ABSTRACT
<p><b>OBJECTIVE</b>To study the effect of selective moderate head cooling therapy on maximum length sequences brainstem auditory evoked potential (MLS-BAEP) in newborn piglets with hypoxic-ischemic brain damage.</p><p><b>METHODS</b>Sixteen newborn piglets aged 5-7 day old were randomly divided into three groups: normothermic control (n=4), HI (n=6) and mild hypothermia-treated (n=6). HI was induced through temporary occlusion of both carotid arteries, followed by mechanical ventilation with low concentration of oxygen (FiO2=0.06) for 30 minutes. Mild hypothermia was induced by equipment via circulating water. MLS-BAER was recorded before HI and at 12 hours, 24 hours, 36 hours, 48 hours, 60 hours, 72 hours, 4 days, 7 days, 10 days, 13 days and 15 days after HI.</p><p><b>RESULTS</b>Compared with the normothermic control group, all latencies and intervals tended to increase significantly at 72 hours in the HI group and reached peak values on day 7. From day 10, all latencies and intervals tended to decrease, but apart from wave I latency, still differed significantly from those of the normothermic control group. MLS-BAER variables did not reach normal values until day 15. Ⅲ latency, Ⅰ-Ⅲ interval and Ⅰ-Ⅴ interval were significantly reduced in the hypothermia-treated group between 60 and 7 days after HI compared with the HI group (P<0.05). V latency and Ⅲ-Ⅴ interval in the hypothermia-treated group were also reduced compared with the HI group between 72 hours and 7 days after HI (P<0.05).</p><p><b>CONCLUSIONS</b>Both peripheral and central auditory systems are disturbed by HI, which shows as a significant increase in MLS-BAER variables (all latencies and intervals) in newborn piglets. Involvement in central brainstem auditory system reaches a peak on day 7 after injury. MLS-BAER variables still cannot reach to normal values until day 15. Selective moderate head cooling therapy can significantly reduce brainstem damage induced by HI.</p>
Subject(s)
Animals , Animals, Newborn , Evoked Potentials, Auditory, Brain Stem , Hypothermia, Induced , Hypoxia, Brain , Therapeutics , SwineABSTRACT
<p><b>OBJECTIVE</b>To study the value of a new technique, maximum length sequences brainstem auditory evoked potential (MLS BAEP), in the assessment of the severity of brain damage following asphyxia in term neonates.</p><p><b>METHODS</b>One hundred and three neonates with perinatal asphyxia and 26 normal term neonates were eligible for the study. Conventional and MLS BAEP examinations were performed within three days after birth. Of the 103 neonates with asphyxia, 17 did not suffer from HIE, 37 had mild HIE, 31 had moderate HIE, and 18 had severe HIE. The latencies and amplitudes of waves I, III and V, and the inter-peak intervals of I-III, III-V, and I-V were analyzed.</p><p><b>RESULTS</b>The latencies of wave V and the inter-peak intervals of I-III, III-V and I-V prolonged gradually with the more severe HIE in both the MLS and the conventional BAEP (P<0.05 or 0.01). The differences among groups were more significant with the increasing repetition rate of click in the MLS BAEP. Compared with the normal controls, conventional BAEP did not show prolonged intervals of I-III and III-V in the mild HIE subgroup, and a prolonged inter-peak interval of III-V in the moderate HIE subgroup, while the MLS BAEP showed significantly prolonged inter-peak intervals of I-III and III-V in the three HIE subgroups and the differences were more and more significant as an increase in the repetition rate of click from 91 to 910 times/seconds.</p><p><b>CONCLUSIONS</b>MLS BAEP is more sensitive and valuable than the conventional one in detecting hypoxic-ischemic brain damage following asphyxia by increasing the repetition rate of click. MLS BAEP provides a new measurement in quantity to assess the severity of HIE in neonates with perinatal asphyxia.</p>