[SRSF2 promotes glioblastoma cell proliferation by inducing alternative splicing of FSP1 and inhibiting ferroptosis]

Objective: To investigate the effect of serine/arginine-rich splicing factor 2 (SRSF2) on ferroptosis and its possible mechanism in glioblastoma cells. Methods: The online database of gene expression profiling interactive analysis 2 (GEPIA 2) and Chinese Glioma Genome Atlas were used to analyze the expression of SRSF2 in glioblastoma tissue and its association with patients prognosis. To validate the findings of the online databases, the pathological sections of glioblastoma and non-tumor brain tissues from Tianjin Medical University General Hospital, Tianjin, China were collected and analyzed by using immunohistochemistry. Silencing SRSF2 gene expression in glioblastoma cells by siRNA was analyzed with Western blot. The proliferation index was detected by using CCK8 assay. The rescued experiment was conducted by using expression plasmid of pcDNA3.1(+)-SRSF2. The activity of ferroptosis was assessed by using the levels of iron ions and malondialdehyde in glioblastoma cells and the changes in the ratio of glutathione to oxidized glutathione. The changes of gene expression and differential pre-mRNA alternative splicing (PMAS) induced by SRSF2 were monitored by using the third-generation sequencing technology analysis, namely Oxford nanopore technologies (ONT) sequencing analysis. Results: SRSF2 expression was higher in glioblastoma tissues than non-tumor brain tissues. Immunohistochemistry also showed a positive rate of 88.48%±4.60% in glioblastoma tissue which was much higher than the 9.97%±4.57% in non-tumor brain tissue. The expression of SRSF2 was inversely correlated with overall and disease-free disease survivals (P<0.01). The proliferation index of glioblastoma cells was significantly reduced by silencing with SRSF2 siRNA (P<0.01) and could be reversed with transfection of exogenous SRSF2. The levels of intracellulariron ions and malondialdehyde increased (P<0.05), but the glutathione/oxidized glutathione ratio and the expression of key proteins in the glutathione pathway remained unchanged (P>0.05). ONT sequencing results showed that silencing SRSF2 in glioblastoma cells could induce a significant alternative 3' splice site change on ferroptosis suppressor protein 1 (FSP1). Conclusion: SRSF2 inhibits the ferroptosis in glioblastoma cells and promotes their proliferation, which may be achieved by regulating FSP1 PMAS.

Suboptimal postnatal function of brainstem auditory pathway in late preterm infants who do not have major perinatal and postnatal complications

OBJECTIVES

To examine postnatal functional status of the brainstem auditory pathway in late preterm infants and detect any postnatal auditory abnormality.

METHODS

Thirty preterm infants born at 33-36 weeks gestation were studied three months after term. None had major perinatal and postnatal complications to minimize confounding effects. Brainstem auditory evoked responses were recorded with 21-91/s clicks.

RESULTS

Compared with postnatal age-matched normal term infants, the late preterm infants did not manifest any major abnormalities in brainstem auditory evoked responses at conventionally used 21/s clicks. At higher click rates, however, the late preterm infants manifested a moderate prolongation in BAER wave V latency. All interpeak intervals tended to be prolonged at higher click rates. The I-V interval was significantly prolonged at 51/s and particularly at 91/s clicks. Both the I-III and III-V intervals were significantly prolonged at 91/s. The late preterm infants also manifested reduced amplitudes of BAER waves III and V at most click rates.

CONCLUSION

The central components of the brainstem auditory evoked responses were abnormal at higher click rates three months after term in the late preterm infants. Postnatal brainstem auditory function is suboptimal in late preterm infants without major complications. This suboptimal brainstem auditory function may not be clearly shown at term or an earlier stage, but can be shown later. Late preterm infants, although they may not have major complications, should be followed for later auditory development, providing valuable information for improving postnatal care.

[Attention should be paid to the differentiationbetween benign paroxysmal positional vertigo and vestibular migraine]

As we know, benign paroxysmal positional vertigo is a peripheral vestibular disorder,while vestibular migraine is a central vestibular disease. Although they are two different independent diseases, patients often choose to consult otolaryngology and neurology. The clinical manifestations of some patients with these two diseases are similar and the diagnosis is easy to be confused, but the treatment methods are completely different, and incorrect treatment methods will inevitably affect the curative effect and prognosis. Vestibular migraine is characterized by a diversity of clinical manifestations and signs, and the migraine symptoms of some patients do not match with the vestibular symptoms. There are 30% of vestibular migraine patients who showed isolated paroxysmal vertigo/dizziness and nystagmus, which is easily confused with benign paroxysmal positional vertigo and needs to be identified. Under the framework of the international classification of vestibular diseases, according to the new guideline of nystagmus examination and classification issued by Barany Association and new diagnostic criteria of two diseases, differential diagnosisof benign paroxysmal positional vertigo from vestibular migrainecan make up for one-sided understanding caused by the specialization of disciplines, improve thediagnosis and treatment of vestibular diseases, and thus reduce the misdiagnosis and mistreatment.

[Etiological analysis on patients with vertigo or dizziness]

Objective: To explore the spectrum of causes for patients with vertigo or dizziness in the Department of Neurology, and provide a reference for diagnosis and treatment of patients with vertigo or dizziness. Methods: Clinical data of patients in the Department of Neurology, Baotou Central Hospital between January 2016 and September 2017 was retrospectively analyzed. The target group under study was diagnosed based on the uniform diagnostic criteria. Results: A total of 9 200 patients with a chief complaint of vertigo or dizziness were included. The ratio of male to female was 1∶1.8, with an age range of 19 to 85 years. The different etiology was as follows: benign paroxysmal positional vertigo (BPPV) (3 148 cases, 34.22%), persistent postural-perceptual dizziness (PPPD) (2 006 cases, 21.80%), vertigo caused by cerebrovascular diseases (1 463 cases, 15.90%), vestibular neuritis (741 cases, 8.05%), vestibular migraine (536 cases, 5.83%), vestibular paroxysmia (336 cases, 3.65%), Ménière disease (187 cases, 2.03%), drug-induced vertigo (96 cases, 1.04%), neurological degenerative diseases (74 cases, 0.80%), sudden sensorineural hearing loss (51 cases, 0.55%), multiple sclerosis and neuromyelitis optica (21 cases, 0.23%), other reasons (22 cases, 0.24%), unknown reasons (519 cases, 5.64%). Conclusions: Dizziness is resulted from various causes, and BPPV is the most common reason. Vertigo caused by cerebrovascular diseases appears to gradually increase along with age. PPPD is very common in clinical practice, so clinicians needs to be highly aware of BPPV and PPPD. Although those dizziness diseases have a low incidence, they should not be ignored. There are still certain proportion of vertigo patients whose diagnosis are undetermined.

