Effects of hypothermal and circulatory arrest on the auditory brainstem response during operation in children

Twenty-two children were monitored by the auditory brainstem response (ABR) during the open chest and/or open heart surgery for cardiac anomalies under the extracorporeal circulation (ECC) with moderate to deep hypothermia. These patients were divided into two groups, namely, the ECC only group (group A: 9 cases) and the total circulatory arrest (TCA) group (group B: 13 cases). The mean age of group A was 36 months and group B was 6.1 months. In group A, moderate hypothermia was conducted with the rectal temperature ranging from 25 degrees C to 30 degrees C, and in group B profound hypothermia was conducted lowering the temperature to 18 degrees C. The ABR recorded at the following points, namely; before inducing anesthesia, before lowering the body temperatures, during the cooling process, at the time of TCA, and during the rewarming process. Accompanying the decrease in body temperature the peak latency of waves I, III and V were markedly prolonged. When the rectal temperature fell to 23 degrees C, the peak latency of each wave was prolonged to about 150% of their precooling values at 36 degrees C. When it fell to 22 degrees C, the ABR disappeared entirely in 16 of 22 cases, and in remaining 6 cases, only I wave was detected. During rewarming, in both the A and B groups, at 24 degrees C, the wave of ABR started to reappear beginning with I waves, and on reaching 26 degrees C, I, III and V waves from became detectable. The peak latency of all waves at rectal temperature of 33 degrees C recovered to almost the same values as these at 36 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)     

Peroxisomal bifunctional enzyme deficiency: serial neurophysiological examinations of a case

We report on a case of 21-month-old girl with peroxisomal bifunctional enzyme deficiency, which was diagnosed by means of complementation analysis. Serial neurophysiological examinations were also carried out. The motor and sensory nerve conduction velocities of the median nerve showed lower borderline values at 3 months of age and were within normal range at 11 months of age. Later, those velocities had gradually decreased. The electrically elicited blink reflex at 3 months of age showed the prolongation of latencies of R1, R2 and R2′ and the interpeak latencies of R1, R2 and R1 -R2′. Furthermore, RI, R2 and R2′ showed prolonged latencies at 11 months of age and were absent at 15 months of age. The auditory brainstem response (ABR) showed, bilaterally, normal latency of wave I, prolonged interpeak latencies of waves I–V. At 11 months of age, waves III and IV–V of ABR were detected, but their amplitude was very low. At the age of 15 months ABR was absent. These results and the following report are valuable for understanding the pathogenesis of neurological symptoms.     

The pattern of auditory brainstem response wave V maturation in cochlear-implanted children.

OBJECTIVE: Maturation of acoustically evoked brainstem responses (ABR) in hearing children is not complete at birth but rather continues over the first two years of life. In particular, it has been established that the decrease in ABR wave V latency can be modeled as the sum of two decaying exponential functions with respective time-constants of 4 and 50 weeks [Eggermont, J.J., Salamy, A., 1988a. Maturational time-course for the ABR in preterm and full term infants. Hear Res 33, 35-47; Eggermont, J.J., Salamy, A., 1988b. Development of ABR parameters in a preterm and a term born population. Ear Hear 9, 283-9]. Here, we investigated the maturation of electrically evoked auditory brainstem responses (EABR) in 55 deaf children who recovered hearing after cochlear implantation, and proposed a predictive model of EABR maturation depending on the onset of deafness. The pattern of EABR maturation over the first 2 years of cochlear implant use was compared with the normal pattern of ABR maturation in hearing children. METHODS: Changes in EABR wave V latency over the 2 years following cochlear implant connection were analyzed in two groups of children. The first group (n=41) consisted of children with early-onset of deafness (mostly congenital), and the second (n=14) of children who had become profoundly deaf after 1 year of age. The modeling of changes in EABR wave V latency with time was based on the mean values from each of the two groups, allowing comparison of the rates of EABR maturation between groups. Differences between EABRs elicited at the basal and apical ends of the implant electrode array were also tested. RESULTS: There was no influence of age at implantation on the rate of wave V latency change. The main factor for EABR changes was the time in sound. Indeed, significant maturation was observed over the first 2 years of implant use only in the group with early-onset deafness. In this group maturation of wave V progressed as in the ABR model of [Eggermont, J.J., Salamy, A., 1988a. Maturational time-course for the ABR in preterm and full term infants. Hear Res 33, 35-47; Eggermont, J.J., Salamy, A., 1988b. Development of ABR parameters in a preterm and a term born population. Ear Hear 9, 283-9] of normal hearing children: a sum of two decaying exponential functions, one showing an early rapid decrease in latency and the other a slower decrease. Remarkably, the time-constants fell well within the ranges described by Eggermont and Salamy (i.e., 3.9 and 68 weeks), consistent with the time-course of the neurophysiological mechanisms presumably involved in auditory pathway maturation during the first 2 years of life: i.e., myelination and increased synaptic efficacy. In contrast, relatively little change in wave V was evident in children with late-onset deafness. In agreement with the notion that EABR maturation follows an apex-to-base gradient as described for ABR, we observed that wave V latencies were longer for the basal than the apical end of the implant electrode array and remained so throughout the study period, whatever the time of onset of deafness. CONCLUSIONS: The findings in the early-onset of deafness group support the theory that auditory pathways remain "frozen" during the period of sensory deprivation until cochlear implant rehabilitation restores the normal chronology of maturational processes. In children with late-onset deafness, however, some maturational processes may occur before the onset of deafness, and thus less additional maturation is required during the first two years of implant use resulting in no significant EABR latency changes being observed in this period. The results suggest that the rehabilitation-induced plasticity of the auditory pathways is, in case of late auditory deprivation, unlikely to result in neurophysiological outcomes similar to those observed in children with early auditory deprivation. SIGNIFICANCE: Changes in EABR wave V latency over the first 2 years of cochlear implant use were found to be well fitted by the sum of two decaying exponential functions in children with early-onset deafness. This is in line with the maturation of ABR wave V latency in normal-hearing children over the first two years of life. Further studies are needed to assess whether the differences observed in terms of auditory pathways maturation are associated with consistent differences in terms of language development.     

