Ratio Of Wave Amplitude Research Articles

Auditory brainstem response in unilateral tinnitus patients: does symmetrical hearing thresholds and within-subject comparison affect responses?

In recent studies, cochlear synaptopathy has been suggested as a potential pathophysiology mechanism for tinnitus, which occurs in individuals with normal hearing thresholds. Auditory Brainstem Response (ABR) is a noninvasive method frequently used in the literature to evaluate cochlear synaptopathy in tinnitus patients. However, possible factors such as high-frequency pure-tone hearing thresholds, age, gender, and head characteristics that may affect ABR were not considered sufficiently in previous studies. Therefore, the present study aims to evaluate tinnitus ears and non-tinnitus ears with ABR in unilateral chronic tinnitus patients with symmetrical hearing. Twenty unilateral chronic tinnitus patients having normal pure-tone average with symmetrical hearing thresholds was included in the study. Subjects were evaluated with 0.25-16kHz pure-tone audiometry, Tinnitus Handicap Inventory (THI) and ABR were administered. All ears were evaluated monaurally using click stimuli at 80dB nHL, alternating polarity (21.1 rate/s, 2000 sweeps). Wave I amplitude of the ABR and the ratio of III/I, V/I, and V/III wave amplitudes from tinnitus ears was higher than non-tinnitus ears. At the same time, there was a positive correlation between THI and V-I and V-III interpeak latency range, and a negative correlation between V/III wave amplitude ratio. ABR can be used as an evaluation method to provide evidence that the neural organizations of individuals with chronic tinnitus differ in certain regions in their auditory pathways. The correlation between THI and ABR findings suggests that there may be a connection between tinnitus distress and the neural organization of the auditory system.

Non-contact Ultrasound Method of Thread Tension Determination for Light Industry Machinery

It has been established that with the help of a pulsed ultrasonic signal of complex shape, it is possible to determine the tension of a filament with a high linear density in a special waveguide with a rectangular crosssection. It has been proved that the amplitude ratios of ultrasonic waves that interact with different textile filaments are influenced by their linear density, the angle between the passage direction of part of the waves enveloping the fibers in the middle and the surface of these fibers, as well as the angle between the direction of wave propagation enveloping the thread itself from the outside, and the surface of the whole material. It should be noted that the corresponding bypass angles of the ultrasonic waves of the textile depend on the material porosity, frequency of the ultrasonic waves, and their power. To enable non-contact control of the change in the tension of the thread branch, it is advisable to use a pulsed ultrasonic signal with two different peaks of the waves, amplitudes, which are adjusted to the linear density of the thread and its conditional radius. Additionally, the use of this method will provide operational technological control in the production of textile fabrics.

High-temperature EMAT with double-coil configuration generates shear and longitudinal wave modes in paramagnetic steel

The non-contact nature of electromagnetic acoustic transducers (EMATs) allows a continuous operation at high temperatures without physical coupling. The existing high-temperature EMATs are mainly shear-wave EMATs, and there are few reports on shear-longitudinal wave or longitudinal-wave EMATs due to the low intensity of the horizontal magnetic field. However, a desirable EMAT design characteristic is the possibility of selecting to generate different acoustic wave modes for various engineering applications. In this paper, a high-temperature EMAT with a double-coil configuration on waveform generation in paramagnetic steel was studied. By adjusting the configuration relationship between the electromagnetic coil and the EMAT eddy-current coil, the selective generation of shear-wave, longitudinal-wave, and shear-longitudinal wave modes was realized. According to quantitative analysis of shear and longitudinal waves generated by the double-coil EMAT, the amplitude ratio of shear and longitudinal waves was about 1 when the diameter of the EMAT eddy-current coil was equal to the inner diameter of the electromagnetic coil. Furthermore, shear-wave mode and shear-longitudinal wave mode high-temperature EMATs were designed and fabricated. The EMAT was placed in a high-temperature environment to continuously measure the paramagnetic steel SUS304. The amplitudes of the shear wave and longitudinal wave at 500 °C decreased by 10.2 times and 3.8 times, respectively, compared with that at 25 °C. The designed EMAT can selectively generate and receive different bulk acoustic wave modes at high temperatures.

Cerebellar Intermittent Theta-Burst Stimulation Reduces Upper Limb Spasticity After Subacute Stroke: A Randomized Controlled Trial.