Brainstem auditory abnormality in extremely premature babies and the impact of neonatal bronchopulmonary dysplasia

INTRODUCTION

Extremely premature babies, particularly those who have neonatal bronchopulmonary dysplasia, are at risk of brain damage and neurodevelopmental impairment. This study aimed to examine functional status of the brainstem auditory pathway in extremely premature babies and assess the impact of bronchopulmonary dysplasia on function.

MATERIAL AND METHODS

Brainstem auditory evoked response was studied at term in babies born at ≤27 weeks of gestation with or without neonatal bronchopulmonary dysplasia. The normal controls were term babies without perinatal problems.

RESULTS

Compared with the normal controls, the extremely premature babies showed an elevated response threshold, increased latencies of waves I, III and particularly V. They also showed significantly increased I-V and III-V intervals. The amplitudes of waves I and V were moderately reduced. These abnormalities were clearly more significant in those with bronchopulmonary dysplasia than those without bronchopulmonary dysplasia. A direct comparison between the two groups of extremely premature babies revealed that wave V latency, and I-V and particularly III-V intervals were significantly longer in the babies with bronchopulmonary dysplasia than those without bronchopulmonary dysplasia.

CONCLUSIONS

Extremely premature babies have functional impairment of the brainstem auditory pathway. The impairment is clearly more significant in those with bronchopulmonary dysplasia than those without bronchopulmonary dysplasia. Neonatal bronchopulmonary dysplasia and associated unfavorable conditions are major contributors to brainstem auditory impairment in extremely premature babies.

Auditory impairment in infants with neonatal chronic lung disease is alleviated after term

AIM

Very premature infants with neonatal chronic lung disease (CLD) have been reported to have major auditory impairment at term, and we examined the outcomes in 30 infants after term age.

METHODS

Brainstem auditory evoked response (BAER) was recorded at a postconceptional age of 46-61 weeks in 13 CLD cases and 14 controls from China and 17 CLD cases and 22 controls from the UK.

RESULTS

The BAER threshold in the CLD infants was slightly higher. Clicks at the normal hearing level (60 dB) showed no significant differences between the cases and controls in the latencies of BAER waves I, III and V and the I-V interval. However, the CLD infants demonstrated marginal shortening in the I-III interval and a marginal increase in the III-V interval. The amplitudes of BAER waves in the CLD infants were all slightly smaller than the controls. At 70 and 40 dB normal hearing level, the BAER findings were similar to those obtained at 60 dB normal hearing level, with only small variations.

CONCLUSION

There were minor BAER abnormalities in the CLD infants, suggesting minor auditory impairment. The auditory impairment previously detected at the term date was later alleviated.

Randomised clinical trial: faecal microbiota transplantation for recurrent Clostridum difficile infection - fresh, or frozen, or lyophilised microbiota from a small pool of healthy donors delivered by colonoscopy

BACKGROUND

Faecal microbiota transplantation (FMT) has become routine in managing recurrent C. difficile infection (CDI) refractory to antibiotics.

AIM

To compare clinical response and improvements in colonic microbiota diversity in subjects with recurrent CDI using different donor product.

METHODS

Seventy-two subjects with ≥3 bouts of CDI were randomised in a double-blind study to receive fresh, frozen or lyophilised FMT product via colonoscopy from 50 g of stool per treatment from eight healthy donors. Recipients provided stools pre- and 7, 14 and 30 days post-FMT for C. difficile toxin and, in a subset, microbiome composition by 16S rRNA gene profiling.

RESULTS

Overall resolution of CDI was 87% during 2 months of follow-up after FMT. Stool samples before FMT had significantly decreased bacterial diversity with a high proportion of Proteobacteria compared to donors. Cure rates were highest for the group receiving fresh product seen in 25/25 (100%), lowest for the lyophilised product 16/23 (78%; P = 0.022 vs. fresh and 0.255 vs. frozen) and intermediate for frozen product 20/24 (P = 0.233 vs. fresh). Microbial diversity was reconstituted by day 7 in the subjects receiving fresh or frozen product. Improvement in diversity was seen by day 7 in those randomised to lyophilised material with reconstitution by 30 days.

CONCLUSIONS

Comparative efficacy in faecal microbiota transplantation was observed in subjects receiving fresh or frozen faecal product from the same donors. The lyophilised product had a slightly lowered efficacy compared with fresh product, but it resembled other treatments in microbial restoration 1 month after faecal microbiota transplantation.

Etiology of travellers' diarrhea

Eleven published studies of the etiology of travellers' diarrhea (TD) were reviewed define the etiology of TD and to exam newly developed technology such as Real-Time multiplex polymerase chain reaction (PCR) to identify multiple pathogens in one assay to define the cause of TD. Using PCR methods bacterial pathogens were found in 72% of patients acquiring diarrhea in Latin America and in 80% in travellers with illness acquired in Southeast Asia). In these studies, enterotoxigenic Escherichia coli as the predominant pathogen (42% in Latin America and 28% in Southeast Asia). Ciprofloxacin-resistant Campylobacter was commonly associated with TD in Southeast Asia. Multiplex PCR has improved the detection of enteropathogens and allowed better assessment returning travellers hospitalized with TD and those with persistent diarrhea.

Short-term outcome of functional integrity of the auditory brainstem in term infants who suffer perinatal asphyxia

OBJECTIVES

To assess short-term outcome of impaired functional integrity of the auditory brainstem in term infants who suffer perinatal asphyxia.

METHODS

Maximum length sequence brainstem auditory evoked response (MLS BAER) was recorded and analyzed at a mean age of 3months in term infants after perinatal asphyxia. The data were compared with age-matched normal term infants.

RESULTS

The infants after asphyxia showed an increase in the latency of MLS BAER wave III at 91, 455 and 910/s, and wave V at all click rates of 91-910/s. The interpeak intervals in the infants after asphyxia were increased at almost all click rates. The IV and I-III intervals were increased at all click rates, and the III-V interval was increased at 455 and 910/s. These increases were generally more significant at higher than at lower click rates. The amplitudes of waves I, III and V in the infants after asphyxia were reduced at all click rates. The V/I amplitude ratio was increased at 91-455/s clicks. The slope of III-V interval-rate function was abnormally increased. 17.1% of the infants after asphyxia had an abnormal increase in IV intervals.

