283 lines
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Markdown
283 lines
25 KiB
Markdown
---
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title: "Inner Ear Lesion, Adult"
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docid: "e5bbf757-d77a-4546-a848-d1a1a64cb230"
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authors:
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- key: "d19354f3-7ff2-495a-ad3f-064122e45602"
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value: "Bernadette L. Koch, MD"
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breadcrumbs:
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-
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name: "Head and Neck"
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slug: "head-and-neck"
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treeNodeId: "ed24ed8c-5d57-4629-879b-447b82d2973d"
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-
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name: "Differential Diagnosis"
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slug: "differential-diagnosis"
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treeNodeId: "40d68862-8975-4dde-ac2b-ebc43ab0fb5c"
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-
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name: "Temporal Bone"
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slug: "temporal-bone"
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treeNodeId: "2f7dc690-4970-486f-abb6-ed24d99b7a04"
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-
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name: "Anatomically Based Differentials"
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slug: "anatomically-based-differentials"
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treeNodeId: "115faedf-cc6e-41cd-a155-665ce5b062ee"
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-
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name: "Inner Ear Lesion, Adult"
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slug: "inner-ear-lesion-adult"
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treeNodeId: null
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category: "Head and Neck"
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documentVersionId: "e47e6e6d-1bca-481c-9123-ff1abb4acc60"
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imageCount: 18
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lastUpdated: "06/24/24"
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pageDescription: "Inner Ear Lesion, Adult"
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pageKeywords: "Head and Neck, Differential Diagnosis, Temporal Bone, Anatomically Based Differentials, Inner Ear Lesion, Adult"
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pageTitle: "Inner Ear Lesion, Adult | STATdx"
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enhancedTitle: "Inner Ear Lesion, Adult"
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type: "DDX"
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references: true
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breadcrumbs:
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- "Head and Neck"
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- "Differential Diagnosis"
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- "Temporal Bone"
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- "Anatomically Based Differentials"
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- "Inner Ear Lesion, Adult"
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---
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# ESSENTIAL INFORMATION
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- ## Key Differential Diagnosis Issues
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- Differential encompasses all lesions, including normal variants, that may be found in inner ear region of adults
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- Inner ear region in temporal bone includes all structures from medial wall of middle ear to lateral aspect of petrous apex
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- ## Helpful Clues for Common Diagnoses
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- **Semicircular Canal Dehiscence**
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- Clinical clues: Tinnitus, dizziness, vertigo, & conductive hearing loss (CHL)
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- Tullio phenomenon: Sound-induced vertigo &/or nystagmus
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- Pathophysiology: Focal superior semicircular canal (SCC) dehiscence causes "3rd" window in inner ear
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- Bone CT findings
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- Superior SCC roof dehiscent ≥ 2 mm into middle cranial fossa dura
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- Transverse oblique CT reformation best shows lesion
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- Rarely, posterior SCC dehiscence
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- **Fenestral Otosclerosis**
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- Clinical clues: Young adult develops gradual increased CHL
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- Early disease location
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- Begins at anterior margin of oval window (fissula ante fenestram)
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- Bone CT findings
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- Lucent & sclerotic lesions along margins of oval & round windows
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- MR findings
