Interhemispheric asymmetry exists in female in the N100m source position of the auditory evoked magnetic fields

OBJECTIVE: To evaluate the affect of families' attitudes about the appropriateness of discussing psychosocial concerns on pediatric providers' identification of psychosocial problems. DESIGN: These data were collected as part of the Greater New Haven Child Health Study, New Haven, Conn. The study design was a prospective cohort. SETTING: Families were recruited from a stratified random sample of all primary care practices in the greater New Haven area. Nineteen of 23 invited practices agreed to participate including 2 prepaid practices, 2 neighborhood health centers, and 7 fee-for-service group and 8 fee-for-service solo practices. PARTICIPANTS: All families of children aged 4 to 8 years who attended these practices during 2 separate 3-week periods (1 in fall 1987 and 1 in spring 1988) were invited to participate in the study. Families were invited to participate only once, on the first contact with any eligible child, using approved procedures. Of 2006 eligible families, 1886 (94%) chose to participate. MAIN OUTCOME MEASURE: The outcome variable for these analyses is the identification of any behavioral, emotional, or developmental problem by the pediatrician on the 13-category checklist. Overall, pediatric clinicians identified 27.5% of children with 1 or more psychosocial problems. RESULTS: Our data suggest that there is a great deal of discrepancy between what parents report is appropriate to do when their children have psychosocial problems and what they actually do when they recognize such problems in their children. Most (81.1%) believed it was appropriate to discuss 4 or more of the 6 hypothetical situations with their children's physician, while only 40.9% actually did discuss any of these problems with a physician when a problem occurred. Given the correlates of parents who intended to discuss such problems (higher education, older age, Euro-American ethnicity, higher income, married, availability of medical insurance) the possibility that parents are providing socially acceptable responses to such questions seems likely. Further, our data indicate that parents' actual reports of discussions of psychosocial problems is unrelated to whether physicians identified those problems in children. CONCLUSIONS: Pediatricians'judgments about the presence of psychosocial problems in their young patients seem to be based on their own observations rather than on what parents report. Physician-parent communication about psychosocial problems will be increasingly important as primary care physicians assume their role as gatekeepers to more expensive services such as mental health interventions.     

Transitory evoked and distortion products of otoacoustic emissions in absent auditory evoked potentials

Transient click-evoked otoacoustic emissions (TEOAE) and distortion-product otoacoustic emissions (DPOAE) are produced by an active biomechanical process in the cochlea, presumably related to outer hair-cell activity. Although it is generally accepted that in most cases of hearing loss with absent auditory evoked potentials neither TEOAE nor DPOAE can be found, some cases with such a constellation have been described. Here we report another four cases of children with severe to profound hearing loss where we discovered reproducible TEOAE and DPAOE, whereas auditory evoked potentials were missing. TEOAE and DPOAE recordings in these cases indicate substantially preserved outer hair-cell function independent of profound pre-sensineural hearing loss. Since the incidence of children with preserved otoacoustic emissions together with impairment of synaptic or postsynaptic function of the first neuron is not known, the unconditioned use of TEOAE nor DPOAE as a screening instrument must be seriously questioned. Secondly, in conjunction with subjective audiometry and brain-stem-evoked potentials, emission recordings is an indispensable measurement prior to cochlear implantation and use of high-power hearing aids.     

Abnormalities of auditory evoked magnetic fields and structural changes in the left hemisphere of male schizophrenics--a magnetoencephalographic-magnetic resonance imaging study

Functional and structural changes in 10 DSM-III-R male schizophrenics and 10 healthy volunteers were investigated using magnetoencephalographically (MEG) detected long-latency (N100 m) auditory evoked fields (AEFs) and magnetic resonance imaging (MRI). The AEFs were characterized by single moving equivalent dipoles, which were superimposed on MRIs. There were significant differences in dipole orientations and in AEF latencies in the left hemisphere of schizophrenics, when compared to the controls. The MEG-detected alterations were found to be associated with a bilateral volume reduction of the posterior superior temporal gyrus (pSTG), which was more pronounced in the left hemisphere. Separate analysis of white and gray matter has shown that the pSTG volume reduction resulted from decreased gray matter volumes without white matter changes. Both the functional and the morphological data indicate a left-hemispheric disturbance in our patients.     