CONCLUSIONS

MLS BAER was moderately abnormal at 3months of age in term infants after perinatal asphyxia, suggesting moderate impairment in the functional integrity of the auditory brainstem. The impairment occurs in 17.1% of the infants. Compared with that found at term, the impairment has improved, but not completely recovered.

Abnormal findings in brainstem auditory evoked response at 36-37weeks of postconceptional age in babies with neonatal chronic lung disease

AIM

To examine brainstem auditory function at 36-37weeks of postconceptional age in preterm infants who are diagnosed to have neonatal chronic lung disease (CLD).

STUDY DESIGN

Preterm infants, born at 31 and less weeks of gestation, were studied at 36-37weeks of postconceptional age when they were diagnosed to have neonatal CLD. Brainstem auditory evoked response (BAER) was recorded and analyzed at different click rates.

RESULTS

Compared with healthy controls at the same postconceptional age, the CLD infants showed a slightly increase in BAER wave V latency. However, the I-V, and III-V interpeak intervals in the CLD infants were significantly increased. The III-V/I-III interval ratio was also significantly increased. The amplitudes of BAER waves III and V in the CLD infants tended to be reduced. These BAER findings were similar at all 21, 51 and 91/s clicks, although the abnormalities tended to be more significant at higher than at low click rates.

CONCLUSION

At 36-37weeks of postconceptional age, BAER was abnormal in preterm infants who were diagnosed to have neonatal CLD. This suggests that at time when the diagnosis of CLD is made there is functional impairment, reflecting poor myelination, in the brainstem auditory pathway in preterm infants with neonatal CLD.

Differential Changes in Peripheraland Central Components of the Brain Stem Auditory Evoked Potentials during the Neonatal Period Interm Infants after Perinatal Hypoxia-Ischemia

To identify any differences in dynamic changes between peripheral and central hearing after perinatal hypoxia-ischemia, we studied 80 term infants during the neonatal period by serially recording brain stem auditory evoked potentials (BAEPs) at 60 dB normal hearing level. All BAEP wave latencies and the I-V interval increased significantly on day 1 (analysis of variance, all p < .001). Thereafter, the wave I latency decreased gradually with some variation. The wave V latency and the I-V interval increased further on day 3 and then decreased progressively. On day 30, neither the latencies nor the I-V interval differed significantly from those of normal controls, but the wave v latency and the I-V interval still tended to increase slightly. These results suggest that hearing is impaired shortly after hypoxia-ischemia. Peripheral hearing gradually recovers after day 1, whereas central impairment progresses during the first 3 days and then starts to recover. We conclude that peripheral impairment recovers sooner than central impairment after perinatal hypoxia-ischemia.

Comparison of maturational process of hearing threshold in early life between at-risk and low-risk preterm infants

AIM

To detect any abnormality in the maturational process of hearing threshold during the early life in at-risk preterm infants.

STUDY DESIGN

The threshold of brainstem auditory evoked response was recorded and analyzed longitudinally from 30 to 42weeks of postconceptional age in 357 at-risk infants born at 23-36weeks of gestation. The results were compared with those in 82 low-risk infants born at 30-42weeks at various postconceptional ages.

RESULTS

From 31 to 42weeks, the response threshold in the at-risk infants was consistently slightly higher than that in the low-risk infants. No statistically significant difference was found between the two groups of infants at any designated postconceptional ages. The threshold in the at-risk infants born at 23-29weeks of gestation tended to be higher than those born at 30-36weeks at various postconceptional ages, but the difference did not reach statistical significance. There was also no significant difference in the slope of BAER threshold-age function between the at-risk infants, irrespective of gestational ages, and the low-risk infants.

CONCLUSION

During the early life, hearing threshold in at-risk preterm, mainly very preterm, infants is marginally elevated, but the maturational process of the threshold is generally similar to that in low-risk infants, without notable abnormality.

Measurement of Thermal Conductivity of Porcine Liver in the Temperature Range of Cryotherapy and Hyperthermia (250~315k) by A Thermal Sensor Made of A Micron-Scale Enameled Copper Wire

　　BACKGROUND: Cryotherapy and hyperthermia are effective treatments for several diseases, especially for liver cancers. Thermal conductivity is a significant thermal property for the prediction and guidance of surgical procedure. However, the thermal conductivities of organs and tissues, especially over the temperature range of both cryotherapy and hyperthermia are scarce.

OBJECTIVE

To provide comprehensive thermal conductivity of liver for both cryotherapy and hyperthermia.

MATERIALS AND METHODS

A hot probe made of stain steel needle and micron-sized copper wire is used for measurement. To verify data processing, both the least square method and the Monte Carlo inversion method are used to determine the hot probe constants, respectively, with reference materials of water and 29.9 % Ca₂Cl aqueous solution. Then the thermal conductivities of Hanks solution and pork liver bathed in Hanks solution are measured.

RESULTS

The effective length for two methods is nearly the same, but the heat capacity of probe calibrated by the Monte Carlo inversion is temperature dependent. Fairly comprehensive thermal conductivity of porcine liver measured with these two methods in the target temperature range is verified to be similar.

CONCLUSION

We provide an integrated thermal conductivity of liver for cryotherapy and hyperthermia in two methods, and make more accurate predictions possible for surgery. The least square method and the Monte Carlo inversion method have their advantages and disadvantages. The least square method is available for measurement of liquids that not prone to convection or solids in a wide temperature range, while the Monte Carlo inversion method is available for accurate and rapid measurement.

DETERMINATION OF CONVECTIVE HEAT TRANSFER COEFFICIENT AT THE OUTER SURFACE OF A CRYOVIAL BEING PLUNGED INTO LIQUID NITROGEN

BACKGROUND

Cell survival upon cryopreservation is affected by the cooling rate. However, it is difficult to model the heat transfer process or to predict the cooling curve of a cryoprotective agent (CPA) solution due to the uncertainty of its convective heat transfer coefficient (h).

OBJECTIVE

To measure the h and to better understand the heat transfer process of cryovials filled with CPA solution being plunged in liquid nitrogen.

MATERIALS AND METHODS

The temperatures at three locations of the CPA solution in a cryovial were measured. Different h values were selected after the cooling process was modeled as natural convection heat transfer, the film boiling and the nucleate boiling, respectively. And the temperatures of the selected points are simulated based on the selected h values. h was determined when the simulated temperature best fitted the experimental temperature.

RESULTS

When the experimental results were best fitted, according to natural convection heat transfer model, h(1) = 120 W/(m(2)·K) while due to film boiling and nucleate boiling regimes h(f) = 5 W/(m(2)·K) followed by h(n) = 245 W/(m(2)·K). These values were verified by the differential cooling rates at the three locations of a cryovial.

