457 lines
33 KiB
Markdown
457 lines
33 KiB
Markdown
---
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title: "Otosclerosis"
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docid: "ddc7b884-3c17-4834-9e96-d985c6b618a9"
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authors:
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- key: "07a2c087-6202-49e7-870b-7aa162d18f06"
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value: "Bronwyn E. Hamilton, MD"
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- key: "4b6589b0-9b8d-4467-8a90-01a0a59742fc"
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value: "Troy A. Hutchins, 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: "Diagnosis"
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slug: "diagnosis"
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treeNodeId: "19b6b986-97d0-40e7-b317-00f0c5cd8fa2"
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-
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name: "Temporal Bone"
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slug: "temporal-bone"
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treeNodeId: "9ad7d7b2-b2e4-4de2-be04-55ce607560c9"
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-
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name: "Inner Ear"
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slug: "inner-ear"
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treeNodeId: "1092a44e-f762-4fab-8991-36dff52535cb"
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-
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name: "Infectious and Inflammatory Lesions"
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slug: "infectious-and-inflammatory-lesions"
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treeNodeId: "c1b8dac8-34f8-4c89-8664-b9b153d878eb"
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-
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name: "Otosclerosis"
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slug: "otosclerosis"
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treeNodeId: null
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category: "Head and Neck"
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cmeTopicId: "ece2b7f0-702e-40e6-908c-dd1ffa3be6e3"
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documentVersionId: "ca5797ec-4f56-46bd-b9d3-a583c34fa6fe"
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imageCount: 18
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lastUpdated: "08/10/21"
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pageDescription: "Otosclerosis"
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pageKeywords: "Head and Neck, Diagnosis, Temporal Bone, Inner Ear, Infectious and Inflammatory Lesions, Otosclerosis"
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pageTitle: "Otosclerosis | STATdx"
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enhancedTitle: "Otosclerosis"
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type: "DX"
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references: true
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breadcrumbs:
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- "Head and Neck"
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- "Diagnosis"
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- "Temporal Bone"
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- "Inner Ear"
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- "Infectious and Inflammatory Lesions"
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- "Otosclerosis"
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---
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# KEY FACTS
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- ## Terminology
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- Synonym:**Otospongiosis**
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- Types: Fenestral otosclerosis (FOto), cochlear otosclerosis (COto)
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- Pathologic appearance of lytic, spongy bone foci in bony labyrinth of unknown cause
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- Starts perifenestral (FOto), progresses to surround cochlea (FOto + COto)
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- **Fissula ante fenestram**: Cleft of fibrocartilaginous tissue between inner & middle ears just anterior to oval window
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- ## Imaging
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- Best diagnostic clue: Temporal bone CT shows **lytic (otospongiotic) foci** involving bony labyrinth
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- FOto: Starts at anterior margin of oval window (fissula ante fenestram)
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- COto: Affects pericochlear bony labyrinth
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- ## Top Differential Diagnoses
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- Chronic otitis media with tympanosclerosis
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- Temporal bone Paget disease
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- Temporal bone fibrous dysplasia
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- Temporal bone osteoradionecrosis
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- Temporal bone osteogenesis imperfecta
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- ## Pathology