Objective: This study aims to explore the efficacy of cerebellar intermittent theta-burst stimulation (iTBS) on upper limb spasticity in subacute stroke patients.Methods: A total of 32 patients with upper limb spasticity were enrolled and randomly assigned to treatment with cerebellar iTBS or sham stimulation before conventional physical therapy daily for 2 weeks. The primary outcomes included the modified Ashworth scale (MAS), the modified Tardieu scale (MTS), and the shear wave velocity (SWV). The secondary outcomes were the H-maximum wave/M-maximum wave amplitude ratio (Hmax/Mmax ratio), motor-evoked potential (MEP) latency and amplitude, central motor conduction time (CMCT), and the Barthel Index (BI). All outcomes were evaluated at baseline and after 10 sessions of intervention.Results: After the intervention, both groups showed significant improvements in the MAS, MTS, SWV, and BI. In addition, patients treated with cerebellar iTBS had a significant increase in MEP amplitude, and patients treated with sham stimulation had a significant decrease in Hmax/Mmax ratio. Compared with the sham stimulation group, the MAS, MTS, and SWV decreased more in the cerebellar iTBS group.Conclusion: Cerebellar iTBS is a promising adjuvant tool to reinforce the therapeutic effect of conventional physical therapy in upper limb spasticity management after subacute stroke (Chinese Clinical Trial Registry: ChiCTR1900026516).

Condensation heat transfer performance in multi-fluid compact heat exchangers with wavy and strip fins

The effect of different geometrical parameters of wavy and strip fins in a three-fluid plate-fin compact heat exchanger on the condensation heat transfer in the middle heat exchanger has been experimentally investigated. The three-fluid heat exchanger consisted of three heat exchangers with strip and wavy fins. In the examined system, the hot and cold fluids flowed through the adjacent heat exchangers (strip channels), while the middle heat exchanger (wavy channels) was occupied with a single-component two-phase flow (condensed vapor). The Nusselt number, the friction factor, the heat transfer surface contribution between the middle heat exchanger and each of the adjacent heat exchangers, and the thermal performance factor were calculated using the measured data at the inlets and outlets of the heat exchangers, and by using the thermal balance equations between the fluids passing through the heat exchangers. In the examined heat exchanger, the hot and cold flows had a cross-direction with the two-phase fluid flow. The two-phase Reynolds number, the vapor quality, and the heat transfer surface contribution of the middle heat exchanger with the adjacent heat exchangers were 50–4800, 0.1–0.67, and 0.19–0.7, respectively. The results show that the two-phase flow pattern in the wavy channels of the middle heat exchanger is stratified and wavy. According to the findings, a higher thermal performance factor is observed when the ratio of the wavy channel heat transfer surface to the heat transfer surface of the cold or hot flows is closer to 1. Also, with higher wave amplitude to wavelength ratios, lower pitch to height ratio of the fins, the lower wavelength to the fin length ratios, and lower fin pitch to wave amplitude ratios are obtained a higher thermal performance factor.

The characteristics of daughter waves emerging from colliding solitary waves in astrophysical plasma media

ABSTRACT The aim is to state the properties of ion acoustic solitary waves in course of collision and extract characteristics of the daughter wave in a magnetized electron–ion plasma. The magnetized plasma medium that is a constituent of white dwarfs and astrophysical plasmas that possesses relativistically degenerate electrons and thermal ions in the presence of a constant background magnetic field. The model is based on the extended Poincaré–Lighthill–Kuo (ePLK) method where a set of Korteweg–de Vries equations is obtained to show the phase shifts of colliding waves together with the amplitude and width of the born daughter solitary waves. The numerical results and presented figures regarding the amplitude and width of solitons provide a description of the influence of plasma parameters on soliton interactions, namely ion to electron temperature ratio (σi), ion cyclotron frequency (ωci), and angle between magnetic field and collision line (θ) together with their interplay in shaping the character of solitary waves. It is concluded that only rarefactive electrostatic non-linear waves are able to propagate in such plasma media. The daughter wave amplitude possesses a scaling behaviour regarding the impact angle. Interplay of the parameters on the phase shifts is presented. Ratio of amplitude and width of the daughter wave is directly proportional to the background field, the impact angle controls its maximum. It is observed that the magnetic field elevates ratio of the solitary wave amplitude to width leading it to a shorter life and hence interaction range with neighbouring sites.

