Ross
24 KiB
24 KiB
title, docid, authors, breadcrumbs, category, cmeTopicId, documentVersionId, imageCount, lastUpdated, pageDescription, pageKeywords, pageTitle, enhancedTitle, type, references, ddx, anatomy, cases, breadcrumbs
| title | docid | authors | breadcrumbs | category | cmeTopicId | documentVersionId | imageCount | lastUpdated | pageDescription | pageKeywords | pageTitle | enhancedTitle | type | references | ddx | anatomy | cases | breadcrumbs | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Intratemporal Facial Nerve Enhancement | a3569ec5-a566-411d-877f-41ad832e3fd2 |
|
|
Head and Neck | 2388da47-1d41-4309-8db6-b977b488180a | 0fdb4514-1f1b-4100-a7fd-91cff6019fde | 10 | 09/24/21 | Intratemporal Facial Nerve Enhancement | Head and Neck, Diagnosis, Temporal Bone, Intratemporal Facial Nerve, Pseudolesions, Intratemporal Facial Nerve Enhancement | Intratemporal Facial Nerve Enhancement | STATdx | Intratemporal Facial Nerve Enhancement | DX | true | true |
|
1 |
|
title: "Intratemporal Facial Nerve Enhancement" docid: "a3569ec5-a566-411d-877f-41ad832e3fd2" authors:
- key: "94f835c8-fa13-4e8a-995b-53048e6b0605" value: "Philip R. Chapman, MD" breadcrumbs:
- name: "Head and Neck" slug: "head-and-neck" treeNodeId: "ed24ed8c-5d57-4629-879b-447b82d2973d"
- name: "Diagnosis" slug: "diagnosis" treeNodeId: "19b6b986-97d0-40e7-b317-00f0c5cd8fa2"
- name: "Temporal Bone" slug: "temporal-bone" treeNodeId: "9ad7d7b2-b2e4-4de2-be04-55ce607560c9"
- name: "Intratemporal Facial Nerve" slug: "intratemporal-facial-nerve" treeNodeId: "35b77f60-796d-460f-8bac-4a187a150171"
- name: "Pseudolesions" slug: "pseudolesions" treeNodeId: "eb1df224-339c-469f-857b-200d08f330df"
- name: "Intratemporal Facial Nerve Enhancement" slug: "intratemporal-facial-nerve-enhance-" treeNodeId: null category: "Head and Neck" cmeTopicId: "2388da47-1d41-4309-8db6-b977b488180a" documentVersionId: "0fdb4514-1f1b-4100-a7fd-91cff6019fde" imageCount: 10 lastUpdated: "09/24/21" pageDescription: "Intratemporal Facial Nerve Enhancement" pageKeywords: "Head and Neck, Diagnosis, Temporal Bone, Intratemporal Facial Nerve, Pseudolesions, Intratemporal Facial Nerve Enhancement" pageTitle: "Intratemporal Facial Nerve Enhancement | STATdx" enhancedTitle: "Intratemporal Facial Nerve Enhancement" type: "DX" references: true ddx: true anatomy:
- "{'authors': 'Philip R. Chapman, MD; Ryan P. Cabeen, PhD', 'bookmarked': False, 'bookmarkUrl': '/document/bookmark/2f4818dd-6438-405b-8561-5cbbb9c91562', 'category': 'Brain', 'compareUrl': '/compare/document/2f4818dd-6438-405b-8561-5cbbb9c91562/related-anatomy/treeNode?subContext=Facial Nerve (CNVII)', 'documentId': '2f4818dd-6438-405b-8561-5cbbb9c91562', 'documentType': 'ANATOMY', 'documentUrl': '/document/facial-nerve-cnvii/2f4818dd-6438-405b-8561-5cbbb9c91562', 'enhancedTitle': 'Facial Nerve (CNVII)', 'entryDate': '10/20/20', 'imageCount': 27, 'imageUrl': '/image/thumbnail/22d61165-f6cb-4f78-83a6-c5b5d308b29f?size=174&quality=85', 'inCompareCart': False, 'rank': 1, 'referenceCount': 0, 'showCompareButton': False, 'title': 'Facial Nerve (CNVII)'}"
- "{'authors': 'Santhosh Gaddikeri, MD; Philip R. Chapman, MD', 'bookmarked': False, 'bookmarkUrl': '/document/bookmark/98cb2d45-e64c-4295-9662-3470cd46513a', 'category': 'Head and Neck', 'compareUrl': '/compare/document/98cb2d45-e64c-4295-9662-3470cd46513a/related-anatomy/treeNode?subContext=CNVII (Facial Nerve)', 'documentId': '98cb2d45-e64c-4295-9662-3470cd46513a', 'documentType': 'ANATOMY', 'documentUrl': '/document/cnvii-facial-nerve/98cb2d45-e64c-4295-9662-3470cd46513a', 'enhancedTitle': 'CNVII (Facial Nerve)', 'entryDate': '12/06/23', 'imageCount': 39, 'imageUrl': '/image/thumbnail/1f7e56c2-da7a-4445-ac01-44eee0776f17?size=174&quality=85', 'inCompareCart': False, 'rank': 2, 'referenceCount': 0, 'showCompareButton': False, 'title': 'CNVII (Facial Nerve)'}" cases: 1 breadcrumbs:
