Longitudinal-Torsional Frequency Coupling Design of Novel Ultrasonic Horns for Giant Magnetostrictive Transducers.

The use of advanced brittle composites in engineering systems has necessitated robotic rotary ultrasonic machining to attain high precision with minimal machining defects such as delamination, burrs, and cracks. Longitudinal-torsional coupled (LTC) vibrations are created by introducing helical slots to a horn's profile to enhance the quality of ultrasonic machining. In this investigative research, modified ultrasonic horns were designed for a giant magnetostrictive transducer by generating helical slots in catenoidal and cubic polynomial profiles to attain a high amplitude ratio (TA/LA) and low stress concentrations. Novel ultrasonic horns with a giant magnetostrictive transducer were modelled to compute impedances and harmonic excitation responses. A structural dynamic analysis was conducted to investigate the effect of the location, width, depth and angle of helical slots on the Eigenfrequencies, torsional vibration amplitude, longitudinal vibration amplitude, stresses and amplitude ratio in novel LTC ultrasonic horns for different materials using the finite element method (FEM) based on the block Lanczos and full-solution methods. The newly designed horns achieved a higher amplitude ratio and lower stresses in comparison to the Bezier and industrial stepped LTC horns with the same length, end diameters and operating conditions. The novel cubic polynomial LTC ultrasonic horn was found superior to its catenoidal counterpart as a result of an 8.45% higher amplitude ratio. However, the catenoidal LTC ultrasonic horn exhibited 1.87% lower stress levels. The position of the helical slots was found to have the most significant influence on the vibration characteristics of LTC ultrasonic horns followed by the width, depth and angle. This high amplitude ratio will contribute to the improved vibration characteristics that will help realize good surface morphology when machining advanced materials.

Pulse amplitude ratio under noninvasive ventilation as a new method in the diagnosis of left heart failure in patients with acute exacerbation of chronic obstructive pulmonary disease.

BACKGROUND: Left heart failure (LHF) is commonly associated with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) but its role is often underestimated. AIM OF STUDY: To evaluate the performance of a new diagnostic technique based on the measurement of the pulse amplitude ratio (PAR) using non-invasive ventilation (NIV) for the early identification LHF in patients admitted to the emergency department (ED) for AECOPD. RESULTS: 73 patients were included in this study: 32 in LHF group and 41 in non LHF- group. The two groups had comparable demographic and clinical characteristics at admission. The mean values of PARNIV was significantly higher among LHF patients (0.86 vs. 0.71; p < 0.01). The area under the receiver operating characteristic curve of PARNIV was 0.75. Using the best cut-off (0.6), the sensitivity of PARNIV was 93% with a specificity 21%, a positive predictive value of 48%, and a negative predictive value of 81%. Correlation between PARNIV and BNP was significant (r = 0.52; p = 0.002). CONCLUSION: Measurement of PARNIV in patients presenting to the ED with AECOPD had a good diagnostic performance for the detection of LHF and could represent an interesting alternative for the currently available methods. Trial registration The study was registered in the Clinical Trial Registration System (clinicaltrials.gov) under the study number NCT05189119, https://register. CLINICALTRIALS: gov/prs/app/action/SelectProtocol?sid=S000BOO4&selectaction=Edit&uid=U0000QAM&ts=2&cx=qrmluh .

Antisymmetric Lamb Wave Simulation Study Based on Electromagnetic Acoustic Transducer with Periodic Permanent Magnets.

Due to its multi-mode and dispersion characteristics, Lamb waves cause interference to signal processing, which profoundly limits their application in nondestructive testing. To resolve this issue, firstly, based on the traditional EMAT, a horizontal polarization periodic permanent magnet electromagnetic acoustic transducer (HP-PPM-EMAT) was proposed. A 2-D finite element model was then developed to compare magnetic flux density, Lorentz force, and signal strength between the traditional EMAT and the HP-PPM-EMAT. The simulation results show that the HP-PPM-EMAT enhances the A0 mode Lamb wave (A0 wave) and suppresses the S0 mode Lamb wave (S0 wave). Finally, the influence of structural parameters of the HP-PPM-EMAT on the total displacement amplitude ratio of A0 and S0 was investigated using orthogonal test theory, and the width of magnet units was improved based on the orthogonal test. The results show that the total displacement amplitude ratio of A0 to S0 of the improved HP-PPM-EMAT can be improved by a factor of 7.74 compared with that of the traditional Lamb wave EMAT, which can produce higher-purity A0 mode Lamb waves.