CONCLUSION

The heat transfer process during cooling in liquid nitrogen is better modeled as film boiling followed by nucleate boiling.

Changes in hearing threshold between 28 and 42 weeks of age in babies born at under 30 weeks of gestation

AIM

This study aimed to describe changes in hearing thresholds in babies born below 30 weeks of gestation at 28-42 weeks of postconceptional age, detect differences between gestational ages and explore the prevalence of hearing impairment.

METHODS

The threshold of brainstem auditory evoked response (BAER) was obtained longitudinally at 28-42 weeks of postconceptional age in 71 babies born at 23-29 weeks of gestation.

RESULTS

The BAER threshold was 28 decibels above normal hearing level (dB nHL) at 28 weeks of postconceptional age and decreased to 13 dB nHL at 39-42 weeks. The threshold was slightly higher in babies born at 23-26 weeks of gestation than in those born at 27-29 weeks at most postconceptional ages studied. From 28 to 36 weeks, the threshold decreased at 0.98 dB/week. At term, BAER threshold elevation (>20 dB nHL) occurred in 12 (16.9%) of the 71 babies.

CONCLUSION

The hearing threshold of babies born at 23-29 weeks of gestation decreased from 28 dB at 28 weeks of postconceptional age to 13 dB at 42 weeks. There were no major differences between gestational ages. During the preterm period, the threshold changed at around 1 dB/week. At term, one in six babies had hearing impairment.

Brainstem auditory electrophysiology is supressed in term neonates with hyperbilirubinemia

BACKGROUND

Whether hyperbilirubinemia suppresses electrophysiological activity of the neonatal auditory brainstem remains to be investigated.

AIM

To determine whether hyperbilirubinemia suppresses the brainstem auditory electrophysiology in term neonates.

METHODS

Maximum length sequence brainstem auditory evoked response (MLS BAER) was recorded shortly after confirming hyperbilirubinemia in 58 term neonates. Wave amplitudes of the response were analyzed in detail.

RESULTS

Compared with age-matched term controls, the neonates with hyperbilirubinemia showed a significant reduction in the amplitudes of MLS BAER waves III and particularly V at all click rates 91-910/s. The reduction tended to be more significant at higher than lower rates. Wave I amplitude was reduced at 910/s. V/I amplitude ratio was decreased at all click rates. Therefore, the amplitudes of MLS BAER, particularly later, waves were all reduced. The amplitudes of all MLS BAER waves tended to be reduced with the increase in total serum bilirubin level. All wave amplitudes were correlated with the level of total serum bilirubin at some or most click rates.

CONCLUSIONS

Brainstem auditory electrophysiology is suppressed in neonates with hyperbilirubinemia, which related to the severity of hyperbilirubinemia. Wave amplitudes are valuable BAER variables to detect functional impairment of the brainstem and auditory pathway in neonatal hyperbilirubinemia, and are recommended to be used in assessing bilirubin neurotoxicity to the neonatal brain.

Comparison of brainstem auditory evoked response at different click rates between preterm babies after neonatal necrotizing enterocolitis and healthy preterm babies

BACKGROUND

Neonatal necrotizing enterocolitis (NEC) is associated with an increased incidence of poor neurodevelopment. The knowledge of underlying neurophysiology is very limited, and the influence of NEC on the preterm brainstem is very poorly understood.

OBJECTIVE

To assess the effect of NEC on the immature auditory brainstem by excluding any possible confounding effect of preterm birth.

METHODS

We recorded and analyzed brainstem auditory evoked response (BAER) at different click rates in preterm babies (30-34 weeks gestation) after NEC. The results were compared with those in age-matched healthy preterm babies who had no NEC.

RESULTS

At click rate 21/s, the latencies of BAER waves I and III in the preterm NEC babies were similar to those babies without NEC. However, wave V latency was longer in the NEC babies than in those without NEC. The I-V interpeak interval was also longer in the NEC babies than in those without NEC. These abnormalities were persistent at higher click rates 51 and 91/s. Wave I amplitude in the preterm NEC babies did not differ significantly from that in those without NEC, but wave III and V amplitudes were smaller than in those without NEC at all 21-91/s clicks.

CONCLUSIONS

Compared with healthy preterm babies, preterm babies after NEC showed a major increase in wave V latency and I-V interval at all 21-91/s clicks. Brainstem auditory function is impaired in preterm NEC babies after excluding the possible confounding effect of preterm birth. Neonatal NEC and associated perinatal conditions adversely affect the premature brainstem.

Clostridium difficile infection in hospitalized cancer patients in Beijing, China is facilitated by receipt of cancer chemotherapy

The purpose of this study was to determine the presence of Clostridium difficile infection (CDI) and risk factors for infection in hospitalized patients with diarrhea in a cancer hospital in Beijing, China. A total of 277 patients with hospital-associated diarrhea (HAD) were studied of which 41 (15%) were positive for fecal C. difficile toxin A/B. For each CDI case identified, a control with HAD but negative C. difficile specimen was enrolled to look for CDI risk factors. Receipt of cancer chemotherapy occurred in 20 (49%) patients with CDI and 9 (22.0%) patients with non-CDI HAD (OR3.39, 95%CI 1.78-10.05). Median length of chemotherapy before HAD developed was 39 days for those with CDI and 22 days for patients with CDI-negative HAD (P = 0.0391). The study found that CDI is commonly seen in cancer patients in China with increasing risk for patients who receive chemotherapy.

Changes in brainstem auditory response threshold in preterm babies from birth to late term

CONCLUSION

The hearing threshold in preterm infants was 23 dB above adult hearing level at 30 weeks gestation, and decreased to around 13 dB at term date. There was no major difference in the threshold for infants born at different gestations. At term, 9% had hearing threshold elevation.

OBJECTIVE

To examine changes in hearing threshold from preterm to term in infants born at 30-36 weeks gestation and to detect the prevalence of threshold elevation.

METHODS

The threshold in brainstem auditory evoked response (BAER) was obtained 656 times from postconceptional age (PCA) 30 to 42 weeks in 268 infants born at 30-36 weeks gestation.

RESULTS

The BAER threshold was 23 dB nHL at the youngest age (PCA 30 weeks), and then decreased to around 13 dB nHL at later preterm and term dates (PCA 35-42 weeks). The threshold was decreased with increasing age at a rate of 1.24 dB per week from PCA 30 to 36 weeks and 0.65 dB per week from PCA 30 to 42 weeks. At PCA 33-42 weeks, there were no significant differences in BAER threshold between the infants born at gestational age (GA) 30-32 weeks and those at GA 33-36 weeks. At term, 9% had threshold elevation (>20 dB nHL).

