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Sensorineural Hearing Loss in Child 08c895da-f2aa-4076-abf0-af9aca1677cd
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d19354f3-7ff2-495a-ad3f-064122e45602 Bernadette L. Koch, MD
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Head and Neck 89f04762-2cc9-4c62-aea2-256ed544510c 44 07/24/18 Sensorineural Hearing Loss in Child Head and Neck, Differential Diagnosis, CPA-IAC and Posterior Fossa, Clinically Based Differentials, Sensorineural Hearing Loss in Child Sensorineural Hearing Loss in Child | STATdx Sensorineural Hearing Loss in Child DDX true
Head and Neck
Differential Diagnosis
CPA-IAC and Posterior Fossa
Clinically Based Differentials
Sensorineural Hearing Loss in Child

title: "Sensorineural Hearing Loss in Child" docid: "08c895da-f2aa-4076-abf0-af9aca1677cd" authors:

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  • "Head and Neck"
  • "Differential Diagnosis"
  • "CPA-IAC and Posterior Fossa"
  • "Clinically Based Differentials"
  • "Sensorineural Hearing Loss in Child"

ESSENTIAL INFORMATION

  • Key Differential Diagnosis Issues

    • History is important - Congenital sensorineural hearing loss (SNHL) - Failed newborn screening hearing test - Look for inner ear anomalies with CT &/or MR - Fluctuating or "cascading" SNHLin child (without history of meningitis) - Look for large vestibular aqueduct (LVA) ± cochlear malformation & modiolar deficiency on CT - Look for large endolymphatic sac/duct ± cochlear malformation & modiolar deficiency on MR - Congenital unilateral SNHL - Look for cochlear nerve & cochlear nerve canal (CNC) hypoplasia/aplasia - Trauma - Look for fracture involving inner ear structures ± pneumolabyrinth on CT - Genetic****disorders with common imaging findings - CHARGE, trisomy 21, Waardenburg, or Apert syndrome: Look for semicircular canal (SCC) malformation - Pendred syndrome: Look for LVA - Biallelic SLC26A4 mutations - Prior****meningitis - CT: Look for labyrinthine ossification - T1 C+ MR: Labyrinthine enhancement during meningitis (acute phase) - T2 MR: Normal high intensity replaced with low-intensity (fibrosis or ossification) membranous labyrinth
    • Best imaging tool - Thin-section T-bone CT for congenital inner ear anomalies & labyrinthine ossificans - High-resolution T2 MR for large endolymphatic sac, cochlear malformation; cochlear nerve aplasia/hypoplasia - C+ MR best for schwannoma, other tumors, acute labyrinthitis, & autoimmune labyrinthitis (delayed enhancement)

  • Helpful Clues for Common Diagnoses

    • Large Endolymphatic Sac Anomaly (IP-II) - Most common congenital anomaly of inner ear found by imaging - Axial CT: Vestibular aqueduct (VA) ≥ 2 mm at operculum or ≥ 1 mm at midpoint - Associated with incomplete cochlear partition type II (IP-II), modiolar deficiency, vestibule, &/or SCC malformation - Additional prognostic information - Avoid contact sports or other activities that may lead to head trauma - Genetic testing forSLC26A4 mutation recommended - Up to 40% of all patients with LVA & IP-II will have pendrin gene mutation: Pendred syndrome (with thyroid organification defect ± goiter) or LVA
    • T-Bone Fractures - Thin-section T-bone CT (0.625-1 mm) - Transverse, longitudinal, or complex fractures may cross inner ear structures, ± pneumolabyrinth - Otic capsule violating vs. otic capsule sparing
    • Semicircular Canal Malformation - Spectrum of abnormalities: ≥ 1SCC is malformed, hypoplastic, or aplastic - Unilateral or bilateral (e.g., syndromic cases) - Most common is short, dilated lateral SCC & vestibule forming single cavity or with small bone island - ± cochlear malformation, oval window atresia, &/or ossicular anomalies - CHARGE syndrome - Bilateralhypoplasia or****absence of all SCCs - Associated anomalies: Small vestibule, absent cochlear nerve aperture ("isolated cochlea"), oval window atresia (± overlying tympanic segment of CNVII), ± choanal atresia, ± coloboma - Lateral SCC last to form embryologically; anomalies most frequently affect lateral SCC - Except if obliterated by labyrinthine ossificans or malformed in Waardenburg, branchiootorenal, & Alagille syndromes
    • Labyrinthine Ossificans - Synonyms: Labyrinthitis ossificans, labyrinthine ossification, chronic labyrinthitis, ossifying labyrinthitis - Acute inflammatory response → fibrous & then osseous replacement of membranous labyrinth; weeks or years - May involve cochlea ± vestibule ± SCCs - Bilateral in meningogenic form (meningitis) & in hematogenic form (blood-borne infections) - Unilateral in tympanogenic form (middle ear infection) - T-bone CT: High-attenuation bone deposition in formerly fluid-filled membranous labyrinth - Areas of ossification crucial to identify when planning cochlear implantation - T2 MR: Focal or diffuse low intensity replaces high-intensity fluid, with apparent "enlargement" of modiolus if cochlea is involved - T1 C+ MR: Enhancement of involved membranous labyrinth structures in early stage, may persist into ossifying stages

