A 34-year-old man comes to the office for evaluation of hearing loss. The patient is a military pilot who has flown the past 8 years in noncombat zones. Regular hearing tests administered by the military have been normal until his most recent one. The patient has noticed no change in his hearing and has no ear pain, tinnitus, or vertigo. The results from the remainder of his annual physical, mental, vision, and cardiac tests were normal. The patient has no medical conditions and takes no medications. Aural examination shows clear, intact tympanic membranes bilaterally with no middle ear effusion. Review of the audiometry reveals a mild, bilateral, high-frequency hearing loss. Which of the following is the most likely cause of this patient's hearing impairment?

Question

A 34-year-old man comes to the office for evaluation of hearing loss.  The patient is a military pilot who has flown the past 8 years in noncombat zones.  Regular hearing tests administered by the military have been normal until his most recent one.  The patient has noticed no change in his hearing and has no ear pain, tinnitus, or vertigo.  The results from the remainder of his annual physical, mental, vision, and cardiac tests were normal.  The patient has no medical conditions and takes no medications.  Aural examination shows clear, intact tympanic membranes bilaterally with no middle ear effusion.  Review of the audiometry reveals a mild, bilateral, high-frequency hearing loss.  Which of the following is the most likely cause of this patient's hearing impairment?

Quizplus · Accepted Answer

11ec25c8_d295_c4ad_bc81_8b59ce962b3b_MD0003_00 Loud noises may induce sensorineural hearing loss (SNHL) via both mechanical damage and metabolic overload of cochlear hair cells. Affected individuals (eg, those with excessive occupational noise exposure) generally experience bilateral, high-frequency SNHL. Although patients may not initially notice the hearing loss (as in this patient), continued exposure can impair the ability to understand speech, impact quality of life (eg, social isolation), and raise safety concerns (eg, while driving). Military personnel are often exposed to loud noises, with pilots being especially at risk (due to jet engine noise). Therefore, people serving in the US military (even if not in combat) are required to have regular hearing evaluations, as in this patient. For civilians, public health agencies (eg, US Occupational Safety and Health Administration) impose limits on occupational noise exposure. Employers in many high-risk fields (eg, manufacturing, mining) are required to provide hearing protection (eg, earplugs) and conduct screening hearing evaluations. Unfortunately, noise-induced hearing loss is usually permanent; therefore, management is aimed at preventing further loss. (Choice B) Abnormal bone deposition leading to decreased ossicular mobility (otosclerosis) causes conductive hearing loss rather than SNHL. In addition, otosclerosis usually results in asymmetric hearing loss, is unrelated to noise exposure, and is most commonly seen in younger patients. (Choice C) Due to frequent, rapid changes in altitude, pilots are at increased risk of barotrauma, which can cause diverse hearing loss patterns (eg, conductive or sensorineural, symmetric or asymmetric). However, patients typically feel ear pain or pressure, and examination often shows abnormalities (eg, middle ear effusion, tympanic membrane retraction). (Choice D) Ossification of the cochlea can result in permanent high-frequency hearing loss. However, it generally has a more severe presentation and follows from significant risk factors (eg, severe otosclerosis, meningitis, temporal bone fracture). Noise exposure is not a risk factor. (Choice E) Tympanic membrane fibrosis is often an asymptomatic, incidental finding on ear examination. It can be a sequela of otitis media or barotrauma but is not associated with noise exposure. Educational objective: Chronic, excessive noise exposure can lead to sensorineural hearing loss due to the irreversible death of hair cells in the cochlea. Hearing screening programs are often mandated in high-risk occupations (eg, manufacturing, transportation). References: Global burden of hearing impairment and ear disease. (http://www.ncbi.nlm.nih.gov/pubmed/30047343)

A 34-Year-Old Man Comes to the Office for Evaluation of Hearing