Normal Enhancement of the Facial Nerve

The circumferential facial arteriovenous plexus provides arterial supply and venous drainage of the facial nerve, the ossicular chain, the middle ear muscles and tendons, and of the mucosa and bone walls of the tympanic cavity. The plexus is suspected to result in non-pathological apparent enhancement of at least one segment of the normal facial nerve in about 75% of cases.

The segments that most commonly show normal apparent enhancement are the mastoid segment (100%) the geniculate ganglion (78%) and the tympanic segment (38%). The intracanalicular (meatal) and labyrinthine segments can also show mild apparent enhancement in some cases (15% and 5%, respectively); however, intense enhancement of these two segments is characteristically seen in Bell palsy.

References

• Gebarski SS, Telian SA, Niparko JK. Enhancement along the normal facial nerve in the facial canal: MR imaging and anatomic correlation. Radiology. 1992 May;183(2):391-4.
• Hong HS, Yi BH, Cha JG, Park SJ, Kim DH, Lee HK, Lee JD. Enhancement pattern of the normal facial nerve at 3.0 T temporal MRI. Br J Radiol. 2010 Feb;83(986):118-21.