AETIOLOGY OF HEARING LOSS

1
AETIOLOGY OF HEARING LOSS

• Dr. Juan Mora
• (Consultant Audiological Physician)
• and Paediatric Audiology Team
• (Yorkhill Hospital, Glasgow)
• October 2007

2
AETIOLOGY OF HEARING LOSS

• (Referring to permanent hearing loss)
• Congenital versus Acquired
• 1)Congenital Genetic or pre-natally acquired
• Genetic Around 50 of all permanent hearing
  losses 70 autosomal recessive, 25 autosomal
  dominant and 5 X-linked.
• 70 non-syndromal and 30 syndromal.
• Pre-natally acquired Cytomegalovirus, Rubella,
  Toxoplasma, Syphilis, Herpes ..
• 2)Acquired (peri or post-natally) Meningitis,
  Hyperbilirrubinemia, Ototoxic treatments (e.g.
  Platin compounds, Aminoglycosides), Head injury

3
AETIOLOGY OF HEARING LOSS - AUTOSOMAL RECESSIVE

• USHER SYNDROME 3 Subtypes
• Retinal dystrophy nyctalopia
• tunnel vision
• pigmentary retinopathy
• SNHL
• Vestibular abnormalities

4
AETIOLOGY OF HEARING LOSS - AUTOSOMAL RECESSIVE

• USHER Type I (several subtypes)
• Commonest (50-70)
• Estimated 3-8 of profoundly deaf children and
  50 of deaf-blind population
• Profound congenital hearing loss
• Onset visual symptoms in 1st decade
• Vestibular dysfunction (late walkers!)

5
AETIOLOGY OF HEARING LOSS - AUTOSOMAL RECESSIVE

• USHER Type II (there are subtypes)
• Moderate to severe SNHL
• - detected during childhood
• Later onset visual symptoms
• - 2nd or 3rd decades
• Normal vestibular function

6
AETIOLOGY OF HEARING LOSS - AUTOSOMAL RECESSIVE

• USHER Type III
• Progressive SNHL of late onset
• Late onset progressive retinitis pigmentosa
• Vestibular function may be impaired
• (Type III is the least common but in the Finnish
  population)

7
AETIOLOGY OF HEARING LOSS - AUTOSOMAL RECESSIVE

• Jervell and Lange-Nielsen syndrome
• (long QTc syndrome)
• Request ECG in bilateral severe and profound SNHL
• UNHS babies Request the ECG after 3/12 of age
• Hearing loss can be progressive in the first
  years of life

A young girl was called before the director of
her school for a minor offense and fell
instantly dead. The parents were not surprised,
having lost 2 other 'deaf-mute' children under
similar circumstances of fright and rage
Apparent case of this syndrome described by
Meissner (1856)
8
AETIOLOGY OF HEARING LOSS AUTOSOMAL RECESSIVE

• Mutations in Connexin 26 (GJB2)
• Deletions Connexin 30 (GJB6)
• Leading cause of Autosomal recessive non
  syndromic hearing loss
• Congenital severe to profound hearing loss
• Missense mutations may cause moderate hearing
  loss (which possible progression)

9
AETIOLOGY OF HEARING LOSS AUTOSOMAL RECESSIVE

• PENDRED syndrome
• Enlarged thyroid gland associated with SNHL
• Gene mapped to 7q31
• Bilateral SNHL, ranging from moderate to
  profound, which may progress
• Vestibular dysfunction not uncommon
• Thyroid enlargement of onset during childhood
• Imaging Mondini anomaly, Wide Vestibular
  Aqueduct
• (Estimated in 5-10 of children in Schools for
  the Deaf)

10
AETIOLOGY OF HEARING LOSS AUTOSOMAL DOMINANT

• BRANCHIO-OTO-RENAL SYNDROME
• Ears from severe microtia to minor anomalies of
  the pinna (cup ears), pre-auricular pits,
  hearing loss (mixed, conductive or SNHL).
• Imaging Wide vestibular aqueducts.
• Branchial clefts cysts, sinuses, fistulas
  usually bilateral lower 1/3 of the neck, medial
  to sternomastoid muscle.
• Renal system different structural renal
  anomalies.

11
AETIOLOGY OF HEARING LOSS AUTOSOMAL DOMINANT

• WAARDENBURG syndrome
• (types I, IIA, IIB, IIC, IID, III, IV Aut. Rec.
  )
• Wide nasal bridge owing to lateral displacement
  of the inner canthus of each eye,
• Pigmentary disturbance (heterochromia irides,
  white forelock, white eye lashes)
• SNHL

12
AETIOLOGY OF HEARING LOSS AUTOSOMAL DOMINANT

• Waardenburg type I dystopia canthorum present
• Waardenburg type II dystopia canthorum absent
• (the most frequent type)
• Waardenburg type III upper limb defects
• Waardenburg type IV Hirschprung disease
• Type IV is autosomal recessive

13
AETIOLOGY OF HEARING LOSS AUTOSOMAL DOMINANT

• WAARDENBURG syndrome
• Sensorineural hearing losses of different
  configurations, generally severe but can be
  unilateral. Vestibular function may be impaired.

