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Muscle tone is defined as the resistance to passive stretch, but this definition is often criticized for its ambiguity since some suggest it is related to a state of preparation for movement. Muscle tone is primarily regulated by the central nervous system, and individuals with neurological disorders may lose the ability to control normal tone and can exhibit abnormalities. Currently, these abnormalities are mostly evaluated using subjective scales, highlighting a lack of objective assessment methods in the literature. This study aimed to use surface electromyography (sEMG) and machine learning (ML) for the objective classification and characterization of the full spectrum of muscle tone in the upper limb. Data were collected from thirty-nine individuals, including spastic, healthy, hypotonic and rigid subjects. All of the classifiers applied achieved high accuracy, with the best reaching 96.12%, in differentiating muscle tone. These results underscore the potential of the proposed methodology as a more reliable and quantitative method for evaluating muscle tone abnormalities, aiming to address the limitations of traditional subjective assessments. Additionally, the main features impacting the classifiers' performance were identified, which can be utilized in future research and in the development of devices that can be used in clinical practice.

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OBJECTIVE: To analyze the correlation between caloric testing response patterns with respect to cochlear impairment in individuals with unilateral Ménière's disease. METHODS: In this observational cross-sectional study, the factor under study was Ménière's disease and the outcome was cochleovestibular function, evaluated through caloric stimulation using videonystagmography and four-frequency averages in pure tone audiometry. RESULTS: A total of 187 patients (equal sex distribution) who met the inclusion criteria were included. In impairment analysis of the affected ear, 17 patients had only vestibular impairment, 56 had only cochlear impairment, and 114 had cochleovestibular impairment. The distribution of Ménière's disease stages according to four-frequency average was grade I: 23.53%, grade II: 16.04%, grade III: 42.25%, and grade IV: 18.18%. There was a significant association (p < 0.001) between the affected ear and labyrinthine preponderance. The Spearman correlation between four-frequency average and labyrinth preponderance (r = 0.326) indicated a moderate correlation, considering p < 0.01. CONCLUSION: Our results show that the greater the cochlear damage due to Ménière's disease, the more impaired the vestibular function in the affected ear. LEVEL OF EVIDENCE: Level 2 - Individual cross-sectional studies with consistently applied reference standard and blinding.

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An extensive literature has focused on the association between human, social, and economic capital and better immigrant economic attainment, and how these characteristics contribute to stratification among members of the same group. However, few studies have explored how racialization processes contribute to these within-group differences. We examine the role of intragroup differences in skin tone in stratifying outcomes among Mexican immigrants in the early twentieth century. We create a new dataset of 1910-1940 Mexican border-crossing records that we then link to the U.S. 1940 census. We use characteristics at entry to predict income in 1940 and find that-in line with dominant assimilation theories-standard measures of capital are associated with within-group attainment differences. However, we also find skin tone to be a source of within-group stratification: being perceived as having darker skin is associated with lower subsequent economic attainment than being perceived as having lighter skin. Furthermore, whereas human and social capital transcended context to allow migrants to transfer those skills anywhere, the effect of skin tone was significant only in Texas and not in other major receiving places like California. We argue that although standard measures of assimilation typically predict later outcomes, the stratifying effect of skin tone has long been a feature of Mexican immigration.

