Inner Ear Lesion in a Child

Inner Ear Lesion in a Child
H. Ric Harnsberger, MD
DIFFERENTIAL DIAGNOSIS
Common
  • Fracture, T-Bone
  • Large Endolymphatic Sac Anomaly (IP-2)
  • Labyrinthine Ossificans
  • Subarcuate Artery Pseudolesion
Less Common
  • Semicircular Canal Dysplasia, CHARGE Syndrome
  • Labyrinthitis
  • Intralabyrinthine Hemorrhage
Rare but Important
  • Cystic Cochleovestibular Anomaly (IP-1)
  • Aplasia-Hypoplasia, Cochlear Nerve Canal
  • Common Cavity, Inner Ear
  • Cochlear Aplasia, Inner Ear
  • Osteogenesis Imperfecta, T-Bone
  • Branchiootorenal Syndrome, Inner Ear
  • X-Linked Mixed Hearing Loss Anomaly
  • Labyrinthine Aplasia
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
  • Congenital lesions in differential diagnosis
    • Congenital deafness has imaging diagnosis associated < 50%
    • If imaging diagnosis is found, large endolymphatic sac anomaly (incomplete partition type 2) is most common diagnosis discovered
    • All other inner ear congenital lesions that can be diagnosed by imaging are rare
  • Imaging recommendations in childhood sensorineural hearing loss (SNHL)
    • Begin with T-bone CT
    • Add high-resolution T2 MR in axial and oblique sagittal plane when cochlear implant under consideration
      • Define IAC size, integrity of cochlear nerve canal, presence of cochlear nerve
Helpful Clues for Common Diagnoses
  • Fracture, T-Bone
    • Complex T-bone fractures may involve inner ear structures
    • T-bone CT: Fracture line crosses inner ear ± pneumolabyrinth
  • Large Endolymphatic Sac Anomaly (IP-2)
    • Clinical clues: Bilateral congenital SNHL that appears in child with cascading hearing loss pattern
    • Most common congenital imaging abnormality
    • CT: Enlarged bony vestibular aqueduct + mild cochlear dysplasia
    • MR: Enlarged endolymphatic sac + mild cochlear aplasia (modiolar deficiency, bulbous apical turn, scala vestibuli larger than scala tympani)
  • Labyrinthine Ossificans
    • Clinical clues: Child develops profound SNHL after episode of meningitis or middle ear infection
    • Healing of suppurative labyrinthitis may result in osteoneogenesis within inner ear fluid spaces
    • CT: Ossific plaques impinges on inner ear fluid spaces
      • Define as cochlear and noncochlear for cochlear implant evaluation
    • MR: High-resolution T2 shows encroachment on membranous labyrinthine fluid spaces
  • Subarcuate Artery Pseudolesion
    • Asymptomatic normal variant that disappears in 1st 2 years of life
    • CT: Prominent canal passes beneath superior semicircular canal arch
    • MR: Conspicuous high signal canal on T2 imaging underneath superior semicircular canal
Helpful Clues for Less Common Diagnoses
  • Semicircular Canal Dysplasia, CHARGE Syndrome
    • Clinical clues: Colobomata, heart defects, choanal atresia, retardation, genitourinary problems, ear abnormalities
    • CT: Bilateral semicircular canal absence, small vestibules, oval window atresia, cochlear nerve canal atresia
    • MR: Cochlear nerve absence
  • Labyrinthitis
    • Clinical clue: Acute onset vertigo, hearing loss ± facial nerve paralysis
    • CT: Acute phase normal
    • MR: Often normal; if positive, diffuse enhancement of inner ear fluid spaces most common presentation
  • Intralabyrinthine Hemorrhage
    • Clinical clue: May be idiopathic or post-traumatic
    • CT: Normal unless associated with trauma
    • MR: High T1 signal in inner ear fluid
Helpful Clues for Rare Diagnoses
  • Cystic Cochleovestibular Anomaly (IP-1)
    • Inner ear morphology: Inner ear looks like tilted “snowman” configuration on axial image
    • CT: Cochlea and vestibule cystic; bony vestibular aqueduct usually normal
    • MR: Both cochlea and vestibule are cystic; endolymphatic sac usually normal
  • Aplasia-Hypoplasia, Cochlear Nerve Canal
    • CT: Complete or partial bony narrowing of base of cochlear nerve canal
    • MR: Fluid in cochlear nerve canal completely or partially replaced by low signal bone
      • Cochlear nerve absent if aplasia of cochlear nerve canal
  • Common Cavity, Inner Ear
    • Inner ear morphology: Inner ear looks like single cyst
    • CT: Single cyst with semicircular canals and vestibular aqueduct blended in
    • MR: Single inner ear fluid-filled cyst
  • Cochlear Aplasia, Inner Ear
    • CT: Cochlea absent with variable deformity of vestibule, semicircular canals and vestibular aqueduct
    • MR: Absent cochlea and cochlear nerve
  • Osteogenesis Imperfecta, T-Bone
    • Clinical clues: Blue sclera; mild form develops deafness by age 40 years
    • Imaging same as cochlear otosclerosis
    • CT: Active disease shows lucent foci in otic capsule surrounding cochlea
    • MR: Active disease shows enhancing foci in otic capsule
  • Branchiootorenal Syndrome, Inner Ear
    • Clinical clues: Auricular deformity, prehelical pits, mixed hearing loss, branchial fistulae and renal abnormalities
    • Genetics: 40% with clinical manifestations have mutations of EYA1 gene on chromosome 8q13.3
    • CT: Hypoplastic apical turn of cochlea, medial deviation of facial nerve, funnel-shaped IAC and patulous eustachian tube
  • X-Linked Mixed Hearing Loss Anomaly
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Aug 10, 2016 | Posted by in PEDIATRICS | Comments Off on Inner Ear Lesion in a Child

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