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OBJECTIVES: The objectives were to measure the effect of stimulus rate and vowel-change direction on the acoustic change complex (ACC) latencies and amplitudes and compare ACC metrics to behavioral measures of vowel-contrast detection for infants tested under the age of 1 year. We tested the hypothesis that the direction of spectral energy shift from a vowel change would result in differences in the ACC, owing to the sensitivity of cortical neurons to the direction of frequency change. We evaluated the effect of the stimulus rate (1/s vs. 2/s) on the infants’ ACC. We evaluated the ACC amplitude ratio’s sensitivity (proportion of ACCs present for each change trial) and compared it to perceptual responses obtained using a visually-reinforced infant speech discrimination paradigm (VRISD). This report provides normative data from infants for the ACC towards the ultimate goal of developing a clinically useful index of neural capacity for vowel discrimination. DESIGN: Twenty-nine infants, nine females, aged 4.0–11.8 months, participated. All participants were born at full-term and passed their newborn hearing screens. None had risk factors for hearing or neurologic impairment. Cortical auditory evoked potentials were obtained in response to synthesized vowel tokens /a/, /i/, /o/ and /u/ presented at a rate of 1- or 2/s in an oddball stimulus paradigm with a 25% probability of the deviant stimulus. All combinations of vowel tokens were tested at the two rates. The ACC was obtained in response to the deviant stimulus. The infants were also tested for vowel-contrast detection using a VRISD paradigm with the same combinations of vowel tokens used for the ACC. The mean age at the time of the ACC test was 5.4 months, while the mean age at the behavioral test was 6.8 months. RESULTS: Variations in ACC amplitude and latency occurred as a function of the initial vowel token and the contrast token. However, the hypothesis that the direction of vowel (spectral) change would result in significantly larger change responses for high-to-low spectral changes was not supported. The contrasts with /a/ as the leading vowel of the contrast pair resulted in the largest ACC amplitudes than other conditions. Significant differences in the ACC presence and amplitude were observed as a function of rate, with 2/s resulting in ACCs with the largest amplitude ratios. Latency effects of vowel contrast and rate were present, but not systematic. The ACC amplitude ratio’s sensitivity for detecting a vowel contrast was greater for the 2/s rate than the 1/s rate. For an amplitude ratio criterion of ≥ 1.5, the sensitivity was 93% for ACC component P2-N2 at 2/s, whereas at 1/s sensitivity was 70%. VRISD tests of vowel-contrast detection had a 71% hit and a 21% false-positive rate. Many infants who could not reach performance criteria for VRISD had ACC amplitude ratios ≥ 2.0. DISCUSSION: The ACC for vowel contrasts presented at a rate of 2/s is a robust index of vowel-contrast detection when obtained in typically developing infants under the age of 1 year. The ACC is present in over 90% of infants tested at this rate when an amplitude ratio criterion of ≥1.5 is used to define a response. The amplitude ratio appears to be a sensitive metric for the difference between a control and contrast condition. The ACC can be obtained in infants who do not yet exhibit valid behavioral responses for vowel change contrasts and may be useful for estimating neural capacity for discriminating these sounds.

To determine whether normal to supernormal 30-Hz flicker ERGs are associated with visual function and prognosis in patients with central retinal artery occlusion (CRAO).A total of 133 patients diagnosed with unilateral acute non-arteritic CRAO by examination with electroretinography (ERG) were examined. Thirty-hertz flicker ERG amplitudes were analyzed according to the severity of CRAO, and their correlation with visual function and prognosis was assessed. All patients were categorized into one of three groups according to the flicker ERG amplitude ratios between affected and fellow eyes: ≥ 110%, supernormal; 90-110%, normal; and 90%, subnormal.Thirty-hertz flicker ERG parameters differed significantly according to the severity of retinal ischemia, i.e., between incomplete versus complete CRAO: mean amplitude (55.89 ± 24.38 45.41 ± 23.47 μV, P = 0.029), amplitude ratio (76.1 ± 23.1% 58.7 ± 25.7%, P 0.001), and proportion of normal to supernormal flicker ERGs (30.5% 12.4%, P .001). One-month and final follow-up visual function and prognosis were better in the normal to supernormal flicker ERGs: 1 month BCVA (1.55 ± 0.65 2.05 ± 0.61 logMAR, P .001), final BCVA (1.32 ± 0.79 1.97 ± 0.68 logMAR, P .001), 1-month VA improvement (- 0.50 ± 0.47 - 0.10 ± 0.29 logMAR, P .001), and final VA improvement (- 0.74 ± 0.61 - 0.18 ± 0.37 logMAR, P .001).Normal to supernormal 30-Hz flicker ERG changes in eyes with CRAO are associated with the milder severity of retinal ischemia and showed better visual function and outcome than the subnormal ERG group.

