Presbycusis

Definition & Epidemiology - Old Ears' Woes

• Definition: Age-related, progressive, bilateral, symmetrical sensorineural hearing loss (SNHL).
• Epidemiology:
  • Commonest cause of SNHL in elderly.
  • Typical onset: > 65 years.
• Risk Factors:
  • Genetics (family history).
  • Chronic noise exposure.
  • Ototoxic drugs (e.g., aminoglycosides).
  • Systemic diseases (e.g., diabetes, hypertension).

⭐ High-frequency hearing loss is the earliest manifestation, causing difficulty with speech discrimination, especially in noisy settings.

Pathophysiology & Types - Why Ears Age

• Age-related degeneration impacts:
  • Cochlea (hair cells, supporting cells)
  • Auditory nerve (spiral ganglion cells)
  • Stria vascularis
  • Central auditory pathways

Schuknecht's Classification: 📌 "Some Naughty Monkeys Cuddle" (Sensory, Neural, Metabolic, Cochlear Conductive)

⭐ Metabolic (Strial) presbycusis typically presents with a flat audiogram and good speech discrimination until late stages.

Clinical Features - Hearing Fades Away

• Hearing Loss: Insidious, progressive, bilateral, symmetrical SNHL (high-frequency first).
• Speech Issues:
  • Difficulty understanding speech, especially in noise (cocktail party effect).
  • Phonemic regression (speech discrimination worse than pure-tone loss suggests).
• Other Symptoms:
  • Tinnitus.
  • Recruitment (abnormal loudness perception).
  • Diplacusis.

⭐ The "cocktail party effect" - difficulty hearing in noisy environments - is a classic early symptom and often the primary complaint motivating a hearing test_._

Diagnosis - Tuning In Trouble

• History: Gradual, bilateral hearing loss, difficulty understanding speech in noisy environments, possible tinnitus.
• Otoscopy: Usually normal tympanic membrane and external auditory canal.
• Tuning Fork Tests:
  • Rinne: Positive bilaterally (AC > BC).
  • Weber: Centralized, or may lateralize to the better ear if hearing loss is asymmetrical.
• Pure Tone Audiometry (PTA):
  • Gold standard for diagnosis.
  • Characteristic finding: Bilateral, symmetrical, sloping high-frequency sensorineural hearing loss (SNHL).
  • 
• Speech Audiometry:
  • Reduced speech discrimination score (SDS).
  • Phonemic regression: SDS may be disproportionately poorer than pure tone thresholds suggest.

  ⭐ Exam Favourite: Phonemic regression (poor speech discrimination disproportionate to the degree of pure-tone hearing loss) is particularly characteristic of sensory presbycusis.

• Other Tests (if indicated):
  • Auditory Brainstem Response (ABR): May show ↑ interpeak latencies.
  • Otoacoustic Emissions (OAEs): Often absent/reduced, especially at high frequencies, indicating cochlear (outer hair cell) dysfunction.

Management & Prevention - Sounding Better Longer

• Core Goal: No cure for underlying degeneration. Aim: improve communication and quality of life.
• Counselling & Education: Essential for patients and families to understand and adapt.
• Auditory Rehabilitation:
  • Hearing Aids: Mainstay for most. Various types (e.g., Behind-The-Ear (BTE), In-The-Canal (ITC)). Selection based on degree/type of loss and patient factors.

  ⭐ Hearing aids significantly improve speech discrimination and overall communication in presbycusis.

  • Assistive Listening Devices (ALDs): Supplement hearing aids in specific environments (e.g., TV listeners, personal amplifiers, FM systems).
  • Cochlear Implants: Considered for severe-profound SNHL with poor hearing aid benefit.
• Prevention Strategies:
  • Noise Protection: Use earplugs/earmuffs in loud settings.
  • Avoid Ototoxic Medications: Judicious use of drugs like aminoglycosides, loop diuretics.
  • Manage Systemic Diseases: Control of diabetes, hypertension, vascular issues.
  • Antioxidants: Evidence for benefit is limited.

High-Yield Points - ⚡ Biggest Takeaways

• Presbycusis: Age-related, progressive, bilateral symmetrical sensorineural hearing loss (SNHL).
• Primarily affects high-frequency sounds first, causing poor speech discrimination.
• Characteristic: Difficulty hearing in noisy environments ("cocktail party deafness").
• Pathophysiology: Mainly cochlear hair cell degeneration, especially outer hair cells in the basal turn.
• Key types: Sensory (hair cells), Neural (neurons), Strial (metabolic), Mechanical (cochlear mechanics).
• Management focuses on hearing aids, assistive listening devices, and auditory rehabilitation.