  • Helpful Clues for Less Common Diagnoses

    • Labyrinthitis - Sudden onset of SNHL, vertigo, &/or tinnitus - Viral disease: Imaging usually not indicated - Bacterial, posttraumatic, or autoimmune causes - Subacute inflammation of fluid-filled inner ear structures - T-bone CT: Normal in early phases, may progress to labyrinthine ossificans - T2 MR: Low intensity replaces normal high-intensity fluid signal within membranous labyrinth structures - T1 C+ MR: Mild to moderate enhancement - Enhancement may persist after symptoms resolve
    • Cochlear Nerve & Cochlear Nerve Canal Aplasia-Hypoplasia - CT: Small IAC & CNC - MR: Fluid in CNC completely or partially replaced by low-signal bone - Cochlear nerve diminutive or absent (if CNC aplasia)
    • CysticCochleovestibular Malformation (IP-I) - Cystic, featureless cochlea + dilated vestibule & horizontal SCC - Cochlea: Absent internal septation & absent modiolus (IP-1), cochlea & vestibule form bilobed cyst - Vestibule: Dilated, large, communicates with cochlea - SCC: Dilated horizontal + vestibule → common cavity - IAC: Small or dilated, defective fundus - VA: Usually normal
    • CPA-IACLipoma - Congenital fatty lesion of CPA ± IAC ± inner ear - Caveat: If T1 C+ MR without fat saturation, may be mistaken for vestibular schwannoma

  • Helpful Clues for Rare Diagnoses

    • Vestibular Schwannoma - Enhancing lesion in IAC or ice cream on cone-shaped mass aligned with CPA-IAC - Hypointense T2WI MR
    • IntralabyrinthineSchwannoma - Rare in children - Intracochlear: Schwannoma within cochlea - Intravestibular: Schwannoma within vestibule - Vestibulocochlear: Involves both vestibule & cochlea - Transmodiolar: Crosses modiolus; cochlea to IAC fundus - Transmacular: Crosses from vestibule into IAC fundus - Transotic: Crosses entire inner ear from IAC fundus to middle ear
    • Facial NerveSchwannoma in CPA-IAC - Rare in children - SNHL with associated facial neuropathy - Enhancing, well-circumscribed mass in CPA-IAC; extends into labyrinthine segment of CNVII - Involvement of inner ear is secondary finding
    • Common Cavity Malformation - Featureless common cavity represents rudimentary cochlea, vestibule, & lateral SCC - Variably sized common cavity - Posterior & superior SCC: Absent, normal, or malformed - IAC: Often small with defective fundus ± anomalous course & small or absent CNVIII components - Middle ear space & ossicles: Normal or anomalous stapes & stenotic oval window - VA: Normal or absent
    • Cochlear Aplasia - Absent cochlea with variable deformity of vestibule & SCCs - Absent/flattened cochlear promontory helps differentiate from labyrinthine ossificans - Absent CNC & nerve - Hypoplastic IAC - Normal VA & normal-sized middle ear cavity - Normal or malformed stapes
    • Labyrinthine Aplasia - Absent cochlea, vestibule, &SCCs - Absent/flattened cochlear promontory - IAC aplasia/hypoplasia - Absent vestibular & cochlear nerves - Normal or malformed ossicles/middle ear - Normal or absent carotid canal - Old synonym: Michel anomaly