Neurophysiological mechanisms of conduction impairment of the auditory nerve during cerebellopontine angle surgery

ObjectiveIntraoperative auditory brainstem response (ABR)-monitoring is useful for hearing preservation in patients undergoing cerebellopontine angle surgery. Prolongation of the latency of wave V, for example, is observed under surgical stress such as cerebellar retraction. We analyzed intraoperative ABR findings to study the neurophysiological mechanism(s) underlying latency prolongation.MethodsThe ABR recorded during microvascular decompression surgery was studied in 18 patients with hemifacial spasm. We measured each trace of the ABR records, both the latency of each wave and some interpeak latencies. We also analyzed their waveforms especially in the early component, to assess changes during surgery.ResultsThe latency of wave V varied with cerebellar retraction. The delayed latency of wave V was correlated with the prolonged interpeak latency of waves I–III. An additional wave (designated wave I′) between waves I and II was appeared; it was accompanied by a prolongation in the latency of wave V. Wave I′ contributed to prolongation of the interpeak latency of waves I–III, resulting in a delay in the latency of wave V. Chronological analysis revealed that the minimum latency of wave I′ was the same as wave IN, suggesting that wave I′ arose near the porus acusticus internus (PAI).ConclusionOur study showed that cerebellar retraction may result in conduction impairment of the auditory nerve near the PAI, suggesting that the Obersteiner-Redlich zone is an electrophysiologically vulnerable site and wave I′ is derived from the change in the vector of wave IN.SignificanceOur findings may provide neurophysiological evidence to support the theoretical model of ABR generators by Scherg and von Cramon.     

Hearing impairment in two boys with I-cell disease.

Auditory brainstem responses (ABR) were analyzed in 2 boys with I-cell disease. Both patients showed a prolonged latency of wave I, a normal I-V interpeak latency and an elevated threshold of wave V. The intensity-latency curve had a steep slope. These abnormal ABR findings reflect the presence of conductive hearing impairment associated with the cochlear component in I-cell disease.     

Auditory function in adrenomyeloneuropathy

Auditory brainstem responses (ABR), ipsilateral and contralateral acoustic reflexes and the masking level difference for speech (MLD) were studied in 29 patients with adrenomyeloneuropathy (AMN). Abnormalities were seen for all ABR components with Waves V and III affected to the greatest degree. For male patients with AMN, the I–III, III–V and I–V interpeak latency intervals were abnormal for a majority of patients. For female patients with AMN, the I–V and III–V interpeak latency intervals were abnormal for a majority of patients with the I–III interval less affected. Contralateral acoustic reflexes were elevated or absent for approximately 50% of ears. Ipsilateral acoustic reflexes were abnormal for 25% of ears. MLDs were significantly reduced in 72% of patients. When considered in terms of the earliest ABR wave abnormality, the earlier components of the ABR (i.e., Waves III and I) were the initial components impaired for the majority of ears. Word recognition in quiet was relatively unimpaired for all subjects. Despite the presence of marked ABR abnormalities, patients with AMN denied the presence of significant difficulty hearing.     

