THE AUDITORY BRAINSTEM RESPONSE (ABR) EVALUATES RISK FACTORS FOR HEARING LOSS IN THE NEWBORN

SUMMARY: Fourteen of 100 unselected patients in an Intensive care nursery were found by the auditory brainstem evoked response (ABR) method to suffer significant hearing loss; of these 8 were ultimately discharged home. Analysis of the 100 clinical records identified 9 risk factors of which most, like low Apgar scores, are already known (Table I). However, neonatal asphyxia appeared to be associated with hearing loss only when repeated episodes of acidosis accompanied it (Table III). We conclude that the ABR readily Identifies the hard-of-hearing premature and estimates the type and amount of his peripheral hearing loss, and that physiological events associated with prolonged perfusion of the cochlea with blood low in pH may be the most common cause of hearing disorder in this group.SPECULATION: Since this study points to the consequences of postnatal addosis as an important factor in producing damage to the cochlea, it reraises the old question of the relative roles played by hypoxia and low pH in producing the Irreversible brain damage that can occur at and near birth. The statistic suggesting that nearly 10 per cent of the babies discharged from an intensive care nursery suffer an irreversible peripheral hearing loss may surprise and dismay neonatologists, and needs in any event to be validated by studies on similar populations. Whether these losses are permanent, furthermore, can only be settled by appropriate follow-up studies.