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- Enhancing millimeter-sized foci along margins of oval & round windows
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- **Labyrinthine Ossificans**
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- Clinical clue: Profound sensorineural hearing loss (SNHL) following episode of meningitis
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- Pathophysiology: Healing of suppurative labyrinthitis may lead to osteoneogenesis in inner ear fluid spaces
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- Bone CT findings
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- Ossific plaques impinge on inner ear fluid spaces
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- MR findings
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- High-resolution T2: Loss of fluid signal/encroachment on membranous labyrinthine fluid spaces
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- **High Jugular Bulb**
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- Clinical clue: Often asymptomatic normal variant, uncommonly cause of pulsatile tinnitus
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- Bone CT findings
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- Cephalad portion of jugular bulb projects to level of internal auditory canal (IAC)
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- MR findings
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- May simulate enhancing lesion posterior to IAC
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- **Jugular Bulb Diverticulum**
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- Clinical clue: Asymptomatic normal variant
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- Bone CT findings
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- Thumb-like projection off jugular bulb
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- Most commonly projects superiorly behind IAC
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- May project in any direction
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- MR findings
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- May simulate enhancing lesion posterior to IAC
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- **I****nner Ear****Fracture**
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- Bone CT findings
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- Transverse or longitudinal fracture line traverses inner ear structures
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- Pneumolabyrinth possible
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- Otic capsule sparing vs. otic capsule violating classification better predicts complications, such as SNHL, CNVII injury, & CSF leak
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- ± ossicular dislocations &/or fractures
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- MR findings
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- High T1 signal (blood) within inner ear fluid spaces
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- ## Helpful Clues for Less Common Diagnoses
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- **Cochlear Incomplete Partition Type II (IP-2)**
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- Clinical clue: Congenital SNHL in child or young adult with cascading hearing loss pattern
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- Key fact: Most common congenital imaging abnormality in adult SNHL
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- Bone CT findings
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- Deficient interscalar septum (ISS) between middle & apical cochlear turns
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- Flattening of interscalar ridge (anchor point) between upper basal & upper middle cochlear turns
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- Usually with enlarged bony vestibular aqueduct
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- MR findings
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- Deficient ISS between middle & apical cochlear turns
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- Usually with enlarged endolymphatic sac/duct
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- Literature suggests dysplastic osseous spiral lamina-basilar membrane neural complex may mimic ISS on high-resolution, 3D cisternographic MR images, resulting in underdiagnosed IP-2 anomalies
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- Reformat images parallel to lateral SCC to measure distance X = distance between osseous spiral lamina-basilar membrane complex of upper basal turn & 1st linear signal void anterior to basilar membrane
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- When 1st linear signal void = normal ISS, distance X < 1.2 mm
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- When 1st linear signal void = dysplastic osseous spiral lamina-basilar membrane neural complex, distance X ≥ 1.2 mm
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- **Facial Nerve Venous Malformation ("Hemangioma")**
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- Clinical clues: Mimics Bell palsy
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- Facial nerve (FN) paralysis; often with rapid onset
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- Location/morphology: Geniculate fossa most common
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- Poorly circumscribed; amorphous
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- Vascular malformation, not hemangioma
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- Bone CT findings
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- Enlarged geniculate fossa