Midlatency auditory evoked responses: differential effects of sleep in the human

Middle latency responses (MLRs) in the 10-100 msec latency range, evoked by click stimuli, were studied in 14 adult volunteer subjects during sleep-wakefulness to determine whether such changes in state were reflected by any MLR component. Evoked potentials were collected in 500 trial averages during continuous presentation of 1/sec clicks during initial awake recordings and thereafter during a 2 h afternoon nap or all-night sleep session. Continuously recorded EEG, EOG and EMG were scored for wakefulness, stages 2-4 of slow wave sleep (SWS), and rapid eye movement (REM) sleep during each evoked potential epoch. The major components included in this study and their latency ranges, as determined by peak latency measurements from the awake records, were: ABR V, 5-8 msec, Pa, 30-40 msec, Nb, 45-55 msec, and P1, 55-80 msec. In agreement with previous reports, ABR V and Pa showed no amplitude changes from wakefulness to either SWS or REM. Not previously reported, however, was the dramatic decrease and disappearance of P1 during SWS and its reappearance during REM to an amplitude similar to that during wakefulness. This unique linkage between a particular evoked potential component and sleep-wakefulness indicates that its generator system must be functionally related to states of arousal. Relevant data from the cat model suggest that the generator substrate for P1 may be within the ascending reticular activating system.     

脑干听觉反应在阿尔茨海默病和血管性痴呆患者中的应用

目的探讨阿尔茨海默病（AD）和血管性痴呆（VaD）在脑干听觉反应（ABR）检测中的特点,为早期痴呆的诊断提供帮助。方法应用美国Nicolet Bravo脑电生理仪及Click短声刺激,测查32例VaD和28例AD和41名健康老人（NC）的ABR。结果AD组、VaD组及NC组波Ⅲ的绝对潜伏期（Cz脑区）分别为（5.1±0.4）ms、（4.6±0.4）ms和（4.5±0.4）ms,组间差异有统计学意义（F=12.84,P〈0.01）;3组波V的绝对潜伏期（Cz脑区）分别为（6.9±0.2）ms、（6.9±0.3）ms和（6.8±0.3）ms,组间差异无统计学意义（F=1.44,P〉0.05）;3组波Ⅲ的绝对波幅（Cz脑区）分别为（0.19±0.07）μV、（0.32±0.13）μV和（0.35±0.15）μV,组间差异有统计学意义（F=15.87,P〈0.01）;3组波V的绝对波幅（Cz脑区）分别为（0.16±0.07）μV、（0.43±0.15）μV和（0.51±0.17）μV,组间差异有统计学意义（F=28.41,P〈0.01）。AD组波Ⅲ的绝对潜伏期较其他2组延迟、绝对波幅较其他2组下降;AD组波V的绝对波幅较其他2组下降;VaD组波V的绝对波幅较正常对照组下降。结论ABR对临床辅助诊断AD和VD有一定参考意义,ABR测定可作为老年神经精神科的常规检查项目。     

A female case with the Kleine-Levin syndrome and its physiopathologic aspects

A female case with the Kleine-Levin syndrome (KLS), which first occurred at the age of 19, was discussed in relation to the following four characteristics: 1) a female case, 2) a loss of memory and the appearance of slow waves in the pathosis, 3) the abnormal pattern of growth hormone (GH) secretion during sleep in the pathosis, and 4) a prolonged latency between the peaks of III and V in the auditory brainstem response (ABR) in both the pathosis and nonpathosis. These characteristics may suggest that there is a slight disturbance of consciousness in the pathosis, and that there is a functional disturbance in the hypothalamus.     

Cerebro-oculo-hepato-renal syndrome (Arima's syndrome) with slowly progressive renal insufficiency and epilepsy]