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BACKGROUND: Hypotension during dialysis arises from vasomotor tone alterations and hypovolemia, with disrupted counterregulatory mechanisms in acute kidney injury (AKI) patients. This study investigated the predictive value of preload dependency, assessed by the passive leg raising (PLR) test, and arterial tone, measured by dynamic elastance (Eadyn), for intradialytic hypotension (IDH). METHODS: In this prospective observational study conducted in a tertiary hospital ICU, hemodynamic parameters were collected from critically ill AKI patients undergoing intermittent hemodialysis using the FloTrac/Vigileo system. Baseline measurements were recorded before KRT initiation, including the PLR test and Eadyn calculation. IDH was defined as mean arterial pressure (MAP) < 65 mmHg during dialysis. Logistic regression was used to identify predictors of IDH, and Kaplan-Meier analysis assessed 90-day survival. RESULTS: Of 187 patients, 27.3% experienced IDH. Preload dependency, identified by positive PLR test, was significantly associated with IDH (OR 8.54, 95% CI 5.25-27.74), while baseline Eadyn was not predictive of IDH in this cohort. Other significant predictors of IDH included norepinephrine use (OR 16.35, 95% CI 3.87-68.98) and lower baseline MAP (OR 0.96, 95% CI 0.94-1.00). IDH and a positive PLR test were associated with lower 90-day survival (p < 0.001). CONCLUSIONS: The PLR test is a valuable tool for predicting IDH in critically ill AKI patients undergoing KRT, while baseline Eadyn did not demonstrate predictive value in this setting. Continuous hemodynamic monitoring, including assessment of preload dependency, may optimize patient management and potentially improve outcomes. Further research is warranted to validate these findings and develop targeted interventions to prevent IDH.

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BACKGROUND: This study examined the relationship between behavioural thresholds as measured by pure tone audiometry and electrophysiological thresholds measured by the Auditory Steady-State Response (ASSR) in children with normal hearing and sensorineural hearing loss. MATERIALS AND METHODS: After being assessed, 45 children of both sexes, ranging in age from 5 to 15, were split into four groups: 10 with moderate to moderately severe sensorineural hearing loss (G2M); 10 with steeply sloping sensorineural hearing loss (G2D); 10 with profound and severe sensorineural hearing loss (G2S); and 15 with normal hearing (G1). ASSR, tympanometry, acoustic reflex testing, pure tone audiometry, and speech audiometry (SRT and SDT) were performed. RESULTS: The electrophysiological maximum in the group with normal hearing thresholds varied from 19 to 27 dB NA. The correlation in the group with moderate to moderately severe hearing loss was 0.42-0.74. The correlation in the steeply sloping hearing loss group was 0.68-0.94. The correlation in the group of people with profound and severe hearing loss was 0.59-0.86. The normal hearing group's mean differences in ASSR threshold and audiometric threshold ranged from -0.3 to 12 dB, in the moderate and moderately severe hearing loss group from -9 to 2 dB, in the steeply sloping hearing loss group from 1.4 to 7.5 dB, and in the severe and profound hearing loss group from -0.40 to 8.5 dB. CONCLUSION: As expected, there was no strong relationship between behavioural and electrophysiological thresholds in the group with normal hearing. But in children with hearing loss, there was a strong correlation between electrophysiological and behavioural thresholds; this relationship was especially evident in children with severe and profound hearing loss and those with steeply sloping hearing loss.

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Accumulating evidence suggests that interactions between the brain and gut microbiota significantly impact brain function and mental health. In the present study, we aimed to investigate whether young, healthy adults without psychiatric diagnoses exhibit differences in metabolic stool and microbiota profiles based on depression/anxiety scores and heart rate variability (HRV) parameters. Untargeted nuclear magnetic resonance-based metabolomics was used to identify fecal metabolic profiles. Results were subjected to multivariate analysis through principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), and the metabolites were identified through VIP score. Metabolites separating asymptomatic and symptomatic groups were acetate, valine, and glutamate, followed by sugar regions, glutamine, acetone, valerate, and acetoacetate. The main metabolites identified in high vagal tone (HVT) and low vagal tone (LVT) groups were acetate, valerate, and glutamate, followed by propionate and butyrate. In addition to the metabolites identified by the PLS-DA test, significant differences in aspartate, sarcosine, malate, and methionine were observed between the groups. Levels of acetoacetate were higher in both symptomatic and LVT groups. Valerate levels were significantly increased in the symptomatic group, while isovalerate, propionate, glutamate, and acetone levels were significantly increased in the LVT group. Furthermore, distinct abundance between groups was only confirmed for the Firmicutes phylum. Differences between participants with high and low vagal tone suggest that certain metabolites are involved in communication between the vagus nerve and the brain.

