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Saturday, August 23, 2025

Deafness


Deafness (Hearing Loss)

Introduction

Deafness refers to partial or complete loss of hearing. It may be temporary or permanent, conductive (problems in sound conduction), sensorineural (inner ear/nerve damage), or mixed.

Globally, more than 430 million people live with disabling hearing loss. Causes include congenital/genetic, infections, trauma, aging, noise, and ototoxic drugs. Early recognition is essential, as interventions (hearing aids, surgery, cochlear implants) can greatly improve outcomes.

Classification of Hearing Loss

  1. Conductive hearing loss

    • Problem in external or middle ear impeding sound conduction.

    • Examples: earwax, otitis media, perforated eardrum, otosclerosis.

  2. Sensorineural hearing loss

    • Damage to cochlea (hair cells) or auditory nerve.

    • Examples: presbycusis (age-related), noise-induced, Menière’s disease, ototoxic drugs.

  3. Mixed hearing loss

    • Combination of conductive and sensorineural components.

  4. Central hearing loss

    • Rare; due to brainstem/cortical lesions (stroke, tumor, multiple sclerosis).

Causes of Deafness

1. External Ear (Conductive)

  • Earwax impaction (cerumen).

  • Foreign body in ear canal.

  • Otitis externa (swimmer’s ear).

  • Trauma.

2. Middle Ear (Conductive)

  • Otitis media with effusion: “Glue ear” in children.

  • Acute otitis media: Infections blocking sound conduction.

  • Chronic suppurative otitis media.

  • Tympanic membrane perforation.

  • Otosclerosis: Abnormal bone growth fixing stapes.

  • Cholesteatoma: Keratinizing cyst destroying middle ear structures.

3. Inner Ear / Cochlea (Sensorineural)

  • Presbycusis (age-related degeneration).

  • Noise-induced hearing loss.

  • Ototoxic drugs: aminoglycosides (gentamicin), chemotherapy (cisplatin), loop diuretics (furosemide).

  • Menière’s disease.

  • Viral infections: mumps, measles, CMV.

  • Congenital/genetic syndromes (Waardenburg, Usher).

4. Auditory Nerve and Central Causes

  • Acoustic neuroma (vestibular schwannoma).

  • Multiple sclerosis.

  • Brainstem infarct or tumor.

Clinical Features

  • Difficulty hearing conversations, needing repetition.

  • Asking for TV/radio volume to be high.

  • Tinnitus (ringing in ears).

  • Vertigo or imbalance (if vestibular involvement).

  • In children: delayed speech, poor school performance.

Conductive loss: Better hearing in noisy environments, soft voice.
Sensorineural loss: Difficulty with speech discrimination, especially in noisy backgrounds.

Diagnostic Approach

1. History

  • Onset (sudden vs gradual), progression, laterality.

  • Noise exposure, ototoxic drugs, infections, trauma.

  • Family history of deafness.

  • Associated symptoms: tinnitus, vertigo, ear discharge, pain.

2. Examination

  • Otoscopy: wax, foreign body, perforation, infection.

  • Tuning fork tests:

    • Rinne test: Air vs bone conduction.

    • Weber test: Lateralization helps distinguish conductive vs sensorineural loss.

3. Investigations

  • Audiometry (pure tone): Quantifies hearing loss type and severity.

  • Tympanometry: Middle ear function.

  • Otoacoustic emissions (OAE): Neonatal screening.

  • Auditory brainstem response (ABR): Neural pathway integrity.

  • Imaging (MRI/CT): Suspected acoustic neuroma, cholesteatoma.

  • Lab tests: Viral serology, autoimmune work-up (if systemic cause suspected).

Management and Treatment

Treatment depends on the cause and severity.

A. Conductive Hearing Loss

1. Earwax / Foreign Body

  • Removal by syringing, suction, or instrumentation.

  • Cerumenolytics: Carbamide peroxide 6.5% ear drops, 5–10 drops twice daily for up to 4 days.

2. Otitis Externa

  • Topical antibiotics:

    • Ciprofloxacin 0.3% ear drops: 3–4 drops twice daily × 7–10 days.

  • Topical corticosteroid–antibiotic combination for inflammation.

3. Otitis Media

  • Acute otitis media:

    • Amoxicillin 500 mg orally every 8 h for 5–7 days (children: 80–90 mg/kg/day in divided doses).

  • Otitis media with effusion: Observation; grommet insertion if persistent.

4. Tympanic Membrane Perforation

  • Often heals spontaneously.

  • Surgical repair (tympanoplasty) if persistent.

5. Otosclerosis

  • Hearing aids.

  • Stapedectomy surgery may restore hearing.

B. Sensorineural Hearing Loss

1. Sudden Sensorineural Hearing Loss (SSNHL)

  • Medical emergency.

  • Prednisone 60 mg orally daily for 7–14 days, taper.

  • Intratympanic steroids if systemic therapy contraindicated.

2. Presbycusis / Noise-Induced

  • Hearing aids (digital programmable).

  • Cochlear implants for profound bilateral loss.

  • Prevention: ear protection from noise.

3. Ménière’s Disease

  • Low-salt diet, reduce caffeine/alcohol.

  • Betahistine 16 mg orally three times daily.

  • Diuretics (hydrochlorothiazide 25 mg daily).

  • Intratympanic gentamicin (for refractory vertigo, but risk of worsening hearing).

4. Acoustic Neuroma

  • Observation (small tumors).

  • Surgery or stereotactic radiotherapy if symptomatic or enlarging.

5. Ototoxicity

  • Stop offending drug if possible.

  • Monitor with serial audiograms.

  • Supportive management (hearing aids, implants).

C. General Supportive and Rehabilitative Options

  • Hearing aids: Amplify sound, improve speech perception.

  • Cochlear implants: Indicated for profound bilateral sensorineural loss unresponsive to aids.

  • Bone-anchored hearing aids (BAHA): For conductive or mixed loss when conventional aids unsuitable.

  • Speech and language therapy (children).

  • Sign language, lip-reading training.

Complications

  • Social isolation, depression.

  • Speech delay in children.

  • Falls and imbalance if vestibular involvement.

  • Risk of progression to profound deafness.

Prognosis

  • Conductive deafness: Usually reversible if treated (wax, infection, surgery).

  • Sensorineural deafness: Often permanent; progression varies. Early amplification improves outcomes.

  • Sudden deafness: Recovery in ~50% if treated early with steroids.

  • Congenital deafness: Early intervention with hearing aids/implants improves language development.

Patient Education

  • Protect ears from loud noise; use earplugs/headphones wisely.

  • Avoid inserting objects (cotton buds, pins) into ear canal.

  • Monitor children’s hearing and speech development.

  • Complete antibiotic course for ear infections.

  • Regular hearing check-ups, especially with risk factors (elderly, diabetics, noise exposure, chemotherapy).




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