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- As it increases, spreads along anterior surface of petrous apex
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- ~ 50% show "honeycomb" ossific matrix
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- MR findings
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- Amorphous enhancing geniculate ganglion area mass
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- **Facial Nerve Schwannoma**
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- Clinical clues: 50% present with hearing loss
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- FN symptoms often subtle or absent
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- Location/morphology: Most commonly found in geniculate fossa
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- Smooth, tubular expanding lesion
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- Bone CT findings
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- Focal or tubular enlargement intratemporal FN canal
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- MR findings
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- High-resolution T2: Hypointense soft tissue nodule replacing normal fluid signal
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- C+ MR: Enhancing mass follows intratemporal FN
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- **Labyrinthitis**
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- Clinical clue: Acute-onset vertigo, hearing loss ± FN paralysis
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- Bone CT findings
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- Acute phase normal
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- MR findings
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- Normal or diffuse enhancement of inner ear fluid spaces
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- **Intralabyrinthine Schwannoma**
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- Clinical clue: 10-20 year history of gradual increased SNHL
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- Bone CT findings
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- Normal unless larger transmodiolar, transmacular, or transotic type present
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- MR findings
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- Focal enhancement within inner ear fluid space
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- T2-hypointense nodule replacing normal fluid signal
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- Recommended descriptive terms include location: Intracochlear, intravestibular, vestibulocochlear, transmodiolar, transmacular, & transotic options
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- ## Helpful Clues for Rare Diagnoses
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- **Cochlear Otosclerosis**
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- Clinical clue: Bilateral mixed CHL & SNHL
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- Bone CT findings
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- Lucent foci in bony labyrinth surrounding cochlea
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- MR findings
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- Punctate or linear enhancing foci in otic capsule
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- **Intralabyrinthine Hemorrhage**
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- Clinical clue: Idiopathic, anticoagulant therapy, posttraumatic, sickle cell disease
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- Bone CT findings
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- Normal unless associated with trauma
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- MR findings
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- High T1 signal in inner ear fluid spaces
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- **Endolymphatic Sac Tumor**
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- Clinical clues: Associated with von Hippel-Lindau disease > sporadic
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- Bone CT findings
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- Permeative lytic destruction of posterior petrous temporal bone at expected location of vestibular aqueduct/endolymphatic sac
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- Spiculated or coarse calcifications within tumor matrix
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- Thin calcification seen along posterior margin
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- MR findings
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- T1 high signal foci from blood products trapped within tumor matrix
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- Avidly enhancing tumor; T1 flow voids ("pepper") also common
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## References
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# Selected References
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1. [Razskazovskiy V et al: Prevalence of cochlear-facial and other non-superior semicircular canal third window dehiscence on high-resolution temporal bone CT. AJNR Am J Neuroradiol. 44(11):1309-13, 2023](http://www.ncbi.nlm.nih.gov/pubmed/?term=37884302%5Bpmid%5D)
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1. [Deng F et al: Diagnostic performance of conebeam CT pixel values in active fenestral otosclerosis. AJNR Am J Neuroradiol. 42(9):1667-70, 2021](http://www.ncbi.nlm.nih.gov/pubmed/?term=34140277%5Bpmid%5D)
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1. [Ganeshan D et al: Tumors in von Hippel-Lindau syndrome: from head to toe-comprehensive state-of-the-art review. Radiographics. 38(3):849-66, 2018](http://www.ncbi.nlm.nih.gov/pubmed/?term=29601266%5Bpmid%5D)