Brainstem auditory evoked potentials and visually evoked potentials in young patients with IDDM

OBJECTIVE: To investigate whether young IDDM patients develop central nervous dysfunction and to establish a possible relationship with various disease parameters. RESEARCH DESIGN AND METHODS: Thirty-two patients, aged 13.5 +/- 2 years, with disease duration of 6 +/- 2.6 years and age of onset of 7.7 +/- 3.2 years (group 1), and 21 patients with short-term disease, age 9.7 +/- 3.5 years, duration of disease < 2 years and age of onset of 9.4 +/- 3.3 years (group 2) were compared with age- and sex-matched control subjects. Exclusion criteria were clinical signs of neuropathy, retinopathy, nephropathy, or hearing impairment. Neurophysiological studies included auditory and visually evoked potentials (EPs). RESULTS: Patients in group 1 revealed increased P100 latencies of visually EPs (103.4 +/- 4.5 vs. 96.8 +/- 3.7 ms) and interpeak latencies I-V of auditory EPs (4.16 +/- 0.10 vs. 3.99 +/- 0.09 ms) and had abnormal latencies (values outside 2.5 SD) in 37%. However, short-term patients (group 2) had results within normal limits compared with control subjects. In group 1, longer disease duration and younger age at onset correlated with an increase of P100 latency (P < 0.001) and IPL I-V (P < 0.001). Patients with a history of severe hypoglycemic episodes had increased latencies compared with patients without hypoglycemia (P < 0.05). Furthermore, metabolic control during the last 2 years was related to P100 latencies (P < 0.05). CONCLUSIONS: EPs noninvasively detect subclinical central nervous system involvement in children and adolescents with IDDM. Most important risk factors are duration of disease and frequency of severe hypoglycemia.     

Middle latency auditory evoked potentials in epilepsy

Heparin (HE) exhibited a protective effect on liposome peroxidation induced by Fe2+ and Cu2+, decreasing the formation of both conjugated dienes and thiobarbituric acid reactive substances (TBARS) in a dose-dependent manner. The antioxidant activity was more relevant in the oxidizing system employing Fe2+ and H2O2 and generating the highly reactive OH radical. The analysis of liposome size distribution by quasielastic laser light scattering showed that: (1) the native structure of the particles was completely lost after exposure to Fenton reagent; (2) the presence of HE in the reaction mixture completely prevented the peroxidative damage on liposomes. Thus, HE acts as an antioxidant factor on membrane lipid bilayer. This suggests that HE, released from mast-cell granules during inflammatory processes, might locally protect the cell membrane from the oxidative injuries.     

Odorant evoked magnetic fields in humans

To verify the optimal hematocrit (Hct) level in the treatment of cerebral ischemia, cerebral oxygen transport (CTO2) and cerebral oxygen metabolism (CMRO2) in graded isovolemic hemodilution were evaluated during cerebral ischemia. Isovolemic hemodilution with low molecular weight dextran to stepwise lower Hct from 43% to 36%, 31%, and 26% was carried out in 13 splenectomized dogs, 6 h after global cerebral ischemia. Global ischemia of the animals was produced by multiple intra- and extracranial ligations of cerebral arteries. Cerebral blood flow (CBF) was measured with radioisotope labeled microspheres. CTO2, CMRO2, and oxygen extraction fraction (OEF) were calculated from CBF, arterial oxygen content (CaO2), and venous oxygen content (CvO2). In dogs with global cerebral ischemia, CBF increased with graded isovolemic hemodilution (r=-0.73, P<0.05). CTO2 reached its highest value at a Hct level of 31.3%. CTO2 at Hct of 36.1% and 31.3% was statistically different from the value measured at a Hct of 43.3%, and there was a decrease when Hct was lowered to 25.9%. CMRO2 was the highest when Hct was at 31.3% and differed significantly from the value measured at a Hct of 43.3%. There was a 10% increase of OEF when Hct was at 25.9%; however this change was not statistically significant compared with the OEF at Hct of 36.1% and 31.3%, respectively. These findings indicate that CTO2 and CMRO2 were the highest when Hct was reduced to 31% in hemodilution. Hct at 31% is the optimum for cerebral metabolism in ischemic status. Uncoupling of CTO2, CMRO2 with CaO2 was also observed in this study. This phenomenon suggests that hemodilution to augment cerebral circulation may be at least partially attributed to the beneficial effects of hemorheologic improvement in the microcirculation of the ischemic brain.     