Valsalva-derived Measures and Phenylephrine Test in Patients With Heart Failure With Reduced Ejection Fraction Receiving Comprehensive Neurohormonal Blockade Drug Therapy: A 5-year Event-free Survival Analysis.

BACKGROUND: To assess the relationships between Valsalva- and phenylephrine test-derived measures and outcome in patients with heart failure with reduced ejection fraction (HFrEF) receiving comprehensive neurohormonal blockade pharmacotherapy. METHODS AND RESULTS: Data from 56 patients with HFrEF (mean left ventricle ejection fraction of 32 ± 6%) subjected to Valsalva and phenylephrine tests were analyzed retrospectively. Baroreflex-related (Valsalva-ratio and blood pressure-RR interval slope from phase IV) and non-baroreflex-related measures (systolic blood pressure rise in phase IV [ΔSBPPHASE_IV], and pulse amplitude ratio [PAR]) were calculated from Valsalva. Short-term outcomes (HF-related hospitalization, implantable cardioverter-defibrillator shock or all-cause death within 24 months from examination) and long-term outcomes (implantable cardioverter-defibrillator shock or all-cause death within 60 months) were analyzed. The end point occurred in 16 and 18 patients, for the short- and long-term outcomes, respectively. A low ΔSBPPHASE_IV identified patients at risk in the long term, as evidenced by a low vs high ΔSBPPHASE_IV comparison (square-wave response patients assigned to low ΔSBPPHASE_IV group, P = .002), and Cox model (hazard ratio 0.91, 95% confidence interval 0.86-0.96, P < .001), and tended to identify patients at risk in the short term outcome (hazard ratio 0.95, 95% confidence interval 0.91-1.00, P = .055). There was a tendency toward a higher event-free survival in the low PAR group (low vs high PAR; hazard ratio 0.44, 95% CI 0.17-1.18, P = .104). CONCLUSIONS: Non-baroreflex-related measures obtained from Valsalva-namely, ΔSBPPHASE_IV and PAR-might carry prognostic value in patients with HFrEF receiving neurohormonal blockade pharmacotherapy.

Performance Degradation in Cross-Eye Jamming Due to Amplitude/Phase Instability between Jammer Antennas.

Cross-eye gain in cross-eye jamming systems is highly dependent on amplitude ratio and the phase difference between jammer antennas. It is well known that cross-eye jamming is most effective for the amplitude ratio of unity and phase difference of 180 degrees. It is assumed that the instabilities in the amplitude ratio and phase difference can be modeled as zero-mean Gaussian random variables. In this paper, we not only quantitatively analyze the effect of amplitude ratio instability and phase difference instability on performance degradation in terms of reduction in cross-eye gain but also proceed with analytical performance analysis based on the first order and second-order Taylor expansion.

Weakly Coupled Piezoelectric MEMS Resonators for Aerosol Sensing.

This paper successfully demonstrates the potential of weakly coupled piezoelectric MEMS (Micro-Electro-Mechanical Systems) gravimetric sensors for the detection of ultra-fine particulates. As a proof-of-principle, the detection of diesel soot particles of 100 nanometres or less is demonstrated. A practical monitoring context also exists for diesel soot particles originating from combustion engines, as they are of serious health concern. The MEMS sensors employed in this work operate on the principle of vibration mode-localisation employing an amplitude ratio shift output metric for readout. Notably, gains are observed while comparing parametric sensitivities and the input referred stability for amplitude ratio and resonant frequency variations, demonstrating that the amplitude ratio output metric is particularly suitable for long-term measurements. The soot particle mass directly estimated using coupled MEMS resonators can be correlated to the mass, indirectly estimated using the condensation particle counter used as the reference instrument.

Inter-frequency amplitude ratio of oVEMP for differentiating Meniere's disease from BPPV: clinical validation using a double-blind approach.