- "Head and Neck"
- "Diagnosis"
- "Temporal Bone"
- "Intratemporal Facial Nerve"
- "Pseudolesions"
- "Intratemporal Facial Nerve Enhancement"
KEY FACTS
-
Terminology
- Normal contrast enhancement (CE) along course of intratemporal facial nerve (CNVII); typically subtle, symmetric with contralateral facial nerve and without bone changes or facial nerve symptoms
- Prominent perineural arteriovenous plexus responsible for normal enhancement
-
Imaging
- T1 C+ MR enhancement along CNVII - Mastoid, tympanic, and geniculate ganglion segments generally show CE - CE variable, dependent on technique and field strength but normally symmetric bilaterally - Facial nerve within internal auditory canal should not enhance normally
-
Top Differential Diagnoses
- Bell palsy
- Ramsay Hunt syndrome
- Perineural parotid tumor of intratemporal CNVII
- Facial nerve schwannoma within temporal bone
- Facial nerve venous malformation
-
Clinical Issues
- Normal nerve enhancement a****symptomatic by definition
-
Diagnostic Checklist
- Asymmetric intratemporal facial nerve CE should be viewed with suspicion - Correlation with facial nerve paralysis or hemifacial spasm important if abnormal CE suspected - Any previous history of H&N cancer should alert to possibility of perineural tumor spread
- High-resolution T1 C+ FS MR through temporal bone should cover from brainstem through parotid glands to evaluate for facial nerve pathology
- Bone CT complementary in evaluation to exclude underlying bony changes
TERMINOLOGY
-
Definitions
- Normal contrast enhancement (CE) along course of intratemporal facial nerve (CNVII); typically mild to moderate, symmetric with contralateral facial nerve and without bone changes or facial nerve symptoms
- Prominent perineural arteriovenous plexus responsible for normal enhancement
IMAGING
-
General Features
-
Best diagnostic clue
- T1 C+ MR CE along CNVII geniculate ganglion, tympanic and mastoid segments without bony CNVII canal changes - CE variable, dependent on technique and field strength but **normally symmetric** bilaterally - Facial nerve within internal auditory canal (IAC) should not enhance normally
-
-
CT Findings
-
Bone CT
- Normal bony intratemporal CNVII canal
-
-
MR Findings
-
T1WI
- Normal CNVII can be seen as isointense signal that can appear prominent compared with surrounding low signal of adjacent osseous or pneumatized structures -
T1WI C+
- Normal CE along portions of CNVII (1.5T spin-echo CE T1) - Mastoid > geniculate ganglion > tympanic segments - Usually symmetrical side-to-side -
MR field strength and sequence summary - 1.5T MR: CE of CNVII canalicular and labyrinthine segments not seen - 3T MR: CE of CNVII - Mastoid (100%), geniculate (75%), tympanic (40%) - Subtle enhancement can even be seenincanalicular (15%) and labyrinthine (5%) segments - Comparing CE spin-echo to CE inversion recovery-prepared fast spoiled gradient-echo (IR-FSPGR) - IR-FSPGR: Greater CNVII signal intensity in all segments
-
-
Imaging Recommendations
-
Best imaging tool
- Normal CE seen best on 3-mm axial and coronal spin-echo T1 C+ MR at 3T
-
DIFFERENTIAL DIAGNOSIS
-
- Clinical: Acute onset of unilateral peripheral CNVII paralysis
- T1 C+ MR: Intense enhancement of intratemporal CNVII - "Tuft" of IAC fundal enhancement highly suggestive