MHD flow study of viscous fluid through a complex wavy curved surface due to bio-mimetic propulsion under porosity and second-order slip effects

The steady laminar flow of viscous fluid from a curved porous domain under a radial magnetic field is considered. The fluid flow by a curved domain is due to peristaltic waves present at the boundary walls. The whole analysis is based on porosity (Darcy number) effects. Moreover, the effects of second-order slip on the rheology analysis are also discussed. Due to the complex nature of the flow regime, we have governed the rheological equations by using curvilinear coordinates in the fixed frame. The physical influence of magnetic (Hartmann number) and porosity (Darcy number) parameters on the rheological features of peristaltic transportation are argued in detailed (in the wave frame). Additionally, in the current study, the complex wavy pattern on both boundary walls of the channel is used. The whole rheological study is based on ancient, but medically valid, assumptions of creeping phenomena and long wavelength assumptions. Analytical solutions of the governing equations are obtained by using the simple integration technique in Mathematica software 11.0. The core motivation of the present analysis is to perceive the physical influence of embedded parameters, such as the dimensionless radius of the curvature parameter, magnetic parameter, porosity parameter, different amplitude ratios of complex peristaltic waves, first- and second-order slip parameters, on the axial velocity, pressure gradient, local wall shear stress, tangential component of the extra-stress tensor, pumping and trapping phenomena.

Rayleigh-wave H/V ratio measurement from ambient noise cross-correlations and its sensitivity to VP: a numerical study

SUMMARY The promise of passive seismology has increasingly been realized in recent years. Given the expense in installing and maintaining seismic station networks, it is important to extract as much information from the measurements as possible. In this context, the ellipticity or H/V amplitude ratio of Rayleigh waves can prove to be a valuable observable in ambient noise seismology due to its complimentary sensitivity to subsurface structure, compared to phase and group-velocity dispersion, as well as its potential for constraining VP structure in addition to VS. However, the suitability of the Rayleigh H/V ratio in noise-based studies depends on the accurate interpretation of measurements made on multicomponent ambient-noise cross-correlations. We present a synthetic study that critically examines measurements commonly interpreted as the Rayleigh-wave H/V ratio, under realistic scenarios of spatially distributed and non-uniform noise sources. Using the surface wave terms of Green’s function in a laterally homogeneous medium, we rigorously model multicomponent cross-correlations for arbitrary noise-source distributions and extract from them standard estimates of the H/V ratio. Variation of these measurements as a function of VP is studied empirically, by brute-force simulation. We find that the measurements depart significantly from the theoretical Rayleigh-wave H/V for the medium in question, when noise sources are strongly directional or anisotropic. Love waves, if present in the cross-correlations, also have the potential to significantly bias interpretation. Accurate interpretation of the H/V ratio measurement thus rests on carefully modelling these effects. However, the sensitivity to VP structure is comparable to that of the classic Rayleigh-wave H/V. We also propose a new measurement for cross-correlations that has slightly greater sensitivity to VP. Finally, uncertainty analysis on synthetic tests suggests that simplistic interpretations of Rayleigh-wave ellipticity are only effective (in resolving VP structure) when the Love-wave contamination is negligible and measurement uncertainties are less than 10 per cent.

Abstract MP10: A Novel Genetic Locus Influences Microvascular Reactivity To Acute Psychological Stress