OBJECTIVE: The study aimed at examining the usefulness of inter-frequency amplitude ratio (IFAR) of ocular vestibular evoked myogenic potential (oVEMP) in identifying Meniere's disease (MD) and differentiating it from benign paroxysmal positional vertigo (BPPV). DESIGN: A case-control design was used with a double blind approach. Phase 1 included 70 healthy individuals and 36 individuals each with MD and BPPV and Phase 2 included 20 individuals each with MD and BPPV. The age range of the participants in both phases was 15-50 years. All participants underwent oVEMP testing using 500 and 1000 Hz tone bursts and IFAR was obtained. RESULTS: The results in phase 1 revealed significantly higher IFARs in Meniere's disease than BPPV and healthy individuals (p < 0.001). An optimum criterion point of IFAR ≥1.11 for diagnosing MD was found which yielded 80% sensitivity and 98% specificity. The results in phase 2 demonstrated 85% correct identification of MD and 95% correct rejection of BPPV as non-MD. CONCLUSIONS: IFAR of oVEMP appears highly sensitive and specific parameter for identifying MD and a clinically valid tool for differentiating MD from BPPV.

Medial plantar-to-radial amplitude ratio: does it have electrodiagnostic utility in distal sensory polyneuropathy?

PURPOSE OF THE STUDY: We proposed a new electrophysiological parameter medial plantar (MP)-to-radial amplitude ratio (MPRAR), similar to sural-to-radial amplitude ratio (SRAR), in the diagnosis of distal sensory polyneuropathy (DSP), based on the concept that distal nerves are affected more and earlier than proximal nerves in axonal neuropathies. We aimed to investigate the diagnostic sensitivity of this parameter in diabetic DSP, together with sensitivities of SRAR and MP nerve action potential (NAP) amplitude. MATERIALS AND METHODS: In 124 healthy controls and 87 diabetic patients with clinically defined DSP and normal sural responses, we prospectively performed sensory nerve conduction studies (NCS), and evaluated the MP NAP amplitude, MPRAR and SRAR values. We determined the lower limits of normal (LLN) of these parameters in the healthy controls and calculated their sensitivities and specificities in detecting DSP in diabetic patients. RESULTS: MP nerve amplitude and MPRAR values were significantly lower in the patient group, compared to controls. However, SRAR values did not differ significantly between the two groups. The LLN of MP NAP amplitude was found to be 4.1 µV. The cutoff values for SRAR and MPRAR were determined as 0.24 and 0.16, respectively. MPRAR was abnormal in 21.8% of patients. However, the most sensitive parameter in detection of DSP was MP NAP amplitude, which showed a sensitivity of 31% and a specificity of 100%. CONCLUSIONS: Although MPRAR is more sensitive than SRAR in detecting DSP, it does not provide additional diagnostic yield to the assessment of MP NCS alone in diabetic DSP patients with normal sural responses.

Predictive value of intraoperative neurophysiologic monitoring in assessing long-term facial function in grade IV vestibular schwannoma removal.

BACKGROUND: Despite routine use of intraoperative neuromonitoring in acoustic neuroma removal, its application in predicting long-term facial function is limited. METHODS: Prospective recording of facial nerve function and subsequent review of intraoperative neurophysiologic data. Stimulation of the facial nerve was performed proximal and distal to the tumor locus after tumor removal with measurement of amplitude and latency responses in the orbicularis oculi and oris muscles. Prospective review of current facial nerve function was performed using the House-Brackmann (HB) scoring system. Good facial function was determined as HB I/II and HB III-VI was considered poor facial function. Minimum follow-up time was 15 months, and averaged 40 months. RESULTS: Twenty-four grade IV acoustic neuromas (54 % larger than 4 cm) were completely removed from October 2008 to November 2013. Nine patients (37.5 %) had HB I/II and 15 (62.5 %) had HB III-VI. The poor prognosis group had a higher latency than the good prognosis group (p = 0.045). Lower proximal amplitude was detected in the poor prognosis group (p = 0.046). Lower proximal-to-distal amplitude ratio was also detected in the poor prognosis group (p = 0.052). Amplitude ratio cut-offs of 0.44 and 0.25 were able to predict poor prognosis with sensitivity of 0.73 and 0.4 and specificity of 0.78 and 1, respectively (p = 0.046). CONCLUSIONS: Lower proximal amplitude and proximal-distal amplitude ratio were previously reported as predictors of poor facial function in different sizes of vestibular schwannomas. We observed that the same applies specifically for large-sized, completely removed, grade IV tumors. Additionally, we describe a difference in proximal latency time between the good and poor prognosis groups, which was not previously reported.

