A 75-year-old man presents to your office for a routine office visit. During the visit, you inquire about hearing loss. He wasn't planning on discussing this but reports that he has trouble understating the television or when someone speaks in a whisper; his family is concerned that he doesn't hear as well as he used to. He hasn't been attending social events or family gatherings recently because he feels embarrassed having to ask people to repeat words or phrases.
- What background and historical data can help suggest a certain type of hearing loss?
- When does hearing loss require urgent specialist evaluation, and what are the historical clues that help you to identify this?
- How can you narrow the differential diagnosis of hearing loss using focused questions after obtaining an open-ended history?
Hearing loss is the third most common chronic condition in older Americans after hypertension and arthritis.1 Ten percent of the US population (28 million Americans) have some degree of hearing loss.2 The prevalence increases significantly with age; between 25% and 40% of patients over the age of 65 are affected.1 The most common causes of hearing loss—presbycusis and noise-induced hearing loss—develop insidiously and are underreported, underdiagnosed, and undertreated. These benign causes of hearing loss, if unrecognized, can lead to decreased functioning, social isolation, and depression. More dramatic but less common presentations of hearing loss, such as sudden-onset hearing loss or hearing loss with associated symptoms, are more likely to be reported by patients and lead to prompt referral and treatment. A careful history allows the clinician to narrow the diagnosis and take appropriate next steps.
The approach to hearing loss involves 2 key steps. First, determine the presence of hearing loss and its severity by asking screening questions or using a questionnaire. Second, focus on alarm symptoms and determine the etiology through a series of specific questions.
It is important to understand the basic anatomy of the auditory system. The auditory system is divided into the outer ear, middle ear, and inner ear. The outer ear is composed of the pinna and external ear canal. Its functions include protection, sound localization, passive augmentation of sound, and transfer of sound waves to the tympanic membrane (eardrum) causing it to vibrate. The middle ear includes the tympanic membrane and the ossicular chain of 3 small bones—the malleus, incus, and stapes—in the air-filled cavity behind it. The ossicular chain transmits sound vibrations from the tympanic membrane to the cochlea. The cochlea, which lies in perilymph fluid within the temporal bone, the vestibular apparatus, and the eighth cranial nerve (vestibulocochlear) comprise the inner ear. This is where mechanical sound is transduced into an electrical impulse via hair cells as sound travels through endolymph fluid within the cochlea to the auditory nerve.
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