Hearing Loss

Introduction

Hearing loss is a common chronic impairment, particularly for older adults.

  • It can range from a mild loss, in which a person misses certain high-pitched sounds to a total loss of hearing.
  • It is associated with depression, social isolation, poor self-esteem, cognitive decline and functional disability.

Pure tone audiometry is the reference standard for screening for hearing loss, but a simple whispered voice test is also highly sensitive and specific.

Hearing Loss Classification



Classification

It may be classified into 3 types.

  • Sensorineural
    • Involving the inner ear, cochlea or the auditory nerve
    • Usually permanent
  • Conductive
    • Involving any cause that in some way limits the amount of external sound from gaining access to the inner ear.
    • Examples include cerumen impaction and middle ear fluid
    • Medical treatment or surgery can usually restore conductive hearing loss.
  • Mixed loss
    • A combination of conductive and sensorineural hearing loss.



Causes

Congenital - The external auditory canal (EAC) develops from the 8th to 28th week of gestation; problems can occur anytime during this developmental phase.

Presbycusis - Age-related hearing loss is a common cause of hearing loss worldwide. The hallmark of presbycusis is the progressive, symmetric loss of high-frequency over many years in an older adult.

Noise exposure - Constant exposure to loud noises can cause high-frequency sensorineural hearing loss.

Infection - Infection may lead of blockage of the EAC due to the accumulation of debris, oedema or inflammation.

Cerumen impaction

Penetrating Trauma

Ototoxic substances - Aminoglycosides, chemotherapeutic agents (e.g. cisplatin, fluorouracil, bleomycin and nitrogen mustard), heavy metals (e.g. lead, mercury, cadmium, arsenic)

Tumour - relatively rare



Sudden Sensorineural Hearing Loss in Adults

Sudden sensorineural hearing loss (SSNHL) is characterized by an acute sensorineural hearing loss, nearly always unilateral (<5% of cases reported to be bilateral), that occurs within a 72-hour period.

  • Often defined as hearing loss of ≥30 decibels over 3 sequential frequencies in standard pure-tone audiogram over <72 hours.

Most cases are idiopathic, and the prognosis for hearing recovery depends largely upon the severity of the hearing loss.

Many patients with idiopathic SSNHL, however, may only notice a sensation of a blocked ear or aural fullness at first, without recognizing that they have lost hearing.
  • Because a blocked ear is a common occurrence and may be attributed to a number of less concerning conditions (e.g., cerumen impaction, serous otitis media), patients may not seek immediate attention.
Provide prompt referral to an otolaryngologist for patients who develop sudden sensorineural hearing loss.

Treatment of Sudden Sensorineural Hearing Loss in Adults



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