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Peripheral Facial Nerve Paralysis 4da52ac4-c03c-4711-ae7e-bb4f2f7c5ab8
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eef2f839-5706-47b9-89c3-60d8315b2b3a Nicholas A. Koontz, MD
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Head and Neck head-and-neck ed24ed8c-5d57-4629-879b-447b82d2973d
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Head and Neck e3a8ceca-c2c5-4be5-a423-e134a0965ae9 2701a4b6-e89a-41e8-a30f-d64d621b420f 48 10/09/18 Peripheral Facial Nerve Paralysis Head and Neck, Differential Diagnosis, Temporal Bone, Clinically Based Differentials, Peripheral Facial Nerve Paralysis Peripheral Facial Nerve Paralysis | STATdx Peripheral Facial Nerve Paralysis DDX true
Head and Neck
Differential Diagnosis
Temporal Bone
Clinically Based Differentials
Peripheral Facial Nerve Paralysis

title: "Peripheral Facial Nerve Paralysis" docid: "4da52ac4-c03c-4711-ae7e-bb4f2f7c5ab8" authors:

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  • "Head and Neck"
  • "Differential Diagnosis"
  • "Temporal Bone"
  • "Clinically Based Differentials"
  • "Peripheral Facial Nerve Paralysis"

ESSENTIAL INFORMATION

  • Key Differential Diagnosis Issues

    • Peripheral facial nerve paralysis - Definition: Unilateral facial nerve injury between pontine motor nucleus & proximal extracranial facial nerve trunk after it emerges from stylomastoid foramen - Clinical manifestation of peripheral facial nerve injury: All muscles of facial expression, including forehead muscles, are paralyzed - Motor: Facial expression muscles; stapedius muscles - Parasympathetic: Lacrimal, submandibular, & sublingual glands - Special sensory: Anterior 2/3 tongue taste
    • Imaging hints in searching for causes - Typical Bell palsy: Does not need imaged routinely - Atypical Bell palsy best examined by thin-section enhanced (C+) MR; increasing role of 3D-FLAIR C+ - Subtle MR abnormalities: Imaged with T-bone CT to exclude facial nerve hemangioma

  • Helpful Clues for Common Diagnoses

    • Bell Palsy - Entire intratemporal facial nerve enhances on MR without mass effect - IAC fundal "tuft" often also present on T1 C+ MR
    • Temporal Bone****Fractures - Tympanic segment of facial nerve most vulnerable
    • MetastasesinCPA-IAC - Poorly marginated enhancing mass in CPA-IAC ± dural enhancement - History of primary cancer usually known - Caveat: CPA-IAC mass with associated facial nerve paralysis is not vestibular schwannoma
    • Pars Flaccida Acquired Cholesteatoma - T-bone CT: Nondependent soft tissue in middle ear filling Prussak space with ossicle + bone erosion ± involving facial nerve canal - MR: Nonenhancing mass with reduced diffusivity - Reduced diffusivity better seen on nonecho-planar (e.g., HASTE) DWI than echo-planar DWI
    • Acute Cerebral Ischemia-Infarction in Pons - MR: Reduced diffusivity (~ 30 minutes) + increased T2/FLAIR signal (~ 6 hours)

