Hereditary Hearing Loss

Posted by e-Medical PPT Tuesday, June 5, 2012
Crouzon Syndrome
DEFINITION –Hearing Loss present at birth or develops any time thereafter and is believed to have a genetic cause.
WHAT IT AIN’T
“Congenital” which is a general term for Hearing Loss present at birth
Acquired Prenatal Hearing Loss (Syphilis, Rubella, CMV, Toxic Exposure)
Other HL (congenital cholesteatoma, otosclerosis, sudden SNHL)

Classification
Associated Anomalies
Syndromic
Non-Syndromic

Developmental Onset
Prelingual
Postlingual

Genetic Classification
Autosomal Dominant
Autosomal Recessive
X-Linked
Mitochondrial

AD Syndromic
Branchio-Oto-Renal – Outer/Middle/Inner Ear Anomalies (preauricular pits common, microtia, etc), Lateral cervical sinus/cyst/cleft, Renal agenesis/dysplasia, HL (90%) is SN/C or Mixed prelingual
NF-II – Bilat Schwannomas, meningiomas, gliomas, cataracts/lenticular opacities, HL is retrocochlear and usually postlingual - MERLIN gene
Stickler – congenital vitreous anomaly AND any 3 of: myopia before age 6, retinal detachment/lattice degen, joint hypermobility, SNHL, midline cleft (may be sumucous). May have Robin Seq, HL may be mixed pre/post lingual, 50% blind by adolescence, marfanoid habitus

AD Syndromic (cont’d)
Waardenburg – Four types: Type I = SNHL, White Forelock, heterochromia/hopoplastic blue eyes, dystopia canthorum. Can also have synophrys, broad nasal root, alar hypoplasia.  Type 2 = no dystopia canthorum. Type 3 = Type 1 + upper limb contracture. Type 4 = incld Hirschprung.  For all types, HL is prelingual.
Treacher Collins – 1st branchial arch abnormalities of midface hypoplasia, micrognathia, macrostomia, colobomas of lower lids, downward palpebral fissures, Cleft Palate, CHL (EE/ME anomalies).
Crouzon – craniosynostosis, hypertelorism, midface hypoplasia, exophthalmos.  1/3 CHL due to EE/ME anomalies.

AR Syndromic
Jervell Lange-Nielsen – Profound prelingual SNHL, syncope, sudden death (prolonged QT). Syncope w/ exertion or emotion. High mortality rate sig reduced w/ Dx and Tx.
Pendred – Prelingual (usu profound) SNHL and Goiter. T-bone abnormalities (Mondini, DVA).  Goiter may develop later in childhood but usually euthyroid.
Usher – Most common AR syndromic HL, has prelingual SNHL plus retinitis pigmentosa.  ½ of all Deaf-Blinds in US.  3 Types: USH1 – includes vestibular areflexia (no caloric response) and profound HL, USH2 – nl vestibular fct and use HA, USH3 – progressive HL and vestibular probs.  In all 3, RP is progressive, starting w/ nyctaltopia (night blindness).  Electroretinography (ERG) for early RP dx.

X-Linked Syndromic
Alport – SNHL (hi freq), progressive glomerulonephritis, anterior lenticonus, white macular flecks (or both). Screen hematuria/proteinuria (multiple specimens) usually found age 3-4 yrs, esp after URI.

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