PRECIS Corvis ST Tonometry and Ocular Response Analyzer (ORA) measurements were conducted in primary open-angle glaucoma and normative subjects. Many parameters were significantly correlated, however, the strengths were weak to moderate. PURPOSE Reichert ORA parameters are derived from pressure information following the application of air-jet, whereas detailed structural observation can be made using the Corneal Visualization Scheimpflug Technology instrument (CST). The purpose of the study was to investigate the association between CST measurements and ORA measured corneal hysteresis (CH). METHODS Measurements of CST, ORA, axial length, average corneal curvature, central corneal thickness (CCT) and intraocular pressure with Goldmann applanation tonometry were carried out in 104 eyes of 104 patients with primary open-angle glaucoma and 35 eyes from normative subjects. The association between CST and ORA parameters was assessed using linear regression analysis, with model selection based on the second order bias corrected Akaike Information Criterion index. RESULTS Deformation amplitude ratio (corneal softness, R=-0.51), SP A1 (corneal stiffness, R=0.41), and Inverse Radius (integrated area under the curve of the inverse concave radius, R=-0.44) were significantly correlated with CH (P

PURPOSE To evaluate the safety and efficacy of photorefractive intrastromal corneal crosslinking (PiXL) for the treatment of low myopia using the epithelium-on approach with supplemental oxygen. SETTING The Eye Foundation, Coimbatore, India. DESIGN Prospective interventional case series. METHODS Myopic nonectatic eyes underwent PiXL using the Mosaic system. Ultraviolet-A (UV-A) irradiation of 365 nm wavelength was delivered in an accelerated (30 mW/cm) pulsed approach to provide a total fluence of 15 J/cm. Supplemental oxygen (concentration greater than 95%) was provided to increase the efficacy of the epithelium-on approach during the UV-A irradiation. Efficacy was determined by improvement in mean refractive spherical equivalent (MRSE), uncorrected distance visual acuity (UDVA), and keratometric flattening. Safety was determined by loss of lines of corrected distance visual acuity, endothelial cell loss, and adverse events. RESULTS Fifty eyes of 26 patients with a mean age of 22.73 ± 3.74 years were included. A significant improvement in UDVA from baseline (logarithm of the minimum angle of resolution [logMAR] 0.63 ± 0.25) was noted at the 3-month (logMAR 0.08 ± 0.15) and 6-month (logMAR 0.13 ± 0.18) follow-up visits (P < .001). Significant keratometric flattening from baseline was noted at all follow-up visits (P < .001). No significant endothelial cell loss or adverse effects were noted. A significant correlation was noted between the change in MRSE and preoperative corneal biomechanics (deformation amplitude ratio, P = .029). CONCLUSIONS Transepithelial PiXL with supplemental oxygen might be a safe and effective approach for reduction of myopia. The change in MRSE and keratometric flattening was greater in comparison with earlier protocols, including the epithelium-off approach.

To investigate whether visual acuity improvement achieved after surgical treatment for macular hole (MH) can be predicted by preoperative multifocal ERG (mfERG) central/peripheral amplitude ratio. Thirty patients with unilateral MH were included. Evaluations with comprehensive ophthalmological examination including best-corrected visual acuity (BCVA) were performed at baseline and 1, 3, 8, 24 and 48 weeks after surgery, while mfERG (Diagnosys LLC; 61 hexagons—30°) and spectral-domain optic coherence tomography (sOCT—Heidelberg Engineering) were performed at baseline and 2 months after surgery. mfERG results are shown by means of the ratio between the amplitudes’ average from rings 1 and 2 (central) and rings 4 and 5 (peripheral): the P1 ratio. mfERG data from 20 normally sighted age-matched subjects was used for comparison. A macular hole index (MH index) was defined as the quotient between hole height and base measured on OCT. Twenty-six patients finished the 48-week follow-up. Mean ± SE (logMAR) preoperative BCVA was 0.93 ± 0.22 and improved in 0.25 ± 0.07 at 48 weeks. mfERG P1 ratio was reduced at baseline and increased significantly after surgery. A significant correlation was observed between preoperative P1 ratio and BCVA gain at week 8 (r = −0.42; P = 0.033). There was no significant correlation between preoperative MH index and postoperative BCVA (P > 0.05). Retinal function assessed using the ratio between central and peripheral mfERG responses might be used as predictor of visual acuity outcome after macular surgery for MH.

We have previously shown that the amplitude of the mfERG response obtained to a single (large) hexagon is significantly smaller than that obtained when summating all the mfERG responses evoked to an array of 7–61 hexagons covering the same retinal area. The purpose of this study was to confirm our initial findings in normal subjects of different ages and in selected patients. Binocular mfERGs (1, 7, 19, 37 and 61 hexagon arrays; Espion V6.0.54 Diagnosys LLC) were recorded from 40 normal subjects (25 aged 18–25, and 15 aged 3–12). Individual mfERG waveforms evoked in response to the multi-hexagon arrays (7, 19, 37 and 61) were summated, and the amplitude of the resulting composite mfERG waveform was compared to that measured in the response evoked to the single (large) hexagon stimulus to yield the amplitude ratio (i.e., 7:1 X100, 19:1X100, etc.). In normal subjects, the 7:1 ratio was 119.5 ± 9.2%, a value that gradually decreased to reach 109.4 ± 20.6% with the 61:1 ratio and a finding that was similar across all ages. The present study indicates a significant enhancement in amplitude of the summed mfERG composite waveform evoked to the 7 hexagon stimulus array (and to a lesser extent to the 19, 37 and 61 stimuli) compared to the 1 hexagon array, possibly mediated through the retinal lateral pathway (horizontal or amacrine cells), a claim that awaits confirmation. Preliminary results obtained from patients treated with Plaquenil suggest that this new method of mfERG analysis might probe a feature of macular function different from that investigated with the more usual method of mfERG ring ratio.

