Comprehensive vestibular assessment in Usher syndrome: genotype/phenotype correlations

Friday, November 08, 2013 — Poster Session III
10:00 a.m. – 12:00 p.m.	FAES Academic Center (Upper-Level Terrace)	NIDCD	CLIN-29

Authors

T Wafa
J Schultz
C Zalewski
K King
A Turiff
A Griffith
T Friedman
W Zein
C Brewer

Abstract

Usher syndrome is the most common cause of deaf-blindness in childhood. This autosomal recessive syndrome is genetically heterogeneous, and presently 12 genetic loci and 10 causative genes have been reported. There are three major types of Usher syndrome (USH1, USH2, and USH3), clinically distinguished by degree and onset of hearing loss, vestibular function, and onset of retinitis pigmentosa. The complex interaction of the somatosensory, visual and vestibular systems in maintenance of balance is of concern in Usher syndrome in which one or two of these systems are compromised. We present vestibular and balance test results from 65 individuals with genetically confirmed USH1 (n=25) and USH2 (n=40), and examine the findings for genotype/phenotype correlations within the USH1 group. Our test battery included videonystagmography, computerized dynamic posturography, rotary vestibular testing and vestibular evoked myogenic potentials (VEMP). We observed vestibular dysfunction in all of the patients with USH1, with evidence of poorer performance for those with PCDH15 and USH1C mutations than for those with mutations in MYO7A. All persons with USH2 had normal horizontal semicircular canal function, however, ~10% had evidence of otolith dysfunction. This is a novel finding for the USH2 group for whom vestibular function has been traditionally reported as normal.