- Bone CT: CNVII bony canal normal
-
- Reactivation of herpes zoster from geniculate ganglion
- Typically robust enhancement of intratemporal facial nerve with typical vesicular rash of ear or soft palate
-
Perineural Parotid Tumor of Intratemporal CNVII
- T1 C+ MR: Nodular, asymmetric enhancement of facial nerve usually extending from intraparotid segment into mastoid segment and beyond
- May occur from primary parotid neoplasm or local spread of cutaneous malignancy
-
Facial Nerve Schwannoma of Intratemporal CNVII
- Most frequently found in geniculate fossa
- T1 C+ MR: Focal, enhancing mass along CNVII course
- Bone CT: Enlargement of intratemporal CNVII canal
-
Facial Nerve Venous Malformation (Hemangioma) Within Temporal Bone
- Clinical: Early, unilateral CNVII paralysis
- Most frequent location = geniculate fossa
- T1 C+ MR: Enhancing mass enlarges geniculate fossa
- Bone CT: Honeycomb bony changes ~ 50% - Irregular margins common
PATHOLOGY
-
General Features
- Embryology/anatomy - CNVII plexus has 3 components - Anterior: From anterior tympanic branch of internal maxillary artery or middle meningeal artery - Middle: Tympanic plexus on medial wall of mesotympanum supplied from ascending pharyngeal artery - Posterior: From stylomastoid artery (from occipital artery) - Lusharteriovenous plexus surrounds CNVII within temporal bone - Labyrinthine segment is least well vascularized
-
Gross Pathologic & Surgical Features
- Arteriovenous plexus consists of combination of relatively large arteries and veins in capillary plexus
-
Microscopic Features
- Dense CNVII circumneutral arteriovenous plexus predominantly located in geniculate ganglion, tympanic and mastoid segments ± greater superficial petrosal nerve
CLINICAL ISSUES
-
Presentation
-
Most common signs/symptoms
- **Asymptomatic** by definition - CNVII normal enhancement seen incidentally during T1 C+ MR work-up for unrelated clinical findings
-
DIAGNOSTIC CHECKLIST
-
Consider
- If facial nerve is normal in size and enhancement is symmetric to corresponding contralateral facial nerve segment, probably normal
- Asymmetric intratemporal facial nerve CE should be viewed with suspicion - Correlation with facial nerve paralysis or hemifacial spasm important if abnormal CE suspected - Any previous history of H&N cancer should alert to possibility of perineural tumor spread
- Higher field strength (3T) and IR-FSPGR MR sequences make normal CNVII CE more conspicuous
- If fundal vestibular schwannoma present, labyrinthine segment of CNVII may enhance normally - Arteriovenous plexus congestion is likely cause
- Evaluation of tympanic or mastoid segments difficult if opacification, inflammation, or infection of middle ear and mastoid air cells
- Significant CE along cisternal, labyrinthine segment or extracranial mastoid CNVII segments not normal
44fba962-014f-4057-a9c3-52a2c22841ca
References
Selected References
- George E et al: Facial nerve palsy: clinical practice and cognitive errors. Am J Med. 133(9):1039-44, 2020
- Radhakrishnan R et al: Comparison of normal facial nerve enhancement at 3T MRI using gadobutrol and gadopentetate dimeglumine. Neuroradiol J. 30(6):554-60, 2017
- Dehkharghani S et al: Redefining normal facial nerve enhancement: healthy subject comparison of typical enhancement patterns--unenhanced and contrast-enhanced spin-echo versus 3D inversion recovery-prepared fast spoiled gradient-echo imaging. AJR Am J Roentgenol. 202(5):1108-13, 2014
- Hong HS et al: Enhancement pattern of the normal facial nerve at 3.0 T temporal MRI. Br J Radiol. 83(986):118-21, 2010