Purpose Approximately 1.3 billion people worldwide have vision impairment. The aim of the present study was to investigate the influence of Late-Onset blindness on cervical vestibular evoked myogenic potentials (cVEMP) responses. Accordingly, this study was performed to investigate and compare the parameters of the cVEMP test in sighted and late-onset blind individuals. Materials and method In this cross-sectional- comparative study, cVEMP was recorded by presenting a tone burst stimulus of 500 Hz with an intensity of 95 dBnHL in 20 sighted and 20 late-onset blind individuals aged between 18 and 30 years old. Results cVEMP was observed in all the individuals (100%). The average latency of P13 and N23, amplitude, amplitude ratio, and VEMP threshold did not differ significantly between the two groups (p > 0.05). Conclusion The findings of the study revealed that the formation of the neural pathway and reflex arch of cVEMP is similar between late-onset blind and sighted individuals. Thus, cVEMP can be a suitable test for assessing the vestibular function of late-onset blind people.

Author(s): Miki, Atsuya; Yasukura, Yuichi; Weinreb, Robert N; Maeda, Naoyuki; Yamada, Tomomi; Koh, Shizuka; Asai, Tomoko; Ikuno, Yasushi; Nishida, Kohji | Abstract: Purpose:To characterize the corneal biomechanical properties of glaucoma eyes by comparing the dynamic Scheimpflug biomechanical parameters between untreated glaucoma and control eyes. Methods:Cross-sectional observational data of dynamic Scheimpflug analyzer (Corvis ST) examinations were retrospectively collected from 35 eyes of 35 consecutive patients with untreated normal tension glaucoma and 35 eyes of 35 healthy patients matched on age and IOP. Ten biomechanical parameters were compared between the two groups using multivariable models adjusting for IOP, central corneal thickness, age, and axial length. The Benjamini-Hochberg method was used to correct for multiple comparison. Results:In multivariable models, glaucoma was associated with smaller applanation 1 time (P l 0.001, coefficient = -0.5865), applanation 2 time (P = 0.012, coefficient = -0.1702), radius (P = 0.006, coefficient = -0.5447), larger peak distance (P = 0.011, coefficient = 0.1023), deformation amplitude ratio at 1 mm (P l 0.001, coefficient = 0.072), and integrated radius (P l 0.001, coefficient = 1.094). These associations consistently indicate greater compliance of the cornea in glaucoma eyes. Conclusions:Untreated normal tension glaucoma eyes were more compliant than healthy eyes. The greater compliance (smaller stiffness) of normal tension glaucoma eyes may increase the risk of optic nerve damage. These results suggest the relevance of measuring biomechanical properties of glaucoma eyes.

Objective We propose a novel method that predicts facial nerve function (FNF) calculated from the drop and recovery of facial motor evoked potential (FMEP) amplitude ratio during the surgery of cerebellopontine angle tumors. Methods We enrolled 73 patients with cerebellopontine angle tumor, and used a biphasic, constant current, and suprathreshold stimulation (BCS) protocol to record FMEP of the orbicularis oris. We measured the intraoperative minimum-to-baseline amplitude ratio (MBR), the final-to-baseline amplitude ratio (FBR), and the recovery value (RV). RV was measured by subtracting MBR from FBR. Using those values, we evaluated FNF both at early postoperative (EP) and late postoperative (LP) periods. Results We successfully obtained 62 FMEP readings. Facial palsies occurred in 22 patients during the EP period, and 14 patients recovered during the LP period. Both MBR and FBR showed a significant correlation with FNF in the EP period. RV showed a good predictive power of FNF recovery during the LP period for the first time. Conclusions RV is a new and useful predictor of FNF recovery. MBR can be an intraoperative predictor of FNF in the EP period. Significance FNF outcome in the early and late postoperative periods can be predicted by FMEP.

To evaluate the corneal biomechanics before and after daily use of contact lenses (CLs), measured by Scheimpflug-based devices.This prospective clinical study includes participants who were scheduled to use CLs daily for refractive error. The biomechanical parameters were measured by the Corneal Visualization Scheimpflug Technology (Corvis ST) before and one month after using the soft CLs.Twenty-three subjects (46 eyes), including 16 female (76.2%) with a mean age of 28±7.29 years, were enrolled. There was no significant difference among biomechanical factors measured before and after contact lens wear (P0.05). Using regression analysis of the biomechanical markers, we found a statistically significant association between second applanation length (A2 length) (P=0.001), highest concavity radius (HCR) (P=0.05), deflection amplitude ratio (DA_ratio) (P=0.05) and integrated radius (P0.001) with age. Regarding spherical equivalent, we found a statistically significant association between central corneal thickness (CCT) (P=0.05), A2 length (P=0.03) and stiffness parameter at first applanation (SPAWe did not find a significant difference in terms of corneal biomechanical parameters between baseline and month 1; but regression analyses showed a statistically significant association between A2 length, HCR, DA_ratio, integrated radius, CCT and SPA

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).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.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.IFAR of oVEMP appears highly sensitive and specific parameter for identifying MD and a clinically valid tool for differentiating MD from BPPV.