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BACKGROUND: Parasympathetic tone activity (PTA) in response to nociceptive stimulus in conscious non-sedated horses is unknown. OBJECTIVES: Study PTA, heart rate (HR), and horse grimace scale (HGS) at rest and during mechanical nociceptive stimulation. ANIMALS: Ninety healthy young adult horses (females, males): 30 each of Friesians, Quarter Horses, and Warmbloods. METHODS: Prospective control study. The study consisted of habituation to equipment (Day 1), baseline recordings (Days 2 and 3), and nociceptive testing applying mild pressure to the metacarpus (Day 4). Parasympathetic tone, HR, and HGS were recorded simultaneously on Days 2 to 4. Each study lasted 30 minutes and was done in triplicate at 3 different time points per day. RESULTS: Baseline PTA was not different among breeds. It decreased in Warmbloods and Quarter Horses during placement of the stimulus device without stimulation (P < .01). A significant decrease in PTA (P < .001) occurred during nociceptive stimulus (marked in Quarter Horses, intermediate in Warmbloods, and mild in Friesians). Heart rate and HGS increased significantly (P < .001) during the stimulus in all breeds but returned to baseline poststimulation. Friesians required higher pressure (P < .05) to elicit an aversive response to the stimulus. CONCLUSIONS: Horses' PTA, HR, and HGS change in response to a mild mechanical nociceptive stimulus with Friesians showing less variation. Stress induced a decrease in PTA in Quarter Horses and Warmbloods but not in Friesians. Friesians appeared to be more tolerant to pain based on PTA, HR, and HGS findings compared with other breeds.

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Purinergic signaling is a crucial determinant in the regulation of pulmonary vascular physiology and presents a promising avenue for addressing lung diseases. This intricate signaling system encompasses two primary receptor classes: P1 and P2 receptors. P1 receptors selectively bind adenosine, while P2 receptors exhibit an affinity for ATP, ADP, UTP, and UDP. Functionally, P1 receptors are associated with vasodilation, while P2 receptors mediate vasoconstriction, particularly in basally relaxed vessels, through modulation of intracellular Ca2+ levels. The P2X subtype receptors facilitate extracellular Ca2+ influx, while the P2Y subtype receptors are linked to endoplasmic reticulum Ca2+ release. Notably, the primary receptor responsible for ATP-induced vasoconstriction is P2X1, with α,ß-meATP and UDP being identified as potent vasoconstrictor agonists. Interestingly, ATP has been shown to induce endothelium-dependent vasodilation in pre-constricted vessels, associated with nitric oxide (NO) release. In the context of P1 receptors, adenosine stimulation of pulmonary vessels has been unequivocally demonstrated to induce vasodilation, with a clear dependency on the A2B receptor, as evidenced in studies involving guinea pigs and rats. Importantly, evidence strongly suggests that this vasodilation occurs independently of endothelium-mediated mechanisms. Furthermore, studies have revealed variations in the expression of purinergic receptors across different vessel sizes, with reports indicating notably higher expression of P2Y1, P2Y2, and P2Y4 receptors in small pulmonary arteries. While the existing evidence in this area is still emerging, it underscores the urgent need for a comprehensive examination of the specific characteristics of purinergic signaling in the regulation of pulmonary vascular tone, particularly focusing on the disparities observed across different intrapulmonary vessel sizes. Consequently, this review aims to meticulously explore the current evidence regarding the role of purinergic signaling in pulmonary vascular tone regulation, with a specific emphasis on the variations observed in intrapulmonary vessel sizes. This endeavor is critical, as purinergic signaling holds substantial promise in the modulation of vascular tone and in the proactive prevention and treatment of pulmonary vascular diseases.

