A 38-year-old man presents with a 10-year history of foul-smelling ear discharge from the left ear. Otoscopy reveals a central perforation with purulent discharge. He has conductive hearing loss on audiometry. Which investigation is most appropriate to determine the extent of ossicular damage and guide surgical planning?

Explanation

## Investigation of Choice for Ossicular Assessment in CSOM **Key Point:** HRCT temporal bone is the gold standard for preoperative evaluation of ossicular chain integrity and extent of bone erosion in chronic suppurative otitis media (CSOM). ### Why HRCT Temporal Bone? HRCT provides: - **Detailed bony anatomy** of the ossicular chain (malleus, incus, stapes) - **Detection of ossicular erosion or discontinuity** — critical for surgical planning - **Assessment of mastoid pneumatization** and presence of mastoiditis - **Identification of cholesteatoma** (if present as a complication) - **Evaluation of facial nerve canal** integrity - **Visualization of tegmental defects** and sinus involvement ### Comparison of Investigations in CSOM | Investigation | Purpose | Utility in CSOM | |---|---|---| | **HRCT temporal bone** | Anatomical detail of bone and ossicles | **Gold standard for ossicular damage & surgical planning** | | Tympanometry | Compliance & middle ear pressure | Confirms TM perforation; cannot assess ossicular continuity | | Speech discrimination | Functional hearing assessment | Indicates sensorineural vs. conductive loss; not diagnostic | | OAE | Cochlear function | Assesses inner ear; irrelevant for ossicular pathology | **High-Yield:** HRCT is mandatory before ossiculoplasty or ossicular reconstruction surgery to determine which ossicles are eroded and which can be salvaged. **Clinical Pearl:** A patient with CSOM and conductive hearing loss may have ossicular erosion (commonly the long process of incus), which HRCT will definitively show. This finding directly influences the choice between ossicular reconstruction (ossiculoplasty) vs. hearing aid fitting. ### Timing of HRCT 1. **Diagnosis of CSOM** — clinical (otoscopy + discharge) 2. **Functional assessment** — audiometry (confirms conductive loss) 3. **Preoperative imaging** — HRCT (determines surgical approach and feasibility) **Tip:** Remember that HRCT is NOT needed for diagnosis of CSOM (clinical diagnosis suffices), but it IS essential before surgery to assess bone erosion and guide reconstruction.