  • Helpful Clues for Less Common Diagnoses

    • Facial Nerve Perineural Tumor - Parotid space malignancy ascends through stylomastoid foramen to mastoid facial nerve (CNVII)
    • Facial Nerve Schwannoma in T-Bone - Fusiform enhancing mass along CNVII canal with expansile bone margins - Geniculate fossa most common location
    • Glomus Jugulare****Paraganglioma - Bone CT: Permeative destructive bone changes along jugular foramen (JF) margins - T1 C+ MR: Enhancing JF mass with high-velocity flow voids projects superolateral through middle ear floor - Clinical clues: Vascular retrotympanic mass, pulsatile tinnitus
    • Meningioma in CPA-IAC - Bone CT: Underlying bone ± hyperostosis or permeative sclerosis - T1 C+ MR: Lobulated, enhancing CPA mass with dural base ± dural tails
    • Congenital Cholesteatoma in Middle Ear - Otoscopy: White mass behind intact tympanic membrane in child - Bone CT: Nondependent soft tissue mass often medial to ossicles - MR: Nonenhancing mass with reduced diffusivity - Reduced diffusivity better seen on nonecho-planar (e.g., HASTE) DWI than echo-planar DWI
    • MeningiomainT-Bone - Bone CT: Hyperostosis or permeative sclerosis of tegmen, JF margins - T1 C+ MR: Middle ear enhancing tumor comes from tegmen tympani, JF, or inner ear
    • Metastasis in T-Bone - Destructive T-bone mass in patient with known cancer
    • Multiple Sclerosisin Brainstem - Young adult with predominantly supratentorial white matter disease - Pontine plaques may or may not be visible in setting of facial nerve paralysis

  • Helpful Clues for Rare Diagnoses

    • Adenoid Cystic CarcinomainParotid - Flame-shaped enhancing parotid space invasive mass - Tumor replaces normal fat in stylomastoid foramen
    • Mucoepidermoid Carcinoma in****Parotid - Ovoid invasive parotid space mass usually with complex matrix
    • Facial Nerve Venous Malformation ("Hemangioma") - Bone CT: Poorly marginated mass in geniculate fossa with “honeycomb” matrix (50%) - T1 C+ MR: Lesion enhances avidly - Geniculate fossa most common location
    • Cavernous Malformation in Pons - CT: Pontine lesion with "popcorn" calcifications - MR: Pontine lesion with complex signal from blood products & calcifications ± nearby DVA
    • Ramsay Hunt Syndrome - Herpes zoster oticus affects facial nerve ± vestibulocochlear nerve ± inner ear - External auditory canal vesicles usually precede facial nerve symptoms - T1 C+ MR: Enhancing facial nerve in IAC & temporal bone - Other MR findings: Enhancement of inner ear structures & vestibulocochlear nerve variable; increasing role of 3D-FLAIR C+ to differentiate from Bell palsy - 3D-FLAIR C+ enhancement of CNVIII, IAC wall, & inner ear more typical of Ramsay Hunt than Bell palsy
    • SarcoidosisinCPA-IAC - MR: Dural-based enhancing "meningioma mimic" that may track along cistern-IAC CNVII
    • Langerhans HistiocytosisinT-Bone - Expansile punched-out T-bone lytic lesion in child
    • Rhabdomyosarcoma in T-bone - Destructive lesion of T-bone in child - Often centered in middle ear
    • Facial NerveSchwannoma in CPA-IAC - CPA-IAC enhancing "vestibular schwannoma mimic" - Diagnosis can be made if schwannoma projects into labyrinthine segment of CNVII - Looks like "labyrinthine tail" projecting off IAC fundus

