Congenital Hearing Loss – समस्या को समझें

Statistics:

• Incidence: 1-3 per 1000 live births में congenital hearing loss
• Most common birth defect affecting sensory system
• 50% cases: Genetic
• 25% cases: Prenatal infections (TORCH), complications
• 25% cases: Unknown cause

Critical Period – “Golden Window”:

• 0-3 years: Maximum brain plasticity for language
• First 6 months especially critical for auditory pathway development
• If child doesn’t hear sounds → auditory cortex doesn’t develop properly
• Goal: Detect by 3 months, treat by 6 months

Impact of Late Detection:

• Speech delay: Child doesn’t learn to speak (never heard language)
• Language delay: Can’t understand, can’t communicate
• Cognitive impact: Learning difficulties
• Social isolation: Can’t interact with peers
• Educational challenges
• Permanent impact on life

Power of Early Intervention:

• If hearing aids fitted <6 months → Speech development nearly normal!
• Cochlear implants if profound loss → Can speak and understand
• Speech therapy से excellent outcomes
• Early detection changes everything!

OAE (Otoacoustic Emissions) Test

What is OAE?

Otoacoustic Emissions are sounds produced by outer hair cells in cochlea (inner ear) when they’re functioning normally. यह एक natural phenomenon है – healthy cochlea “echoes” produce करता है।

How OAE Test Works:

Procedure:

• एक small soft probe ear canal में रखा जाता है
• Probe delivers clicking sounds या pure tones
• If cochlea healthy → outer hair cells vibrate → produce echoes
• Probe में microphone है जो इन echoes को record करता है
• Computer analyzes और result देता है

Result:

• PASS: OAEs present = Cochlea function normal (hearing likely normal)
• REFER: OAEs absent/weak = Needs further testing (BERA)

Advantages:

• Very quick: 5-10 minutes both ears
• Non-invasive: Completely painless
• No cooperation needed: Baby can be asleep!
• Excellent screening tool
• Can be done within 24-48 hours of birth

Limitations:

• Only tests up to cochlea (inner ear)
• Doesn’t check auditory nerve या brain
• Can give false “refer” if:
  • Middle ear fluid present (common in newborns first few days)
  • Wax/vernix in canal
  • Baby crying/moving
• If refer → needs BERA for confirmation

When to Do OAE:

• Universal newborn hearing screening: Ideally all babies within 1 month of birth
• High-risk babies: Especially important if:
  • Family history of hearing loss
  • NICU admission >5 days
  • Birth asphyxia
  • Maternal infections (TORCH)
  • Ototoxic medications
  • Craniofacial abnormalities

BERA (Brainstem Evoked Response Audiometry) / ABR (Auditory Brainstem Response)

What is BERA?

BERA एक advanced test है जो complete auditory pathway check करता है – inner ear से brain तक। यह brain waves record करता है in response to sound।

How BERA Works:

Principle:

• जब sound ear में जाती है → inner ear → auditory nerve → brainstem → brain
• इस pathway के different points पर electrical activity generate होती है
• BERA इन electrical responses को record करता है

Procedure:

Step 1: Preparation

• Baby को feed करें, diaper change
• Baby should sleep (natural sleep या sedation – doctor decides)
• Small electrodes scalp पर लगाए जाते हैं (painless, skin पर stick)

Step 2: Sound Delivery

• Headphones/earphones से clicking sounds deliver होती हैं
• Different intensities (loud to soft)
• One ear at a time

Step 3: Wave Recording

• Electrodes brain waves record करते हैं
• Computer averages hundreds of responses
• Generates waveform

Step 4: Analysis

• Doctor waveforms analyze करते हैं
• Waves present हैं? At what intensity?
• Latencies normal हैं?

Result Interpretation:

Normal BERA:

• Waves present at normal intensities (20-30 dB)
• Wave latencies normal
• Indicates: Hearing normal from ear to brain

Abnormal BERA:

• Waves present only at high intensities → Hearing loss
• Degree measured: Mild, moderate, severe, profound
• Can quantify loss (approximately)

No waves:

• Profound hearing loss OR
• Auditory neuropathy (nerve problem despite normal cochlea)

BERA Advantages:

• Objective: No patient response needed
• Tests entire pathway: Ear to brain
• Quantifies loss: Approximate degree
• Can do in babies (sleeping)
• Guides hearing aid fitting
• Detects auditory neuropathy (OAE misses this)

When BERA is Done:

• OAE refer: Confirmation needed
• High-risk newborns: Direct BERA sometimes
• Cannot do behavioral testing: Very young babies, uncooperative children
• Pre-hearing aid fitting: In infants
• Suspected auditory neuropathy

Newborn Hearing Screening Protocol

Recommended Timeline:

Birth to 1 Month:

• OAE screening for all newborns (ideally before hospital discharge)

If OAE “Refer”:

• Repeat OAE at 1 month (could be temporary middle ear fluid)
• If still refer → BERA by 3 months

If BERA Confirms Hearing Loss:

• Start intervention by 6 months:
  • Hearing aids if moderate-severe loss
  • Cochlear implant evaluation if profound
  • Speech therapy
  • Early intervention program

What Parents Should Do

हर बच्चे को Screen करवाना चाहिए:

• Even if no risk factors
• Early detection = Key to normal development

Watch for Signs (Even if Screening Normal):

• By 3 months: Should startle to loud sounds
• By 6 months: Turn to sound source
• By 12 months: Simple words (mama, dada), respond to name
• If any delay → Get tested!

High-Risk Babies – Extra Vigilant:

• Even if pass screening, can develop late-onset hearing loss
• Regular follow-ups needed