Hereditary hearing impairment, experience of Ferrara cooperative study group.

Since 1972 the Audiology Service of the ENT Clinic of Ferrara University has been engaged in the assessment and evaluation of hearing and vestibular disorders, especially oriented towards primary and secondary prevention of hearing loss in infancy. The Clinical Genetic Service was established in 1982 to provide genetic counselling for the Ferrara district and since 1991 both Genetic and Audiological services joined forces in research and genetic counselling of hereditary deafness. Successful genetic counseling for hearing impaired individuals requires special provisions due to complex family histories, syndromic conditions and different methods of communication. The staff have developed and implemented a standardised system of data collection (family and medical histories) and clinical evaluation by the consultant clinical geneticist and audiologist. Over the period January 1991 - January 1994 at the Audiological Service of the ENT Clinic of the University of Ferrara, 497 children aged ≤3 years were tested by use of Auditory Brainstem Responses (ABR). During the same period 100 children aged ≤11 years and suspected of severe hearing impairment were tested by use of electrocochleography (ECochG). The authors present their protocol for clinical evaluation, which has proved useful for genetic counselling purposes.