We reported an additional case of Arima's syndrome with slowly progressive renal insufficiency and epilepsy. The patient is a 20-year-old man whose parents are consanguineous. He had a history of mild asphyxia at birth, and unexplained tachypnea developed during the neonatal period. But it disappeared later, and he have had no respiratory problem since then. Physical examination on admission at the age of 19 years revealed bilateral blephaloptosis, narrow palate, searching nystagmoid movement, absence of light reflex, muscle hypotonia and wasting of extremities. Funduscopic study showed optic hypoplasia, choroid coloboma and narrowing of vessels. Head CT scan showed agenesis of cerebellar vermis and hypoplasia of brainstem. CT scan and echography of the kidney disclosed the bilateral multiple cysts. Liver was hyperechoic in echographic study; this finding is consistent with fatty change. EEG showed dysrhythmic slow wave activity with sporadic spike and wave complex. Compared with previously reported cases, the present case has the following features: (1) slowly progressive renal insufficiency, (2) generalized tonic clonic convulsion developing from the age of 11 months, (3) ABR abnormalities including the right-sided shortening of wave I-II interpeak latency and bilateral ill-defined wave V. Slow progress of renal failure in our case may reflect the mild pathological process of the kidney with sparing functional nephrons. It shows the diversity of the kidney pathology in Arima's syndrome. Epilepsy is a less common association in the syndrome, whereas EEG abnormalities were reported. ABR abnormalities may reflect the morphological alteration of the brainstem structure including auditory pathway. In our case it is uncertain whether the neonatal tachypnea was due to birth asphyxia or brainstem malformation responsible for abnormal respiration as suggested in Joubert's syndrome.     

A Female Case with the Kleine-Levin Syndrome and Its Physiopathologic Aspects

Abstract: A female case with the Kleine-Levin syndrome (KLS), which first occurred at the age of 19, was discussed in relation to the following four characteristics: 1) a female case, 2) a loss of memory and the appearance of slow waves in the pathosis, 3) the abnormal pattern of growth hormone (GH) secretion during sleep in the pathosis, and 4) a prolonged latency between the peaks of III and V in the auditory brainstem response (ABR) in both the pathosis and nonpathosis. These characteristics may suggest that there is a slight disturbance of consciousness in the pathosis, and that there is a functional disturbance in the hypothalamus.     

Auditory brainstem responses in young adults with Down syndrome

Auditory brainstem response (ABR) wave V detection levels, latency, and amplitude were studied in a group of 15 young adults with Down syndrome for whom behavioral measures of hearing sensitivity were also obtained. Comparisons were made to a group of nonretarded control subjects matched by age and sex. Auditory brainstem response detection levels were elevated, response amplitude was reduced, and latency-intensity functions were significantly steeper for the subjects with Down syndrome than for the control group. These findings were associated with a high frequency (8000 Hz) hearing loss prevalent in the otherwise normal-hearing experimental group.     

Marked latency change of auditory brainstem response in preterm infants in the early postnatal period

In order to evaluate the influence of extrauterine life on auditory brainstem response in neonates, we performed serial ABR recordings twice a week in 10 preterm infants. A marked decrease of I-III interpeak latency was observed in 7 infants during the first 2 or 3 weeks after birth. Wave I latency also remarkably reduced during this period in 5. These findings were related not to the conceptional age but to the extrauterine age. In 2 infants III-V interpeak latency increased during the first 1 or 2 weeks after birth, and the rate of latency increase seemed to be inversely proportional to that of decrease of I-III interpeak latency.     

PROGNOSTIC SIGNIFICANCE OF THE AUDITORY BRAINSTEM EVOKED RESPONSE HIGH-RISK NEONATES

The prognostic significance of the auditory brainstem evoked response (ABR) was examined in this prospective study of neonates at risk for neurodevelopmental sequelae. ABR testing was performed in the neonatal period (37 to 45 weeks conceptional age) and at two and/or six months corrected age. 34 high-risk newborns and 14 controls were followed to one year of age, when they received neurological and developmental assessments. Increased I to III and I to V interwave latencies predicted gross motor delay at one year, with a positive predictive power of 83 per cent and a specificity of 94.7 per cent. Increased brainstem conduction, dispersal of waves III to V and V/I amplitude ratio abnormalities predicted abnormal neurological findings at one year, with positive predictive values of 100, 100 and 80 per cent, respectively. A standard clinical examination of the newborn, performed on the at-risk and control infants at 40 weeks conceptional age, was not found to be strongly predictive of neurodevelopmental deficits at one year.     

Neonatal brainstem dysfunction risks infant social engagement

The role of the brainstem in mediating social signaling in phylogenetic ancestral organisms has been demonstrated. Evidence for its involvement in social engagement in human infants may deepen the understanding of the evolutionary pathway of humans as social beings. In this longitudinal study, neonatal brainstem functioning was measured by auditory brainstem-evoked responses (ABRs) in 125 healthy neonates born prematurely before 35 weeks’ gestational age. At 4 months, infants were tested in a set of structured vignettes that required varying levels of social engagement and cardiac vagal tone was assessed. Data show that neonates with a disrupted I–V waveform, evident mostly by delayed wave V, exhibit shorter latencies to gaze averts in episodes involving direct face-to-face interactions but engage gaze as controls when interacting with masked agents or with agents whose faces are partly veiled by toys. Analysis of variance of infants’ social engagement with ABR, neonatal risk, maternal stress and cardiac vagal tone showed a main effect for ABR and an ABR by gestational age interaction. The integrity of brainstem transmission of sensory information during the final weeks of gestation may scaffold the development of social disengagement, thereby attesting to the brainstem''s preserved evolutionary role in developing humans as social organisms prior to engaging in social encounters.     

