Hearing loss in neonatal intensive care units (NICUS): Follow-up surveillance

Infants admitted to the neonatal intensive care unit (NICU), who represent the 4-8% of all births, present problems such as prematurity, low Apgar scores, infections, hyperbilirubinemia and hearing impairment. In particular significant hearing loss is the most common disorder at birth, occurring in 1 to 2 newborns per 1000 in the general population and 24% to 46% of newborns who are admitted to a NICU. This leads more difficulty to develope verbal skills (learning vocabulary, grammar, word order and idiomatic expressions), language, learning and speech. Hearing impairment influences also cognitive and affective development of infants making consequences in their interpersonal relationships. Joint Committee on Infants Hearing (JCIH) identified many risk factors in NICU infants like as prolonged mechanical ventilation, asphyxia, low birth weight and ototoxic medication and therefore the first step for early diagnosis of hearing loss is identify these factors. Second step is to plan a correct screening strategy. Screening procedures to detect hearing impairment may be divided into two categories: behavioral and electrophysiological. Behavioral techniques produce a high number of false-negative results due to the relative subjectivity of the assessment and difficulty in detecting mild or unilateral hearing loss. Electrophysiological procedures have greater sensitivity and specificity and include measuring the following: auditory brainstem responses (ABR), automated auditory brainstem responses (AABR), and evoked otoacoustic emissions (EOAE). In this chapter will analyze the prevalence of the risk factors in NICU infants most often associated with hearing loss and the screening methods to arrive as soon as possible an early diagnosis.