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1. [Conte G et al: MR imaging in sudden sensorineural hearing loss. Time to talk. AJNR Am J Neuroradiol. 38(8):1475-9, 2017](http://www.ncbi.nlm.nih.gov/pubmed/?term=28546251%5Bpmid%5D)
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1. [Reinshagen KL et al: Measurement for detection of incomplete partition type II anomalies on MR imaging. AJNR Am J Neuroradiol. 38(10):2003-7, 2017](http://www.ncbi.nlm.nih.gov/pubmed/?term=28775060%5Bpmid%5D)
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1. [Sparacia G et al: Diagnostic performance of reformatted isotropic thin-section helical CT images in the detection of superior semicircular canal dehiscence. Neuroradiol J. 30(3):216-21, 2017](http://www.ncbi.nlm.nih.gov/pubmed/?term=28627985%5Bpmid%5D)
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1. [Bausch B et al: Characterization of endolymphatic sac tumors and von Hippel-Lindau disease in the international ELST registry. Head Neck. 38 Suppl 1:E673-9, 2015](http://www.ncbi.nlm.nih.gov/pubmed/?term=25867206%5Bpmid%5D)
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1. [Kennedy TA et al: Imaging of temporal bone trauma. Neuroimaging Clin N Am. 24(3):467-86, viii, 2014](http://www.ncbi.nlm.nih.gov/pubmed/?term=25086807%5Bpmid%5D)
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1. [Nevoux J et al: Management of endolymphatic sac tumors: sporadic cases and von Hippel-Lindau disease. Otol Neurotol. 35(5):899-904, 2014](http://www.ncbi.nlm.nih.gov/pubmed/?term=24662627%5Bpmid%5D)
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1. [Young JY et al: Preoperative imaging of sensorineural hearing loss in pediatric candidates for cochlear implantation. Radiographics. 34(5):E133-49, 2014](http://www.ncbi.nlm.nih.gov/pubmed/?term=25208295%5Bpmid%5D)
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1. [Nadgir RN et al: Superior semicircular canal dehiscence: congenital or acquired condition? AJNR Am J Neuroradiol. 32(5):947-9, 2011](http://www.ncbi.nlm.nih.gov/pubmed/?term=21393404%5Bpmid%5D)
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1. [Benoit MM et al: Facial nerve hemangiomas: vascular tumors or malformations? Otolaryngol Head Neck Surg. 142(1):108-14, 2010](http://www.ncbi.nlm.nih.gov/pubmed/?term=20096233%5Bpmid%5D)
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1. [Offiah CE et al: Imaging appearances of unusual conditions of the middle and inner ear. Br J Radiol. 81(966):504-14, 2008](http://www.ncbi.nlm.nih.gov/pubmed/?term=18316346%5Bpmid%5D)
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1. [Salomone R et al: Sudden hearing loss caused by labyrinthine hemorrhage. Braz J Otorhinolaryngol. 74(5):776-9, 2008](http://www.ncbi.nlm.nih.gov/pubmed/?term=19082362%5Bpmid%5D)
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1. [Tieleman A et al: Imaging of intralabyrinthine schwannomas: a retrospective study of 52 cases with emphasis on lesion growth. AJNR Am J Neuroradiol. 29(5):898-905, 2008](http://www.ncbi.nlm.nih.gov/pubmed/?term=18321986%5Bpmid%5D)
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## Images
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### Selected Images
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**Semicircular Canal Dehiscence**
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*Transverse oblique bone CT reformation displays the dehiscent roof of the superior semicircular canal <img src='img/arrows/WS.png'/> to best advantage by showing the entire extent of the dehiscence in a single image. Symptomatic patients typically present with sound-induced vertigo &/or nystagmus, i.e., Tullio phenomenon.*
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**Semicircular Canal Dehiscence**
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*Transverse oblique bone CT reformation displays the dehiscent roof of the superior semicircular canal <img src='img/arrows/WS.png'/> to best advantage by showing the entire extent of the dehiscence in a single image. Symptomatic patients typically present with sound-induced vertigo &/or nystagmus, i.e., Tullio phenomenon.*
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**Fenestral Otosclerosis**
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*Axial bone CT demonstrates a subtle active otosclerotic plaque along the anterior margin of the oval window <img src='img/arrows/WS.png'/>. This is the location of the fissula ante fenestram where fenestral otosclerosis begins.*
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**Labyrinthine Ossificans**
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*Axial bone CT in a patient with prior history of meningitis shows complete ossification of the vestibule <img src='img/arrows/WS.png'/> and lateral semicircular canal <img src='img/arrows/WO.png'/>. There was also partial opacification of the cochlea (not shown).*
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**High Jugular Bulb**
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*Axial bone CT shows a high jugular bulb <img src='img/arrows/BS.png'/> visible at the level of the internal auditory canal <img src='img/arrows/WC.png'/>. The high jugular bulb abuts the bony vestibular aqueduct <img src='img/arrows/WO.png'/>. Note that it does not enter the middle ear cavity as a dehiscent jugular bulb might.*
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**Jugular Bulb Diverticulum**
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*Coronal bone CT demonstrates a jugular bulb diverticulum as a superomedial projection off the top of the jugular bulb <img src='img/arrows/WS.png'/>. These lesions are often asymptomatic but can be the cause of pulsatile tinnitus.*