Tinnitus affects about 10% of population worldwide. Most patients present with some degrees of hearing impairment, while others remain normal. The aim of this study was to analyze the latency and amplitude of auditory brain stem response (ABR) waveforms in patients with unilateral tinnitus. The tinnitus ears and non-tinnitus ears were compared for each patient. Sixty-seven patients with single-sided tinnitus were enrolled, including 26 male and 41 female patients with a mean age of 54.4 (age ranged from 22 to 79). Eighteen patients had bilateral normal hearing, while 49 patients had some degree of sensorineural hearing. The ABR waveforms were retrospectively analyzed in terms of waves I, III, and V absolute latency, as well as waves I-III, waves II-V, and waves I-V latency intervals, amplitude, and amplitude ratio (III/I, V/I). Statistical analyses were performed within patients. There was no significant ABR difference between the tinnitus and non-tinnitus ears with regard to all the wave latencies and amplitudes in our patients (all P values >0.1). Our result that ABR changes were not found between tinnitus and non-tinnitus ears implies that tinnitus does not simply originate from the defect of the peripheral auditory system. It conforms to the contemporary theory that a higher level of the brain is involved in the generation of tinnitus.

We aimed to analyse the ictal electrographic changes on scalp electroencephalography (EEG), focusing on high-voltage slow waves (HVSs) in children with epileptic spasms (ES) and tonic spasms (TS) and then identified factors associated with corpus callosotomy (CC) outcomes. We enrolled 17 patients with ES/TS who underwent CC before 20 years of age. Post-CC Engel’s classification was as follows: I in 7 patients, II in 2, III in 4, and IV in 4. Welch’s t-test was used to analyse the correlation between ictal HVSs and CC outcomes based on the following three symmetrical indices: (1) negative peak delay: interhemispheric delay between negative peaks; (2) amplitude ratio: interhemispheric ratio of amplitude values for the highest positive peaks; and (3) duration ratio: interhemispheric ratio of slow wave duration. Ages at CC ranged from 17–237 months. Four to 15 ictal EEGs were analysed for each patient. The negative peak delay, amplitude ratio and duration ratio ranged from 0–530 ms, 1.00–7.40 and 1.00–2.74, respectively. The negative peak delay, amplitude ratio and duration ratio were significantly higher in the seizure residual group (p = 0.017

PURPOSE To investigate corneal stiffness and analyze its possible influence on other corneal biomechanical and nonbiomechanical parameters in myopic eyes of Chinese patients. METHODS A total of 387 healthy (right) myopic eyes were included in this study. Corneal visualization Scheimpflug technology was used to measure the corneal stiffness parameter at the first applanation (SP-A1), deformation amplitude ratio at 1.0 and at 2.0 mm, biomechanically corrected intraocular pressure (bIOP), and corneal deformation parameters during the first applanation (A1: A1-time, A1-length, and A1-velocity), second applanation (A2; A2-time, A2-length, and A2-velocity), and highest concavity (HC; HC-time, HC-radius, HC deformation amplitude, and HC peak distance). The Pentacam was used to evaluate central corneal thickness, mean corneal curvature (Km), anterior corneal central elevation, and corneal asphericity (Q value) of the anterior cornea. RESULTS The mean SP-A1 and bIOP values were 90.46 ± 15.39 mm Hg/mm and 13.5 ± 1.85 mm Hg, respectively. The SP-A1 increased with age (β = 0.41 [95% CI, 0.28%-0.54%]; P < 0.0001). Corneal stiffness was positively correlated with central corneal thickness, uncorrected intraocular pressure, and bIOP and was also significantly correlated with all corneal deformation parameters (P < 0.05), except A1-length, HC-time, and HC peak distance. Corneal stiffness was negatively correlated with central corneal elevation of the anterior surface (r = -0.124, P = 0.014) and mean corneal curvature (r = -0.114, P = 0.025) and positively correlated with the Q value of the anterior surface (r = 0.109, P = 0.032). CONCLUSIONS Corneal stiffness increased with age. Stronger corneal stiffness may be related to flattening of the cornea and higher intraocular pressure.

Objectives Using the triple stimulation technique (TST) and conventional transcranial magnetic stimulation (TMS), this study was designed to investigate the effect of venlafaxine on central motor conduction in healthy adults. Patients and Methods In this crossover, self-controlled trial, eight healthy adult volunteers were randomly divided into groups A and B. In group A, the volunteers were administered 1 venlafaxine capsule once daily for 7 consecutive days, followed by a 3-day break. Next, volunteers in this group received 1 placebo capsule once daily for 7 consecutive days. Group B received the treatments in the opposite order. The index finger tapping test, grip strength test, TST and conventional TMS examination for each hand were recorded before and one week after the administration of venlafaxine or placebo. Results Compared to the placebo stage, in the venlafaxine stage, the number of index finger taps was significantly increased for both hands, and the TST amplitude and area ratios were significantly increased. The improvement in the TST amplitude ratio was significantly and positively correlated with the improvements in performance on the index finger tapping test. Conclusion Venlafaxine positively regulates central motor conduction in healthy adults.

