Congenital Hearing Impairment- Aetiology and Risk Factors. Flashcards
Deafness may be as a result of _________ or _____ loss.
Conductive
Sensorineural
What structures does conductive hearing loss involve?
- Canal
- Middle ear
What structures does sensorineural hearing loss involve?
- Cochlea
- Cochlear Nerve
- Brain.
What does congenital mean?
You are born with it.
Name the features of conductive hearing impairment.
- Involves mostly the middle ear
- Most commonly Otitis Media with Effusion
- Mild
- Self-limiting
Name the features of sensorineural hearing impairment.
- Involves mostly the cochlea (& auditory nerve)
- Congenital (or acquired early)
- Permanent
Describe the clinical picture if congenital hearing impairment.
- Varies in severity (mild, moderate, severe and profound).
- Is Unilateral or Bilateral
- Can be static or progressive (gets worse)
- Various aetiologies.
What has an incidence of 1.3 per 1000 live births?
Bilateral Hearing Impairment of 40 dB.
Why is hearing important?
- to develop speech and language
- for behaviour- don’t react to sound so pathways won’t develop
- for education eg. classroom environment
- Employment- can’t hear= poorer opportunities.
Explain what is meant by the window of opportunity.
It’s thought that by age 2, it’s too late to have sound input.
What are the 2 types of cause of congenital hearing impairment?
1/3 Acquired
2/3 Hereditary (Genetic )
When can acquired cases of congenital hearing impairment occur?
- Prenatal (before birth)
- Perinatal (during birth)
- Postnatal (shortly after birth)
What are the prenatal causes of congenital hearing impairment?
Infection eg. rubella, syphilis, toxoplama, CMV
What are the perinatal causes of congenital hearing impairment?
- Premature baby- in SCBU (special care baby unit)
- Perinatal probelms eg. hypoxia, antibiotics, jaundice
What are the postnatal causes of congenital hearing impairment?
Meningitis
Mumps
Measles
Head Injury
What does meningitis do to affect hearing?
It blocks up the cochlea (6-8 weeks or no chance of cochlear implant).
How is congenital hearing loss identified?
Babies are screened in the hospital.
2/3 of congenital Hearing Impairment is down to _______ causes.
Genetic.
In genetic cases, 25% are ________ and 75% are _____________.
Syndromal (associated w/ syndromes)
Non-Syndromal (no warning, random, fam have normal hearing).
Name the syndromic genetic causes of congenital hearing impairment.
- usher
- pendred (thyroid symptoms, mild bump to head=lose ehearing)
- Stickler (no chin)
- Waardenberg (white patch, wide apart eyes)
- Jervell and Lange-Nielsen (heart problems too).
What are the Non-Syndromal genetic causes of congenital hearing impairment?
- Autosomal recessive inheritance (80% of cases)- parents normal, past generations passed down- connexin 26 mutation
- Autosomal dominant inheritance (15% of cases)- family history
- Sex-linked inheritance eg. missing X chromosome- turner’s syndrome.
- Mitochondrial Inheritance- can’t process gentomyosin= hearing loss.
What should we ask in the clinic?
- Family History
- Normal Pregnancy?
- Normal Delivery?
- SCBU (special care baby unit)?
- Jaundice?- enough to need phototherapy?
- Head Injury?
- Severe illnedd in hospital?- otoxic drugs?
What should be looked for in clinic?
- Syndromes eg. dysmorphic appearance
- Abnormalities around the ear, head and neck
- Otoscopy
- Audiometry
- If bit older- developmental delay? problems with speech?
What is the most common congenital anomaly?
Deafness.
The implications for congenital hearing impairment are ______________.
Serious.
There’s __________ and ____________ causes of congenital hearing impairment.
Genetic, Environmental
_________ is more important for treatment than the underlying cause.
Severity.
What may children need if they have congenital hearing impairment?
A Cochlear Implant.