Background: Excessive peripheral microvascular constriction during acute psychological stress, measured using peripheral arterial tonometry reflects similar changes in coronary blood flow.The ratio of digital pulse wave amplitude during stress compared to rest (sPAT) is used to estimate the degree of microvascular response to stress. Hypothesis: We hypothesized that genetic factors contribute to the degree of microvascular constriction during mental stress and that excessive vasoconstriction is associated with adverse cardiovascular outcomes. Methods: A total of 580 stable CAD subjects of European and African ancestries from two prospective cohort studies underwent mental stress testing with a standardized public speaking stressor. Digital pulse wave amplitude was continuously measured using PAT and the stress/rest PAT ratio (sPAT) of pulse wave amplitude during mental stress/baseline was calculated. Genotyping was performed using Illumina’s Multi-Ethnic Genotyping Array platform and imputed to the 1000 Genome reference panel. Ethnicity-specific genome-wide association studies (GWAS) of sPAT were conducted using linear regression of additive genetic mode adjusted for age, sex and population stratification in both cohorts. A trans-ethnic meta-analysis integrated the GWAS results from four sub-cohorts. Upon 5-year follow-up, Fine and Gray’s sub-distribution hazard ratios (sHR) were used to examine the association between sPAT ratio (> vs=< median) and the composite endpoint of cardiovascular death, myocardial infarction, revascularization, and hospitalization for heart failure. Results: Mean age was 63±9; 65% male, 35% African American. We identified three SNPs in linkage disequilibrium on chr7:111,666,943 T>C (rs6466396); chr7: 111,668,622 T>G (rs876170); chr7: 111,668,623 T>G (rs876169) that were associated with greater sPAT ratio by means of 0.13, 0.12 and 0.10, ( P = 1.42E-08). The sPAT-associated locus was within DOCK4 gene which encodes Dedicator of Cytokinesis 4, an essential protein for angiogenesis and brain development, and a known locus for obesity. After adjusting for demographic and cardiovascular risk factors, medications, and rate-pressure product change during mental stress, those with low sPAT ratio were at significantly higher risk of adverse outcomes (sHR 1.8 [95% CI 1.1 - 2.8]). Conclusion: We have identified a genetic basis for stress-induced vasomotion. Presence of allele C (rs6466396) is associated with increased vasoconstriction during mental stress, and thus may predispose CAD patients to a higher risk for adverse cardiovascular outcomes with stressful exposure.

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This study characterized the differences in K-complex (KC) morphology features between obstructive sleep apnea-hypopnea syndrome (OSAHS) patients and healthy controls and analyzed the effect of respiratory events on KC morphology. We enrolled 42 male subjects (21 OSAHS patients and 21 age-matched healthy controls) who underwent overnight polysomnography. KCs in stage N2 were manually identified. We found that KCs in healthy controls had larger negative and whole amplitudes, longer durations, and smoother positive waves than OSAHS patients but smaller positive amplitudes. Most features showed highly significant differences after Bonferroni correction (p < 0.001/3). After separating out the KCs associated with respiratory events in OSAHS patients, the differences between the groups remained but were relatively smaller. In OSAHS patients, compared with the spontaneous KCs not evoked by obvious factors, the KCs occurring after respiratory events had larger amplitudes, steeper slopes, larger negative wave amplitude and duration ratios. KCs occurring during respiratory events showed lower amplitudes and shorter durations. These results may reveal the impact of respiratory events on sleep and brain function.

Seismic Moment Tensor Inversion of an Induced Microseismic Event, Offshore Norway: An Insight into the Possible Cause of Wellbore Liner Failure during a Drilling Operation

Abstract A microseismic event with Mw∼0.8 was recorded at the Grane oilfield, offshore Norway, in June 2015. This event is believed to be associated with a failure of the wellbore liner in well 25/11-G-8 A. The failure mechanism has been difficult to explain from drilling parameters and operational logs alone. In this study, we analyzed the detected microseismic event to shed light on the possible cause of this event. We inverted for the seismic moment tensor, analyzed the S/P amplitude ratio and radiation pattern of seismic waves, and then correlated the microseismic data with the drilling reports. The inverted seismic moment indicates a shear-tensile (dislocation) event with a strong positive isotropic component (67% of total energy) accompanied by a positive compensated linear vector dipole (CLVD) and a reverse double-couple (DC) component. Drilling logs show a strong correlation between high pump pressure and the occurrence of several microseismic events during the drilling of the well. The strongest microseismic event (Mw∼0.8) occurred during peak pump pressure of 277 bar. The application of high pump pressure was associated with an attempt to release the liner hanger running tool (RT) in the well, which had been obstructed. Improper setting of the liner hanger could have caused the forces from the RT release to be transferred to the liner and might have resulted in ripping and parting of the pipe. The possible direct impact of the ripped liner with the formation or the likely sudden hydraulic pressure exposure to the formation caused by the liner ripping may explain the estimated isotropic component in the moment tensor inversion in the well. This impact can promote slip along the pre-existing fractures (the DC component). The presence of gas in the formation or the funneled fluid to the formation caused by the liner ripping may explain the CLVD component.

