Differential Diagnosis of Otosclerosis

Differential Diagnosis: Case Scenario 1

Differential diagnosis enables a systematic, scientific approach towards patient management, enabling the audiologist to:

    - Quickly eliminate conditions, which may be life threatening
    - Gain insight in to prognosis and plan effective management
    - Provide information useful to future differential diagnoses
    - Enable the patient to understand their condition and develop coping strategies

Audiological testing


In this patient otoscopy is reported as normal, indicating that the pinna and ear canal are clear and normal and the tympanic membrane (TM) is of normal colour- translucent pearly grey, normal malleus orientation, no perforation/surgical legacy, bright cone of light, no retraction pockets or evidence of fluid accumulation.

Tuning Fork Tests:

A positive Rinne result requires AC to be reported as louder than BC. A negative Rinne result requires BC to be reported as louder than AC, indicative of conductive hearing loss (CHL). Where AC and BC are equally depreciated (e.g. in sensorineural (SNHL)/mixed (MHL) hearing loss) a false positive result is possible.

The Weber test enables the audiologist to see whether one ear is hearing better than the other. A person with CHL or SNHL would report localisation in the affected or unaffected ear respectively. A patient with a symmetric hearing loss may report central localisation and therefore an equivocal result.
In this patient a negative Rinne is reported bilaterally suggesting bilateral CHL. The Weber provided “equivocal” results, thus providing initial support for a bilateral pathology.

Pure Tone Audiometry (PTA)

In PTA the AC threshold provides information on the sensitivity of overall hearing function. The BC threshold provides a measure of integrity of cochlea function only (reflecting SNHL). Any air bone gap (ABG) provides a measure of the magnitude of CHL.

PTA for this patient shows a “mild” CHL resulting from...