Visual and auditory evoked responses in acute severe hepatitis

Evoked responses have not been studied in patients with acute severe hepatitis (ASH) with or without hepatic encephalopathy. This prospective study was undertaken to find out diagnostic as well as prognostic value of visual evoked responses (VER), and brain stem auditory evoked responses (BAER) in patients with ASH with or without encephalopathy. Visual evoked responses and BAER were studied in 20 patients (14 males and six females) with ASH. The patients were diagnosed as having severe hepatitis if acute hepatitis was associated with raised serum bilirubin and serum transaminases, and if they had a prothrombin time index of < 50%. After a detailed neuropsychiatric examination of each patient, the study sample was divided into two groups of 10 patients: ASH without encephalopathy (ASH-WOE), and ASH with encephalopathy (fulminant hepatic failure, FHF). The median P100 latencies of FHF patients were significantly increased compared with controls and patients in the ASH-WOE group. Abnormal P100 latencies, exceeding 95th percentile values of the controls, were present in one patient in the ASH-WOE group and six patients in the FHF group. The median interpeak latencies I-III, III-V and I-V were significantly prolonged in the FHF group. Interpeak latencies III-V were also increased significantly in patients in the ASH-WOE group. While abnormal BAER were seen frequently in both groups, VER abnormalities were largely confined to patients in the FHF group. In the FHF group, six out of 10 patients survived and exhibited clinical improvement in the status of hepatic encephalopathy. Evoked responses were repeated after 2-3 weeks of recovery in these patients and VER abnormalities showed a tendency to normalize, thereby suggesting a prognostic implication. The incidence of abnormal VER in hepatic encephalopathy complicating ASH far exceeded that of abnormal BAER. Markedly prolonged P100 latencies in FHF patients indicate poor prognosis.     

Brainstem auditory evoked responses in patients with tinnitus

Brainstem auditory evoked responses of 355 patients with uni- or bilateral tinnitus were recorded in order to evaluate the effect of tinnitus on the central auditory system. The amplitudes of waves I, III and V and the latencies of each wave and interpeak latencies were compared to those of a group of 129 controls with normal hearing. The study of the control group initially identified a certain number of concurrent parameters. The brainstem evoked responses of men and women evolved differently from the age of 30 years, latencies of I-III and I-V in men lengthening with age and those of women tending to shorten. The patient groups were therefore compared to a control group of the same sex ratio or of the same sex, half being between 30 and 56 years of age. The tinnitus patients were divided into three groups according to the side affected by tinnitus. Latencies and amplitudes in these groups differed significantly from those of the control group. In order to eliminate hearing loss, the most difficult concurrent factor and almost always associated with tinnitus, the results of individuals with symmetrical hearing loss were compared to those of the control group. Tinnitus was always associated with significant lengthening of 0-I and I-V latencies on the tinnitus-affected side, with a significant reduction in amplitudes of waves I and III, and sometimes of wave V, particularly in the group with left-sided tinnitus. Comparison of tinnitus patients with symmetrical and asymmetrical hearing by sex showed that tinnitus patients of all groups had lengthening of right and left 0-I latencies, apart from the women in the group with right-sided tinnitus, and significant reduction in amplitudes of waves I and III in women and of left III only in men. When hearing loss was asymmetrical and on the tinnitus-affected side, there was also lengthening of 0-I latencies on the tinnitus-affected side in both sexes and of ipsi- and contralateral I-V latencies in women. Right- and left-sided tinnitus was associated with additional differences between the three groups. Correlation coefficient study confirmed that 0-I, I- III and I-V latencies were independent of the mean degree of deafness, deafness at high frequencies and at frequencies around the tinnitus, up to a threshold of hearing loss of 40 dB, above which 0-I and 0-V lengthened in addition to tinnitus. On the other hand, whatever the frequency, tinnitus involved significant lengthening of wave I latencies and modification of the previously recorded amplitudes. Two groups of tinnitus patients could be distinguished: the first, with symmetrical hearing loss, with symmetrical normal latencies, apart from 0-I latencies and the amplitude of the wave on the tinnitus side, and the second with hearing loss predominant on the tinnitus-affected side, with different latencies on each side, 0-I being shorter on the unaffected side, I-III and I-V being lengthened on the unaffected side and 0-I being lengthened on the tinnitus-affected side. Moreover, as disturbances of brainstem evoked responses caused by tinnitus particularly affected waves I and III, the hypothesis of possible involvement of the efferent systems could be proposed.     