Novel Scientific Simulations (Finite Element Method) for Peristaltic Blood Flow in an Asymmetric Channel: Applications of Magnetic and Inertial Forces

Background: Recently, an utmost attention has been devoted by researchers on the prestaltic movement of viscous flows due to its novel importance in daily life problems, human body and many physical systems. In era of biological systemns and health sciences, the prestaltic mechanism attribute impotant applications blood circulation in vessels, blood pumping in heart, food in esophagus etc. Moreover, the applications of novel Galerkin finite element scheme for solution of nonlinear partial differential equations associated with peristaltic flow problems is another challenging task for mathematicians. Owing to such motivativations in mind, this computational presents the magnetohydrodynamic peristaltic flow of viscous fluid at high Reynolds number induced by an asymmetric wall channel. The novel impact of magnetic force are also utilized as a novelty. Method: The equations which exploit the flow problem are numerically tackled with help of Galerkin finite element scheme. Results: The results are computed and show great validation for physical parameters like wave constants, amplitude ratio and Reynolds number. The validation of obtained results are worked out with already claimed data and achieved an excellent accuracy. The mechanisms of transport process is addressed in view of involved physical parameters namely wave constant, Reynolds number and Hartmann number. The graphical observations are successfully revealed for all parameters.

Dual-frequency acousto-ultrasonic sensing of impact damage in composites for mitigating signal instability

Signal instability due to temperature fluctuations, sensor degradation, and debonding introduces additional amplitude loss in the detected signals during acousto-ultrasonic detection, which may be falsely attributed to defects in a structure. First, we determined that the amplitudes of both high-frequency and low-frequency Lamb waves decrease after propagation through a damaged area. Then, we found that the amplitude ratio of such waves not only exhibits a downward trend but is also immune to fluctuations in the input signals. A qualitative numerical expression was proposed to explain this phenomenon, and preliminary experiments were conducted to demonstrate that the amplitude ratio is an effective parameter for mitigating instability in signal detection. Particularly, the number of impacts on a composite laminate was evaluated with respect to changes in the input signal amplitude. Notably, this method can be further simplified by designing a dual-frequency input signal. After conclusively validating the performance of the novel method in a composite subjected to temperature fluctuations, we conclude that the proposed acousto-ultrasonic detection method is robust in mitigating signal instability, and that it yields reliable information for damage evaluation.

Neurobiological Pathways Linking Acute Mental Stress to Impairments in Executive Function in Individuals with Coronary Artery Disease.

Background:Individuals with coronary artery disease (CAD) have worse executive function compared to the general population but the mechanisms are unknown.Objective:To investigate the role of acute mental stress (MS) on the executive function of patients with CAD.Methods:Participants with stable CAD underwent acute MS testing with simultaneous peripheral vascular function measurements and brain imaging using high resolution-positron emission tomography. Digital pulse wave amplitude was continuously measured using peripheral artery tonometry (PAT, Itamar Inc). Stress/rest PAT ratio (sPAT) of pulse wave amplitude during MS/baseline was calculated as a measure of microvascular constriction during MS. Plasma levels of catecholamine and interleukin-6 were assessed at baseline and after MS. Executive function was assessed both at baseline and at 2 years follow-up using the Trail Making Test parts A and B.Results:We studied 389 individuals with brain data available for 148 participants. Of this population follow-up cognitive assessments were performed in 226 individuals (121 with brain imaging). After multivariable adjustment for baseline demographics, risk factors, and medication use, a lower sPAT, indicating greater vasoconstriction, a higher inferior frontal lobe activation with MS, and increases in norepinephrine and IL-6 levels with MS were all independently associated with greater time to complete Trail B test.-38.4ptConclusion:In response to acute MS, greater peripheral vasoconstriction, higher inferior frontal lobe brain activation, and increases in the levels of norepinephrine and IL-6 are associated with worse executive function.

