Next Step: Formal Audiometry
When otoscopy, tuning-fork testing, cranial nerve examination, neck examination, and neurologic examination are all normal, the next step is formal audiometry with tympanometry to objectively assess hearing function and guide further evaluation 1, 2.
Rationale for Audiometry
Even when physical examination findings are unremarkable, audiometric testing frequently reveals objective abnormalities that were not apparent clinically. In patients presenting with neurotologic complaints, audiometric testing demonstrates hearing loss in approximately 91% of cases, even when not all patients report subjective hearing loss 3. This high yield makes audiometry essential before proceeding to more invasive or expensive testing.
What Audiometry Provides
- Pure-tone audiometry establishes the presence, degree, and type of hearing loss (conductive vs. sensorineural)
- Tympanometry assesses middle ear function and can detect subtle middle ear pathology not visible on otoscopy
- Speech discrimination scores help localize the lesion along the auditory pathway 4
Subsequent Imaging Based on Audiometry Results
The audiometry results will determine whether and what type of imaging is needed:
If Sensorineural Hearing Loss is Detected
MRI of the head and internal auditory canal is the imaging modality of choice 5. MRI can:
- Identify vestibular schwannomas and other cerebellopontine angle tumors
- Demonstrate signal alterations from inflammation or hemorrhage within the cochlear contents
- Assess the vestibulocochlear nerve and auditory pathways
- Visualize abnormalities affecting brain parenchyma along auditory pathways
CT temporal bone is insensitive for soft-tissue abnormalities causing sensorineural hearing loss 5.
If Conductive Hearing Loss is Detected
High-spatial resolution CT of the temporal bone is the appropriate imaging modality 5. This can:
- Define small inflammatory or neoplastic masses within the middle ear cavity
- Demonstrate ossicular erosions or other inner ear structural abnormalities
- Aid in surgical planning
MRI is insufficient for delineating the bony details needed in conductive hearing loss evaluation 5.
Common Pitfalls to Avoid
- Do not skip audiometry and proceed directly to imaging—this wastes resources and may lead to inappropriate imaging modality selection
- Do not order CT head or CTA head—there is no evidence supporting these studies for isolated hearing complaints 5
- Do not assume normal tuning fork testing excludes hearing loss—formal audiometry is far more sensitive and can detect subtle abnormalities 3
Additional Considerations
If audiometry is normal but symptoms persist, consider:
- Vestibular function testing with electronystagmography if dizziness is a component 1, 3
- Selective use of auditory brainstem response (ABR) testing for retrocochlear pathology screening 4, 6
- Laboratory evaluation for systemic conditions (thyroid function, glucose, autoimmune markers) which are abnormal in 9-13% of patients with neurotologic complaints 3