A 54-year-old woman comes to the clinic due to difficulty hearing for the past few weeks. During the neurologic examination, the physician assesses her hearing using a vibrating tuning fork. The handle of the tuning fork is placed on her left mastoid process until the sound is no longer audible. The tines are then quickly placed near the patient's left auditory meatus, and she reports hearing no sound. When the handle of the vibrating fork is placed on the middle of her forehead, she hears the vibration more strongly in her left ear than her right. This patient is most likely experiencing which of the following types of hearing loss?
Show Explanatory Sources
Hearing loss is classified as either conductive (impaired transmission of air vibrations to inner ear) or sensorineural (involving the cochlea or auditory nerve). The Rinne and Weber tests can be used to help determine the type of hearing loss.
The Rinne test compares air versus bone conduction (via the mastoid bone). As the vibration of the tuning fork fades, air-conducted sound is normally louder and heard longer than bone-conducted sound. The Rinne test is considered positive (normal) if the sound is heard best at the external auditory meatus (air conduction) and negative (abnormal) if the patient hears the vibration better at the mastoid (bone conduction).
The Weber test is performed by placing a vibrating tuning fork on the middle of forehead equidistant from both ears. The vibration carried by bone conduction is normally heard equally in both ears; vibration heard louder in one ear is abnormal.
The Rinne test is abnormal in this patient's left ear, and the Weber test lateralizes to her left ear. These findings suggest conductive hearing loss in the left ear.
Educational objective:
In conductive hearing loss, bone conduction will be greater than air conduction (abnormal Rinne test), and the Weber test will lateralize to the affected ear. In sensorineural hearing loss, air conduction will be greater than bone conduction (normal Rinne test), and the Weber test will lateralize to the unaffected ear.