AETIOLOGY OF HEARING LOSS

AETIOLOGY OF HEARING LOSS Dr. Juan Mora (Consultant Audiological Physician) and Paediatric Audiology Team (Yorkhill Hospital, Glasgow) October 2007 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 .. Ototoxic treatments (e.g. Platin compounds, Aminoglycosides), Head injury 2)Acquired (peri or post-natally): Meningitis, Hyperbilirrubinemia, AETIOLOGY OF HEARING LOSS - AUTOSOMAL RECESSIVE USHER SYNDROME: 3 Subtypes Retinal dystrophy: nyctalopia tunnel vision pigmentary retinopathy + SNHL + Vestibular abnormalities 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!) 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 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) 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) 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) 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”) 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. 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 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 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. AETIOLOGY OF HEARING LOSS – AUTOSOMAL DOMINANT VELO-CARDIO-FACIAL SYNDROME (Also DiGeorge sequence) Estimated prevalence of 1:2000 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 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 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). AETIOLOGY OF HEARING LOSS – AUTOSOMAL DOMINANT TREACHER COLLINS syndrome (Francheschetti-Klein synd., Mandibulofacial dysostosis) Relatively rare (1:10,000) but distinctive appearance Microtia, generally bilateral and symmetric, absence of eyelashes on the inner third of the lower eyelid. CONDUCTIVE hearing loss 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) AETIOLOGY OF HEARING LOSS CONGENITAL CYTOMEGALOVIRUS CMV INFECTION CMV cultured from blood, urine or throat < 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 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) 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  AETIOLOGY OF HEARING LOSS – CASE STUDY AETIOLOGY OF HEARING LOSS – CASE STUDY INSERT VISUAL REINFORCEMENT AUDIOMETRY .5 kHz 1 kHz 2 kHz 3 kHz 4 kHz Left ear Right ear 50 NR 55 NR 40 NR 45 NR 35 (NR: No responses) 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) 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