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**Inner Ear Fracture**
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*Axial bone CT in a patient with multiple skull base fractures secondary to a high-speed collision shows fractures <img src='img/arrows/WS.png'/> traversing the left temporal bone, crossing the right posterior limb of the lateral semicircular canal with associated pneumolabyrinth in the vestibule <img src='img/arrows/WO.png'/> and basal turn of the cochlea <img src='img/arrows/WC.png'/>.*
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**Cochlear Incomplete Partition Type II (IP-2)**
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*Axial T2 MR shows a large endolymphatic sac <img src='img/arrows/WS.png'/> along the posterior wall of the temporal bone. Note the associated cochlear dysplasia with modiolar deficiency <img src='img/arrows/WO.png'/> and bulbous asymmetric scalar chambers <img src='img/arrows/WC.png'/>. These patients present with a cascading pattern of progressive hearing loss.*
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**Facial Nerve Venous Malformation ("Hemangioma")**
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*Axial bone CT demonstrates a nonossifying, amorphous, geniculate ganglion lesion <img src='img/arrows/WS.png'/> protruding into the anterior epitympanic recess. The anterior tympanic segment of CNVII <img src='img/arrows/WO.png'/> is also shown.*
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**Facial Nerve Schwannoma**
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*Coronal T1 C+ FS MR reveals an enhancing well-circumscribed lesion of the geniculate ganglion <img src='img/arrows/WS.png'/>. Notice that this ovoid facial nerve schwannoma sits just superior to the normal-appearing cochlea <img src='img/arrows/WO.png'/>, the most common location for facial nerve schwannomas to occur.*
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**Labyrinthitis**
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*Coronal T1 C+ MR shows a diffusely enhancing cochlea <img src='img/arrows/WS.png'/> along with facial nerve enhancement in the geniculate ganglion area <img src='img/arrows/WO.png'/>. Clinical presentation included acute-onset vertigo and sensorineural hearing loss.*
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**Intralabyrinthine Schwannoma**
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*Axial T2 DRIVE image shows a very small intralabyrinthine hypointense schwannoma <img src='img/arrows/WS.png'/> in the posterior aspect of the vestibule surrounded by otherwise normal hyperintense T2 signal intensity fluid. There was typical corresponding enhancement after contrast (not shown).*
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**Cochlear Otosclerosis**
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*Axial bone CT in a patient with severe cochlear <img src='img/arrows/WS.png'/> and fenestral <img src='img/arrows/WO.png'/> otosclerosis shows multifocal osteolytic foci surrounding the cochlea.*
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**Intralabyrinthine Hemorrhage**
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*Axial T1 MR reveals high-signal intralabyrinthine hemorrhage involving the cochlea <img src='img/arrows/WS.png'/>, vestibule <img src='img/arrows/WO.png'/>, and endolymphatic sac <img src='img/arrows/WC.png'/>.*
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**Endolymphatic Sac Tumor**
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*Axial T1 MR shows a very large right endolymphatic sac tumor. The high-signal blood in the tumor matrix <img src='img/arrows/WS.png'/> and broad involvement of the posterior temporal bone wall suggest this diagnosis. The majority of these lesions are associated with von Hippel-Lindau disease.*
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### Additional Images
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**Inner Ear Fracture**
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*Axial bone CT reveals a transverse fracture traversing the inner ear structures <img src='img/arrows/WS.png'/>, crossing obliquely from just anterior to the vestibular aqueduct to the vestibule and then anterolaterally to cross the cochlea. Notice the pneumolabyrinth <img src='img/arrows/WO.png'/> in the vestibule indicating a perilymphatic fistula at the oval window level.*
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**Cochlear Otosclerosis**
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*Axial bone CT shows a patient with severe cochlear <img src='img/arrows/BO.png'/> and fenestral <img src='img/arrows/WS.png'/> otosclerosis. The cochlear otospongiosis plaque initially appears to be a "3rd turn of the cochlea."*
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**Labyrinthine Ossificans**
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*Axial bone CT shows severe labyrinthine ossificans. Notice that the basal turn of the cochlea is partially ossified but still identifiable <img src='img/arrows/WS.png'/> whereas the 2nd turn is nearly invisible <img src='img/arrows/WO.png'/>.*
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**Intralabyrinthine Schwannoma**
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*Axial T1 C+ FS MR shows a mildly enhancing schwannoma <img src='img/arrows/WS.png'/> involving the posterolateral aspect of the basal turn of the cochlea <img src='img/arrows/WO.png'/>. The lesion protrudes into the middle ear cavity. These patients typically present with gradual increase in sensorineural hearing loss.*
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