  • Alternative Differential Approaches

References

Selected References

  1. Jindal G et al: Imaging evaluation and treatment of vascular lesions at the skull base. Radiol Clin North Am. 55(1):151-166, 2017
  2. Kuya J et al: Usefulness of high-resolution 3D multi-sequences for peripheral facial palsy: differentiation between Bell's palsy and Ramsay Hunt syndrome. Otol Neurotol. 38(10):1523-1527, 2017
  3. Lingam RK et al: A meta-analysis on the diagnostic performance of non-echoplanar diffusion-weighted imaging in detecting middle ear cholesteatoma: 10 years on. Otol Neurotol. 38(4):521-528, 2017
  4. Chevallier KM et al: Differentiating pediatric rhabdomyosarcoma and Langerhans cell histiocytosis of the temporal bone by imaging appearance. AJNR Am J Neuroradiol. 37(6):1185-9, 2016
  5. Chung MS et al: The clinical significance of findings obtained on 3D-FLAIR MR imaging in patients with Ramsay-Hunt syndrome. Laryngoscope. 125(4):950-5, 2015
  6. Gamss C et al: Imaging evaluation of the suprahyoid neck. Radiol Clin North Am. 53(1):133-44, 2015
  7. Ho ML et al: Anatomy and pathology of the facial nerve. AJR Am J Roentgenol. 204(6):W612-9, 2015
  8. Singh AK et al: Imaging spectrum of facial nerve lesions. Curr Probl Diagn Radiol. 44(1):60-75, 2015
  9. McRackan TR et al: Facial nerve outcomes in facial nerve schwannomas. Otol Neurotol. 2012 Jan;33(1):78-82. Erratum in: Otol Neurotol. 33(3):472, 2012
  10. Magliulo G et al: Facial nerve dehiscence and cholesteatoma. Ann Otol Rhinol Laryngol. 120(4):261-7, 2011
  11. Benoit MM et al: Facial nerve hemangiomas: vascular tumors or malformations? Otolaryngol Head Neck Surg. 142(1):108-14, 2010
  12. Nakata S et al: 3D-FLAIR MRI in facial nerve paralysis with and without audio-vestibular disorder. Acta Otolaryngol. 130(5):632-6, 2010
  13. Finsterer J: Management of peripheral facial nerve palsy. Eur Arch Otorhinolaryngol. 265(7):743-52, 2008
  14. Moody MW et al: Incidence of dehiscence of the facial nerve in 416 cases of cholesteatoma. Otol Neurotol. 28(3):400-4, 2007
  15. Quaranta N et al: Facial paralysis associated with cholesteatoma: a review of 13 cases. Otol Neurotol. 28(3):405-7, 2007
  16. Critchley EP: Multiple sclerosis initially presenting as facial palsy. Aviat Space Environ Med. 75(11):1001-4, 2004
  17. Park SU et al: The usefulness of MR imaging of the temporal bone in the evaluation of patients with facial and audiovestibular dysfunction. Korean J Radiol. 3(1):16-23, 2002
  18. Martin N et al: Haemangioma of the petrous bone: MRI. Neuroradiology. 34(5):420-2, 1992
  19. Curtin HD et al: "Ossifying" hemangiomas of the temporal bone: evaluation with CT. Radiology. 164(3):831-5, 1987

Images

Selected Images

Axial T1 C+ FS MR in a patient with Bell palsy shows the classic faint, tuft-like enhancement at the fundus of the IAC , which extends as a linear enhancement along the labyrinthine segment , anterior genu , and anterior tympanic segments of the facial nerve. Bell Palsy Axial T1 C+ FS MR in a patient with Bell palsy shows the classic faint, tuft-like enhancement at the fundus of the IAC , which extends as a linear enhancement along the labyrinthine segment , anterior genu , and anterior tympanic segments of the facial nerve.

Axial T1 C+ FS MR in a patient with Bell palsy shows the classic faint, tuft-like enhancement at the fundus of the IAC , which extends as a linear enhancement along the labyrinthine segment , anterior genu , and anterior tympanic segments of the facial nerve. Bell Palsy Axial T1 C+ FS MR in a patient with Bell palsy shows the classic faint, tuft-like enhancement at the fundus of the IAC , which extends as a linear enhancement along the labyrinthine segment , anterior genu , and anterior tympanic segments of the facial nerve.

Coronal T1 C+ FS MR shows a classic "tuft" of enhancement at the superior fundus of the IAC as well as along the tympanic segment of the facial nerve in a patient with Bell palsy. Bell Palsy Coronal T1 C+ FS MR shows a classic "tuft" of enhancement at the superior fundus of the IAC as well as along the tympanic segment of the facial nerve in a patient with Bell palsy.

Axial NECT shows a complex temporal bone fracture with a longitudinal component traversing the anterior genu of the facial nerve canal and resulting in facial nerve injury. Note a large distracted fragment of the anterior petrous ridge and temporal squamosal fracture component . Temporal Bone Fractures Axial NECT shows a complex temporal bone fracture with a longitudinal component traversing the anterior genu of the facial nerve canal and resulting in facial nerve injury. Note a large distracted fragment of the anterior petrous ridge and temporal squamosal fracture component .