Numerical study on significance of wave amplitude, wavelength and aspect ratio on heat transfer and fluid flow characteristics in circular wavy MC heat sink design

In this study, hydrothermal characteristics in a circular wavy microchannel (CWMC) design under laminar flow conditions with uniform heat flux is numerically studied. Parametric studies in an innovative CWMC design were carried out at various wave amplitudes, wavelengths and aspect ratios. Three dimensional numerical study was performed in the Reynolds number (Re) range from 100 to 300 with uniform heat flux (50 W/cm2) applied at bottom of the channel, treating copper as channel material and water as working fluid. The obtained results were compared to sinusoidal wavy microchannel (SWMC).The results showed that heat transfer and fluid flow characteristics were significantly influenced by wave amplitude, wavelength and aspect ratio. Velocity vectors and contours were presented to understand the heat transfer and fluid flow characteristics. Stream-wise local Nusselt number, overall performance factor, span-wise velocity and temperature variation are also presented. It is concluded that CWMC with higher wave amplitude, smaller wave length and smaller aspect ratio gives higher heat transfer augmentation with corresponding pressure drop penalty.

Relationship between amplitude anisotropy and compressive strength of reinforced concrete depending on curing conditions

Determination of anisotropy has crucial to assess the quality of the concrete structures. The signal amplitudes of ultrasonic wave measured on different surfaces of concrete can be used for determining the anisotropy. In this study, a total of 27 cube reinforced concrete samples with different strengths (low, medium and high) have prepared. First, signals of ultrasonic waves (P and S waves) have obtained to use direct measurement technique from two opposite surfaces of the all samples. After, Fast Fourier Transform (FFT) has applied on ultrasonic signals for determining amplitude anisotropies and amplitude ratios. Finally, amplitude anisotropies and ratios have correlated with concrete strength, porosity and reinforcement diameter depending on curing conditions and new equations have developed. In addition, these equations have determined both depending on curing conditions and regardless of curing type. As a result, it has been shown that P and S wave amplitude anisotropies and ratios of reinforced concrete increased with decreasing of concrete strength. These increasing have obtained higher for P wave than that of S wave.

Out-of-Plane Free Vibration and Forced Harmonic Response of a Curved Beam

Based on the governing differential equation of out-of-plane curved beam, the wave propagation behavior, free vibration, and transmission properties are presented theoretically in this paper. Firstly, harmonic wave solutions are given to investigate the dispersion relation between frequency and wave number, cut-off frequency, displacement, amplitude ratio, and phase diagram. The frequency spectrum results are obtained to verify the work by Kang and Lee. Furthermore, natural frequencies of the single and composite curved beam are calculated through solving the characteristic equation in the case of free-free, clamped-clamped, and free-clamped boundaries. Finally, the transfer matrices of the out-of-plane curved beam are derived by combining the continuity between the different interfaces. The transmissibility curves of the single and composite curved beam are compared to find the vibration attention band. This work will be valuable to extend the study of the out-of-plane vibration of curved beams.

Probing the Analytical Cancellation Factor of Short Scale Gravity Waves Using Na Lidar and Nightglow Data from the Andes Lidar Observatory

The cancellation factor (CF) is a model for the ratio between gravity wave perturbations in the nightglow intensity to those in the ambient temperature. The CF model allows us to estimate the momentum and energy flux of gravity waves seen in nightglow images, as well as the divergence of these fluxes due to waves propagating through the mesosphere and lower thermosphere region, where the nightglow and the Na layers are located. This study uses a set of wind/temperature Na lidar data and zenith nightglow image observations of the OH and O(1S) emissions to test and validate the CF model from the experimental perspective. The dataset analyzed was obtained during campaigns carried out at the Andes Lidar Observatory (ALO), Chile, in 2015, 2016, and 2017. The modeled CF was compared with observed CF values calculated using the ratio of wave amplitude in nightglow images to that seen in lidar temperatures for vertically propagating waves. We show that, in general, the modeled CF underestimates the observed CF results. However, the O(1S) emission line has better agreement with respect to the modeled value due to its supposedly simpler nightglow photochemistry. In contrast, the observed CF for the OH emission deviates by a factor of two from the modeled CF asymptotic value.

Stability of Early Auditory Evoked Potential Components Over Extended Test-Retest Intervals in Young Adults.