Normal ECG values in newborns, infants, and children have been collected and published. ECG in the adolescent, however, remains, to be collected and studied. The present study was designed and carried out to establish the normal ECG standards in male and female adolescents. A total of 898 school children and adolescents screened and examined as healthy were divided by age and sex into 6-9, 9-13, and 13-18 years age-groups. A 12 lead conventional ECG was recorded in 10 mm/mV and 25 mm/s, utilizing an automated Fukuda Denshi FCP-4301, MS-DOS/IBM-AT ECG machine. Lead V3R was not taken. Analog-to-digital conversion was performed by Fukuda signal acquisition module at a sampling rate of 500 Hz. The data on 69 ECG parameters were analyzed for the mean, standard deviation, 2nd to 98th percentiles, 95% confidence intervals, and sex difference. Normal values on 69 ECG parameters, sex-specific heart rate, P-QRS-T interval, duration, axis, wave amplitude, and calculated R/S amplitude ratio and ventricular activation time by age-group and sex were established. Male and female difference was noted in 49 (71.0%) parameters, of which 3 (6.1%) began in 6-9 years age-group, 30 (61.2%) began in 9-13 years age-group, and 16 (32.7%) in 13-18 years age-group. No sex difference occurred in 20 (29.0%) parameters. Normal male and female ECG standards on 69 ECG parameters in the adolescent were established. ECG sex difference began to appear the earliest at ages 6-9 years, and it occurred mostly at ages 9-13 years and 13-18 years, reflecting the anatomical and physiological consequences of puberty.

Purpose Interfrequency amplitude ratio (IFAR), the ratio of amplitude between ocular vestibular evoked myogenic potentials (oVEMPs) for tone bursts of 500 and 1000 Hz, aids in identification of Ménière's disease with high sensitivity and specificity. However, it requires recording of oVEMP for 2 frequencies, which doubles the time of recording. Use of simultaneous recording of responses for both frequencies could potentially bring down testing time. Simultaneous recording might be possible by modifying the oddball paradigm and using a ratio of 1:1 for the 2 frequencies. This might also reduce variation in oVEMP amplitude between frequencies due to changes in gaze angle between the recordings. However, it remains to be explored whether or not the use of modified oddball paradigm to record oVEMP (MoVEMP) will produce comparable responses to conventional sequential recording of oVEMP (CoVEMP) for obtaining IFAR. Hence, the study aimed to compare MoVEMP and CoVEMP on various measures of oVEMP. Method The study included 29 healthy adults in the age range of 18–30 years, 23 of which were used for validation and 6 for finding test–retest reliability. All participants underwent contralateral oVEMP recording using 500- and 1000-Hz tone bursts presented using MoVEMP and CoVEMP paradigms. Results Comparable outcomes on latencies, amplitude, and IFAR were obtained between CoVEMP and MoVEMP. Furthermore, MoVEMP took significantly lesser time per ear and also produced better test–retest reliability than CoVEMP. Conclusion MoVEMP is a quicker and more reliable clinical stimulation paradigm for obtaining IFAR than CoVEMP.

The objective of this non-randomized trial was comparison of two-year changes in dynamic corneal response (DCR) between 18 mW/cm2 (5- min) and 9 mW/cm2 (10-min) cross-linking (CXL) protocols, using novel stiffness parameters and correlating them to clinical indices. The two groups were evaluated before and 2 years after the procedure using Corvis ST (Oculus Optikgerate GmbH, Germany) and DCR parameters such as deformation amplitude ratio at 1 mm and 2 mm (DA ratio-1 mm and DA ratio-2 mm) and integrated radius and stiffness parameters at A1 (SP-A1). Two-year follow-up was completed for 16 of the 30 eyes in the 5-min group and 21 of the 25 eyes in the 10-min group; data from those who were lost to follow-up was not included in the analyses. Mean age at baseline was 21.7 ± 4.9 and 21.5 ± 5.2 years in the 5- and 10-min groups, respectively (P = 0.895). At 2 years after CXL, in the 5-min group, the reduction in integrated radius (−1.12 ± 1.27 mm, P = 0.003) was significant, and the increase in SP-A1 (7.11 ± 14.86 mmHg/mm, P = 0.075) was borderline, while in the 10-min group, the decrease in DA ratio-2 mm (−0.43 ± 0.58, P = 0.003) and integrated radius (−1.89 ± 1.72 mm, P

