Introduction
Definition
Permanent childhood hearing impairment (PCHI) is defined as permanent bilateral hearing impairment ≥40 dB HL (hearing level) averaged over 0.5, 1, 2, and 4 kHz in the better-hearing ear. Onset may be prenatal, perinatal, or postnatal, and aetiology may be congenital or acquired
Incidence
One infant per thousand is born with permanent deafness or significant hearing impairment. A further one infant per thousand develops permanent deafness during childhood.
Congenital Hearing Loss
Syndromic
Syndrome | Pathophysiology | Features |
|---|---|---|
Pendred's Syndrome SLC26A4 pendrin gene—Chr 7 | SNHL Goitre Widening vestibular aqueduct | |
Usher’s syndrome (USH) 15 loci and 12 genes— MY07A/CDH23 50% of deaf-blind children in the United States. Three major types are distinguished by severity of deafness, vestibular dysfunction, and age of onset. Type 1 patients have: • Congenital severe-to-profound SNHL • Vestibular dysfunction • Retinitis
Usher’s syndrome (USH)