[Progressive sensorineural hearing loss in childhood].

Prevalence of progressive sensorineural hearing loss in childhood seems to be extremely variable, as percentages reported range from 4 to 30%. Differences in the criteria employed for identifying the deterioration, in the groups of patients, and the age range, could explain this wide range of reported figures. The etiology of the progressive sensorineural hearing loss in infants can be hereditary or acquired. Hereditary causes are divided into syndromic and non-syndromic, whereas the acquired causes include congenital or acquired infection (syphilis, cytomegalovirus, rubella virus and toxoplasma infections, bacterial meningitis and acquired viral infections) and congenital inner ear anomalies (Mondini's dysplasia, large vestibular aqueduct, large cochlear aqueduct). Other acquired causes such as disorders of the metabolism, chronic use of ototoxic drugs, autoimmune diseases, perilymphatic fistula and head or acoustic trauma are less common. The age of onset of deterioration shows a great variability because even the congenital hearing losses may occur late after birth. The progressive evolution seems to be binaural in most patients, but more commonly it presents interaural differences, and when the hearing deficit is initially asymmetrical the deterioration is usually greater in the ear which appeared least affected in the first audiogram. Furthermore, at the different frequencies, there is a tendency to a greater deterioration at the frequencies initially least affected, but some authors are not in agreement because they report a uniform pattern of progression in the range of 0.5 to 4 kHz with no modification of the audiometric shape in most of the examined patients.