Cognitive styles such as field dependence/independence and empathizing influence individual personalities. Sensory gating is conceptualized as an automatic inhibitory function related to human higher cognitive processing. The present study investigated the relationship between cognitive styles and the automatic inhibitory function using electroencephalographic evoked potentials (EPs) during auditory and somatosensory tasks with a paired stimulus. The Embedded-Figures Test (EFT) and Empathy Questionnaire (EQ) were performed to assess the cognitive styles (field dependence: FD; field independence: FI; empathizing: EM; non-empathizing: Non-EM). Sensory gating was evaluated as an amplitude ratio of EP responses to the second stimulus (S2) over responses to the first stimulus (S1). Subjects were divided into two groups based on EFT scores (FD vs. FI) or EQ scores (EM vs. Non-EM). The S2/S1 amplitude ratio of the auditory long-latency component was significantly smaller in the FD than FI group, while the S2/S1 amplitude ratio of a somatosensory long-latency component was significantly smaller in the FI than FD group. In contrast, these differences in the S2/S1 amplitude ratios of any auditory and somatosensory components were not observed between EM and Non-EM groups. Our results suggest that sensory gating conceptualized as an automatic inhibitory function is related to FD and FI cognitive styles.

Gaussian modelling method has been reported as a useful method to analyze arterial pulse waveform changes. This study aimed to provide scientific evidence on Gaussian modelling characteristics changes derived from the finger photoplethysmographic (PPG) pulses during exercise and recovery.\ud \ud 65 healthy subjects (18 female and 47 male) were recruited. Finger PPG pulses were digitally recorded with 5 different exercise loads (0, 50, 75, 100, 125W) as well as during each of 4 minute (min) recovery period. The PPG pulses were normalized in both width and amplitude for each recording, which were decomposed into three independent Gaussian waves with nine parameters determined, including the peak amplitude (H1, H2, H3), peak time position (N1, N2, N3) and half-width (W1, W2, W3) from each Gaussian wave, and four extended parameters determined, including the peak time interval (T1,2, T1,3) and amplitude ratio (R1,2, R1,3) between 1st Gaussian wave and 2nd, 3rd Gaussian waves. These derived parameters were finally compared between different exercise loads and recovery phases.\ud \ud With gradually increased exercise loads, the peak amplitude H2, peak time position N1, N2, N3, and half-width W1, W2 increased, peak amplitude H3 decreased significantly (all P < 0.05). The peak time interval T1,2 and T1,3 increased significantly from 10.6 ± 1.2 and 36.0 ± 4.4 at rest to 14.4 ± 2.3 and 45.1 ± 6.5 at 100W exercise load, respectively (both P < 0.05). The amplitude ratio R1,2 also increased from 1.07 ± 0.2 at rest to 1.22 ± 0.2 at 100W, and the amplitude ratio R1,3 decreased from 1.10 ± 0.3 at rest to 0.42 ± 0.2 at 125W (all P < 0.05). An opposite changing trend of these parameters was observed during recovery phases.\ud \ud In conclusion, this study has quantitatively demonstrated significant changes of Gaussian modelling characteristics derived from finger PPG pulse with exercise and during recovery, providing scientific evidence for the physiological mechanism that exercise increases cardiac ejection and vasodilation, and reduces the total peripheral vascular resistance.

Arterial pulse wave analysis has been attempted to monitor the maternal physiological changes of circulatory system during pregnancy. This study aimed to quantify the difference of Gaussian modelling characteristics derived from radial pulses measured from the three trimesters of healthy pregnant women. Radial pulses were recorded from seventy pregnant women between gestational week 11–13, week 20–22, and then week 37–39. They were then normalized and decomposed into three independent Gaussian waves for deriving four key modelling characteristic parameters: including the peak time interval (T) and peak amplitude ratio (R) between the first and second Gaussian waves (T1,2andR1,2), and their corresponding values between the first and third Gaussian waves (T1,3andR1,3). Post hoc multiple comparisons after analysis of variance was then applied to study the within-subject differences in Gaussian modelling characteristics between the three trimesters. The key results were thatT1,2andT1,3increased significantly (T1,2: 12.8 ± 1.3 vs 13.2 ± 1.3,p<0.05;T1,3: 39.5 ± 4.3 vs 45.4 ± 5.1,p<0.001), andR1,3decreased significantly from the first to second trimester (0.60 ± 0.15 vs 0.53 ± 0.11,p<0.001). From the second to third trimester,T1,2decreased significantly (13.2 ± 1.3 vs 12.8 ± 1.2,p<0.01), andT1,3andR1,3decreased slightly but nonsignificantly. Since largerT1,2andT1,3and smallerR1,3are associated with more compliant peripheral arteries, our results indicated that peripheral arteries become more compliant from the first to second trimester and then have a tendency of returning to baseline during normal pregnancy. In conclusion, this study has quantitatively demonstrated significant changes of Gaussian modelling characteristics derived from radial pulses at the three trimesters of normal pregnant women, suggesting that these modelling characteristics could be used as parameters in monitoring maternal physiological changes during normal pregnancy.