Axial NECT shows a complex T-bone fracture with transverse component violating the anterior genu and anterior tympanic segments of the CNVII canal. Temporal Bone Fractures Axial NECT shows a complex T-bone fracture with transverse component violating the anterior genu and anterior tympanic segments of the CNVII canal.

Axial T1 C+ MR in a patient with breast cancer & progressive facial weakness shows enhancement along CNVII & CNVIII within the right IAC due to leptomeningeal metastatic disease. Additional enhancing focus is present at the left IAC fundus . Metastases in CPA-IAC Axial T1 C+ MR in a patient with breast cancer & progressive facial weakness shows enhancement along CNVII & CNVIII within the right IAC due to leptomeningeal metastatic disease. Additional enhancing focus is present at the left IAC fundus .

Axial FLAIR C+ MR in a melanoma patient presenting with progressive facial weakness, vestibular symptoms, & hearing loss shows avid enhancement in IAC & cochlea bilaterally at left trigeminal cave due to florid leptomeningeal metastatic disease. Metastases in CPA-IAC Axial FLAIR C+ MR in a melanoma patient presenting with progressive facial weakness, vestibular symptoms, & hearing loss shows avid enhancement in IAC & cochlea bilaterally at left trigeminal cave due to florid leptomeningeal metastatic disease.

Axial NECT in a patient with cholesteatoma post mastoidectomy and new facial weakness shows a large soft tissue mass within the mastoidectomy bowl corresponding to recurrent cholesteatoma, which has eroded into the descending mastoid segment of the CNVII canal. Pars Flaccida Acquired Cholesteatoma Axial NECT in a patient with cholesteatoma post mastoidectomy and new facial weakness shows a large soft tissue mass within the mastoidectomy bowl corresponding to recurrent cholesteatoma, which has eroded into the descending mastoid segment of the CNVII canal.

Coronal nonecho-planar (HASTE) DWI in a patient with pars flaccida cholesteatoma shows a markedly hyperintense mass in the right middle ear. Cholesteatomas characteristically show reduced diffusivity on DWI. Pars Flaccida Acquired Cholesteatoma Coronal nonecho-planar (HASTE) DWI in a patient with pars flaccida cholesteatoma shows a markedly hyperintense mass in the right middle ear. Cholesteatomas characteristically show reduced diffusivity on DWI.

Axial T2 MR demonstrates a subacute lateral pontine infarction on the right. This patient presented with acute onset of right facial nerve paralysis and facial numbness. Acute Cerebral Ischemia-Infarction in Pons Axial T2 MR demonstrates a subacute lateral pontine infarction on the right. This patient presented with acute onset of right facial nerve paralysis and facial numbness.

Axial T1 C+ FS MR demonstrates adenoid cystic carcinoma spreading along a branch of the extracranial facial nerve . In cases where antegrade perineural tumor spreads from the parotid distally along CNVII, peripheral facial nerve paralysis may be only partial. Facial Nerve Perineural Tumor Axial T1 C+ FS MR demonstrates adenoid cystic carcinoma spreading along a branch of the extracranial facial nerve . In cases where antegrade perineural tumor spreads from the parotid distally along CNVII, peripheral facial nerve paralysis may be only partial.

Axial NECT in a patient with CNVII schwannoma shows a soft tissue middle ear mass extending eccentrically from tympanic segment of CNVII. Widening of the CNVII canal at the posterior genu was a helpful feature in recognizing the CNVII origin of this lesion. Facial Nerve Schwannoma in T-Bone Axial NECT in a patient with CNVII schwannoma shows a soft tissue middle ear mass extending eccentrically from tympanic segment of CNVII. Widening of the CNVII canal at the posterior genu was a helpful feature in recognizing the CNVII origin of this lesion.

Axial NECT shows a permeative-destructive lesion of the left jugular foramen , typical of a glomus jugulare. Facial weakness was due to invasion of the descending mastoid segment of CNVII . Note normal appearance of right jugular foramen . Glomus Jugulare Paraganglioma Axial NECT shows a permeative-destructive lesion of the left jugular foramen , typical of a glomus jugulare. Facial weakness was due to invasion of the descending mastoid segment of CNVII . Note normal appearance of right jugular foramen .

