[Age-specific dynamics of the auditory function in the extremely premature babies]

Extremely early premature babies (i.e. those born before the 32^nd week of pregnancy) constitute a group at high risk of development of the perceptive forms of hearing impairment represented mostly by chronic sensorineural hearing loss (CSNHL) and hearing neuropathy (HN). The timely diagnostics of these hearing disorders in premature children and, accordingly, their early and adequate rehabilitation provide a basis for the prevention of hearing and speech problems. At the same time, the hearing function in prematurely born babies is known to be highly unstable and can undergo substantial changes with age; these changes are most frequently observed during the early childhood. This paper was designed to report the results of observations of the hearing function dynamics in a cohort of the extremely early premature children. A total of 186 babies were available for the examination. It was shown that 14 (7.5%) of them had hearing problems. They disappeared by the 12^th and 24^th months of life in 3 children. Three other babies experienced transformation of NH into CSNHL at the age of 12, 14, and 18 months. NH transformed into CSNHL in three children by the age of 12, 24, and 48 months. Five children developed delayed CSNHL by the 10^th, 15^th, 24^th, 28^th, and 36^th months of the actual life. These findings give evidence that the extremely premature children may experience both the improvement of the hearing function due largely to the processes of maturation in the auditory system and its deterioration or delayed formation of hearing impairment. It is concluded that the extremely early premature children born before the 32^nd week of pregnancy should remain under the dynamic audiological observation at least as long as the third or fourth years of life.