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Aging is accompanied by considerable deterioration of homeostatic systems, such as autonomic imbalance characterized by heightened sympathetic activity, lower parasympathetic tone, and depressed heart rate (HR) variability, which are aggravated by hypertension. Here, we hypothesized that these age-related deficits in aged hypertensive rats can be ameliorated by exercise training, with benefits to the cardiovascular system. Therefore, male 22-mo-old spontaneously hypertensive rats (SHRs) and age-matched Wistar Kyoto (WKY) submitted to moderate-intensity exercise training (T) or kept sedentary (S) for 8 wk were evaluated for hemodynamic/autonomic parameters, baroreflex sensitivity, cardiac sympathetic/parasympathetic tone and analysis of dopamine ß-hydroxylase (DBH+) and oxytocin (OT+) pathways of autonomic brain nuclei. Aged SHR-S versus WKY-S exhibited elevated mean arterial pressure (MAP: +51%) and HR (+20%), augmented pressure/HR variability, no cardiac vagal tone, and depressed reflex control of the heart (HR range, -28%; gain, -49%). SHR-T exhibited a lower resting HR, a partial reduction in the MAP (-14%), in the pressure/HR variabilities, and restored parasympathetic modulation, with improvement of baroreceptor reflex control when compared with SHR-S. Exercise training increased the ascending DBH+ projections conveying peripheral information to the paraventricular nucleus of hypothalamus (PVN), augmented the expression of OT+ neurons, and reduced the density of DBH+ neurons in the rostral ventrolateral medulla (RVLM) of SHR-T. Data indicate that exercise training induces beneficial neuroplasticity in brain autonomic circuitry, and it is highly effective to restore the parasympathetic tone, and attenuation of age-related autonomic imbalance and baroreflex dysfunction, thus conferring long-term benefits for cardiovascular control in aged hypertensive individuals.NEW & NOTEWORTHY Exercise training reduces high blood pressure and cardiovascular autonomic modulation in aged hypertensive rats. The dysfunction in the baroreflex sensitivity and impaired parasympathetic tone to the heart of aged hypertensive rats are restored by exercise training. Exercise induces beneficial neuroplasticity in the brain nuclei involved with autonomic control of cardiovascular function of aged hypertensive rats.

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Objective: To describe audiological symptoms, audiometric profile, and distortion product otoacoustic emission in symptomatic patients recovering from SARS-CoV-2 infection (positive RT-PCR test) and asymptomatic patients (negative RT-PCR test). Methods: An analytical cross-sectional study was conducted using data obtained from clinical charts, physical examination, audiometry, and distortion product otoacoustic emission on 40 patients [case patients (CP)] recovering from SARS-CoV-2 infection diagnosed by a positive RT-PCR test and 22 asymptomatic participants with a negative RT-PCR test [non-case (NC)]. Results: Sixty-two patients (mean age: 31.1 and 28.2 years in the CP and NC groups, respectively) were included. All participants were young without significant comorbidities, risk factors for hearing loss or otological history. Vertigo (5%), tinnitus (17.5%) and aural fullness/hearing loss (35%) were found in the CP group. A statistically significant difference was found in specific frequencies (1000, 4000, and 8000 Hz) and pure tone average (low and high conversational frequencies with increased threshold in the PC group compared with the NC group), which was not found in distortion product otoacoustic emission. Conclusion: Audiovestibular symptoms are frequent in symptomatic patients recovering from SARS-CoV-2 infection. SARS-CoV-2 infection was consistently associated with an increased audiometric hearing threshold at specific frequencies and low tone average.

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Calcitonin gene-related peptide (CGRP), an endogenous neuropeptide released from perivascular sensory nerves, exerts a powerful vasodilatation. Interestingly, adenosine triphosphate (ATP) stimulates the release of CGRP by activation of prejunctional P2X2/3 receptors, and adenosine 5'-O-2-thiodiphosphate (ADPßS), a stable adenosine diphosphate (ADP) analogue, produces vasodilator/vasodepressor responses by endothelial P2Y1 receptors. Since the role of ADP in the prejunctional modulation of the vasodepressor sensory CGRPergic drive and the receptors involved remain unknown, this study investigated whether ADPßS inhibits this CGRPergic drive. Accordingly, 132 male Wistar rats were pithed and subsequently divided into two sets. In set 1, ADPßS (5.6 and 10 µg/kg·min) inhibited the vasodepressor CGRPergic responses by electrical stimulation of the spinal T9-T12 segment. This inhibition by ADPßS (5.6 µg/kg·min) was reverted after i.v. administration of the purinergic antagonists MRS2500 (300 µg/kg; P2Y1) or MRS2211 (3000 µg/kg; P2Y13), but not by PSB0739 (300 µg/kg; P2Y12), MRS2211 (1000 µg/kg; P2Y13) or the KATP blocker glibenclamide (20 mg/kg). In set 2, ADPßS (5.6 µg/kg·min) failed to modify the vasodepressor responses to exogenous α-CGRP. These results suggest that ADPßS inhibits CGRP release in perivascular sensory nerves. This inhibition, apparently unrelated to activation of ATP-sensitive K+ channels, involves P2Y1 and probably P2Y13, but not P2Y12 receptors.