Axial T1 C+ FS MR shows an avidly enhancing extraaxial mass centered in the CPA but extending into the IAC . Note the prominent dural tails of enhancement, characteristic of meningioma. Meningioma in CPA-IAC Axial T1 C+ FS MR shows an avidly enhancing extraaxial mass centered in the CPA but extending into the IAC . Note the prominent dural tails of enhancement, characteristic of meningioma.

Coronal bone CT shows a large congenital cholesteatoma of the middle ear that has eroded the lateral bony wall of the anterior tympanic segment of the facial nerve canal as well as the ossicles. This child presented with a middle ear mass behind the intact tympanic membrane and CNVII paresis. Congenital Cholesteatoma in Middle Ear Coronal bone CT shows a large congenital cholesteatoma of the middle ear that has eroded the lateral bony wall of the anterior tympanic segment of the facial nerve canal as well as the ossicles. This child presented with a middle ear mass behind the intact tympanic membrane and CNVII paresis.

Axial T1 C+ FS MR shows an enhancing extraaxial mass with dural tail , intraosseous extension, and hyperostosis consistent with aggressive meningioma that obliterates the CPA. Note schwannomas of left CNV and right IAC in this NF2 patient. Meningioma in T-Bone Axial T1 C+ FS MR shows an enhancing extraaxial mass with dural tail , intraosseous extension, and hyperostosis consistent with aggressive meningioma that obliterates the CPA. Note schwannomas of left CNV and right IAC in this NF2 patient.

Axial T1 C+ MR shows a large left T-bone mass obliterating the middle ear, including the expected course of CNVII . Note a similar-appearing but smaller mass in the right occipital bone . Multiplicity is a helpful clue to metastatic disease, in this case, from neuroblastoma. Metastasis in T-Bone Axial T1 C+ MR shows a large left T-bone mass obliterating the middle ear, including the expected course of CNVII . Note a similar-appearing but smaller mass in the right occipital bone . Multiplicity is a helpful clue to metastatic disease, in this case, from neuroblastoma.

Axial FLAIR MR demonstrates a large pontine multiple sclerosis plaque in this patient with florid supratentorial white matter disease (not shown). Multiple Sclerosis in Brainstem Axial FLAIR MR demonstrates a large pontine multiple sclerosis plaque in this patient with florid supratentorial white matter disease (not shown).

Axial T1 MR in a patient with adenoid cystic carcinoma of the parotid shows an irregular-shaped, infiltrative mass replacing the deep lobe of the parotid and extending through the stylomandibular tunnel into the superficial parotid , obliterating the plane of the facial nerve. Adenoid Cystic Carcinoma in Parotid Axial T1 MR in a patient with adenoid cystic carcinoma of the parotid shows an irregular-shaped, infiltrative mass replacing the deep lobe of the parotid and extending through the stylomandibular tunnel into the superficial parotid , obliterating the plane of the facial nerve.

Axial T2 FS MR shows an infiltrating, ill-defined mass spanning deep & superficial lobes of parotid gland, obliterating plane of CNVII. Note T2-bright mucous cystic regions as well as areas of dark T2 signal intensity from high cellularity portions of the tumor. Mucoepidermoid Carcinoma in Parotid Axial T2 FS MR shows an infiltrating, ill-defined mass spanning deep & superficial lobes of parotid gland, obliterating plane of CNVII. Note T2-bright mucous cystic regions as well as areas of dark T2 signal intensity from high cellularity portions of the tumor.

Axial NECT in a patient with CNVII venous malformation shows a permeative expansile lesion centered at geniculate fossa that widens labyrinthine segment of CNVII canal. Note the characteristic "honeycomb" matrix within the lesion. Facial Nerve Venous Malformation (Hemangioma) Axial NECT in a patient with CNVII venous malformation shows a permeative expansile lesion centered at geniculate fossa that widens labyrinthine segment of CNVII canal. Note the characteristic "honeycomb" matrix within the lesion.

