Vestibular system in infants with hereditary nonsyndromic deafness.

OBJECTIVE: Seventy percent of genetic deafness occurs without associated phenotypic characteristics and is termed nonsyndromic hereditary hearing impairment, analyzed by numerous genetic loci. Many forms of nonsyndromic hereditary hearing impairment are secondary to diverse cochleosaccular dysfunctions. The purpose of the present study was to evaluate vestibular function in a group of infants with hereditary nonsyndromic deafness using caloric tests and vestibular evoked myogenic potentials. PATIENTS: Fifty-eight infants aged 3 months: 40 healthy controls and 18 infants with hereditary nonsyndromic deafness. Infants with other risk factors of inner ear damage were excluded. INTERVENTION: Diagnostic. Vestibular evoked myogenic potentials and auditory brainstem responses were recorded, and caloric tests were performed. MAIN OUTCOME MEASURES: The vestibular function was impaired in 14 patients.
RESULTS: The results of all the tests in the controls were normal. In the patients, no reaction to caloric stimulation was elicited from 12 examined ears, and no vestibular evoked myogenic potentials were recorded from 24 ears. Caloric responses elicited from 12 ears were weakened. Hearing thresholds were in the interval 40- to 80-dB hearing level in 20 ears and more than 80-dB hearing level in 16 ears. The presence of caloric responses correlated with the hearing threshold interval.
CONCLUSION: In the group of infants with hereditary nonsyndromic deafness, the degree of the semicircular canal impairment is higher in individuals with profound hearing loss. Vestibular evoked myogenic potentials are more frequently absent than caloric responses. The vestibular organ should be routinely examined in infants with hereditary nonsyndromic deafness.