AAO-HNSF Primary Care Otolaryngology Handbook

CHAPTER 5

music can cause a specific type of hearing loss with a characteristic audiometric pattern (Figure 5.4). Patients with noise-induced hearing loss have a symmetric “noise notch” in bone-conduction thresholds at approxi- mately 4000 Hz. Prevention is vital, and counseling on noise avoidance should be part of routine health maintenance. Treatment consists of education, noise avoidance when possible, and appropriate hearing

protection with ear plugs or ear muffs when exposure to loud noise is unavoidable. Patients should also have regularly scheduled audio- metric follow-up. Sudden SNHL is an acute loss of hearing, usually in one ear only. The differential diagnosis is extensive, and in most cases, the true cause is never identified. Common causes are a viral neuritis of the auditory nerve and vascular occlusive etiologies. Sudden SNHL is not an emergency, but is rather an urgent problem that should be diagnosed and addressed

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Figure 5.4. This audiogram suggests a history of noise exposure. Note the high-frequency dip, with a maximum hearing loss at 4000 Hz.

as soon as possible, preferably within a week of occurrence. Patients with asymmetric SNHL require a more thorough evaluation to rule out a benign tumor of the eighth cranial nerve, known as a vestibular schwannoma . Although most patients with an asymmetric hearing loss do not have a vestibular schwannoma, hearing loss is by far the most common presenting complaint in patients with such tumors. In addition, these patients frequently have tinnitus and lower-than-expected speech discrimination scores in the affected ear. They may also have disequilib- rium complaints, although true vertigo is rare. Specialized audiometric testing can be performed to assist in the diagnosis of vestibular schwan- nomas, but magnetic resonance imaging with gadolinium is the diag- nostic test of choice. Physical exam and testing may elucidate an easily treatable cause of hearing loss. However, more serious conditions can be present that require careful assessment and complex management. To ensure that

Primary Care Otolaryngology