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- Enchondral layer of bony labyrinth displays spongy, vascular, decalcified, irregular bone formation
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- ## Clinical Issues
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- Bilateral progressive conductive (FOto) or mixed (FOto + COto) hearing loss in young adult
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- ## Diagnostic Checklist
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- Typical otospongiotic plaques of otosclerosis are **lytic** & affect **bony** labyrinth
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# TERMINOLOGY
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- ## Abbreviations
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- Fenestral otosclerosis (FOto)
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- Cochlear otosclerosis (COto)
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- ## Synonyms
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- Otospongiosis, fenestral otospongiosis, cochlear otospongiosis
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- ## Definitions
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- Pathologic appearance of **lytic, spongy bone foci** in bony labyrinth of unknown cause
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- Starts perifenestral (FOto), progresses to surround cochlea (FOto + COto)
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- **Fissula ante fenestram**: Cleft of fibrocartilaginous tissue between inner & middle ears just anterior to oval window
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- Cochlear cleft is fatty marrow due to incomplete ossification that parallels cochlea rather than localizing to fissula antefenestram
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- May be present in children & adults, should be differentiated from otosclerosis
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# IMAGING
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- ## General Features
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- ### Best diagnostic clue
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- Temporal bone CT: Lucent (otospongiotic) foci involving bony labyrinth
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- Usually in context of normally aerated middle ear
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- ### Location
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- FOto: Starts at anterior margin of oval window (fissula ante fenestram)
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- May involve any bony area along medial wall middle ear
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- COto: Affects pericochlear bony labyrinth
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- May involve any portion of bony labyrinth
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- ### Size
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- Millimeter punctate or linear foci; may become confluent
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- ### Morphology
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- FOto: Ovoid plaques most common
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- COto: Ovoid to linear (confluent foci)
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- ## CT Findings
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- ### CECT
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- No role for CECT in diagnosis of otosclerosis
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- ### Bone CT
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- **Early** temporal bone CT findings
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- Begins as radiolucent focus at oval window anterior margin (FOto)
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- Spreads to involve all margins of oval & round windows
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- Abnormal thickening of otic capsule bone near oval window (> 2.3 mm) with bulging contour
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- May spread to inner ear otic capsule (COto)
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- Double ring sign or "halo" of radiolucency surrounds cochlea in severe COto
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- Progressive disease may involve any portion of bony labyrinth, including internal auditory canal lateral walls
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- **Late**, chronic (healing phase) temporal bone CT findings
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- FOto: "Heaped up" new bone along oval & round window margins
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- Healed plaque may occlude oval ± round window
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- COto: Mixed radiolucent-radiodense foci present in bony labyrinth
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- ## MR Findings
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- ### T1WI
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- Faint intermediate T1 signal of plaques
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- ### T2WI
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- Thin-section high-resolution T2 may not visualize otosclerosis, even when extensive
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- Large plaques can show increased signal
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- ### T1WI C+
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- Enhancing punctate foci in medial wall of middle ear (FOto) ± pericochlear bony labyrinth (COto)