Amplitude reduction in brainstem auditory response in term infants under neonatal intensive care

OBJECTIVE

To examine brainstem auditory electrophysiology in term neonates under intensive care due to perinatal conditions other than hypoxia-ischemia.

METHODS

Maximum length sequence brainstem auditory evoked response was studied in term neonates in an intensive care unit. The amplitudes of wave components of the response were analysed to assess brainstem auditory electrophysiology.

RESULTS

The amplitudes of all wave components in the neonates under intensive care tended to be smaller than in those in normal term controls. Wave I amplitude was significantly reduced at all 91-910/s clicks (p < 0.05-0.01). The amplitudes of waves III and V were also reduced, respectively, at 227-910/s (all p < 0.05) and at 455 and 910/s (both p < 0.01). The amplitude reduction was slightly more significant at higher than lower click rates, but there were no significant differences in the slopes of wave I, III and V amplitude-rate functions between the neonates under intensive care and the controls.

CONCLUSIONS

Wave amplitudes of maximum length sequence brainstem auditory evoked response were reduced in term neonates under intensive care due to perinatal conditions other than hypoxia-ischemia.

SIGNIFICANCE

Brainstem auditory electrophysiology is depressed in term neonates under intensive care, possibly due to collective adverse effects of perinatal conditions. The impairment to the neonatal, particularly rostral, brainstem due to other perinatal conditions is less severe than that due to hypoxia-ischemia previously reported.

Brainstem auditory response findings in preterm infants after necrotizing enterocolitis

AIM

To examine brainstem auditory function and detect any abnormality at term in preterm infants after neonatal necrotizing enterocolitis (NEC).

METHODS

Brainstem auditory evoked response (BAER) was recorded at 21/sec and 60 dB nHL in 37 preterm infants who had NEC. The data obtained at term equivalent age were analyzed and compared with those in normal term infants.

RESULTS

The threshold of BAER in infants after NEC, though slightly elevated, did not differ significantly from that in the controls. The latencies of waves I and III were slightly longer than in the controls, without any statistical significance. However, wave V latency was prolonged and differed significantly from the controls (p < 0.01). I-V interpeak interval was also prolonged (p < 0.05). The data point distribution of wave V latency and I-V interval was higher in the infants after NEC than in the controls. The amplitudes of BAER wave components in the infants after NEC did not differ significantly from those in the controls.

CONCLUSION

Preterm infants after NEC have no major abnormality in peripheral auditory function. However, neural conduction in the brainstem auditory pathway is abnormal, suggesting that NEC adversely affects brainstem auditory conduction.

Brainstem auditory response findings in term neonates in intensive care unit

OBJECTIVES

Whether term infants in neonatal intensive care unit (NICU) have brainstem auditory abnormalities remains to be determined. This study aimed to detect any abnormality in brainstem auditory function in term neonates who are admitted to NICU.

METHODS

From a NICU, we recruited 55 term neonates with various perinatal problems. They were studied during the first week after birth using brainstem auditory evoked response (BAER), and the results were compared with normal term controls.

RESULTS

Wave I and III latencies and I-III interpeak interval of the evoked response in the NICU term neonates were similar to those in the controls. Wave V latency and I-V and III-V interpeak intervals tended to be increased at 21/s clicks. The increase was more obvious at higher rates 51 and 91/s. Analysis of variance revealed that at 21/s clicks only III-V interval was significantly increased (p < 0.05). At 51 and 91/s clicks, wave V latency and III-V and I-V intervals were significantly increased (p < 0.05-0.01). The rates of the abnormalities were seen more at higher than at lower click rates. The amplitudes of waves I, III, and V in the NICU neonates were all slightly reduced, but none differed significantly from the controls.

CONCLUSIONS

There are some abnormalities in BAER in term neonates in NICU, suggesting functional abnormality in the auditory brainstem in NICU infants.

Cochlear function in 1-year-old term infants born with hypoxia-ischaemia or low Apgar scores

AIM

To examine the influence of perinatal hypoxia-ischaemia (HI) or low Apgar scores on distortion product otoacoustic emissions (DPOAEs) in infants at 1 year and detect any postnatal changes.

METHODS

Eighty-eight term infants born with perinatal HI or low Apgar scores alone were recruited at 1 year of age. The ears with type A tympanogram (normal) were studied with DPOAEs at 10 frequencies between 0.5 kHz and 10 kHz.

RESULTS

DPOAE pass rates were decreased at all frequencies 1-10 kHz, particularly 1 and 2 kHz in both infants born with HI and those with low Apgar scores (χ(2) = 3.80-15.09, P < 0.05-0.01). Overall pass rates in the two groups were also decreased (X(2) = 10.78 and 12.12, P < 0.01 and 0.01). No marked differences were found between infants born with HI and those with low Apgar score. Compared with those recorded at 1 and 6 months, DPOAE pass rates at 1 year were increased slightly in infants born with HI, but showed no marked changes in those born with low Apgar scores.

CONCLUSIONS

DPOAE pass rates, mainly at 1 and 2 kHz, were decreased at 1 year in infants born with perinatal HI and low Apgar scores, suggesting a relative poor cochlear function. Further studies are needed to ascertain the hearing acuity.

Brainstem auditory response findings in late preterm infants in neonatal intensive care unit

AIM

To examine brainstem auditory function at term in late preterm infants admitted to neonatal intensive care unit (NICU).

METHODS

Fifty-two preterm infants, born at 33-36 week gestation, were recruited in an NICU and were studied at term using brainstem auditory evoked response (BAER).

RESULTS

Compared with normal term infants, BAER wave V latency in the NICU preterm infants was increased at 51 and 91/sec (p<0.05, 0.05). Intervals of III-V and I-V were increased at all 21, 51 and 91/sec clicks (p<0.05-0.01), which was more significant at higher than lower rates. Interval ratio of III-V/I-III was increased significantly at 51 and 91/sec (p<0.05 and 0.01). Wave I and III latencies and I-III interval did not differ significantly from normal controls at any click rates. All amplitudes of waves I, III and V amplitude tended to be reduced at higher rates, while wave I amplitude was reduced significantly at 91/sec clicks.

CONCLUSION

There were BAER abnormalities in the NICU late preterm infants, suggesting compromised brainstem auditory function. Compared with a basically normal BAER in low-risk late preterm infants previously reported, the abnormalities suggest that perinatal problems or complications adversely affect the late preterm auditory brainstem.

