AAO-HNSF Primary Care Otolaryngology Handbook

CHAPTER 5

Hearing Loss

Clinical Practice Guideline: Cerumen Impaction Clinical Practice Guideline: Tinnitus

Hearing loss can be caused by numerous factors. Patients may present with the complaint of being unable to hear, or they may complain of having difficulty understanding speech. Often, a family member brings the patient for a hearing test because of communication difficulties. Older individuals often complain of tinnitus , which may be described as a sound like ringing, buzzing, or “crickets” in the ears. While tinnitus is usually a manifestation of hearing loss, it may have other causes as well. Hearing loss in children may be particularly difficult to detect and is often confused with inattention or speech delay. Depending on the specific type and etiology of the hearing loss, dramati- cally different treatments may be prescribed. It is important to determine whether the problem is with the conductive pathway of the ear (conduc- tive) or with the inner ear or eighth cranial nerve (sensorineural). Conductive hearing loss can be due to cerumen impaction, infection of the external auditory canal (EAC), tympanic membrane (TM) perfora- tion, middle ear fluid, or ossicular chain abnormalities. Sensorineural hearing loss can occur as a result of injury to the hair cells in the cochlea or neural elements innervating the hair cells. The most common etiologic factors are presbycusis (age-related changes of the cochlea and eighth cranial nerve), persistent noise exposure , genetic factors, infectious/ inflammatory processes, stroke, and exposure to ototoxic substances. Tumor growth ( vestibular schwannoma ) along the course of the eighth cranial nerve can also be the etiology of sensorineural loss, though unilateral, and must be included in the differential diagnosis. Pure-tone audiometry (hearing test or audiogram) is used to assess the patient’s hearing levels. An audiogram is performed by an audiologist in a sound-proof booth. The test requires the patient’s ability and willingness to cooperate. Special methods exist to assess hearing levels in young chil- dren. Hearing threshold levels are determined between 250 and 8000 Hertz (Hz) for pure tones and measured in decibels. The 0 decibel (dB) level is a quiet tone, “normalized” to a level that an average young adult

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Primary Care Otolaryngology