Objective Previous studies showed "F-wave inversion" (F-INV) as a sensitive method in the electrodiagnosis of early stage of carpal tunnel syndrome (CTS). This study aimed at evaluating the sensitivity and specificity of F-wave and nerve conduction velocity (NCV) testing in CTS. Methods We consecutively enrolled 244 cases and 108 controls. F-waves analysis included: Fwave minimum and mean latencies, F-wave persistence and chronodispersion, mean-F/CMAP amplitude ratio, F-INV. Specificity and sensitivity of F-waves parameters were calculated in the whole sample of CTS patients and by grouping the patients according to CTS severity. Multivariate logistic regression was also performed using F-INV as a dependent variable. Results In the whole sample the sensitivity of F-mean-INV and of median–ulnar NCV comparative testing was 50.8% and 93.7%, respectively. F-INV sensitivity dropped to 8% in CTS early stage. F-INV could be predicted only by distal motor latency of the median nerve. The sensitivity of all F-wave parameters increased only in the most severe stages of CTS. Conclusions This study does not confirm the electrodiagnostic usefulness of F-INV in early stage of CTS. All F-wave parameters, including F-INV, are much less sensitive than conventional NCV in CTS electrodiagnosis. F-wave does not add further useful information specifically related to CTS.

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 ± 14.2 years) underwent 48 catheter ablation procedures (range 1–6, six epicardial). During a mean follow-up of 18.7 ± 15.1 months, 13 patients (46.5%) experienced VT recurrence. Age N50 years 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 N50 years 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.

A variety of ultrasonic techniques have been developed to detect changes in bone caused by osteoporosis. One approach, called the backscatter difference technique, analyzes the power difference between two different portions of a backscatter signal. Analysis gates with a certain delay τd, width τw, and separation τs are used to define portions of the backscatter signal for analysis. The goal of the present study was to investigate how different choices of τd, τw, and τs affect four backscatter difference parameters: the normalized mean of the backscatter difference (nMBD), the normalized slope of the backscatter difference (nSBD), the normalized intercept of the backscatter difference (nIBD), and the normalized backscatter amplitude ratio (nBAR). Backscatter measurements were performed on 54 cube shaped specimens of human cancellous bone. nMBD, nSBD, nIBD, and nBAR were determined for 34 different combinations of τd, τw, and τs for each specimen. nMBD and nBAR demonstrated the strongest correlations with apparent bone density (0.48 ≤ Rs ≤ 0.90). Generally, the correlations were found to improve as τw + τs was increased and as τd was decreased. Among the four backscatter difference parameters, the measured values of nMBD were least sensitive to gate choice (

The present study attempted to determine the effect of practicing yoga on functioning of sacculo-collic pathway using cervical vestibular evoked myogenic potential (cVEMP). cVEMP was recorded from 40 participants (20 who practice yoga regularly and 20 who do not practice yoga regularly). The differences in amplitude of P1, N1, P1–N1 complex, asymmetry ratio and latencies of P1 and N1 of cVEMP were compared between both the groups. The results of the study showed that there was a significant increase (p

PURPOSE: To report early corneal biomechanical changes after corneal cross-linking (CXL) in patients with keratoconus. METHODS: Thirty-four eyes of 34 patients undergoing CXL for progressive keratoconus were included in this prospective clinical study. Dynamic corneal response (DCR) parameters obtained with the Corvis ST (OCULUS Optikgeräte GmbH; Wetzlar, Germany) were assessed at baseline (day of CXL) and after 1 month of follow-up; conversely, corneal tomography with the Pentacam (OCULUS Optikgeräte GmbH) was assessed at baseline and at 1, 3, and 6 months after CXL. RESULTS: At the last follow-up visit (123.7 ± 69.6 days), all morphological parameters including steepest point (Kmax) and thinnest corneal thickness (ThCT) indicated stabilization of keratoconus ( P > .05). Comparative analyses showed a rise of corneal stiffness demonstrated by a significant increase of Stiffness Parameter A1 (SP-A1) and Highest Concavity (SP-HC) and a significant decrease of Inverse Concave Radius (1/R) and Deformation Amplitude Ratio (DA Ratio) ( P < .05). There was a significant correlation between the preoperative keratoconus characteristics (Kmax, Belin/Ambrósio final D value [BAD-D], and ThCT) and the DCR parameters ( P < .05). Kmax and BAD-D showed a significant positive correlation with DA Ratio, Deflection Amplitude (DefA), and 1/R and a significant negative correlation with SPA1 and SP-HC. ThCT showed a significant positive correlation with SP-A1 and SP-HC and a significant negative correlation with DA Ratio, DefA, and 1/R. CONCLUSIONS: This study suggests that the new DCR parameters of the Corvis ST are able to detect early changes in biomechanics following CXL and those that are measurable before corneal shape modifications take place. Based on these results, the authors suggest the use of these metrics to assess the early efficacy of cross-linking. [ J Refract Surg . 2017;33(12):840–846.]

One of the predominant clinical features that differentiates vascular Parkinsonism (VP) from Parkinson's disease (PD) is the pyramidal sign. The triple stimulation technique (TST) is one of the most sensitive methods for comparing upper motor neuron involvement in patients with VP and PD. This study aimed to evaluate the usefulness of the TST as a diagnostic tool for VP.Thirteen VP patients, 18 PD patients and 10 age-matched healthy controls were enrolled in this study. We obtained basic participant demographic information and transcranial magnetic stimulation (TMS) parameters, including the TST amplitude ratio, from all participants. We compared the TMS parameters among the VP, PD and control groups.The TST amplitude ratio was significantly lower in the VP group than in the PD and control groups (71.59 ± 11.86 vs. 96.42 ± 5.11 and 97.70 ± 3.82, respectively; p0.01). The TST amplitude ratio was positively correlated with scores obtained on the United Parkinson's Disease Rating Scale-III, which reflects motor function.The TST is an effective and easy technique that offers improved diagnostic sensitivity in patients with VP by assessing upper motor neuron involvement. The TST may also represent a useful monitoring tool for evaluating disease progression.This study is the first to assess pyramidal involvement in patients with VP using the collision technique.