Depressed brainstem auditory function in children with cerebral palsy

Brainstem auditory evoked responses were studied to examine brainstem auditory function in 80 children with cerebral palsy. The response waveform, particularly later waves, tended to be depressed. Thirty-three (41.3%) showed abnormal results. The main abnormality was reduced wave V amplitude. Other abnormalities were decreased V/I amplitude ratio, missing waves, prolonged I-V interval, and increased interaural difference in I-V interval. The abnormalities were persistent during the follow-up. In contrast to common findings in the responses in progressive neurologies, abnormalities in interpeak intervals were rare in children with cerebral palsy. There were some characteristic changes in the responses in certain etiologies. These results suggest that brainstem auditory function in children with cerebral palsy is depressed, which may be owing to decreased or altered neural firing or synchrony in the auditory brainstem. A detailed analysis of central components of the responses is valuable in detecting central auditory dysfunction in children with cerebral palsy.

Maximum length sequence brainstem auditory evoked response in low-risk late preterm babies

OBJECTIVES

Recent research indicates that there is delayed development in the more central part of the auditory brainstem in very preterm babies. We aimed to study whether this is also the case for late preterm babies.

METHODS

The maximum length sequence brainstem auditory evoked response (MLS BAER) was used to study functional status of the auditory brainstem. Babies born at 33-36 week gestation and without any major perinatal complications were recruited. MLS BAER was recorded and analyzed at term age.

RESULTS

No significant correlation was found between most MLS BAER variables and physiological factors (gender, postconceptional age, bodyweight, and head circumference obtained at time of testing). Wave latencies and amplitudes, and I-V and I-III intervals in the preterm babies were essentially similar to those in the term controls at all click rates. However, III-V interval increased significantly at 227-910/s clicks (p<0.05-0.01). All latencies, amplitudes and intervals correlated significantly with click rates (all p<0.001). No differences were found in the slopes of MLS BAER variables-rate functions between the later preterm babies and term controls.

CONCLUSIONS

Babies born at 33-36 weeks gestation without major complications had an increased III-V interval at high-rate stimulation. This suggests that late preterm babies have a mild delay in neural conduction in the more central part of the auditory brainstem.

Impairment of perinatal hypoxia-ischemia to the preterm brainstem

Hypoxia-ischemia is a major perinatal problem that results in severe damage to the newborn brain. This study assessed functional integrity of the brainstem at term in preterm infants after perinatal hypoxia-ischemia to shed light on the influence of hypoxia-ischemia on the preterm brainstem. We recruited sixty-eight preterm infants after perinatal hypoxia-ischemia, ranging in gestation 28-35 weeks. Brainstem evoked response was studied at term age (37-42 weeks postconceptional age) with 91-910/s clicks using the maximum length sequence technique. Compared with healthy preterm infants, the preterm infants after perinatal hypoxia-ischemia showed a significant increase in I-V interval at very high rates 455 and 910/s of clicks (P<0.05, 0.05). III-V interval and III-V/I-III interval ratio also increased significantly at 455 and 910/s (P<0.05-0.01). The slope of III-V interval-rate function was significantly steeper than in the healthy preterm infants (P<0.05). Compared with normal term controls, the preterm infants after hypoxia-ischemia showed similar, but slightly more significant, abnormalities. The differences between the preterm infants after hypoxia-ischemia and the healthy preterm and term infants generally increased with increasing click rate. These results demonstrated that central components of brainstem auditory evoked response were abnormal at very high click rates in the preterm infants after perinatal hypoxia-ischemia. Click rate-dependent change in the more central part of the brainstem is also abnormal. Apparently, functional integrity of the brainstem, mainly in the more central part, is impaired. Hypoxic-ischemic damage to the preterm brainstem is unlikely to completely recover within a relatively short period after the insult, which is of clinical importance.

Relative maturation of peripheral and central regions of the human brainstem from preterm to term and the influence of preterm birth

Relative maturation of peripheral and central regions of the neonatal brainstem was studied using brainstem auditory evoked responses in 174 healthy preterm infants (gestational age 30-36 wk). From 30- to 42-wk postconceptional age (PCA), I-III and III-V intervals shortened with increasing age. It was difficult to detect any apparent differences in maturational rate between the two intervals. However, III-V/I-III interval ratio decreased with increasing age, indicating that from preterm to term III-V interval shortens more than I-III interval. During term period (37- to 42-wk PCA), I-III interval was similar to term controls, but III-V interval was significantly longer and III-V/I-III interval ratio was significantly greater than controls at 37- to 38-wk PCA and 39-40 wk PCA and was the same as controls at 41-42 wk. Therefore, from 30- to 42-wk PCA maturation of central regions of the brainstem, reflected by III-V interval, is relatively faster than peripheral regions, reflected by I-III interval which seems to be already more mature than III-V interval before 30 wk. Maturation in central regions in preterm infants is relatively delayed at early term, but "catches-up" later, whereas peripheral regions already reach normal level of maturation at early term. Preterm birth slightly delays early maturation of central brainstem regions.

Normal brainstem responses in moderately preterm infants

AIM

The aim of this study was to detect any differences in brainstem auditory evoked responses (BAERs) to different click rates between moderately preterm and term infants.

METHODS

BAER was recorded with 21-91/s clicks at term age (37-42 weeks postconceptional age) in 39 moderately preterm infants (gestation 33-36 weeks). The results were compared with 37 healthy term infants.

RESULTS

The latencies of waves I, III and V, and I-V interval in preterm infants were all similar to term infants at all click rates. The I-III interval decreased slightly and differed from term infants at 91/s (ANOVA, p < 0.05), while the III-V interval increased slightly. The III-V/I-III interval ratio increased slightly and differed from term infants at 91/s (p < 0.05). Wave amplitudes were similar in the two groups of infants, except an increase in wave V amplitude at 91/s in preterm infants (p < 0.05). No significant differences were found in BAER click rate-dependent changes between the two groups.

CONCLUSION

No marked differences were found in BAER at any click rates at term age between moderately preterm and term infants, suggesting that moderately preterm birth does not have a marked effect on neonatal BAER. BAER normal data and criteria from term infants can generally be used for moderately preterm infants.