14
AETIOLOGY OF HEARING LOSS AUTOSOMAL DOMINANT

• VELO-CARDIO-FACIAL SYNDROME
• (Also DiGeorge sequence)
• Estimated prevalence of 12000 people with a
  higher birth incidence as some babies do not
  survive the neonatal period
• Chromosomal deletion from long arm of chromosome
  22 (22q11)
• Extensive phenotype

15
AETIOLOGY OF HEARING LOSS AUTOSOMAL DOMINANT

• VELO-CARDIO-FACIAL SYNDROME
• Hearing Conductive, mixed and SNHL. If SNHL
  generally unilateral and mild to moderate.
• Major systems affected Heart, vascular, CNS,
  craniofacial, skeletal, renal, immune, metabolic,
  cognitive, digestive, respiratory..
• Characteristic face vertically long face,
  pear-shaped nose, overfolded helices
• plus small hands with tapered digits

16
AETIOLOGY OF HEARING LOSS AUTOSOMAL DOMINANT

• Up to 25 of congenitally profound losses may be
  autosomal dominant. The majority are
  Non-syndromal.
• Late-onset progressive SNHL is a feature of
  dominant inheritance (and early onset of
  recessive cases).

17
AETIOLOGY OF HEARING LOSS AUTOSOMAL DOMINANT

• TREACHER COLLINS syndrome
• (Francheschetti-Klein synd., Mandibulofacial
  dysostosis)
• Relatively rare (110,000) but distinctive
  appearance
• Microtia, generally bilateral and symmetric,
  absence of eyelashes on the inner third of the
  lower eyelid.
• CONDUCTIVE hearing loss

18
AETIOLOGY OF HEARING LOSS X - LINKED

• ALPORT SYNDROME
• Glomerulonephritis (renal function deteriorates)
  presents with haematuria
• Progressive SNHL of onset between 5-10 years
• Eyes anterior lenticonus progressing to
  cataracts
• (Commonest variety is X-linked, the remainder
  generally autosomal recessive)

19
AETIOLOGY OF HEARING LOSS

• CONGENITAL CYTOMEGALOVIRUS CMV INFECTION
• CMV cultured from blood, urine or throat lt 3
  weeks indicates a congenital infection
• SNHL of different configurations Often
  Progressive or fluctuating
• Risk of late onset and progression follow up
  until 6 years

20
AETIOLOGY OF HEARING LOSS

• CONGENITAL CYTOMEGALOVIRUS CMV INFECTION
• 10 Symptomatic (of which 50 develop SNHL)
• 90 Asymptomatic (of which 7-15 develop SNHL)
• It may be missed by NHSP
• Consider Congenital CMV in unexplained SNHL,
  including unilateral cases
• (Can be diagnosed via access to Guthrie cards)

21
AETIOLOGY OF HEARING LOSS CASE STUDY

• Congenital cytomegalovirus infection with
  associated cerebral palsy
• Targeted newborn hearing screening REFER
  (otoacoustic emissions) but normal results on
  Click Auditory Brainstem Responses in Left Ear
  and Borderline in Right Ear (at 7 weeks of age)
• Surveillance arranged

22
(No Transcript)
23
AETIOLOGY OF HEARING LOSS CASE STUDY
24
AETIOLOGY OF HEARING LOSS CASE STUDY

• INSERT VISUAL REINFORCEMENT AUDIOMETRY
•   .5 kHz 1 kHz 2 kHz 3 kHz 4 kHz
• Left ear 50 55 40 45 35
• Right ear NR NR NR NR
• (NR No responses)

25
AETIOLOGY OF HEARING LOSS

• CHARGE ASSOCIATION (sporadic)
• C coloboma
• H heart anomalies
• A atresia of choanae
• R retarded growth/development
• G genital hypoplasia
• E ear anomalies (all types of hearing loss)

26
AETIOLOGY OF HEARING LOSS

• Oculo-Auriculo-Vertebral spectrum
• (hemifacial microsomia, Goldenhar syndr.)
• Most cases are sporadic.
• Wide spectrum of anomalies
• Ear From isolated microtia to anotia. Mainly
  conductive but also SNHL.
• Facies Marked facial asymmetry
• Eyes From blepharoptosis to anophthalmia
• CNS, Heart, Trachea, Lung, Skeletal, Renal,
  Gastrointestinal and oral manifestations