Synaptic damage from noise exposures can occur even in the absence of changes in hearing sensitivity in animal models. There is an unmet clinical need for measurements sensitive to such damage to the human auditory system that can augment the pure-tone audiogram. Early components (i.e., <10 msec) of the auditory evoked potential (AEP) may be useful noninvasive indicators of synaptic integrity. Wave I is a measure of synchronous neural activity at the level of the synapse between cochlear inner hair cells and the auditory nerve and may be of particular clinical utility. This amplitude measure has historically been classified as too variable in humans to be used for clinical waveform interpretation, though several recent reliability studies have challenged this view. The focus of the present study is to examine across-session stability of early AEP amplitude measures. In this study, amplitudes of early components (wave I, wave V, summating potential [SP]) of the AEP were measured in a cohort of 38 young adults aged 19 to 33 years (21 female). Stability of these amplitude measures was examined in a subset of 12 young adults (8 female), at time intervals ranging from 15 hr to 328 days between tests. Eligibility criteria included normal pure-tone hearing sensitivity, normal tympanometry, and intact acoustic reflexes. Participants were tested at up to four time points. Each evaluation included pure-tone thresholds, tympanometry, speech-in-noise testing, distortion-product otoacoustic emissions (DPOAE), and early AEPs. AEPs were collected in response to click and tone burst stimuli, with both ear canal and mastoid electrode montages. No clinical changes in pure-tone hearing were found between baseline and follow-up visits. Intraclass correlation coefficients (ICCs) indicated good to excellent reliability for wave I and wave V peak-to-trough amplitudes within individuals across time, with greatest reliability (0.92, 95% confidence interval [0.81 to 0.96]) and largest amplitudes for wave I when measured from the ear canal in response to a click stimulus. Other measures such as amplitude ratios of waves V/I and the SP and action potential (AP) showed lower ICC values when measured from the ear canal, with SP/AP ratio demonstrating the lowest reliability. The results of this study suggest that, when recorded under certain conditions, wave I amplitude can be a stable measure in humans. These findings are consistent with previous work and may inform the development of clinical protocols that utilize wave I amplitude to infer inner ear integrity.

Magnetic resonance imaging and dynamic X-ray\u2019s correlations with dynamic electrophysiological findings in cervical spondylotic myelopathy: a retrospective cohort study

BackgroundDynamic somatosensory evoked potentials (DSSEP) can be used to disclose abnormalities of ascending sensory pathways at dynamic positions and diagnose cervical spondylotic myelopathy (CSM). However, radiographic tests including magnetic resonance imaging (MRI) and dynamic X-ray are used much more widely in the management of CSM. Our study aims to clarify the correlations between several radiographic parameters and the DSSEP results, and further determine their reliability with clinical data.MethodsWe retrospectively enrolled 38 CSM patients with surgical intervention. DSSEP tests were performed before surgery. Amplitude ratios of DSSEP N13 and N20 waves at extension and flexion were calculated and recorded as N13_E, N20_E, N13_F, N20_F, respectively. Baseline severity was evaluated with the modified Japanese Orthopedic Association (mJOA) score and the Nurick grades. Prognosis was evaluated based on the 2-year recovery rate. Sagittal diameter and transverse areas of the cord and canal were measured and the the compressive ratios at the compressed site (Compression_Ratio), central (Central_Ratio), and 1/4-lateral points (1/4-Lateral_Compression_Ratio), and spinal cord/Canal Area Ratio were calculated. The intramedullary T2 hyperintensity patterns (Ax-CCM types) were also collected from MRI axial images. Dynamic X-rays were used to test for segmental instability of the cervical spine. The correlations between radiologic findings, DSSEP data, and clinical assessments were investigated.ResultsWe found that DSSEP N13_E and N13_F correlated with the Compression_Ratio, Central_Ratio, 1/4-Lateral_Compression_Ratio (Pearson, p < 0.05) and Ax-CCM types (ANOVA, p < 0.05) in MRI axial images and cervical segmental instability in dynamic X-ray (t-test, p < 0.05). Apart from the 1/4-Lateral_Compression_Ratio, these radiographic parameters above also correlated with the baseline clinical assessments (Spearman or ANOVA or t-test, p < 0.05) and postoperative recovery rate (Pearson or ANOVA or t-test, p < 0.05).ConclusionsWe found that the preoperative Compression_Ratio, Central_Ratio and 1/4-Lateral_Compression_Ratio in MRI and cervical segmental instability in dynamic X-ray could reflect the dynamic neural dysfunction of the spinal cord. Different Ax-CCM types corresponded to different DSSEP results at extension and flexion, suggesting divergent pathophysiology. These radiographic parameters could help evaluate disease severity and predict postoperative prognosis.