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- Most obvious when FOto & COto combined
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- Enhancing lesions may be seen anywhere in bony labyrinth in severe cases
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- ## Imaging Recommendations
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- ### Best imaging tool
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- Temporal bone CT
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- ### Protocol advice
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- T1 C+ MR shows enhancing foci in active phase
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- High-resolution T2 MR may miss otosclerosis
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# DIFFERENTIAL DIAGNOSIS
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- [Chronic Otitis Media With Tympanosclerosis](/document/chronic-otomastoiditis-with-tympan-/e8b91656-ad18-405d-bf67-b0b902f04265)
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- Clinical: Obvious chronic middle ear-mastoid inflammatory disease
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- Imaging: Postinflammatory new bone deposition is not limited to oval & round windows as with most FOto
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- Seen in tympanic membrane (TM), middle ear, ossicles, & mastoids
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- New bone deposition is irregular, not smooth, in oval window area
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- [Temporal Bone Paget Disease](/document/temporal-bone-paget-disease/d0c7cbca-1489-488e-ae7d-1b9aee88467d)
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- Clinical: Bone disease of old age (> 50 years)
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- Imaging: Diffuse skull base involvement is rule
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- Diffuse involvement of bony labyrinth, not confined to lateral wall
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- Usually seen as diffuse temporal bone cotton wool appearance
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- [Temporal Bone Fibrous Dysplasia](/document/temporal-bone-fibrous-dysplasia/e5b44f77-f666-4f32-8eb0-6ed2da7d9898)
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- Clinical: Bone disease of young (age < 30 years)
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- Imaging: Involves all parts of temporal bone
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- Relative sparing of inner ear is rule
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- Usually sclerotic, ground-glass in appearance
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- [Temporal Bone Osteoradionecrosis](/document/temporal-bone-osteoradionecrosis/95475621-6d44-4bbd-a779-476154a5a2cc)
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- Clinical: History of skull base or nasopharyngeal radiation therapy
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- Imaging: CT shows diffuse, permeative lucencies of otic capsule
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- [Temporal Bone Osteogenesis Imperfecta](/document/temporal-bone-osteogenesis-imperfe-/d819723f-660b-4067-9b47-f8aeec3ba0b8)
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- Clinical: Blue sclera; patients with mild form develop deafness by 40 years of age
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- Imaging: Looks like severe COto with more generalized demineralization of bony labyrinth
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# PATHOLOGY
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- ## General Features
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- ### Etiology
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- Unknown
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- ### Genetics
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- Sporadic or autosomal dominant gene transmission
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- Bony otic capsule development: 3 layers
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- Thin inner endosteal layer
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- **Middle layer** of combined endochondral & intrachondral bone (**otosclerosis occurs here**)
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- Outer periosteal layer
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- Normal otosclerosis progression
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- Begins at fissula ante fenestram (FOto)
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- Disease spreads from fissula ante fenestram posteriorly along oval window margins to round window
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- Continued active disease spreads to otic capsule (both FOto & COto present)
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- Active **FOto fixes stapes footplate** in oval window niche
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- This "donut" FOto ankyloses stapes footplate
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- Pathophysiology of **conductive hearing loss**
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- COto leads to sensorineural hearing loss
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- Best hypothesis: Spiral ligament becomes compromised
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- Secondary hypothesis: Toxic proteases affect cochlear nerve cells
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- ## Staging, Grading, & Classification
