## Ossicular Erosion in CSOM **Key Point:** The incus is the most frequently eroded ossicle in chronic suppurative otitis media, followed by the stapes and then the malleus. ### Anatomical Basis The incus is particularly vulnerable because: - It has the most tenuous blood supply of the three ossicles - It is suspended by ligaments and is relatively mobile - The long process of the incus is exposed to direct contact with granulation tissue and pus - Osteitis from chronic inflammation preferentially affects the incus body and long process ### Order of Erosion Frequency | Ossicle | Frequency | Reason | | --- | --- | --- | | Incus | Most common (60–70%) | Poor blood supply, exposed long process | | Stapes | Intermediate (20–30%) | Relatively protected by oval window | | Malleus | Least common (10–15%) | Attached to tympanic membrane, better vascularized | **High-Yield:** Incus erosion → conductive hearing loss of 20–30 dB. Complete ossicular chain disruption can cause up to 60 dB loss. **Clinical Pearl:** Ossicular erosion is one of the indications for ossicular reconstruction (ossiculoplasty) after disease control in CSOM. 
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