References

Selected References

  1. Conte G et al: MR Imaging in Sudden Sensorineural Hearing Loss. Time to Talk. AJNR Am J Neuroradiol. ePub, 2017
  2. Johnson K et al: High-frequency sensorineural hearing loss in children. Laryngoscope. 126(5):1236-40, 2016
  3. Shupak A et al: Primary solitary intralabyrinthine schwannoma: A report of 7 cases and a review of the literature. Ear Nose Throat J. 95(12):481-491, 2016
  4. Prosser JD et al: Diagnostic evaluation of children with sensorineural hearing loss. Otolaryngol Clin North Am. 48(6):975-82, 2015
  5. Kenna MA et al: Temporal bone abnormalities in children with GJB2 mutations. Laryngoscope. 121(3):630-5, 2011
  6. Ozgen B et al: Comparison of 45 degrees oblique reformats with axial reformats in CT evaluation of the vestibular aqueduct. AJNR Am J Neuroradiol. 29(1):30-4, 2008
  7. Vijayasekaran S et al: When is the vestibular aqueduct enlarged? A statistical analysis of the normative distribution of vestibular aqueduct size. AJNR Am J Neuroradiol. 28(6):1133-8, 2007
  8. Sennaroglu L et al: A new classification for cochleovestibular malformations. Laryngoscope. 112:2230-41, 2002

Images

Selected Images

Axial bone CT in an 8-year-old child with severe bilateral sensorineural hearing loss (SNHL) shows incomplete partitioning between the middle and apical turns of the left cochlea , typical of IP-II morphology. Large Endolymphatic Sac Anomaly (IP-II) Axial bone CT in an 8-year-old child with severe bilateral sensorineural hearing loss (SNHL) shows incomplete partitioning between the middle and apical turns of the left cochlea , typical of IP-II morphology.

Axial bone CT in an 8-year-old child with severe bilateral sensorineural hearing loss (SNHL) shows incomplete partitioning between the middle and apical turns of the left cochlea , typical of IP-II morphology. Large Endolymphatic Sac Anomaly (IP-II) Axial bone CT in an 8-year-old child with severe bilateral sensorineural hearing loss (SNHL) shows incomplete partitioning between the middle and apical turns of the left cochlea , typical of IP-II morphology.

Axial bone CT in the same patient shows a markedly enlarged left vestibular aqueduct , much larger than 2 mm at the operculum. Large Endolymphatic Sac Anomaly (IP-II) Axial bone CT in the same patient shows a markedly enlarged left vestibular aqueduct , much larger than 2 mm at the operculum.

Axial FIESTA image in a 3 year old with SNHL shows bilateral enlargement of the endolymphatic sacs , incomplete cochlear partitioning , and mildly dysmorphic vestibules . SCL26A4 mutation/Pendred syndrome was found negative. Large Endolymphatic Sac Anomaly (IP-II) Axial FIESTA image in a 3 year old with SNHL shows bilateral enlargement of the endolymphatic sacs , incomplete cochlear partitioning , and mildly dysmorphic vestibules . SCL26A4 mutation/Pendred syndrome was found negative.

Axial bone CT in a 14 year old involved in a dirt bike accident reveals a horizontal, otic capsule violating right temporal bone fracture crossing the vestibule . Notice air in the vestibule and cochlea as well as multiple skull base and orbital fractures . T-Bone Fractures Axial bone CT in a 14 year old involved in a dirt bike accident reveals a horizontal, otic capsule violating right temporal bone fracture crossing the vestibule . Notice air in the vestibule and cochlea as well as multiple skull base and orbital fractures .

Axial bone CT in a 6-year-old girl demonstrates a short, dilated lateral semicircular canal (SCC) forming a single cavity with the vestibule , a common type of SCC anlage malformation. Semicircular Canal Malformation Axial bone CT in a 6-year-old girl demonstrates a short, dilated lateral semicircular canal (SCC) forming a single cavity with the vestibule , a common type of SCC anlage malformation.

Axial bone CT in a 3-year-old child with a history of bilateral choanal atresia and hearing loss demonstrates diminutive vestibules and absence of the SCCs bilaterally, which is the characteristic appearance of the labyrinth in children with CHARGE syndrome. Semicircular Canal Malformation Axial bone CT in a 3-year-old child with a history of bilateral choanal atresia and hearing loss demonstrates diminutive vestibules and absence of the SCCs bilaterally, which is the characteristic appearance of the labyrinth in children with CHARGE syndrome.

Axial bone CT in a child with Alagille syndrome shows a relatively normal caliber posterior limb of the left superior SCC , aplasia of the anterior limb of the superior SCC , and aplasia of the posterior SCC . In the presence of a normal lateral SCC, these findings are typical of Alagille syndrome. Semicircular Canal Malformation Axial bone CT in a child with Alagille syndrome shows a relatively normal caliber posterior limb of the left superior SCC , aplasia of the anterior limb of the superior SCC , and aplasia of the posterior SCC . In the presence of a normal lateral SCC, these findings are typical of Alagille syndrome.