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- Symons/Fanning CT grading system of otosclerosis (2005) has high intra- & interobserver agreement
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- Grade 1: Solely fenestral
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- Grade 2: Patchy localized cochlear disease (± FOto)
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- To basal cochlear turn (grade 2A)
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- To middle/apical turns (grade 2B)
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- Grade 3: Diffuse confluent cochlear involvement (± FOto)
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- ## Gross Pathologic & Surgical Features
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- Otoscopic vascular hue behind TM = **Schwartze sign**
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- Active otosclerotic areas along margins of oval & round windows or beneath cochlear promontory
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- Bony ankylosis of stapes footplate is reflected as stapes immobilization when pulled on by surgeon
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- ## Microscopic Features
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- Enchondral layer of bony labyrinth displays spongy, vascular, decalcified, irregular bone formation
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- 3 pathologic phases of otosclerosis
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- Acute phase: Deposition of islets of osteoid tissue
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- Subacute phase: Spongiotic remodeling with osteoclasts causing focal bone resorption
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- Chronic-sclerotic phase: Osteoblasts create new bone with irregular features resembling mosaic
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- **Otospongiosis** better describes active disease process
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- Chronic, healing phase appears truly **sclerotic**
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- May be histologically indistinguishable from Paget disease
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# CLINICAL ISSUES
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- ## Presentation
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- ### Most common signs/symptoms
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- Bilateral progressive conductive (FOto) or mixed (FOto + COto) hearing loss
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- ### Other signs/symptoms
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- Tinnitus (ringing in ears)
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- Otoscopy: Vascular hue behind TM = Schwartze sign
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- ### Clinical profile
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- Young adult presenting with unexplained **bilateral progressive** conductive or **mixed** **hearing loss**
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- ## Demographics
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- ### Age
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- Appears in 2nd to 3rd decades of life
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- ### Sex
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- M:F = 1:2
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- ### Epidemiology
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- Occurs in 1% of population
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- Most common type is **FOto alone (85%)**; COto in 15%
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- **FOto** causes ~ **90%****conductive hearing loss in a****dults**
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- ## Natural History & Prognosis
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- FOto: Conductive hearing loss is progressive
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- COto: Untreated, will evolve to profound hearing loss
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- ## Treatment
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- FOto: **Stapedectomy** with stapes prosthesis
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- Results negatively impacted by concurrent COto
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- If round window is obliterated, stapes prosthesis will fail
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- If narrow oval window niche height (< 1.4 mm on coronal CT reformat), stapes surgery more challenging
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- Cochlear implantation
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- Used when severe FOto & COto present bilaterally, resulting in profound mixed hearing loss
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- If round window obliteration present bilaterally, cochlear implantation may be more challenging
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- **Fluoride** treatment if COto present
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- Early treatment can arrest progression
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# DIAGNOSTIC CHECKLIST
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- ## Consider
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- Always check oval window anterior margin for FOto in CT evaluation of conductive hearing loss
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- Common blind spot; CT findings can be subtle
