Epidemiology of neurosensorial deafness in the Foral Community of Navarra

Congenital deafness is a relatively frequent disorder that shows a heterogeneous aetiology. Knowledge and the control of some risk factors have decreased the incidence of acquired deafness and increased the relative importance of genetic cause. In an attempt to investigate the clinical relevance of congenital deafness and the mechanisms of prevention in our population, a clinical and genetic study of cases with neurosensorial deafness born in Navarra between 1975 and 1990 was carried out. A total of eighty-one cases were identified, giving an incidence of 0.8 per thousand. Thirty per cent of the cases showed deafness associated with defects. Cause of deafness was identified in seventy per cent of the cases with whom a detailed clinical and genetic study could be performed (n=50). Genetic factors were responsible for the disorder in more than half of these cases. The most frequent hereditary factor was of the autosomic recessive type. This was associated with a more severe form of hearing loss.