Extra-axial Lower Motor Neuron Facial Palsy MRI and CT Findings

Abstract

The facial ncrH: is a mixed motor, secretomotor, and sensory nerve. The tacial nerve can be divided into six segments : the cisternal segment in the ccrchcllopontine angle ci tcrn: the canalicular segment in the internal auditor:• canal •. the IX:tr•ws or lab:rrintl1ine segment : the horizontal or intra tympanic segment: the Yertica I or mastoid segment posterior to the e ""ternal auditory canr,J: and the intraparotid segment interior to the stylomastoid foramen. The aim of this work is to study the CT & MRI anatomy of the tacial ncn•c as well as the various pathologic processes atlectin it along its intracrani 1L intratcmporal & extracranial course. Sixty­ eight c.ases cmnplainir,g or lower motor neuron facial palsy underwent clinical examination. either CT. or MRI ex:: minations or both. Patients were classified into five groups regarding the etiological cause oflower motor neuron t'acial palsy. Ciroupl traumatic: Group II Bell's palsy; Group Ill intlammatorv: Group IV Neoplastic: Group V Miscellaneous. \J.,'c concluded that CT examination is the best modality tor evaluating the facinl nerve canal r> 1ilc cnlwnced MR imaging will show the nen'e itself and ,•arious pathulogi•processes implicating the lacial nerve along its course t'rom the Ci!rct.dlnpontinc angle to its extracranial portion in the p:: rotiu .2lanu. CT is the modality of choice for diagnosis of traumatic cases as well a;; the bnnY ch:lllgcs in inllammatory and other miscellaneous conditiu!!s. 13ell's p;,!s,• cases need clinical and clcctroneurographic evaluati,-.n at tirst. t lr.h- :lt\•pical cases that do not respond to physical and mcdic:d tn:atmcnt O\.: r 2 Jll<mths duration need further evaluation bv cnhan..:ed lVIRI cxaminuti<>n <)t' th..: pctrous bone.