- Tabuchi T et al: Vascular permeability to fluorescent substance in human cranial nerves. Ann Otol Rhinol Laryngol. 111(8):736-7, 2002
- Martin-Duverneuil N et al: Contrast enhancement of the facial nerve on MRI: normal or pathological? Neuroradiology. 39(3):207-12, 1997
- Gebarski SS et al: Enhancement along the normal facial nerve in the facial canal: MR imaging and anatomic correlation. Radiology. 183(2):391-4, 1992
Differential diagnosis
Facial Nerve Lesion, Temporal Bone
DDX:1428754b-a8ee-48a0-98f8-4faeebf8dbab
Anatomy
Facial Nerve (CNVII)
Brain/ANATOMY:2f4818dd-6438-405b-8561-5cbbb9c91562
CNVII (Facial Nerve)
Head and Neck/ANATOMY:98cb2d45-e64c-4295-9662-3470cd46513a
Cases
- {'cases': [{'authors': [{'key': '624acd80-0502-4325-be71-e68fec740eb3', 'value': 'Richard H. Wiggins, III, MD, CIIP, FSIIM, FAHSE, FACR'}], 'caseVersionId': '1e34cd15-48c8-4451-b42b-14d967d90b75', 'description': 'This is a classic case of normal enhancement of the intra-temporal bone facial nerve on MR.\n\nThe right axial T1 weighted post-contrasted image (#1) shows normal enhancement at the geniculate ganglion (open arrow) and proximal tympanic segment (arrow). The coronal post-contrasted T1 weighted image (#2) also demonstrates the normal enhancement at the right geniculate ganglion (open arrow), superior to the normal cochlea (curved arrow).', 'history': None, 'imagePoolId': 'ad489f2a-935a-42a8-9c38-0fd41bfbc40a', 'name': 'Classic', 'teachingPoint': None, 'demographics': '35 Years old male'}, {'authors': [{'key': '624acd80-0502-4325-be71-e68fec740eb3', 'value': 'Richard H. Wiggins, III, MD, CIIP, FSIIM, FAHSE, FACR'}], 'caseVersionId': '32a339bf-b7cc-49ec-ae61-8c92fb74a06a', 'description': 'This is a classic case of normal enhancement along the facial nerve on MR.\n\nThe axial post-contrasted T1 weighted MRI with fat-saturation (#1) shows normal enhancement at the right geniculate ganglion (arrow).\n\nThe coronal images (#2-3) show the normal enhancement along the proximal tympanic segment (arrow, #2), superior to the cochlea (curved arrow, #2). A more posterior coronal image also show the normal tympanic segment enhancement (arrow, #3), below the lateral semicircular canal (open arrow, #3).', 'history': None, 'imagePoolId': 'be5d1b24-1eab-41b1-9c48-497b9c4667a8', 'name': 'Classic', 'teachingPoint': None, 'demographics': '44 Years old female'}, {'authors': [{'key': '624acd80-0502-4325-be71-e68fec740eb3', 'value': 'Richard H. Wiggins, III, MD, CIIP, FSIIM, FAHSE, FACR'}], 'caseVersionId': '53a809ba-0d87-4e1c-8e0a-91f32d64b307', 'description': 'This is a typical case of normal enhancement along the intratemporal facial nerve on MR.\n\nThe axial, whole brain, post-contrasted T1 weighted MR fat-saturated images (#1-5) shows normal enhancement at the geniculate ganglion on the left (arrow, #1), and the right (arrow, #2), and the proximal left tympanic segment (open arrow, #2). The magnified axial images confirm this enhancement at the right geniculate ganglion (arrow, #3), and on the left (arrow, #4), and at the left proximal tympanic segment (open arrow, #5).\n\nThe coronal post-contrasted images (#6-7) also show the normal enhancement at the left geniculate ganglion (arrow), and the proximal tympanic segment (open arrow).', 'history': None, 'imagePoolId': '07ca0ec3-ae96-4902-b30e-b3c5de01328b', 'name': 'Classic', 'teachingPoint': None, 'demographics': '68 Years old male'}, {'authors': [{'key': '624acd80-0502-4325-be71-e68fec740eb3', 'value': 'Richard H. Wiggins, III, MD, CIIP, FSIIM, FAHSE, FACR'}], 'caseVersionId': '8346972f-258e-4307-a8e2-c75c98682cbb', 'description': 'This is a classic case of normal facial nerve enhancement on MR.