Brainstem auditory evoked potentials in liver transplant candidates

BAEPs were recorded on 18 patients before, and/or after liver transplantation. Clinical assessment included 5 standardized scales. Data were divided by stringent criteria into 2 groups: clinical hepatic encephalopathy present (HE) or absent (nonHE). Dependent variables were BAEP configuration and I-V, I-III and III-V IPLs. The following comparisons were made: all patients vs. controls; HE vs. controls; nonHE vs. controls; HE vs. nonHE. BAEP configuration changes were not significantly associated with HE. I-V and III-V IPLs were prolonged for all patients, nonHE patients, and HE patients vs. controls; I-III IPL differences were not significant. There were no correlations between BAEP variables and EEG grade or grades on any single clinical scale. The results suggest that BAEP IPLs (especially the I-V IPL) are a sensitive, although not specific, measure of HE and may be sensitive enough to detect incipient HE.     

The silent period between sounds has a stronger effect than the interstimulus interval on auditory evoked magnetic fields

Lymphocyte activation remains an area of intense interest to immunologists and cell biologists and the dynamics of expression of surface molecules during the process are widely studied. The CD69 C-type lectin is reportedly the earliest activation antigen on lymphocytes and can be detected within hours of mitogenic stimulation. Recently reports have described differential activation dynamics with respect to different antigenic or mitogenic stimuli. This study has investigated the dynamics of CD69 expression over time after mitogenic, allogeneic, cytokine and target cell mediated activation of T-cell and NK cell subsets. It is apparent that the dynamics of CD69 expression differ with respect to the cell type and the method of stimulation. Mitogenic stimulation resulted in the most rapid expression of CD69 on both T- and NK cells while alloantigen stimulation induced a far slower response. Target cell stimulation of NK cells gave paradoxical results in that the CD69 + ve subset increased as a proportion of the total NK cells but did not increase in number. This was due to the selective binding of CD69 - ve NK cells to the target cells and their subsequent loss from the lymphoid gate. We confirmed this by showing that CD69 + ve NK cells do not lyse K562 target cells. This observation demonstrates the caution needed in the analysis of flow cytometric data based solely upon relative proportions of cells within discrete subsets.     

Clinical significance of electrically evoked auditory brainstem response

Electrically evoked auditory brainstem responses (EABR) were recorded in 31 postlingually deafened adults, who had recently received cochlear implants (mini-system, Cochlear Ltd). The wave consisted of three distinct positive peaks labeled P1, P2, and P3 with latency of 1.35 (+/- 0.14), 2.17 (+/- 0.18) and 4.08 (+/- 0.31) ms, respectively. The P3 threshold (EABR-T) and slope (EABR-S) were 0.9 (+/- 0.47) mA and 0.6 (+/- 0.28) muv/mA, respectively. The relationships between the EABR parameters (EABR T and -S of the P3 wave) and age, duration of deafness, promontory test and subjective response (T and C-level) were investigated. The scattergram showed a strong negative linear relationship between EABR-S and subjective T-level. This finding suggests that EABR-S is good measure of postoperative perception.     

