Noise-Induced Hearing Loss (NIHL) π§π:
A preventable form of sensorineural hearing loss caused by loud sound exposure that damages cochlear hair cells.
Once hair cells are lost, the damage is irreversible.
About βΉοΈ
- Results from acoustic trauma (single loud blast π₯) or chronic loud sound exposure (e.g. concerts, workplaces ποΈ).
- One of the most common causes of acquired hearing loss worldwide π.
- Prevention with ear protection is key! π§π‘οΈ
Aetiology π§¬
- Acute Exposure π₯: Explosion, gunshot, firework.
- Chronic Exposure πΆβοΈ: Repeated loud noise (factories, concerts, headphones at high volume).
- Pathology: Cochlear hair cell damage β apoptosis β permanent loss (no regeneration π«).
Risk Factors β οΈ
- Recreational:
- Target shooting π― / hunting.
- Motorsports ποΈ / snowmobiles.
- Headphones/earbuds at high volume π§.
- Concerts / musicians πΈπ€.
- Occupational:
- Construction sites ποΈ, factories π, workshops π§.
- Power tools, lawnmowers, leaf blowers, woodworking equipment πͺ.
Clinical Features π
- Progressive hearing loss β first noticed as difficulty following speech in noisy environments π».
- Tinnitus π (ringing/buzzing) β may precede or accompany loss.
- Typically bilateral, symmetrical, high-frequency hearing loss.
Differential Diagnoses π
- Presbycusis π΅ (age-related high-frequency loss).
- Ototoxic drug exposure π (aminoglycosides, loop diuretics, cisplatin).
- Sudden sensorineural hearing loss β‘.
- Middle ear pathology 𦻠(otosclerosis, chronic otitis media).
Investigations π§ͺ
- Audiometry π§:
- Classic β4 kHz notchβ π β maximum loss at 4000 Hz.
- Pattern persists even in advanced NIHL.
Management ππ οΈ
- Prevention π‘οΈ:
- Earplugs / earmuffs π§.
- Safe listening practices: lower device volume π±πΆ.
- Occupational noise controls (soundproofing, equipment maintenance ποΈ).
- Hearing Rehabilitation π:
- Hearing aids for significant loss.
- Counselling + education on hearing conservation.
- Tinnitus Management π: Sound therapy, CBT/counselling, relaxation techniques π§.
References π
π‘ Clinical Pearls
- Classic β4 kHz notchβ = exam clue for NIHL π―.
- NIHL is preventable but irreversible β patient education is crucial π’.
- Differentiate from presbycusis (age-related, gradual, symmetric high-frequency loss π΅).