\n\nThis axial post-contrasted T1 weighted MRI with fat-saturation show the normal enhancement along the proximal tympanic segment (arrow). There is no enhancement seen within the internal auditory canal (open arrow).', 'history': None, 'imagePoolId': '6573d494-b008-42da-b7b7-91aa1ebb4142', 'name': 'Classic', 'teachingPoint': None, 'demographics': '74 Years old female'}, {'authors': [{'key': '624acd80-0502-4325-be71-e68fec740eb3', 'value': 'Richard H. Wiggins, III, MD, CIIP, FSIIM, FAHSE, FACR'}], 'caseVersionId': 'b5352292-4ccc-473b-892e-1c190d205953', 'description': 'This is a typical case of normal enhancement of the intratemporal facial nerve.\n\nThese axial T1 weighted post-contrasted images (#1, 2) with fat-saturation show subtle normal enhancement along the proximal tympanic segment of the left facial nerve (arrow) and the geniculate ganglion (open arrow, #1). There is no enhancement seen in the cisternal or canalicular segments of the facial nerve.', 'history': None, 'imagePoolId': '1afc0120-5710-4f04-b641-4ad3ebd006bd', 'name': 'Classic', 'teachingPoint': None, 'demographics': '59 Years old female'}], 'caseType': 'typical', 'name': 'TYPICAL'}
Images
Selected Images
Typical normal enhancement pattern of facial intratemporal facial nerves in a patient with vestibular schwannoma is shown. On this axial MR, the geniculate ganglia (triangular structures superolateral to the IAC) 
demonstrate moderate symmetric enhancement. Right vestibular schwannoma is noted 
.
Typical normal enhancement pattern of facial intratemporal facial nerves in a patient with vestibular schwannoma is shown. On this axial MR, the geniculate ganglia (triangular structures superolateral to the IAC) demonstrate moderate symmetric enhancement. Right vestibular schwannoma is noted .
Axial MR slightly lower shows mild to moderate symmetric enhancement of the tympanic portions of the facial nerves . Aside from the vestibular schwannoma , no IAC enhancement is identified.
Axial (slightly oblique) MR in the same patient demonstrates little or no enhancement of the posterior genu of the left facial nerve and subtle normal enhancement of the proximal mastoid segment 
of the right facial nerve. The lower vestibular schwannoma is noted.
Axial MR in the same patient shows moderate, normal linear enhancement of the lower mastoid segments of the facial nerves. Contrast enhancement of mastoid segment CNVII is usually more robust distally.
Additional Images
Axial T1 C+ FS MR through the internal auditory canals reveals a normal geniculate ganglion and anterior tympanic segment CNVII enhancement on the left. On the right, normal anterior tympanic segment enhancement is visible.
Axial T1 C+ FS MR in a patient with right vestibular schwannoma demonstrates increased enhancement of the labyrinthine CNVII, geniculate ganglion , and anterior tympanic segment CNVII.
Coronal T1 C+ FS MR at the level of the vestibules reveals normal enhancement of the midtympanic segment of the facial nerves .
Coronal T1 C+ FS MR in the same patient shows the normal geniculate ganglion enhancement just superior to the cochleas . Note that the tensor tympani muscles both also enhance. With 3T imaging, more normal enhancement of structures within the temporal bone is seen.
Axial T1 C+ MR at 3T shows prominent but normal enhancement of geniculate ganglion as well as the anterior tympanic segment of intratemporal CNVII.
; compare the degree of enhancement to the nonenhancing cochlea that is seen inferiorly.