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- If COto present, FOto also is present, so look for it
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- MDCT sometimes shows normal fissula ante fenestram on pediatric temporal bone exams as focal radiolucency
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- ## Image Interpretation Pearls
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- Typical otospongiotic plaques of otosclerosis are lucent & affect bony labyrinth
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- If bony fills in membranous labyrinth, diagnosis is **labyrinthine ossificans**, not COto
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- ## Reporting Tips
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- Assess oval & round window patency; narrowing or obliteration have important surgical implications
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383a23f2-eea4-4589-bce6-050a80b7aac1
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## References
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# Selected References
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1. [Fujima N et al: Utility of deep learning for the diagnosis of otosclerosis on temporal bone CT. Eur Radiol. 31(7):5206-11, 2021](http://www.ncbi.nlm.nih.gov/pubmed/?term=33409781%5Bpmid%5D)
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1. [Akazawa Y et al: Measurement of stapes footplate thickness in otosclerosis by ultra-high-resolution computed tomography. Acta Otolaryngol. 140(11):899-903, 2020](http://www.ncbi.nlm.nih.gov/pubmed/?term=32700991%5Bpmid%5D)
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1. [Kösling S et al: Imaging of otosclerosis. Rofo. 192(8):745-53, 2020](http://www.ncbi.nlm.nih.gov/pubmed/?term=32215901%5Bpmid%5D)
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1. [Maxwell AK et al: Sensitivity of high-resolution computed tomography in otosclerosis patients undergoing primary stapedotomy. Ann Otol Rhinol Laryngol. 129(9):918-23, 2020](http://www.ncbi.nlm.nih.gov/pubmed/?term=32432485%5Bpmid%5D)
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1. [Maxwell AK et al: Failure to close the gap: concomitant superior canal dehiscence in otosclerosis patients. Laryngoscope. 130(4):1023-7, 2020](http://www.ncbi.nlm.nih.gov/pubmed/?term=31271445%5Bpmid%5D)
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1. [McClellan J et al: Stapes surgery outcomes in patients with concurrent otosclerosis and superior semicircular canal dehiscence. Otol Neurotol. 41(7):912-5, 2020](http://www.ncbi.nlm.nih.gov/pubmed/?term=32472923%5Bpmid%5D)
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1. [Pucetaite M et al: The cochlear cleft: CT correlation with histopathology. Otol Neurotol. 41(6):745-9, 2020](http://www.ncbi.nlm.nih.gov/pubmed/?term=32221113%5Bpmid%5D)
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1. [Purohit B et al: Role of MRI as first-line modality in the detection of previously undiagnosed otosclerosis: a single tertiary institute experience. Insights Imaging. 11(1):71, 2020](http://www.ncbi.nlm.nih.gov/pubmed/?term=32430577%5Bpmid%5D)
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1. [Andreu-Arasa VC et al: Otosclerosis and dysplasias of the temporal bone. Neuroimaging Clin N Am. 29(1):29-47, 2019](http://www.ncbi.nlm.nih.gov/pubmed/?term=30466643%5Bpmid%5D)
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1. [Bae YJ et al: "Third window" and "single window" effects impede surgical success: analysis of retrofenestral otosclerosis involving the internal auditory canal or round window. J Clin Med. 8(8), 2019](http://www.ncbi.nlm.nih.gov/pubmed/?term=31394873%5Bpmid%5D)
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1. [Brown LA et al: Diagnostic protocol for detecting otosclerosis on high-resolution temporal bone CT. Ann Otol Rhinol Laryngol. 128(11):1054-60, 2019](http://www.ncbi.nlm.nih.gov/pubmed/?term=31288548%5Bpmid%5D)
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1. [Nguyen T et al: Conductive hearing loss with a "dry middle ear cleft"-a comprehensive pictorial review with CT. Eur J Radiol. 110:74-80, 2019](http://www.ncbi.nlm.nih.gov/pubmed/?term=30599877%5Bpmid%5D)
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1. [Shim YJ et al: Involvement of the internal auditory canal in subjects with cochlear otosclerosis: a less acknowledged third window that affects surgical outcome. Otol Neurotol. 40(3):e186-90, 2019](http://www.ncbi.nlm.nih.gov/pubmed/?term=30741893%5Bpmid%5D)
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1. [Yagi C et al: Otosclerosis: anatomical distribution of otosclerotic loci analyzed by high-resolution computed tomography. Eur Arch Otorhinolaryngol. 276(5):1335-40, 2019](http://www.ncbi.nlm.nih.gov/pubmed/?term=30887165%5Bpmid%5D)
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1. [Berrettini S et al: 3D fluid attenuated inversion recovery (FLAIR) magnetic resonance imaging at different stages of otosclerosis. Eur Arch Otorhinolaryngol. 275(11):2643-52, 2018](http://www.ncbi.nlm.nih.gov/pubmed/?term=30191304%5Bpmid%5D)
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1. [Puac P et al: Cavitary plaques in otospongiosis: CT findings and clinical implications. AJNR Am J Neuroradiol. 39(6):1135-9, 2018](http://www.ncbi.nlm.nih.gov/pubmed/?term=29622557%5Bpmid%5D)
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1. [Quesnel AM et al: Otosclerosis: temporal bone pathology. Otolaryngol Clin North Am. 51(2):291-303, 2018](http://www.ncbi.nlm.nih.gov/pubmed/?term=29397947%5Bpmid%5D)