Precordial QRS amplitude ratio predicts long-term outcome after catheter ablation of electrical storm due to ventricular tachycardias in patients with arrhythmogenic right ventricular cardiomyopathy.

BACKGROUND: Radiofrequency catheter ablation is currently considered as the therapeutic option of choice in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) and recurrent ventricular tachycardia (VT). METHODS: This study intended to assess the long-term outcome of catheter ablation in patients with ARVC and electrical storm. The specific objective was to assess the relationship between precordial QRS amplitude ratio and outcome of catheter ablation in these patients. RESULTS: Twenty-eight patients (19 men, age 52.3±14.2years) underwent 48 catheter ablation procedures (range 1-6, six epicardial). During a mean follow-up of 18.7±15.1months, 13 patients (46.5%) experienced VT recurrence. Age >50years and ∑QRSmvV1-V3/∑QRSmvV1-V6≤0.48 but not right ventricular size and acute ablation outcome were associated with VT recurrence during the follow up. CONCLUSION: Age >50years and ∑QRSmvV1-V3/∑QRSmvV1-V6≤0.48 predict recurrence of VT after successful radiofrequency catheter ablation of VT in patients with ARVC and electrical storm.

Changes in spinal motoneuron excitability during the improvement of fingertip dexterity by actual execution combined with motor imagery practice.

Since there is an upper limit to skill improvement through the repetition of actual execution, we examined whether motor imagery could be used in combination with actual execution to maximize motor skill improvement. Fingertip dexterity was evaluated in 25 healthy participants performing a force adjustment task using a pinch movement with the left thumb and index finger. In the intervention condition, six sets of repetitions of combined actual execution and motor imagery were performed, while in the control condition, the same flow was performed, but with motor imagery replaced by rest. Changes in the excitability of spinal motoneurons during motor imagery compared to rest were compared in terms of the F/M amplitude ratio. Motor skill changes were compared before and after repeated practice and between the conditions, respectively, using the absolute amount of adjustment error between the target pinch force value and the delivered pinch force value (absolute error) as an index. The results showed that the repetition of exercise practice and motor imagery decreased the absolute error, which was greater than that of exercise practice alone in terms of motor skill improvement. The F/M amplitude ratio for motor imagery compared to rest did not increase. This suggests that motor imagery is involved in the degree of the increase of spinal motoneuron excitability based on the real-time prediction of motor execution and that there may be no need for an increase in excitability during motor skill control.

Impact of Latency Variations on the Predictive Value of Facial Nerve Proximal-to-Distal Amplitude Ratio during Vestibular Schwannoma Surgery.

Introduction This study highlights the relation between compound muscle action potential (CMAP) latency variations and the predictive value of facial nerve (FN) proximal-to-distal (P/D) amplitude ratio measured at the end of vestibular schwannoma resection. Methods Forty-eight patients underwent FN stimulation at the brainstem (proximal) and internal acoustic meatus (distal) using a current intensity of 2 mA. The proximal latency and the P/D amplitude ratio were assessed. House-Brackmann grades I & II indicated good FN function, and grades III to VI were considered fair/poor function. A P/D amplitude ratio > 0.6 was used as a cutoff to indicate a good FN function, while a ratio of ≤ 0.6 indicated a fair/poor FN function. Results The P/D amplitude ratio was measured for all patients, and the calculated sensitivity (SE), specificity (SP), positive predictive value (PPV), and negative predictive value (NPV) were 85.2, 85.7, 88.5, and 81.8%, respectively. The CMAPs from the mentalis muscle were then classified based on their proximal latency into group I (< 6 ms), group II (6-8 ms), and group III (> 8 ms). The SE, SP, PPV, and NPV became 90.5, 90.9, 95, and 83.3%, respectively, in group II. In group I, SE and NPV increased, whereas SP and PPV decreased. While in group III, SP and PPV increased, whereas SE and NPV decreased. Conclusion At a latency between 6 and 8 ms, the P/D amplitude ratio was predictive of outcomes with high SE and SP. When latency was < 6 ms or > 8 ms, the same predictive ability was not observed. Knowing the strengths and limitations is important for understanding the predictive value of the P/D amplitude ratio.

