A 27-year-old male presents with reduced hearing in the left ear for 2 months. He denies tinnitus or vertigo. Pure tone audiometry is done, and the audiogram is shown. Which of the following is the most likely diagnosis?
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In PTA, an air-bone gap suggests conductive hearing loss.
Step 1: Understanding the Question:
The question requires the interpretation of a Pure Tone Audiometry (PTA) chart to identify the type and side of hearing impairment. Step 2: Interpretation of PTA Symbols:
'X': Left ear Air Conduction (AC).
'>': Left ear Bone Conduction (BC).
Air-Bone Gap: A difference between AC and BC thresholds of $>15$ dB indicates Conductive Hearing Loss (CHL).
Step 3: Detailed Explanation:
Analyzing the Chart: On the provided audiogram, the 'X' symbols (representing the left ear's air conduction) are plotted between 40 dB and 60 dB. This indicates a moderate degree of hearing loss for sound traveling through the ear canal.
Bone Conduction Status: The bone conduction symbols for the left ear ('>') are plotted in the normal range (0 dB to 10 dB). This demonstrates that the inner ear (cochlea) and auditory nerve are functioning perfectly.
Calculating the Gap: There is a significant "Air-Bone Gap" of approximately 40-50 dB in the left ear. This pattern is the hallmark of Conductive Hearing Loss, where the problem lies in the external or middle ear.
Conclusion: Because the deficit is localized to the 'X' marks and the history specifies left-sided symptoms, the diagnosis is Left ear CHL. Common causes could include wax, fluid (serous otitis media), or ossicular problems.
Step 4: Final Answer:
The presence of a normal bone conduction threshold with a depressed air conduction threshold in the left ear confirms a diagnosis of Left ear CHL.