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1. [Sanghan N et al: Retrospective review of otic capsule contour and thickness in patients with otosclerosis and individuals with normal hearing on CT. AJNR Am J Neuroradiol. 39(12):2350-5, 2018](http://www.ncbi.nlm.nih.gov/pubmed/?term=30467217%5Bpmid%5D)
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1. [Wolfovitz A et al: Impact of imaging in management of otosclerosis. Otolaryngol Clin North Am. 51(2):343-55, 2018](http://www.ncbi.nlm.nih.gov/pubmed/?term=29502724%5Bpmid%5D)
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1. [Dudau C et al: Diagnostic efficacy and therapeutic impact of computed tomography in the evaluation of clinically suspected otosclerosis. Eur Radiol. 27(3):1195-201, 2017](http://www.ncbi.nlm.nih.gov/pubmed/?term=27364152%5Bpmid%5D)
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1. [Yamashita K et al: Additive value of "otosclerosis-weighted" images for the CT diagnosis of fenestral otosclerosis. Acta Radiol. 58(10):1215-21, 2017](http://www.ncbi.nlm.nih.gov/pubmed/?term=28090791%5Bpmid%5D)
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1. [Anand V et al: Obliquity of the stapes in otosclerosis: a new radiological sign. Int Arch Otorhinolaryngol. 20(2):94-8, 2016](http://www.ncbi.nlm.nih.gov/pubmed/?term=27096011%5Bpmid%5D)
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1. [Atan D et al: Relation of otosclerosis and osteoporosis: a bone mineral density study. Auris Nasus Larynx. 43(4):400-3, 2016](http://www.ncbi.nlm.nih.gov/pubmed/?term=26656733%5Bpmid%5D)
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1. [Mukaida T et al: Magnetic resonance imaging evaluation of endolymphatic hydrops in cases with otosclerosis. Otol Neurotol. 36(7):1146-50, 2015](http://www.ncbi.nlm.nih.gov/pubmed/?term=25522197%5Bpmid%5D)
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1. [Whetstone J et al: Surgical and clinical confirmation of temporal bone CT findings in patients with otosclerosis with failed stapes surgery. AJNR Am J Neuroradiol. 35(6):1195-201, 2014](http://www.ncbi.nlm.nih.gov/pubmed/?term=24481328%5Bpmid%5D)
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1. [Ukkola-Pons E et al: Oval window niche height: quantitative evaluation with CT before stapes surgery for otosclerosis. AJNR Am J Neuroradiol. 34(5):1082-5, 2013](http://www.ncbi.nlm.nih.gov/pubmed/?term=23179652%5Bpmid%5D)
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1. [Lee TC et al: CT grading of otosclerosis. AJNR Am J Neuroradiol. 30(7):1435-9, 2009](http://www.ncbi.nlm.nih.gov/pubmed/?term=19321627%5Bpmid%5D)
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1. [Moser T et al: The hypodense focus in the petrous apex: a potential pitfall on multidetector CT imaging of the temporal bone. AJNR Am J Neuroradiol. 29(1):35-9, 2008](http://www.ncbi.nlm.nih.gov/pubmed/?term=17925374%5Bpmid%5D)
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1. [Marshall AH et al: Cochlear implantation in cochlear otosclerosis. Laryngoscope. 115(10):1728-33, 2005](http://www.ncbi.nlm.nih.gov/pubmed/?term=16222185%5Bpmid%5D)
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1. [Chadwell JB et al: The cochlear cleft. AJNR Am J Neuroradiol. 25(1):21-4, 2004](http://www.ncbi.nlm.nih.gov/pubmed/?term=14729522%5Bpmid%5D)
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1. [Pekkola J et al: Localized pericochlear hypoattenuating foci at temporal-bone thin-section CT in pediatric patients: nonpathologic differential diagnostic entity? Radiology. 230(1):88-92, 2004](http://www.ncbi.nlm.nih.gov/pubmed/?term=14617763%5Bpmid%5D)
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1. [Rondini-Gilli E et al: [Otosclerosis surgical techniques and results in 150 patients] Ann Otolaryngol Chir Cervicofac. 119(4):227-33, 2002](http://www.ncbi.nlm.nih.gov/pubmed/?term=12410119%5Bpmid%5D)
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1. [Stimmer H et al: Magnetic resonance imaging and high-resolution computed tomography in the otospongiotic phase of otosclerosis. ORL J Otorhinolaryngol Relat Spec. 64(6):451-3, 2002](http://www.ncbi.nlm.nih.gov/pubmed/?term=12499773%5Bpmid%5D)
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1. [Chole RA et al: Pathophysiology of otosclerosis. Otol Neurotol. 22(2):249-57, 2001](http://www.ncbi.nlm.nih.gov/pubmed/?term=11300278%5Bpmid%5D)
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1. [Ruckenstein MJ et al: Management of far advanced otosclerosis in the era of cochlear implantation. Otol Neurotol. 22(4):471-4, 2001](http://www.ncbi.nlm.nih.gov/pubmed/?term=11449102%5Bpmid%5D)
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1. [Shin YJ et al: Correlations between computed tomography findings and family history in otosclerotic patients. Otol Neurotol. 22(4):461-4, 2001](http://www.ncbi.nlm.nih.gov/pubmed/?term=11449100%5Bpmid%5D)
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1. [Swartz JD et al: Fenestral and cochlear otosclerosis: computed tomographic evaluation. Am J Otol. 6(6):476-81, 1985](http://www.ncbi.nlm.nih.gov/pubmed/?term=4073255%5Bpmid%5D)
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## Images
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### Selected Images
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*Coronal graphic illustrates findings of fenestral otosclerosis with a "donut" otospongiotic plaque <img src='img/arrows/WS.png'/> surrounding the stapes footplate in the oval window. The crisp margins of the oval window are obscured by plaque.*
