Cochlear Implantation in Siblings With Refsum's Disease

Area of Science:

• Genetics
• Otolaryngology
• Neurology

Background:

• Refsum's syndrome causes progressive hearing and vision loss.
• The exact cause of hearing loss (cochlear vs. retrocochlear) is debated.

Observation:

• Two siblings with Refsum's syndrome and severe hearing loss underwent cochlear implantation.
• Genetic testing identified a novel PHYH gene mutation.
• Pre-implantation otoacoustic emissions were absent.

Findings:

• Post-implantation speech perception improved significantly for bisyllabic words.
• Monosyllabic word perception showed initial improvement but declined over 5 years.
• A new mutation (c.768del63bp) in the PHYH gene was identified.

Implications:

• Cochlear implantation is beneficial for Refsum's syndrome patients with severe hearing loss, particularly those with vision impairment.
• Long-term speech perception decline may indicate progressive retrocochlear degeneration.
• Identification of new mutations aids in Refsum's disease diagnosis.