Coronal T2* GRE MR reveals a "blooming" cavernous malformation in the left pons . T1 images (not shown) showed hyperintense foci of methemoglobin, consistent with prior hemorrhage. Cavernous Malformation in Pons Coronal T2 GRE MR reveals a "blooming" cavernous malformation in the left pons . T1 images (not shown) showed hyperintense foci of methemoglobin, consistent with prior hemorrhage.*

Axial T1 C+ MR in Ramsay Hunt syndrome shows enhancement along the IAC and intratemporal facial nerve . A compelling clinical history is helpful, as distinguishing from Bell palsy on imaging alone is challenging. 3D-FLAIR C+ has shown promise in this regard. Ramsay Hunt Syndrome Axial T1 C+ MR in Ramsay Hunt syndrome shows enhancement along the IAC and intratemporal facial nerve . A compelling clinical history is helpful, as distinguishing from Bell palsy on imaging alone is challenging. 3D-FLAIR C+ has shown promise in this regard.

Axial T1 C+ FS MR reveals sarcoid affecting the 7th and 8th CNs in the IAC . Notice that the tympanic segment of the facial nerve is also avidly enhancing . Sarcoidosis in CPA-IAC Axial T1 C+ FS MR reveals sarcoid affecting the 7th and 8th CNs in the IAC . Notice that the tympanic segment of the facial nerve is also avidly enhancing .

Axial T1 C+ FS MR in a child with Langerhans histiocytosis shows a destructive middle ear/mastoid mass with ossicular encasement and encroachment of the CNVII tympanic segment . Note aggressive periosteal reaction not commonly seen with Langerhans calvarial lesions. Langerhans Histiocytosis in T-Bone Axial T1 C+ FS MR in a child with Langerhans histiocytosis shows a destructive middle ear/mastoid mass with ossicular encasement and encroachment of the CNVII tympanic segment . Note aggressive periosteal reaction not commonly seen with Langerhans calvarial lesions.

Coronal T1 C+ FS MR shows transspatial mass of middle ear , external auditory canal , & infratemporal fossa . Note obliteration of the tympanic segment of CNVII . Histology revealed rhabdomyosarcoma. Rhabdomyosarcoma in T-Bone Coronal T1 C+ FS MR shows transspatial mass of middle ear , external auditory canal , & infratemporal fossa . Note obliteration of the tympanic segment of CNVII . Histology revealed rhabdomyosarcoma.

Axial T2 MR shows a CPA mass extending along posterior IAC into CNVII labyrinthine segment . While CNVII lives anteriorly in IAC, close attention shows a near-CSF signal-associated arachnoid cyst displacing CNVII schwannoma posteriorly. Note CSF is slightly brighter. Facial Nerve Schwannoma in CPA-IAC Axial T2 MR shows a CPA mass extending along posterior IAC into CNVII labyrinthine segment . While CNVII lives anteriorly in IAC, close attention shows a near-CSF signal-associated arachnoid cyst displacing CNVII schwannoma posteriorly. Note CSF is slightly brighter.

Additional Images

Axial T1 C+ FS MR shows a "tuft" sign in this patient with acute onset of left peripheral CNVII paralysis. The enhancing fundal portion of the IAC CNVII often has this diffuse, less linear appearance. Bell Palsy Axial T1 C+ FS MR shows a "tuft" sign in this patient with acute onset of left peripheral CNVII paralysis. The enhancing fundal portion of the IAC CNVII often has this diffuse, less linear appearance.

Axial T1 C+ FS MR demonstrates enhancement of the labyrinthine and tympanic segments of the intratemporal facial nerve. Mastoid segment enhancement was also present (not shown). Bell Palsy Axial T1 C+ FS MR demonstrates enhancement of the labyrinthine and tympanic segments of the intratemporal facial nerve. Mastoid segment enhancement was also present (not shown).

Coronal T1 C+ FS MR demonstrates avid enhancement of the mastoid segment of the facial nerve and the proximal extracranial segment in the stylomastoid foramen in this patient with typical acute onset Bell palsy. Bell Palsy Coronal T1 C+ FS MR demonstrates avid enhancement of the mastoid segment of the facial nerve and the proximal extracranial segment in the stylomastoid foramen in this patient with typical acute onset Bell palsy.

