Table 6.

Paraneoplastic involvement of cranial nerves.

CN	Neoplastic	Paraneoplastic syndromes	Other mechanisms
II	Base of the skull	Optic nerve neuropathy/neuritis	Other immune-mediated causes, hyper-viscosity
	Leptomeningeal carcinomatosis	CAR, MAR
III, IV, VI	Base of the skull tumors/metastasis	Individual cases	/
	Orbital metastasis
	Leptomeningeal carcinomatosis
V	Local metastasis, base of the skull metastasis, mandibular metastasis	Numbness trigeminal nerve, or parts (chin, cheek)	Isolated facial pain, neuralgia
VIII	Leptomeningeal carcinomatosis	Few reports on vestibular neuritis	/
Caudal CNs	Base of the skull metastases	Not reported (isolated nerves)	Focal amyloid in plasma cell dyscrasia
	Leptomeningeal carcinomatosis
	Lesions after the exit of CN of the bony skull
Multiple CNs	Base of the skull metastasis	Few reports, not homogeneous	/
	Leptomeningeal carcinomatosis

CAR, cancer associated retinopathy; MAR, melanoma associated neuropathy.