Brain stem auditory evoked potentials in neurological diagnosis]

In the presented work brainstem auditory evoked potentials were assessed as noninvasive nonclinical tests in diagnosis of neurological diseases. The most often disorders in particular parts of the recording were also considered. The use of brainstem auditory evoked potentials in diagnosis of multiple sclerosis, polyneuropathy, vessel disorders, brain traumas, inflammatory and sclerotic processes was evaluated.     

Short-latency auditory evoked potentials in infants with otitis media

Auditory brain-stem potential findings in 154 healthy infants and infants with different forms of middle-ear pathological conditions (306 ears) were indicative of the inflammatory process influence on the parameters of auditory reception in most cases. The changes in the waves' forms and intraoperative morphological findings in the middle ear were correlated. Objective audiometry allows definite determination of the middle ear trouble which is important in diagnosis of latent otitis in infants who are especially prone to this disease.     

Electrically evoked auditory brainstem response in peripherally myelin-deficient mice

The integrity of the myelin sheath is important for normal electrophysiological function and survival of neurons that make up the auditory nerve. It is hypothesized that myelin deficiency of the auditory nerve may change the electrophysiologic characteristics of the auditory system, especially the temporal properties. In this study, the electrically evoked auditory brainstem response (EABR) was systematically evaluated in TrJ and Po-DT-A mice. Both of these mice have a deficit of their peripheral myelin. Correlation between the EABR and degree of myelin deficiency was also evaluated. The EABR in both strains of poorly myelinated mice exhibited prolonged latency, decreased amplitude, elevated threshold of wave I evoked by short-duration stimuli (20 microseconds/phase). A 2-pulse stimulation paradigm was used to evaluate refractory properties. Myelin-deficient mice exhibited slower recovery from the refractory state than controls. Long-duration stimuli (4 ms/phase) were used to assess integration properties. Myelin-deficient mice demonstrated prolonged wave I latency and more gradual latency changes with current level. Myelin thickness showed a strong correlation with EABR threshold for short-duration stimulation (r = -0.784), maximum wave I latency (r = -0.778) and the time constant of the wave I latency-current level function (r = -0.736) for long-duration stimulation and normalized wave I recovery functions (r = -0.718). These findings suggest that EABR measurement may be a promising tool to assess the electrically stimulated properties of auditory neurons, particularly related to the status of myelin sheath.     

Effects of postinatal stress on visual and auditory evoked potentials

Maturation of visual and auditory evoked potentials (mainly the P3 wave) of 10 controls and of 10 infants exposed to recurrent postnatal stressful events (crying spells lacking organic basis) have been compared. The sourse of maturation of P3 waves may serve as indicator of growth and nature of cognitive processes (including perception). Recurrent srying spells seemed to delay appearance of visual P3 wave, prolonged its latency, and delayed appearance of visible differences in the shape of visual P3 wave upon exposure of the subjects to different visual experiences. A compensatory increase of maturation of the auditory P3 wave appeared. The results suggest that recurrent exposure to stressful events during the early postnatal period may delay the ability of the memory banks of auditory engrams with unusual contents (including memory traces of stresses), a potential basis for future auditory hallucinations.     

