Aina Venkatasamy, Presenter: Nothing to Disclose

Marcela DE ALMEIDA CAVALCANTI, Abstract Co-Author: Nothing to Disclose

Sophie Anne Cahen Riehm MD, Abstract Co-Author: Nothing to Disclose

Francis P. Veillon MD, Abstract Co-Author: Nothing to Disclose

Anomalies of the course of the tympanic portion of the CN7 (VII-2) are the most common. An anterior displacement of the mastoid portion of the CN7 (VII-3) is important to specify before cochlear implantation. The CN7canal may be dehiscent, with or without inferior herniation of the corresponding nerve. The CN7 must always be analyzed on temporal bone CT / MRI.  

1) Agenesia or hypoplasia of the CN7 2) Anatomical anomalies of the course of the facial nerve and/or canal 2.1 Above the internal auditory meatus 2.2 Open angle between VII-1 and VII-2  2.3 Absence of VII-2 2.4 Lateralized VII-2 in the tympanic cavity 2.5 Inferior herniation of the nerve in a dehiscent bony canal  2.6 Lowered facial nerve in, close or not to the stapes, or below the oval window 2.7 Medialized VII-3 canal in or close to the jugular bulb 2.8 Anteriorized VII-3 3) Anomalies of size of the facial nerve canal The normal CN7 canal size has numerous normal variants: geniculate ganglion fossa ranging from 1.8 to 4.5 mm, VII-2 from 1.3 to 2.9mm. MRI HR T2 images are necessary for the detection of CSF in the geniculate ganglion fossa, which is a normal variant. The T1 postcontrast images eliminate a tumor. The enlarged geniculate ganglion fossa may also be due to a meningocele. 4) Nerve duplication VII-1, VII-2 or VII-3 duplication    

http://abstract.rsna.org/uploads/2014/14018881/14018881_qpoy.pdf

Venkatasamy, A, DE ALMEIDA CAVALCANTI, M, Riehm, S, Veillon, F, Imaging of the Congenital Anomalies of the Facial Nerve (CN7): How to Make Sure Your Favorite Surgeon Does Not Hit CN7 during His Procedure?.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14018881.html