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-YieldNEET PG
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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