Axial bone CT in a patient with prior meningitis and subsequent rapid onset hearing loss shows near complete osseous replacement of the posterior and lateral aspects of the lateral SSCs and the left cochlea . Labyrinthine Ossificans Axial bone CT in a patient with prior meningitis and subsequent rapid onset hearing loss shows near complete osseous replacement of the posterior and lateral aspects of the lateral SSCs and the left cochlea .

Axial high-resolution CISS MR in a patient with prior meningitis and known partial labyrinthine ossification shows lack of normal T2 hyperintensity in the left membranous labyrinth and decreased T2 hyperintensity in the right. The right cochlea and vestibule are barely visible. Labyrinthine Ossificans Axial high-resolution CISS MR in a patient with prior meningitis and known partial labyrinthine ossification shows lack of normal T2 hyperintensity in the left membranous labyrinth and decreased T2 hyperintensity in the right. The right cochlea and vestibule are barely visible.

Axial T1 C+ MR in the same patient shows mild, patchy abnormal enhancement of the bilateral cochlea and vestibule . Labyrinthine Ossificans Axial T1 C+ MR in the same patient shows mild, patchy abnormal enhancement of the bilateral cochlea and vestibule .

Axial T2 FS MR shows corresponding loss of hyperintense T2 signal in the cochlea , vestibule , and IAC . Labyrinthitis Axial T2 FS MR shows corresponding loss of hyperintense T2 signal in the cochlea , vestibule , and IAC .

Axial T1 C+ FS MR shows abnormal contrast enhancement in the middle ear, mastoid, cochlea , vestibule , and IAC , secondary to actinomycosis labyrinthitis. Labyrinthitis Axial T1 C+ FS MR shows abnormal contrast enhancement in the middle ear, mastoid, cochlea , vestibule , and IAC , secondary to actinomycosis labyrinthitis.

Axial bone CT in a 3-year-old girl with unilateral SNHL who failed her newborn hearing test shows an absent cochlear nerve canal , sometimes referred to as an "isolated" or "detached" cochlea. Cochlear Nerve & Cochlear Nerve Canal Aplasia-Hypoplasia Axial bone CT in a 3-year-old girl with unilateral SNHL who failed her newborn hearing test shows an absent cochlear nerve canal , sometimes referred to as an "isolated" or "detached" cochlea.

Sagittal oblique T2 MR at the level of the left IAC clearly shows a normal-appearing facial nerve , superior/inferior vestibular nerve complex , and diminutive left cochlear nerve . Cochlear Nerve & Cochlear Nerve Canal Aplasia-Hypoplasia Sagittal oblique T2 MR at the level of the left IAC clearly shows a normal-appearing facial nerve , superior/inferior vestibular nerve complex , and diminutive left cochlear nerve .

Axial high-resolution T2 MR shows absence of the definable right cochlear nerve within the right IAC, and lack of a cochlear nerve canal and hypoplasia of the right modiolus . Cochlear Nerve & Cochlear Nerve Canal Aplasia-Hypoplasia Axial high-resolution T2 MR shows absence of the definable right cochlear nerve within the right IAC, and lack of a cochlear nerve canal and hypoplasia of the right modiolus .

Sagittal oblique T2 MR in the same child shows nonvisualization of the right cochlear nerve , which should normally be at least as large as the facial nerve on sagittal oblique images through the IAC. Cochlear Nerve & Cochlear Nerve Canal Aplasia-Hypoplasia Sagittal oblique T2 MR in the same child shows nonvisualization of the right cochlear nerve , which should normally be at least as large as the facial nerve on sagittal oblique images through the IAC.

Axial bone CT shows the typical CT appearance of cystic cochleovestibular anomaly. The vestibule is globular . Cystic Cochleovestibular Malformation (IP-I) Axial bone CT shows the typical CT appearance of cystic cochleovestibular anomaly. The vestibule is globular .

Axial bone CT in the same patient reveals a featureless cochlea without a definable modiolus, also termed an IP-I anomaly. Cystic Cochleovestibular Malformation (IP-I) Axial bone CT in the same patient reveals a featureless cochlea without a definable modiolus, also termed an IP-I anomaly.