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*Coronal graphic illustrates findings of fenestral otosclerosis with a "donut" otospongiotic plaque <img src='img/arrows/WS.png'/> surrounding the stapes footplate in the oval window. The crisp margins of the oval window are obscured by plaque.*
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*Coronal right temporal bone CT shows a lytic focus anterior to the oval window <img src='img/arrows/WC.png'/>, the typical appearance and location of an otospongiotic plaque of fenestral otosclerosis.*
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*Axial graphic demonstrates a classic example of cochlear otosclerosis. Note otospongiotic plaques in a "halo" around the cochlea <img src='img/arrows/BS.png'/> with concurrent fenestral otosclerosis <img src='img/arrows/BO.png'/>.*
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*Axial left temporal bone CT shows cochlear otosclerosis as osteolytic foci surrounding the cochlea <img src='img/arrows/BS.png'/>. Concurrent fenestral otosclerosis is noted as bony lucency along cochlear promontory extending from the fissula ante fenestram <img src='img/arrows/WO.png'/>.*
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*Axial bone CT shows a thick, lucent otosclerotic plaque anterior to the oval window <img src='img/arrows/WS.png'/> in the expected location of the fissula ante fenestram. An abnormal bulging convex contour is also noted due to the thickened bone. Stapes prosthesis is noted in the oval window <img src='img/arrows/WC.png'/>.*
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*Coronal right temporal bone CT in a patient with mixed hearing loss shows a "halo" of radiolucency surrounding the cochlea <img src='img/arrows/BS.png'/>, representing cochlear otosclerosis. Also note the associated fenestral otosclerosis <img src='img/arrows/WO.png'/>.*
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*Axial bone CT shows a small lucent plaque of fenestral otosclerosis <img src='img/arrows/WS.png'/> thickening the otic capsule bone immediately anterior to the oval window. Note the stapes visualized within the oval window <img src='img/arrows/WC.png'/>.*
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*Axial left temporal bone CT demonstrates mixed lucent and sclerotic otospongiotic plaque obstructing the round window <img src='img/arrows/BS.png'/>. This predisposes to stapes prosthesis failure and makes cochlear implantation more challenging.*
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*Axial left temporal bone CT shows typical lytic plaques of combined fenestral <img src='img/arrows/WS.png'/> and cochlear otosclerosis <img src='img/arrows/WO.png'/>. The patient has undergone stapedectomy with insertion of a stapes prosthesis. Note the metallic density stapes prosthesis <img src='img/arrows/WC.png'/> at the oval window.*
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*Axial T1WI C+ FS MR in the same patient reveals enhancement anterior to the oval window (fissula ante fenestram) <img src='img/arrows/WO.png'/> and surrounding the cochlea <img src='img/arrows/WS.png'/>, representing active fenestral and cochlear otosclerosis, respectively.*
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### Additional Images
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*Axial bone CT shows an extensive pericochlear lucent "halo" <img src='img/arrows/WS.png'/> of cochlear otosclerosis.*
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*Axial thin T2 MR in the same patient shows multifocal otic capsule hyperintensities <img src='img/arrows/WS.png'/> that corresponded to plaques on CT.*
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*Coronal right temporal bone CT shows fenestral otosclerosis involving all the margins of the oval window <img src='img/arrows/BS.png'/>. The net effect is to create a blurring and disappearance of the oval window niche.*
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*Axial temporal bone CT demonstrates a classic otospongiotic plaque <img src='img/arrows/WS.png'/> as extra lucent foci on the anterior margin of the oval window (fissula ante fenestram location). The otic capsule is otherwise spared.*
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*Coronal bone CT in a patient who has undergone stapedectomy for fenestral otosclerosis shows metallic stapes prosthesis. Also note otospongiotic plaque just anterior to the oval window <img src='img/arrows/WS.png'/>.*
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*Axial bone CT demonstrates a severe case of combined fenestral <img src='img/arrows/WS.png'/> and cochlear <img src='img/arrows/BO.png'/> otosclerosis. The Schwartze sign was clearly seen on otoscopic examination.*
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*Axial T1WI C+ FS MR of the right temporal bone in a severe case of combined fenestral <img src='img/arrows/WC.png'/> and cochlear <img src='img/arrows/BS.png'/> otosclerosis with enhancement signifying active disease is shown. Less avid enhancement in the vestibule <img src='img/arrows/WS.png'/> and cochlea <img src='img/arrows/WO.png'/> represents endolymphatic hydrops, which is sometimes associated with otosclerosis.*
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*Coronal left temporal bone CT in the same patient again demonstrates the lytic otospongiotic plaque of fenestral otosclerosis <img src='img/arrows/WC.png'/> in the expected location anterior to the oval window.*
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