Auditory brainstem response (ABR) waveform analysis program.

Auditory brainstem responses (ABR) are a high-throughput assessment of auditory function. Many studies determine changes to the threshold at frequencies that span the normal hearing range of their test subjects, but fewer studies evaluate changes in waveform morphology. The goal of developing this program was to make a user-friendly semiautomatic peak-detection algorithm to encourage widespread analysis of the amplitudes and latencies of the ABR, which may yield informative details about the integrity of the auditory system with development, aging, genetic manipulations, or damaging conditions. This method incorporates automated peak detection with manual override and inter-rater validation to calculate the amplitude and latency for waves 1-5, as well as interpeak latencies and amplitude ratios between waves. The output includes raw data and calculations in a format compatible with graphical and statistical software.•The method yields a high-throughput peak-detection algorithm with manual override and inter-rater capabilities to streamline ABR waveform analysis.•Data output includes amplitudes, latencies, amplitude ratios, and interpeak latencies for generation of input-output curves.•While complete automation of peak detection with this tool is dependent on good signal-to-noise ratios, relevant amplitude and latency calculations are fully automated, and manual spot-checking is simplified to significantly reduce the time to analyze waveforms.

Bone Conduction Cervical Vestibular Evoked Myogenic Potentials as an Alternative in Children with Middle Ear Effusion.

OBJECTIVE: To compare the amplitude ratio and P-wave latency of cervical vestibular evoked myogenic potentials (c-VEMPs) for bone conduction (BC) and air conduction (AC) stimulation in children with otitis media with effusion (OME). MATERIAL AND METHODS: This is an observational study of a cohort of 27 children and 46 ears with OME. The c-VEMP amplitude ratio and P-wave latency were compared between BC and AC in children with OME and healthy age-matched children. RESULTS: The c-VEMP response rate in children with OME was 100% when using BC stimulation and 11% when using AC stimulation. The amplitude ratio for BC was significantly higher in the OME group than the age-matched healthy control group (p = 0.004). When focusing on ears with an AC c-VEMP response (n = 5), there was a significant difference in the amplitude ratio between the AC and BC stimulation modes, but there was no significant difference in the AC results between the OME group and the age-matched control group. CONCLUSIONS: BC stimulation allows for reliable vestibular otolith testing in children with middle ear effusion. Given the high prevalence of OME in children, clinicians should be aware that recording c-VEMPs with AC stimulation may lead to misinterpretation of otolith dysfunction in pediatric settings.

Optical data of graphene grown by chemical vapor deposition on copper foil using spectroscopic ellipsometry.

Hexagonal, carbon-based structures were prepared on bare and treated copper foil substrates by Chemical Vapor Deposition at 1075 ᵒC using a graphite box for limiting copper reactivity with hydrocarbon gases during growth reactions. Spectroscopic ellipsometry with a digital camera was used to collect the amplitude ratio and the phase of structures various spots. The amplitude ratio of hexagonal structures on copper substrates was collected based on substrate treatment type and thickness as well as reaction zone conditions and methane flow rates. Matched amplitude ratio was obtained only for 75 µm thick acetic acid copper foil substrates inside and outside the graphite box at a low methane flow rate of 0.2 sccm. Moreover, the amplitude ratio of 75 µm bare copper foil and 75 µm electro-polished copper foil substrates at methane flow rates of 0.2 - 0.3 sccm were unmatched. Ellipsometric parameters data use potential is assessment of graphene layer thickness on different surfaces. Data shows dependence of the amplitude ratio on the surface roughness of copper foil, gas concentrations and reaction zone conditions.

Influence of temperature-dependent acoustic and thermal parameters and nonlinear harmonics on the prediction of thermal lesion under HIFU ablation.