Axial NECT shows the typical CT appearance of a small lipoma in the left CPA cistern . There is low-attenuation focus of CPA lipoma. CPA-IAC Lipoma Axial NECT shows the typical CT appearance of a small lipoma in the left CPA cistern . There is low-attenuation focus of CPA lipoma.

Coronal T1 MR shows a hyperintense lipoma in the left CPA cistern . CPA-IAC Lipoma Coronal T1 MR shows a hyperintense lipoma in the left CPA cistern .

Axial T1 C+ FS MR in a 2-year-old boy with neurofibromatosis type 2 clearly shows enhancing masses within the bilateral IAC, inseparable from the CNVII/CNVIII complexes. Vestibular Schwannoma Axial T1 C+ FS MR in a 2-year-old boy with neurofibromatosis type 2 clearly shows enhancing masses within the bilateral IAC, inseparable from the CNVII/CNVIII complexes.

Axial T2WI MR in the same patient demonstrates corresponding hypointense signal within the IAC masses , replacing the normal hyperintense T2-signal fluid, typical of small schwannomas. Vestibular Schwannoma Axial T2WI MR in the same patient demonstrates corresponding hypointense signal within the IAC masses , replacing the normal hyperintense T2-signal fluid, typical of small schwannomas.

Axial T1 C+ FS MR in a 15-year-old girl with unilateral SNHL shows an enhancing intracochlear mass in the middle turn of the cochlea. The tumor enlarged over time and was subsequently resected, confirming intracochlear schwannoma. Intralabyrinthine Schwannoma Axial T1 C+ FS MR in a 15-year-old girl with unilateral SNHL shows an enhancing intracochlear mass in the middle turn of the cochlea. The tumor enlarged over time and was subsequently resected, confirming intracochlear schwannoma.

Axial bone CT demonstrates a common cavity anomaly with a cystic structure representing the vestibule, rudimentary cochlear bud, and horizontal semicircular canal , with a relatively normal-appearing posterior semicircular canal . Common Cavity Malformation Axial bone CT demonstrates a common cavity anomaly with a cystic structure representing the vestibule, rudimentary cochlear bud, and horizontal semicircular canal , with a relatively normal-appearing posterior semicircular canal .

Axial bone CT in a 1 year old with SNHL demonstrates a small left IAC and absence of the left cochlea . Notice also the mild associated hypoplasia of the left petrous apex . Cochlear Aplasia Axial bone CT in a 1 year old with SNHL demonstrates a small left IAC and absence of the left cochlea . Notice also the mild associated hypoplasia of the left petrous apex .

Axial bone CT shows that the otic capsule is featureless and without definable labyrinthine structures. The lateral wall is flat , indicating congenital absence rather than acquired ossificans. Labyrinthine Aplasia Axial bone CT shows that the otic capsule is featureless and without definable labyrinthine structures. The lateral wall is flat , indicating congenital absence rather than acquired ossificans.

Additional Images

Axial bone CT shows complete osseous replacement of the right cochlea . Notice the presence of a normal right cochlear promontory , convex laterally, indicating acquired ossification rather than cochlear aplasia. Labyrinthine Ossificans Axial bone CT shows complete osseous replacement of the right cochlea . Notice the presence of a normal right cochlear promontory , convex laterally, indicating acquired ossification rather than cochlear aplasia.

Axial high-resolution T2 MR in a 14 year old with a recent dirt bike accident (resulting in bilateral otic capsule fractures) shows decreased hyperintense T2 signal in the right vestibule and lateral semicircular canal (SCC) , consistent with early fibrous replacement of normal labyrinthine fluid. Labyrinthine Ossificans Axial high-resolution T2 MR in a 14 year old with a recent dirt bike accident (resulting in bilateral otic capsule fractures) shows decreased hyperintense T2 signal in the right vestibule and lateral semicircular canal (SCC) , consistent with early fibrous replacement of normal labyrinthine fluid.

Axial T1 C + FS MR in the same patient depicts abnormal contrast enhancement involving the right cochlea , vestibule , and lateral SCC , which may persist for months in labyrinthine ossificans. Labyrinthine Ossificans Axial T1 C + FS MR in the same patient depicts abnormal contrast enhancement involving the right cochlea , vestibule , and lateral SCC , which may persist for months in labyrinthine ossificans.

Axial T1 C+ FS MR shows abnormal enhancement of the right cochlea , indicative of labyrinthitis in this patient with Cogan syndrome. Labyrinthitis Axial T1 C+ FS MR shows abnormal enhancement of the right cochlea , indicative of labyrinthitis in this patient with Cogan syndrome.