Axial bone CT shows healing bone fragments in the lateral geniculate fossa . This patient suffered temporal bone fracture with persistent facial nerve paralysis 6 weeks before this CT. Temporal Bone Fractures Axial bone CT shows healing bone fragments in the lateral geniculate fossa . This patient suffered temporal bone fracture with persistent facial nerve paralysis 6 weeks before this CT.

Sagittal bone CT demonstrates disrupted ossicles in the attic and healing bone in the lateral roof of the geniculate fossa . Six weeks after temporal bone fracture, persistent conductive hearing loss and facial nerve paralysis were still present. Temporal Bone Fractures Sagittal bone CT demonstrates disrupted ossicles in the attic and healing bone in the lateral roof of the geniculate fossa . Six weeks after temporal bone fracture, persistent conductive hearing loss and facial nerve paralysis were still present.

Axial T1 C+ MR shows breast carcinoma metastases in both IACs . This type of linear enhancement is seen when the metastasis is in the pia-arachnoid of CNVII and CNVIII. Metastases in CPA-IAC Axial T1 C+ MR shows breast carcinoma metastases in both IACs . This type of linear enhancement is seen when the metastasis is in the pia-arachnoid of CNVII and CNVIII.

Axial T2WI MR reveals bilateral IAC breast carcinoma metastases thickening the facial and vestibulocochlear nerve bundles. Pia-arachnoid metastasis has a floating in CSF appearance. Metastases in CPA-IAC Axial T2WI MR reveals bilateral IAC breast carcinoma metastases thickening the facial and vestibulocochlear nerve bundles. Pia-arachnoid metastasis has a floating in CSF appearance.

Axial bone CT demonstrates an epitympanic cholesteatoma that has eroded the anterior superior wall of the attic, shaved off the anterior head of the malleus , and dehisced the lateral bony wall of the anterior tympanic segment of the facial nerve canal . Pars Flaccida Acquired Cholesteatoma Axial bone CT demonstrates an epitympanic cholesteatoma that has eroded the anterior superior wall of the attic, shaved off the anterior head of the malleus , and dehisced the lateral bony wall of the anterior tympanic segment of the facial nerve canal .

Sagittal bone CT shows an anterior middle ear cholesteatoma that has both eroded the tegmen tympani and dehisced the lateral bony wall of the geniculate fossa . Pars Flaccida Acquired Cholesteatoma Sagittal bone CT shows an anterior middle ear cholesteatoma that has both eroded the tegmen tympani and dehisced the lateral bony wall of the geniculate fossa .

Axial T1 C+ FS MR in a patient with facial nerve schwannoma shows an avidly enhancing middle ear mass growing along the expected course of the tympanic segment of the facial nerve. Facial Nerve Schwannoma in T-Bone Axial T1 C+ FS MR in a patient with facial nerve schwannoma shows an avidly enhancing middle ear mass growing along the expected course of the tympanic segment of the facial nerve.

Coronal T1 C+ FS MR in a patient with facial nerve schwannoma shows an avidly enhancing middle ear mass growing below the level of the lateral semicircular canal, which is the typical course of the tympanic segment of the facial nerve . Note the eccentric growth pattern relative to the nerve of origin, typical of schwannomas. Facial Nerve Schwannoma in T-Bone Coronal T1 C+ FS MR in a patient with facial nerve schwannoma shows an avidly enhancing middle ear mass growing below the level of the lateral semicircular canal, which is the typical course of the tympanic segment of the facial nerve . Note the eccentric growth pattern relative to the nerve of origin, typical of schwannomas.

Axial bone CT shows smooth enlargement of the geniculate fossa by a facial nerve schwannoma. T1-enhanced MR (not shown) revealed enhancing tissue within the enlarged geniculate fossa. Facial Nerve Schwannoma in T-Bone Axial bone CT shows smooth enlargement of the geniculate fossa by a facial nerve schwannoma. T1-enhanced MR (not shown) revealed enhancing tissue within the enlarged geniculate fossa.