According to the traditional method of high intensity focused ultrasound (HIFU) treatment, the acoustic and thermal characteristic parameters of constant temperature (room temperature or body temperature) are used to predict thermal lesion. Based on the nonlinear spherical beam equation (SBE) and Pennes bio-heat transfer equation, and a new acoustic-thermal coupled model is proposed. The constant and temperature-dependent acoustic and thermal characteristic parameters are used to predict thermal lesion, and the predicted lesion area are compared with each other. Moreover, the relationship between harmonic amplitude ratio (P2/P1) and thermal lesion is studied. Combined with the known experimental data of acoustic and thermal characteristic parameters of biological tissue and data fitting method, the relationship between acoustic and thermal characteristic parameters and temperature is obtained; and the thermal lesion simulation calculation is carried out by using the acoustic and thermal characteristic parameters under constant temperature and temperature- dependent acoustic and thermal characteristic parameters, respectively. The simulation results show that under the same irradiation condition, the thermal lesion predicted by temperature-dependent acoustic and thermal characteristic parameters is larger than that predicted by traditional method, and the thermal lesion increases with the decrease of harmonic amplitude ratio.

Standard Clinical Screening Tests, Sural Radial Amplitude Ratio and F Wave Latency Compared to Conventional Nerve Conduction Studies in the Assessment of Sensorimotor Polyneuropathy in Patients with Type 2 Diabetes Mellitus.

Background and Aims: The measuring tools used for assessment of neuropathy include various questionnaires, monofilament testing, Biothesiometry and the gold standard test, nerve conduction studies (NCS). This study aims to evaluate the diagnostic accuracies of Michigan Neuropathy Screening Instrument (MNSI), Biothesiometry, Semmes Weinstein Monofilament (SWMF), Sural Radial Amplitude Ratio (SRAR) and minimal F wave latency as compared to conventional NCS and arrive at a simple diagnostic algorithm for early detection of Diabetic Peripheral Neuropathy (DPN). Methods: In a cross-sectional observational study on 48 Type 2 diabetes mellitus patients, MNSI, Biothesiometry, SWMF and NCS including F waves and SRAR were done and diagnostic accuracies (sensitivity, specificity, positive and negative predictive values) calculated taking NCS as gold standard. Results: MNSI, Biothesiometry, SWMF, SRAR and minimal F wave latency had a sensitivity of 64.3%, 78.6%, 14.3%, 100% and 78.6% and specificity of 67.7%, 52.9%, 94.1%, 23.53% and 76.47% respectively, with reference to NCS. Based on combined sensitivities and specificities, we arrived at a simple algorithm for early diagnosis of DPN, which showed that DPN could either be diagnosed or ruled out in 75% of the patients by a combination of the Biothesiometry, SRAR and left lower limb minimal F wave latency results. Conclusions: In the setting of an outpatient, multidisciplinary diabetic clinic, simple tests such as questionnaires, monofilament testing and biosthesiometer could be performed with greater ease while considering NCS as the gold standard. This algorithm, combining Biothesiometry, SRAR and left lower limb minimal F wave latency would be less time consuming and help in early diagnosis of DPN.

Median somatosensory evoked potential as a predictor of clinical outcome after urgent surgical extracranial internal carotid artery recanalization.

OBJECTIVE: Changes in the N20/P25 amplitude of somatosensory evoked potentials (SEP) of the median nerve have been found to correlate with those in cortical regional cerebral blood flow (rCBF). Our study presents the use of median nerve SEP amplitude in predicting the clinical outcome of urgent surgical internal carotid artery (ICA) recanalization. METHODS: A total of 27 patients suffering an acute ischemic stroke (AIS) with extracranial ICA occlusion within 24 h were prospectively recruited. The primary preoperative endpoints included the SEP amplitude absolute value (SEP-amp) and the SEP amplitude side-to-side ratio (SEP-ratio). Clinical outcome at 3 months postoperatively was assessed using the modified Rankin scale (mRS-3M). RESULTS: The positive predictive values (PPVs) for SEP-amp and SEP-ratio were 95.5% and 100%, respectively, with the negative predictive values (NPVs) being 60.0% and 100%, respectively. The SEP-ratio correlated fully with mRS-3M. CONCLUSION: The median SEP side-to-side N20/P25 amplitude ratio seems to be a very strong positive and negative predictor of the clinical outcome of urgent recanalization of an extracranial ICA occlusion. SIGNIFICANCE: The results suggest that cortical evoked activity may help in selection patient for surgical recanalization and predict clinical recovery after an acute ischemic stroke.