Brainstem auditory outcomes and correlation with neurodevelopment after perinatal asphyxia

We used brainstem auditory-evoked responses and neurodevelopmental assessment to detect abnormalities and correlations between such responses and neurodevelopmental outcomes in 78 children (aged 4-12 years) who survived perinatal asphyxia. Twenty children had brainstem auditory-evoked response abnormalities, including increased threshold, reduced wave V amplitude, decreased V/I amplitude ratio, and prolonged I-V interval. Thirty-seven exhibited neurodevelopmental deficits, including cerebral palsy and developmental delay. The remaining 41 exhibited no deficits. Brainstem auditory-evoked response abnormalities were evident in 15 of 37 (40.5%) children with neurodevelopmental deficits, but in only 5 of 41 (12.2%) with no deficits, which differed significantly (chi(2) = 8.2, P < 0.05). The sensitivity, specificity, positive predictive value, and false-negative rate of brainstem auditory-evoked responses to reflect neurodevelopmental outcomes were 40.5%, 87.8%, 75.0%, and 59.5%, respectively. These findings suggest that in children who survive perinatal asphyxia, brainstem auditory impairment occurs more frequently in those with versus those without neurodevelopmental deficits. Brainstem auditory-evoked responses display a moderate correlation with clinically determined neurodevelopmental outcomes. Despite limitations, brainstem auditory-evoked response is valuable for assessing auditory and neurodevelopmental outcomes after perinatal asphyxia.

A clinical risk index for Clostridium difficile infection in hospitalised patients receiving broad-spectrum antibiotics

Identification of a population at high risk for Clostridium difficile infection (CDI) would enable CDI prevention strategies to be designed. The purpose of this study was to create a clinical risk index that would predict those at risk for CDI. A CDI risk index was therefore developed, based on a cohort of hospital patients given broad-spectrum antibiotics, and divided into a development and validation cohort. Logistic regression equations helped identify significant predictors of CDI. A scoring algorithm for CDI risk was created using identified risk factors and collapsed to create four categories of CDI risk. The area under the receiver operating characteristic (aROC) curve was used to measure goodness-of-fit. Among 54 226 patients, 392 tested positive for C. difficile. Age 50-80 years [odds ratio (OR: 0.5; P<0.0116)], age >80 years (OR: 2.5; P<0.0001), haemodialysis (OR: 1.5; P=0.0227), non-surgical admission (OR: 2.2; P<0.0001) and increasing length of stay in the intensive care unit (OR: 2.1; P<0.0001) were significantly associated with CDI. A simple risk index using presence of significant variables was significantly associated with increasing risk for CDI in both development (OR: 3.57; P<0.001; aROC: 0.733) and validation (OR: 3.31; P<0.001; aROC: 0.712) cohorts. An OR-derived risk index did not perform as well as the simple risk index. This easily implemented risk index should allow stratification of patients into risk group categories for development of CDI and help fashion preventive strategies.

Sustained depression of brainstem auditory electrophysiology during the first months in term infants after perinatal asphyxia

OBJECTIVE

To gain further insights into the pathophysiological processes of neuronal impairment in neonatal brainstem after perinatal asphyxia.

METHODS

Maximum-length sequence brainstem auditory-evoked response (MLS BAER) was recorded with clicks at 91, 227, 455 and 910/s on days 1, 3, 5, 7, 10, 15 and 30 after birth in 108 term infants who suffered perinatal asphyxia. Wave amplitude variables in the MLS BAER were analysed in detail at 40 dB above BAER threshold in 86 infants who had no peripheral hearing impairment.

RESULTS

On day 1 the amplitudes of MLS BAER waves I, III and V were all reduced significantly at all click rates, especially at higher ones (91-910/s, ANOVA P<0.05-0.001). On day 3 these amplitudes were reduced further. On days 5 and 7, the amplitude reduction persisted and did not show any significant further changes. On days 10 and 15 the reduced amplitudes were increased slightly. On day 30 all amplitudes were still reduced significantly (P<0.05-0.0001). During the first month, the reduction of wave amplitudes was more significant for the later MLS BAER components than for the earlier ones, and occurred most significantly at 455 and 910/s clicks. By comparison, the amplitude reduction in conventional BAER was much less significant.

CONCLUSIONS

During the first month after perinatal asphyxia the amplitudes of MLS BAER waves were reduced significantly and persistently, which was more significant at higher rates of clicks than at lower rates. The reduction is much more persistent than the increase in wave latencies and intervals we previously reported.

SIGNIFICANCE

There is sustained depression of brainstem auditory electrophysiology, indicating neuronal damage of the auditory brainstem, in infants after perinatal asphyxia. This may have important clinical implications.

Functional impairment of the brainstem in infants with bronchopulmonary dysplasia

OBJECTIVES

To gain new insights into the influence of bronchopulmonary dysplasia on the immature brain and to detect abnormalities, we studied the functional integrity of the brainstem in infants with bronchopulmonary dysplasia.

METHODS

Forty-one very preterm infants with bronchopulmonary dysplasia were studied at postconceptional ages of 37 to 42 weeks. Brainstem auditory evoked responses were recorded and analyzed by using the maximal length sequence technique.

RESULTS

Compared with term control subjects, wave V latency in the maximal length sequence brainstem auditory evoked response of the infants with bronchopulmonary dysplasia increased significantly at all 91 to 910 clicks per second rates. Similarly, I-V and particularly III-V interpeak intervals increased significantly. The III-V/I-III interval ratio also increased significantly at all click rates. All of these abnormalities became more significant as the click rate was increased. Compared with healthy, very preterm control subjects, all of these maximal length sequence brainstem auditory evoked response variables increased significantly at all click rates, although the differences between the 2 groups were slightly smaller than those between the infants with bronchopulmonary dysplasia and the term control subjects. The wave I and III latencies and I-III interval in the infants with bronchopulmonary dysplasia did not show any abnormalities. The slopes of the wave V latency-rate function and I-V and particularly III-V interval-rate functions for the infants with bronchopulmonary dysplasia were significantly steeper than those for both term and healthy, very preterm control subjects. The slope of the III-V/I-III interval ratio-rate function for the infants with bronchopulmonary dysplasia was also significantly steeper than those for the 2 control groups.

CONCLUSIONS

The results suggest poor myelination and synaptic function of the brainstem in infants with bronchopulmonary dysplasia, resulting in impaired functional integrity. In comparison, peripheral neural function was relatively intact.

Distortion product otoacoustic emissions during the first year in term infants: a longitudinal study

Understanding of any age-related differences in distortion product otoacoustic emissions (DPOAEs) during infancy is important for the use of DPOAEs in detection of cochlear impairment in infants. We studied DPOAEs at 10 frequencies of f2 primary tone between 500 Hz to 10 kHz longitudinally during the first year of life in 70 ears of 35 normal term infants. On days 3-5 after birth DPOAE pass rates ranged between the highest 98.6% at f2 frequencies 6-10 kHz and the lowest 22.9% at 750 Hz. The higher the frequency, the higher was the pass rate. At 6 months the pass rates at various frequencies were generally similar to those on days 3-5, and were greater than 91% across the frequencies of 3-10 kHz. At 12 months the pass rates were 100% or near 100% across 3-10 kHz. During the first year the pass rate was always very low at 750 Hz (<40%) and tended to decrease at 1 kHz with the increase in age. DPOAE level at f2 frequencies 4kHz increased from birth to 6 months but then reduced slightly at 12 months. At lower frequencies the age-related DPOAE levels change was less significant. These results indicate that there are no major changes in DPOAE or cochlear function during the first year of life at most frequencies. However, the interpretation of DPOAE results in infants need to take into account the age-related difference in DPOAE pass rate at low-frequency and in DPOAE level at high-frequency.

