglion, V2(R)
8	cheek	CN VII, ATN, V3			VII(S), ATN, V3(S)
9	cheek	CN VII, ATN, V3			VII(C), ATN, V3(R)
10	nasal ala	CN VII and V			VII(C), V(C)
11A	primary not identified	left V3	left CN VII		left V3(C), VII(C)
11B	ear	right CN VII (excluding the cochlea)	right tympanic portion of CN VII		right VII(C)