Axial T1 C+ FS MR shows abnormal enhancement of the left cochlea , indicative of labyrinthitis in this patient with Cogan syndrome. Labyrinthitis Axial T1 C+ FS MR shows abnormal enhancement of the left cochlea , indicative of labyrinthitis in this patient with Cogan syndrome.

Axial T1 C+ MR shows a variant appearance of a heterogeneously enhancing extraaxial mass in the right CPA with extension into the porous acusticus of the right IAC . Facial Nerve Schwannoma in CPA-IAC Axial T1 C+ MR shows a variant appearance of a heterogeneously enhancing extraaxial mass in the right CPA with extension into the porous acusticus of the right IAC .

Coronal T1 C+ MR shows a large heterogeneously enhancing mass in the CPA cistern and proximal IAC . Facial Nerve Schwannoma in CPA-IAC Coronal T1 C+ MR shows a large heterogeneously enhancing mass in the CPA cistern and proximal IAC .

Axial bone CT shows a transverse otic capsule violating T-bone fracture with associated pneumolabyrinth and gas in the vestibule and lateral SCC. T-Bone Fractures Axial bone CT shows a transverse otic capsule violating T-bone fracture with associated pneumolabyrinth and gas in the vestibule and lateral SCC.

Axial bone CT demonstrates enlargement of the left bony vestibular aqueduct . Large Endolymphatic Sac Anomaly (IP-II) Axial bone CT demonstrates enlargement of the left bony vestibular aqueduct .

Axial bone CT shows incomplete partitioning of the left cochlea in a patient with large vestibular aqueduct. Large Endolymphatic Sac Anomaly (IP-II) Axial bone CT shows incomplete partitioning of the left cochlea in a patient with large vestibular aqueduct.

Axial bone CT shows longitudinal temporal bone fracture with associated pneumolabyrinth . T-Bone Fractures Axial bone CT shows longitudinal temporal bone fracture with associated pneumolabyrinth .

Axial bone CT shows lack of the normal right cochlear aperture and severe hypoplasia of the vestibule and SCCs in a patient with CHARGE syndrome. Semicircular Canal Malformation Axial bone CT shows lack of the normal right cochlear aperture and severe hypoplasia of the vestibule and SCCs in a patient with CHARGE syndrome.

Axial T1WI C+ FS MR shows abnormal contrast enhancement in the middle ear, mastoid, cochlea , vestibule , and IAC secondary to actinomycosis labyrinthitis. Labyrinthitis Axial T1WI C+ FS MR shows abnormal contrast enhancement in the middle ear, mastoid, cochlea , vestibule , and IAC secondary to actinomycosis labyrinthitis.

Axial bone CT reveals hypoplastic right IAC related to right cochlear nerve deficiency. Cochlear Nerve & Cochlear Nerve Canal Aplasia-Hypoplasia Axial bone CT reveals hypoplastic right IAC related to right cochlear nerve deficiency.

Axial bone CT demonstrates a malformed vestibule that communicates with a small IAC through a broad gap at the IAC fundus . There is no cochlea anterior to the vestibule. Cochlear Aplasia Axial bone CT demonstrates a malformed vestibule that communicates with a small IAC through a broad gap at the IAC fundus . There is no cochlea anterior to the vestibule.

Axial T2WI MR shows a tiny left IAC and nonvisualization of the cochlear nerve. Cochlear Nerve & Cochlear Nerve Canal Aplasia-Hypoplasia Axial T2WI MR shows a tiny left IAC and nonvisualization of the cochlear nerve.

Sagittal oblique T2 MR shows nonvisualization of the cochlear nerve in association with a small IAC. CNVIII and CNVII formation in the IAC area provides the stimulus for IAC formation. Cochlear Nerve & Cochlear Nerve Canal Aplasia-Hypoplasia Sagittal oblique T2 MR shows nonvisualization of the cochlear nerve in association with a small IAC. CNVIII and CNVII formation in the IAC area provides the stimulus for IAC formation.

Axial high-resolution FSE MR in a child with bilateral hearing loss shows bilateral enlargement of the extraosseous endolymphatic sacs and cochlear modiolar deficiency . Large Endolymphatic Sac Anomaly (IP-II) Axial high-resolution FSE MR in a child with bilateral hearing loss shows bilateral enlargement of the extraosseous endolymphatic sacs and cochlear modiolar deficiency .

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