Coronal T1 C+ FS MR shows a glomus jugulare paraganglioma filling the jugular foramen and spreading superolaterally through the middle ear floor to involve the tympanic segment of CNVII . Glomus Jugulare Paraganglioma Coronal T1 C+ FS MR shows a glomus jugulare paraganglioma filling the jugular foramen and spreading superolaterally through the middle ear floor to involve the tympanic segment of CNVII .

Axial T2 FS MR reveals a lobulated dural-based meningioma with a CSF vascular cleft and asymmetric relationship to the porus acusticus . Meningioma in CPA-IAC Axial T2 FS MR reveals a lobulated dural-based meningioma with a CSF vascular cleft and asymmetric relationship to the porus acusticus .

Axial bone CT reveals the permeative-sclerotic bone changes of an anterior tegmen tympani meningioma . Notice that the lateral wall of the anterior tympanic segment of the facial nerve canal is affected by the meningioma . Meningioma in T-Bone Axial bone CT reveals the permeative-sclerotic bone changes of an anterior tegmen tympani meningioma . Notice that the lateral wall of the anterior tympanic segment of the facial nerve canal is affected by the meningioma .

Axial bone CT shows a large floor of middle cranial fossa destructive metastasis eroding the anterior wall of the middle ear cavity and invading the geniculate fossa . This patient with known colon cancer presented with acute onset of facial nerve paralysis. Metastasis in T-Bone Axial bone CT shows a large floor of middle cranial fossa destructive metastasis eroding the anterior wall of the middle ear cavity and invading the geniculate fossa . This patient with known colon cancer presented with acute onset of facial nerve paralysis.

Axial CECT shows a poorly marginated adenoid cystic carcinoma of the parotid gland with deep invasion toward the stylomastoid foramen and proximal extracranial facial nerve . Adenoid Cystic Carcinoma in Parotid Axial CECT shows a poorly marginated adenoid cystic carcinoma of the parotid gland with deep invasion toward the stylomastoid foramen and proximal extracranial facial nerve .

Axial T1 C+ FS MR shows an aggressive-appearing enhancing left parotid mucoepidermoid carcinoma that involves both the superficial and the deep lobes. Note the spread into the lower portion of the stylomastoid foramen . Mucoepidermoid Carcinoma in Parotid Axial T1 C+ FS MR shows an aggressive-appearing enhancing left parotid mucoepidermoid carcinoma that involves both the superficial and the deep lobes. Note the spread into the lower portion of the stylomastoid foramen .

Axial bone CT reveals a venous malformation enlarging the geniculate fossa . Note the central tumor matrix calcifications. Facial Nerve Venous Malformation (Hemangioma) Axial bone CT reveals a venous malformation enlarging the geniculate fossa . Note the central tumor matrix calcifications.

Axial bone CT demonstrates a lesion of the right temporal bone eroding the bones of the petrous apex and middle ear . The lateral wall of the middle ear/mastoid is absent with periauricular soft tissue mass visible. Langerhans Histiocytosis in T-Bone Axial bone CT demonstrates a lesion of the right temporal bone eroding the bones of the petrous apex and middle ear . The lateral wall of the middle ear/mastoid is absent with periauricular soft tissue mass visible.

Axial T1 C+ FS MR shows a very large skull base and temporal bone rhabdomyosarcoma. The inner ear bony otic capsule appears to be "floating" in the tumor . Rhabdomyosarcoma in T-Bone Axial T1 C+ FS MR shows a very large skull base and temporal bone rhabdomyosarcoma. The inner ear bony otic capsule appears to be "floating" in the tumor .

Axial T1 C+ MR shows an enhancing tumor of the CPA and IAC . This tumor can be correctly identified as a facial nerve schwannoma because of the "labyrinthine tail" of enhancement of the facial nerve . Facial Nerve Schwannoma in CPA-IAC Axial T1 C+ MR shows an enhancing tumor of the CPA and IAC . This tumor can be correctly identified as a facial nerve schwannoma because of the "labyrinthine tail" of enhancement of the facial nerve .

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