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BACKGROUND: To test whether a Shallow Neural Network (S-NN) can detect and classify vascular tone dependent changes in arterial blood pressure (ABP) by advanced photopletysmographic (PPG) waveform analysis. METHODS: PPG and invasive ABP signals were recorded in 26 patients undergoing scheduled general surgery. We studied the occurrence of episodes of hypertension (systolic arterial pressure (SAP) >140 mmHg), normotension and hypotension (SAP < 90 mmHg). Vascular tone according to PPG was classified in two ways: 1) By visual inspection of changes in PPG waveform amplitude and dichrotic notch position; where Classes I-II represent vasoconstriction (notch placed >50% of PPG amplitude in small amplitude waves), Class III normal vascular tone (notch placed between 20-50% of PPG amplitude in normal waves) and Classes IV-V-VI vasodilation (notch <20% of PPG amplitude in large waves). 2) By an automated analysis, using S-NN trained and validated system that combines seven PPG derived parameters. RESULTS: The visual assessment was precise in detecting hypotension (sensitivity 91%, specificity 86% and accuracy 88%) and hypertension (sensitivity 93%, specificity 88% and accuracy 90%). Normotension presented as a visual Class III (III-III) (median and 1st-3rd quartiles), hypotension as a Class V (IV-VI) and hypertension as a Class II (I-III); all p < .0001. The automated S-NN performed well in classifying ABP conditions. The percentage of data with correct classification by S-ANN was 83% for normotension, 94% for hypotension, and 90% for hypertension. CONCLUSIONS: Changes in ABP were correctly classified automatically by S-NN analysis of the PPG waveform contour.

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The aim was to assess and report the effects of menstrual cup on pelvic floor muscles (PFM) function and tone, as well as check the acceptability after a period of three menstrual cycles in healthy young women. The data collected in assessments and reassessments included the International Consultation on Incontinence Questionnaire - Vaginal Symptoms (ICIQ-VS) questionnaire, evaluation of PFM function through PERFECT Scheme, PFM muscle tone, and PFM manometry (Peritron 9300®). A diary regarding the overall colletor acceptability and satisfaction was collected. Ten healthy young women completed the study. There was an improvement in the mean values of maximal voluntary contraction (MVC) (p = 0.032), a decrease in the vaginal resting pressure (VRP) (p = 0.05), and an increase in the number of repetitions of sustained muscle contractions (p = 0.042). Seven women reported some discomfort while using the vaginal cup only in the first cycle while three revealed discomfort during the whole experiment. This study provides preliminary case-based evidence that the use of the vaginal cup for a period of three menstrual cycles changes the VRP, MVC, and PFM tone, as well as improves the repetitions of PFM assessed by digital palpation. Moreover, the women reported the use of vaginal cup as a positive experience.