A comparison of the three-dimensional auditory brainstem response and the conventional auditory brainstem response in children

For measurement of neural activity in the brainstem auditory pathway, the conventional two-dimensional (2D) auditory brainstem response (ABR) does not provide a true response, because the equivalent dipoles originate from the stereoregularity pathway. It is thus necessary to use three-dimensional (3D) ABR to estimate the true response of the brainstem. We recorded 3D ABR in a group of children and adults, and compared the results with those of the conventional 2D ABR.

The subjects were 22 children (age range 3–10 years) and 10 adults with no neurological disorders, and three patients: a boy and a girl who had experienced sudden brainstem dysfunction, and a girl who had sudden deafness. 3D ABR was recorded for all subjects, and the results were displayed on a computer screen for off-line analysis using an original 3D ABR analysis program.

Four leaf-like vector segments of 3D ABR existed during the first 8 ms after stimulation. Each vector segment corresponded to a peak of the conventional ABR, and showed the original directivity. The amplitudes of waves II and IV of the 3D ABR were significantly larger than those of the conventional ABR. 3D ABR was shown to be superior to the conventional ABR in obtaining absolute amplitude. We were able to clarify the development of brainstem function using 3D ABR. In one patient in whom only one wave was obtained, 3D ABR was able to identify the wave as wave V. These results indicate that ABR is useful both for identifying the kind of wave produced and for suggesting the wave origin.     

Ipsilateral and contralateral recordings of auditory brainstem responses to monaural stimulation

The developmental changes of the ipsilateral and contralateral auditory brainstem responses (ABRs) were studied in 105 normal infants and children. In both ipsilateral and contralateral recordings, the peak and interpeak latencies shortened with increasing age, while the amplitudes of wave V had a tendency to become higher. Contralateral ABR amplitudes were always smaller than those of ipsilateral ABRs. In the contralateral recording, wave I was absent and the contralateral wave II and wave III complex began to separate after birth (25%); separation percentage reached 80–100% at 7 months of age. Our results suggest that the contralateral recording of ABRs is a useful measure of developmental changes in infant auditory pathways.     

Correlation between morphological abnormalities of Chiari malformation and evoked potentials]

We studied correlation between morphological abnormalities of Chiari malformation and evoked potentials (short-latency somatosensory evoked potential [SSEP] and auditory brainstem response [ABR]). On SSEP the inter-peak latency prolongation of P3-N1 was revealed in 6 out of 8 cases with Chiari malformations. The feature of positive wave between P3 and N1 was divided into 2 groups. The tendency of the positivity between P3 and N1 was more marked in cases of prolonged P3-N1 latency and correlated with the medullary kink. On ABR the prolongation of III-V inter-peak latency was revealed in one side in 3 patients Chiari malformations with malformed pons and tegmentum.     

Circadian variation in the latency of auditory brainstem response]

The auditory brainstem response (ABR) has been found to reflect many pathological conditions within the auditory system and brainstem. And now, many neurosurgeons are using it to monitor the integrity of the auditory pathway during neurosurgical procedures. It is said that ABR shows little variation from person to person or laboratory to laboratory, nor is it easily affected by anesthesia, level of consciousness, fluctuation of blood pressure or hypoxemia. On the other hand, previous studies have shown that component waves of the ABR increase in latency and decrease in amplitude with lowered temperature. We reported here that naturally occurring circadian variations in body temperature were correlated with similar changes in the latency of the ABR. Tympanic temperature (Tty), deep forehead temperature (Thd) and ABR were recorded every 3 hours during a 24-hour period for a total of 8 recording sessions from each of 6 healthy persons (2 males and 4 females, mean age 24.3 years). The subjects were free to come and go during the day but slept overnight in the laboratory. All subjects had circadian variations in each temperature on the order of one degree. Thd had a tendency to fluctuate and its range of difference from Tty was -0.5-0.4 degree C. There was a more significant negative correlation between the latency of the ABR and Tty than that of Thd. It has become apparent that ABR latency is affected by small temperature changes such as circadian variation. The rate of a latency change in the ABR was 0.15msec per degree (C).(ABSTRACT TRUNCATED AT 250 WORDS)