Disease Description (Causes and Symptoms)
- Definition: Sensorineural hearing loss is a condition in which hearing decreases because damage to the hair cells in the cochlea (inner ear) or to the auditory nerve (cochlear nerve) reduces the detection of sound and its transmission to the brain.
- Pathophysiology: When hair-cell damage or impaired function of the auditory nerve axons occurs due to various causes such as noise, medications, aging, genetic factors, infection, or trauma, an elevated hearing threshold (primarily in the high-frequency range), distortion of sound quality, and reduced speech discrimination may occur.
- Major causes: Sudden (idiopathic) hearing loss (suspected to involve viral, vascular, or immune-related factors), noise exposure, medication (ototoxic) exposure, head trauma, congenital or hereditary causes (approximately 50% of congenital cases are genetic), presbycusis (aging), inner-ear malformations, and tumors (e.g., vestibular schwannoma). In a considerable proportion of cases, the cause is unknown (approximately 25%).
- Major symptoms: Hearing loss (especially reduced ability to understand speech in noisy places), tinnitus, dizziness or balance problems (when inner-ear damage is present), and a feeling of fullness in the ear; pain is uncommon. Acute onset (rapid hearing loss within a day or two) raises suspicion of sudden hearing loss.
Treatment Methods
- Acute (sudden) sensorineural hearing loss
- Standard initial treatment: High-dose steroids (oral or intravenous) — administration as early as possible is important for the prognosis.
- Depending on the case, intratympanic steroid injection (perfusion) may be considered when there is no response to high-dose steroids.
- Depending on the cause, adjunctive treatments such as antiviral agents, anticoagulant or antithrombotic therapy, and immunomodulatory treatment may be considered (evidence and indications are limited).
- Chronic or progressive SNHL
- Hearing aids: Intended to improve speech understanding in cases ranging from mild sensorineural hearing loss to moderate or more severe loss. Selection of customized hearing aids suited to the hearing level and regular adjustment are necessary.
- Cochlear implant: Indicated when hearing aids do not provide improvement in cases of severe-to-profound bilateral hearing loss. In children, early implantation within the language-development period is recommended.
- Rehabilitation: Auditory rehabilitation (speech-sound training), hearing-aid acclimatization training, speech and auditory rehabilitation programs, and vestibular rehabilitation (physical therapy) if balance problems are present.
- Surgical treatment
- For purely sensorineural causes, general surgical methods to restore the inner-ear structures themselves are limited. However, appropriate surgery can be performed for distinguishable outer- or middle-ear diseases (when a conductive component coexists).
- Lifestyle management and medication precautions
- Avoidance and monitoring of ototoxic medications (such as aminoglycosides), blocking noise exposure (using hearing protection), smoking cessation, and management of cardiovascular risk factors (when vascular factors are suspected).
Checklist Before an Outpatient Visit (Including Example Questions)
- Items/information to prepare
- Record when the symptoms began (acute vs. gradual), whether one or both ears are affected, and how the symptoms have progressed
- Presence or absence of tinnitus, dizziness, ear pain, or a feeling of fullness in the ear
- Recent ear infection, head trauma, acute illness (cold, surgery), and pregnancy or childbirth history
- Medications currently being taken (especially antibiotics, anticancer drugs, and medications that may be ototoxic), supplements, and records of regularly administered medications
- Information about occupational and environmental noise exposure (occupation, hobbies), military service, etc.
- Family history (congenital hearing loss or genetic diseases) and neonatal history (prematurity, severe jaundice, etc.)
- Previous hearing test results (a copy, if available) and recent MRI/CT results
- Major tests received during the outpatient visit (performed at the hospital)
- Pure-tone audiometry, speech audiometry, and tympanometry (middle-ear function)
- Otoacoustic emissions (OAE) and auditory brainstem response (ABR/BERA) — useful for evaluating children and nonresponsive patients
- Vestibular function tests (when dizziness is present) and MRI (to differentiate vestibular nerve tumors)
- Examples of questions to ask before the visit (items that are useful for patients to record themselves)
- "Exactly when did the symptoms begin? Record the date and time by day."
- "Did any event occur before the symptoms began (medication use, infection, noise exposure, or trauma)?"
Examples of General Questions to Ask the Doctor
- "What is the most likely cause of my hearing loss?"
- "Please explain which tests you recommend and what each test is intended to identify."
- "What are the expected effects and side effects of the prescribed medications (such as steroids)?"
- "What is the likelihood of hearing recovery (prognosis), and what is the expected timeframe?"
- "What should I be careful about in daily life (noise, medications, etc.)?"
Examples of Disease-Specific Questions
- If acute (sudden) hearing loss is suspected
- "If the symptoms are acute, should steroid treatment be started immediately? If so, by when is treatment expected to be effective?"
- When considering hearing aids or a cochlear implant
- "Based on my current hearing test results, how do you determine whether hearing aids alone will be sufficient or whether a cochlear implant should be considered?"
Summary: Sensorineural hearing loss is hearing loss caused by damage to the inner ear or auditory nerve and has various causes. When it is acute, early diagnosis and treatment (especially steroids) are important for the prognosis. In chronic or severe cases, hearing aids or a cochlear implant, along with auditory rehabilitation, are key components of treatment. Preparing the onset timing, medication history, noise-exposure history, and previous test results before an outpatient visit can help with diagnosis and treatment planning.