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OBJECTIVE: There is no consensus in the literature regarding the relationship between high-resolution computed tomography findings and hearing thresholds in pure-tone audiometry in otosclerosis. This study evaluated the association between high-resolution computed tomography findings and pure-tone audiometry in otosclerosis in the spongiotic phase. METHODS: A cross-sectional study was conducted of 57 ears with surgically confirmed stapes fixation and tomographic findings. Air conduction and bone conduction thresholds on audiometry, and air-bone gap, were analysed. RESULTS: There were no correlations between sites affected by otospongiosis and air conduction threshold, bone conduction threshold or air-bone gap in the analysed tomographic images, but the diameter of the otospongiotic focus was greater in the presence of extension of the otospongiotic foci to the cochlear endosteum. CONCLUSION: There were no relevant associations between high-resolution computed tomography findings and pure-tone audiometric measurements. However, the diameter of the otospongiotic focus was greater in the presence of extension of the otospongiotic foci to the cochlear endosteum.

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RESUMO Objetivo Caracterizar os limiares auditivos nas frequências de 500, 1000, 2000 e 4000 Hz em crianças submetidas ao reimplante com follow-up de no mínimo 10 anos. Método Revisão retrospectiva de prontuários de crianças submetidas a cirurgia de reimplante há pelo menos 10 anos. Foram avaliados os limiares auditivos obtidos na audiometria tonal liminar em campo livre com o implante coclear nas frequências de 500, 1000, 2000 e 4000 Hz em quatro momentos distintos: 1 (antes da falha), 2 (ativação), 3 (cinco anos após o reimplante) e 4 (dez anos após o reimplante, independentemente do tempo de uso do uso do 2o IC) em pacientes com follow-up de no mínimo 10 anos. Resultados Avaliando-se pacientes submetidos ao reimplante, observou-se que os limiares de 500, 1000, 2000, 4000 Hz apresentaram-se a longo prazo semelhante àqueles obtidos nos pacientes implantados somente uma única vez, não apresentando prejuízo assim na detecção dos sons. Conclusão O reimplante não teve efeito de longo prazo sobre os limiares auditivos obtidos em crianças que se submeteram a esta cirurgia por falha do componente interno.

ABSTRACT Purpose To characterize hearing thresholds at frequencies of 500, 1000, 2000 and 4000 Hz in children undergoing reimplantation with a follow-up of at least 10 years. Methods Retrospective review of medical records of children who underwent reimplantation surgery for at least 10 years. The auditory thresholds obtained in free-field pure tone audiometry with the cochlear implant were evaluated at frequencies of 500, 1000, 2000 and 4000 Hz at four different times: 1 (before failure), 2 (activation), 3 (five years after reimplantation) and 4 (ten years after reimplantation, regardless of the time of use of the 2nd CI) in patients with a follow-up of at least 10 years. Results Evaluating patients who underwent reimplantation, it was observed that the thresholds of 500, 1000, 2000, 4000 Hz were similar in the long term to those obtained in patients who were implanted only once, thus not presenting damage in the detection of sounds. Conclusion Reimplantation had no long-term effect on the hearing thresholds obtained in children who underwent this surgery due to internal component failure.

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Abstract Objective: To investigate the impact of certain clinical parameters on likelihood of hearing recovery after SSNHL and to detect potential variables that predict its outcome. Methods: A retrospective study was conducted in order to identify the clinical parameters which influence hearing recovery after SSNHL. Medical charts of 87 patients diagnosed with SSNHL and treated in the clinic from January 2015 to December 2019 were retrospectively reviewed. The effects of several parameters on the success of the treatment were statistically evaluated. Such parameters studied were age, gender, the severity of hearing loss, audiometric curve pattern, the time treatment was initiated, and metabolic factors. Results: Patient categorization according to tonal audiometric curve results statistically differed in terms of recovery (complete, partial, no recovery) (x2 = 32.5; p< 0.001). There are 2× more diabetic patients in the group no recovery than in the group partial recovery (OR = 3.1; 95% CI 0.95-10; p = 0.061), and 5.3× more than in the group complete recovery (OR = 10.4; 95% CI 2.3-45; p = 0.002) (χ2 = 11.2; p = 0.004). There is a statistically significant correlation between onset of therapy and recovery on a scale of significance of 93% (χ2 = 5.3, p= 0.069). Conclusion: In our study tonal audiometry results, diabetes mellitus and onset of therapy were shown to be a statistically significant negative predictive factors for recovery. Results of pure tone audiometry suggest a flat profound curve is statistically associated with the no recovery rates, and a down sloping curve proved to be statistically associated with complete recovery rates. Level of evidence: Level 1.