Clinical and Physiological Significance of F-Wave in Spinocerebellar Ataxia Type 3.

Objective: To evaluate the characteristics of F-wave in spinocerebellar ataxia type 3 (SCA3) patients and preclinical carriers of SCA3 gene mutation (PreSCA3), and explore the relationship between disease severity and F-wave parameters and evaluate F-wave parameters as potential biomarkers for monitoring of disease progression in SCA3. Methods: We performed F-wave recordings in median, ulnar and tibial nerves of 39 SCA3 patients, 20 PreSCA3, and 27 healthy controls, and compared F-wave parameters between them. Results: In all nerves studied, the mean F-wave amplitude, maximum F-wave amplitude, and F/M amplitude ratio were significantly increased in the SCA3 patients in comparison with the normal controls. And the minimal F-wave latency of SCA3 patients was significantly prolonged and the F-wave persistence (%) was significantly decreased in the median nerve. For the PreSCA3, the maximum F-wave amplitude was significantly higher than normal controls for both median, ulnar, and tibial nerves. The mean F-wave amplitude and F/M amplitude ratio in all nerves were comparable between PreSCA3 and normal controls. The frequency of giant F-wave and frequency of patients with giant F-wave were similar between PreSCA3 and SCA3. The values of F/M amplitude ratio in both median, ulnar, and tibial nerves were correlated positively with disease severity and disease duration. Conclusion: Significant F-wave abnormalities occur in patients with SCA3, even in PreSCA3. F-wave may therefore reveal subclinical alterations and provide objective parameters for evaluating the progression of SCA3.

Effects of lifetime noise exposure on the middle-age human auditory brainstem response, tinnitus and speech-in-noise intelligibility.

Recent animal studies have shown that the synapses between inner hair cells and the dendrites of the spiral ganglion cells they innervate are the elements in the cochlea most vulnerable to excessive noise exposure. Particularly in rodents, several studies have concluded that exposure to high level octave-band noise for 2 h leads to an irreversible loss of around 50% of synaptic ribbons, leaving audiometric hearing thresholds unaltered. Cochlear synaptopathy following noise exposure is hypothesized to degrade the neural encoding of sounds at the subcortical level, which would help explain certain listening-in-noise difficulties reported by some subjects with otherwise 'normal' hearing. In response to this peripheral damage, increased gain of central stages of the auditory system has been observed across several species of mammals, particularly in association with tinnitus. The auditory brainstem response (ABR) wave I amplitude and waves I-V amplitude ratio have been suggested as non-invasive indicators of cochlear synaptopathy and central gain activation respectively, but the evidence for these hearing disorders in humans is inconclusive. In this study, we evaluated the influence of lifetime noise exposure (LNE) on the human ABR and on speech-in-noise intelligibility performance in a large cohort of adults aged 29 to 55. Despite large inter-subject variability, results showed a moderate, but statistically significant, negative correlation between the ABR wave I amplitude and LNE, consistent with cochlear synaptopathy. The results also showed (a) that central gain mechanisms observed in animal studies might also occur in humans, in which higher stages of the auditory pathway appear to compensate for reduced input from the cochlea; (b) that tinnitus was associated with activation of central gain mechanisms; (c) that relevant cognitive and subcortical factors influence speech-in-noise intelligibility, in particular, longer ABR waves I-V interpeak latencies were associated with poorer performance in understanding speech in noise when central gain mechanisms were active; and (d) absence of a significant relationship between LNE and tinnitus, central gain activation or speech-in-noise performance. Although this study supports the possible existence of cochlear synaptopathy in humans, the great degree of variability, the lack of uniformity in central gain activation and the significant involvement of attention in speech-in-noise performance suggests that noise-induced cochlear synaptopathy is, at most, one of several factors that play a role in humans' speech-in-noise performance.