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Terms in this set (15)

the most common type of autosomal recessive syndromic hearing loss. It consists of dual sensory impairments: affected individuals are born with sensorineural hearing loss and then develop retinitis pigmentosa (RP). Usher syndrome affects over 50% of the deaf-blind in the United States. The vision impairment from RP is usually not apparent in the first decade, making fundoscopic examination before age ten years of limited utility. However, electroretinography (ERG) can identify abnormalities in photoreceptor function in children as young as age two to four years. During the second decade, night blindness and loss of peripheral vision become evident and inexorably progress.

Three types of Usher syndrome are recognized based on the degree of hearing impairment and result of vestibular function testing.

Usher syndrome type I is characterized by congenital severe-to-profound sensorineural hearing loss and abnormal vestibular dysfunction. Affected persons find traditional amplification ineffective and usually communicate manually. Because of the vestibular deficit, developmental motor milestones for sitting and walking are always reached at later-than-normal ages.

Usher syndrome type II is characterized by congenital mild-to-severe sensorineural hearing loss and normal vestibular function. Hearing aids provide effective amplification for these persons and their communication is usually oral.

Usher syndrome type III is characterized by progressive hearing loss and progressive deterioration of vestibular function.