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Abstract Introduction Measurement of the electrically-evoked stapedial reflex threshold (ESRT) is an objective tool used to set the comfort levels in pediatric cochlear implant (PCI) users. The levels of ESRT have a strong correlation with comfort levels. However, the clinical utility of ESRT is limited because the ESRT response is not observed in all cochlear implant users. Objective To assess the effects of probe-tone frequency on ESRT and its relationship with the behavioral comfort levels in PCI users. Methods A total of 14 PCI users aged between 5 and 8 years participated in the study. The ESRT levels were measured using high-frequency probe tones (678 Hz and 1,000 Hz), and the default 226 Hz probe tone. The ESRT was measured with single-electrode stimulation across the three electrode locations (basal [E01]; middle [E11]; and apical [E22]). The ESRT levels measured with different probe tone frequencies were compared with the behavioral comfort levels. Results The mean ESRT levels using 1,000Hz and 678 Hz were lower than those measured using 226 Hz, but there was no main effect of probe-tone frequency (p > 0.05). A significantly high incidence of successful ESRT measurements occurred with higher-frequency probe tone (p < 0.039). Additionally, ESRT using higher probe tones significantly correlated with comfort levels. Conclusion The ESRT with higher probe tones was correlated with behavioral comfort levels and increased the success rate of the measurements. Higher-frequency probe tones may be useful whenever ESRT with 226 Hz is not measurable.

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Introduction Measurement of the electrically-evoked stapedial reflex threshold (ESRT) is an objective tool used to set the comfort levels in pediatric cochlear implant (PCI) users. The levels of ESRT have a strong correlation with comfort levels. However, the clinical utility of ESRT is limited because the ESRT response is not observed in all cochlear implant users. Objective To assess the effects of probe-tone frequency on ESRT and its relationship with the behavioral comfort levels in PCI users. Methods A total of 14 PCI users aged between 5 and 8 years participated in the study. The ESRT levels were measured using high-frequency probe tones (678 Hz and 1,000 Hz), and the default 226 Hz probe tone. The ESRT was measured with single-electrode stimulation across the three electrode locations (basal [E01]; middle [E11]; and apical [E22]). The ESRT levels measured with different probe tone frequencies were compared with the behavioral comfort levels. Results The mean ESRT levels using 1,000Hz and 678 Hz were lower than those measured using 226 Hz, but there was no main effect of probe-tone frequency ( p > 0.05). A significantly high incidence of successful ESRT measurements occurred with higher-frequency probe tone ( p < 0.039). Additionally, ESRT using higher probe tones significantly correlated with comfort levels. Conclusion The ESRT with higher probe tones was correlated with behavioral comfort levels and increased the success rate of the measurements. Higher-frequency probe tones may be useful whenever ESRT with 226 Hz is not measurable.

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The autonomic profile of mice submitted to sustained hypoxia (SH) was not yet fully evaluated. Herein, we characterized the cardiovascular and autonomic profile of conscious freely moving mice submitted to SH using two sequential experimental protocols to evaluate the parasympathetic and sympathetic tone to the heart and the sympathetic tone to the vascular resistance. In the first protocol the sequence of antagonists was methyl-atropine followed by propranolol and then by prazosin, while in the second protocol the sequence was propranolol followed by methyl-atropine and then by prazosin. In SH the baseline heart rate was significantly lower than in control mice and the antagonism of the parasympathetic and sympathetic tone to the heart in both experimental protocols indicated an increased parasympathetic tone in SH mice and no changes in the sympathetic tone. Antagonism of the sympathetic tone to the vascular resistance with prazosin produced similar changes in arterial pressure in control and SH mice. Altogether these findings support the concept that mice submitted to SH present a significant increase in the parasympathetic but not in the sympathetic tone, which may explain why the baseline arterial pressure was not increased in SH mice.