Brainstem auditory evoked potentials during brainstem ischemia and reperfusion in gerbils

To evaluate the reversibility of neural function in the brainstem following ischemia, we investigated the effect of transient brainstem ischemia on the brainstem auditory evoked potential in gerbils. Brainstem ischemia was produced by bilateral extracranial occlusion of vertebral arteries. Local cerebral blood flow was measured by quantitative autoradiography after 5 min of ischemia and was reduced to less than 3 ml/100 g per min in the pons and lower midbrain, indicating severe and reproducible brainstem ischemia. During brainstem ischemia, brainstem auditory evoked potential waveforms disappeared completely. After a brief ischemic insult (5 min), all four brainstem auditory evoked potential components recovered to normal. After longer ischemic insults (10-30 min), brainstem auditory evoked potential components never recovered to normal. Microtubule-associated protein 2 immunoreactivity revealed differential vulnerability of the acoustic relay nuclei in the brainstem. Neurons in the lateral lemniscus were most vulnerable, followed in order by neurons in the trapezoid body, the superior olive and the cochlear nucleus. We also demonstrated a close relationship between the reversibility of ischemia-induced changes on brainstem auditory evoked potential and ischemic lesions of these relay nuclei. These data may be useful for evaluating the therapeutic window of thrombolytic therapy during acute vertebrobasilar occlusion.     

Cardiopulmonary bypass-induced changes in plasma concentrations of propofol and in auditory evoked potentials

Unbound, rather than total, plasma concentrations may be related to the anaesthetic action of propofol. Therefore, we measured plasma concentrations of propofol and recorded Nb wave latencies of auditory evoked potentials (AEP) during continuous infusion of propofol in 15 patients undergoing coronary artery bypass grafting (CABG) surgery. After induction of anaesthesia with fentanyl, propofol was infused continuously at a rate of 10 mg kg-1 h-1 for 20 min, and then the rate was reduced to 3 mg kg-1 h-1. Administration of heparin before cardiopulmonary bypass (CPB) did not affect total or unbound propofol concentration. Initiation of CPB decreased mean total propofol concentration from 2.6 to 1.7 micrograms ml-1 (P < 0.01). Simultaneously, mean unbound propofol concentration remained at 0.06 micrograms ml-1 because of a slight increase in the mean free fraction of plasma propofol (from 2.3 to 3.5%; P > 0.05). During hypothermic CPB, mean total propofol concentration increased to concentrations measured before bypass (to 2.1 micrograms ml-1; P > 0.05 vs value before CPB) and the mean unbound propofol concentration was at its highest (0.07 microgram ml-1; P < 0.05 vs value before heparin). After CPB and administration of protamine, the mean total propofol concentration remained lowered (1.7 micrograms ml-1; P < 0.05 vs value before heparin) and the mean unbound propofol concentration returned to the level measured before heparin (P < 0.001 vs value during hypothermia). The latency of the Nb wave from recordings of AEP increased after induction of anaesthesia, reached its maximum during hypothermia and was prolonged during the subsequent phases of the study. The latency of the Nb wave did not correlate with total or unbound propofol concentration. We conclude that the changes in total and unbound concentrations of plasma propofol were not parallel in patients undergoing CABG. During CPB or at any other time during the CABG procedure, the unbound propofol concentration did not decrease and Nb wave latency was prolonged compared with baseline values measured after induction of anaesthesia before the start of CPB.     

Brain stem auditory evoked potentials from bone stimulation in dogs

Brain stem auditory evoked potential (BAEP) testing with air-conducted click stimuli can be used to diagnose sensorineural deafness in dogs if conductive deafness can be ruled out. Detection of conductive deafness can be performed by recording BAEP elicited by a vibratory stimulus transducer placed against the skull. Air- and bone-conducted BAEP were compared in dogs, varying bone stimulator placement, click polarity, and stimulus intensity. Optimal bone stimulator placement was determined to be over the mastoid process, followed by the mandible and the zygomatic arch. Condensation polarity clicks gave responses preferable to those elicited by rarefaction or alternating polarity. Bone-conducted BAEP peak latencies were significantly longer than air-conducted latencies after correction of the latencies for the air conduction time accompanying air-conducted stimuli. Significant differences between stimulus modalities were not seen for BAEP peak amplitudes or interpeak latencies. Latency-intensity and amplitude-intensity regressions had similar effects for both modalities: latencies decreased and amplitudes increased as stimulus intensity increased.