Brainstem auditory evoked responses in very low birthweight infants with chronic lung disease

Very low birthweight (VLBW) infants who had prolonged oxygen dependence due to chronic respiratory problems, typically neonatal chronic lung disease (CLD), are at high risk of neurodevelopmental impairment. To assess the effect of CLD on neonatal auditory function we studied brainstem auditory evoked response (BAER) in VLBW infants who suffered CLD but no other major perinatal complications or problems. At 37-42 week postconceptional age, the latencies of waves I, III and V in CLD infants were all significantly longer than in normal term infants (all p<0.001). The differences between CLD infants and the term controls were greater for the later waves than for the earlier waves. Abnormally prolonged wave latency (>2.5 SD of the mean measurement) was seen in 7 (21.2%) CLD infants for wave I, suggesting peripheral auditory impairment, 8 (24.2%) for wave III and 14 (42.4%) for wave V. I-V interval in CLD infants was significantly longer than in the term controls (p<0.001). Seven (21.2%) infants had abnormally prolonged I-V interval, suggesting brainstem or central auditory impairment. Of these infants, 2 had both prolonged wave latencies and prolonged I-V interval, suggesting both peripheral and central auditory impairment. Similar abnormalities were found in CLD infants when compared with the BAER in birthweight- and age-matched healthy VLBW infants without CLD.

CONCLUSION

Neonatal auditory function is impaired, both peripherally and centrally, at term age in VLBW infants who suffer neonatal CLD.

Sub-optimal function of the auditory brainstem in term infants with transient low Apgar scores

OBJECTIVES

To assess functional integrity of the auditory brainstem in neonates with transient low Apgar scores.

METHODS

Forty-two term infants were studied with brainstem auditory evoked response (BAER) using the maximum length sequence during the first month of life. All had transient low Apgar scores but no clinical signs of hypoxic-ischaemic encephalopathy (HIE).

RESULTS

The latencies of BAER waves I and III in these infants were similar to those of age-matched normal controls at all click rates (91/s, 227/s, 455/s and 910/s) during the period studied. Wave V latency was increased at 910/s on day 1 (P<0.01), but did not differ from that in the controls on any other days. I-V interval was increased significantly at 455/s and 910/s on day 1 (P<0.01 and 0.001) and day 3 (P<0.05 and 0.01). On days 5 and 7, BAER wave latencies and intervals were similar to those in the controls. On day 30, all latencies and intervals reached the values in the controls. No abnormalities were seen in BAER wave amplitude variables on any days.

CONCLUSIONS

Neonates with transient low Apgar scores but without HIE had a significant increase in I-V interval at very high click rates on the first three days of life.

SIGNIFICANCE

Brainstem auditory function is sub-optimal during the first few days in neonates with transient low Apgar scores.

Brainstem auditory evoked response in neonatal neurology

Over the last three decades, the brainstem auditory evoked response (BAER) has been used to assess functional integrity and development of the auditory system and the brain in conditions that affect the brainstem auditory pathway. As a non-invasive objective test, BAER is particularly suitable in very young or sick infants. It is the major tool to detect hearing impairment in high-risk infants, and a component in universal hearing screening. BAER is also a valuable adjunct to detect neurological impairment in many developmental disorders and functional abnormalities in a range of neurological diseases. The maximum length sequence (MLS) technique has recently been incorporated into neonatal BAER study. Recent results indicate that the MLS has the potential to improve the diagnostic value of BAER in some clinical situations, although the wider utility of this relative new technique remains to be further explored.

Neonatal auditory function and depressed Apgar score: correlation of brainstem auditory response with Apgar score

AIM

To examine the relationship between neonatal auditory function and Apgar score in term infants with depressed Apgar scores.

METHODS

Brainstem auditory evoked response (BAER) was recorded on day 3 after birth in term infants who had Apgar scores < or = 7 at 1 and/or 5 min. Half of the infants also had Apgar scores at 10 min, with 17 < or = 7.

RESULTS

No BAER variables correlated significantly with 1-min Apgar score. However, wave III and V latencies, and I-V, I-III and III-V intervals correlated significantly and negatively with 5-min Apgar score (p < 0.05-0.01). These BAER variables were significantly longer in infants with 5-min Apgar scores < or = 7 than those > 7. Wave V latency and all intervals also correlated negatively with 10-min Apgar score (p < 0.05-0.01). Compared to normal controls, all latencies were prolonged in infants with depressed Apgar scores (all p < 0.05-0.01). All intervals were also prolonged in those with 5-min scores < or = 7 (p<0.05-0.01). Similar results were found when defining the depression of Apgar score as < or = 6.

CONCLUSION

A depressed 5- and/or 10-min Apgar score is an indicator associated with neonatal auditory, mainly central, impairment. Apgar score < or = 7 or 6 at 1 min alone is unlikely to be associated with central impairment.

Brainstem auditory evoked response at term in preterm infants after perinatal hypoxia-ischaemia

AIM

To examine brainstem auditory function in preterm infants after perinatal hypoxia-ischaemia (HI).

METHODS

Brainstem auditory evoked response (BAER) was studied at 37-42 wk postconceptional age in preterm infants who suffered perinatal HI, and were compared with those in preterm and term infants without any major perinatal problems.

RESULTS

None of the latencies of waves I, III and V in the BAER in preterm infants after perinatal HI differed significantly from those in preterm and term controls. There were also no significant differences in the I-V and I-III interpeak intervals between preterm infants after HI and the controls. However, III-V interval in infants after HI tended to increase, and was significantly longer than in term controls (p<0.01), although it did not differ significantly from that in preterm controls. Similarly, the III-V/I-III interval ratio was greater than in term controls (p<0.05), but was similar to that in preterm controls. All amplitude variables did not differ significantly from the controls.

CONCLUSION

BAER in preterm infants after perinatal HI did not differ significantly from that in preterm infants without perinatal problems, but differed slightly from that in normal term infants. The prolonged III-V interval as compared with the term controls suggests a minor impairment in central auditory function.