Our results indicate that electrocochleography (ECoG) has limited value in diagnosing Meniere's disease during the early symptomatic period.We hypothesized that if endolymphatic hydrops is a cause of Meniere's disease, ECoG results obtained in normal subjects would differ from those obtained during the early symptomatic period of Meniere's disease. We aimed to investigate the usefulness of ECoG in the diagnosis of Meniere's disease during the early symptomatic period.Extratympanic ECoG was used to evaluate 60 patients in a Meniere's group (17 men, 43 women; mean age 43.6 years, range 19-62 years) and 30 controls (11 men, 19 women; mean age 43.5 years, range 21-63 years). The summating potential/action potential (SP/AP) amplitude ratio and SP/AP area ratio were compared between the groups.Statistically significant differences were not demonstrated in the SP/AP amplitude ratio between the definite Meniere's, probable Meniere's, overall Meniere's, or control groups (0.35 ± 0.02, 0.30 ± 0.03, 0.33 ± 0.02, and 0.30 ± 0.01, respectively). Additionally, statistically significant differences were not indicated in the mean SP/AP area ratio between the definite Meniere's, probable Meniere's, overall Meniere's, or control groups (5.18 ± 0.98, 4.78 ± 0.21, 4.01 ± 0.78, and 3.72 ± 0.66, respectively).

PURPOSE: To evaluate the ability of a new combined biomechanical index called the Corvis Biomechanical Index (CBI) based on corneal thickness profile and deformation parameters to separate normal from keratoconic patients. METHODS: Six hundred fifty-eight patients (329 eyes in each database) were included in this multicenter retrospective study. Patients from two clinics located on different continents were selected to test the capability of the CBI to separate healthy and keratoconic eyes in more than one ethnic group using the Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany). Logistic regression was employed to determine, based on Database 1 as the development dataset, the optimal combination of parameters to accurately separate normal from keratoconic eyes. The CBI was subsequently independently validated on Database 2. RESULTS: The CBI included several dynamic corneal response parameters: deformation amplitude ratio at 1 and 2 mm, applanation 1 velocity, standard deviation of deformation amplitude at highest concavity, Ambrósio's Relational Thickness to the horizontal profile, and a novel stiffness parameter. The receiver operating characteristic curve analysis of the training database showed an area under the curve of 0.983. With a cut-off value of 0.5, 98.2% of the cases were correctly classified with 100% specificity and 94.1% sensitivity. In the validation dataset, the same cut-off point correctly classified 98.8% of the cases with 98.4% specificity and 100% sensitivity. CONCLUSIONS: The CBI was shown to be highly sensitive and specific to separate healthy from keratoconic eyes. The presence of an external validation dataset confirms this finding and suggests the possible use of the CBI in everyday clinical practice to aid in the diagnosis of keratoconus. [ J Refract Surg. 2016;32(12):803–810.]

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.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.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%.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.

OBJECTIVE Several parameters of ocular vestibular-evoked myogenic potential (oVEMP) have been used to identify Meniere's disease. Nonetheless frequency-amplitude ratio (FAR), which is the ratio of amplitude between two frequencies, is one among the parameters that has failed to attract researchers' attention despite proving its worth in diagnosis of Meniere's disease when used in conjunction with cervical VEMP. Thus, the present study aimed at investigating the utility of FAR of oVEMP in identifying Meniere's disease and finding out an optimum frequency pair for its diagnosis. DESIGN Using a case-control design, oVEMPs were recorded for tone bursts of 500, 750, 1000, and 1500 Hz from 36 individuals with unilateral definite Meniere's disease in the age range of 15 to 50 years. For comparison purposes, oVEMP at the above frequencies were also obtained from an equal number of age- and gender-matched healthy individuals. The amplitudes of 750, 1000, 1500 Hz and tuned frequency, which was the frequency with the largest peak to peak amplitude among the above-mentioned frequencies, were divided by the amplitude of 500 Hz to obtain FARs for 750/500, 1000/500, 1500/500, and tuned frequency/500 frequency pairs. RESULTS The results revealed significantly higher FAR in the Meniere's disease group than the healthy controls for all the frequency pairs (p < 0.05). The sensitivity of almost 90% and the specificity 100% was obtained for 1000/500 and 750/500, whereas the other frequency pairs produced a sensitivity of about 56% while still showing a specificity of 100%. CONCLUSIONS High sensitivity and specificity, coupled with considerably lowered test duration when using only two frequencies, makes the use of FAR a more attractive prerogative, with 1000/500 as the frequency pair of choice.

To study differences between electrocochleography (ECochG) and cochlear hydrops analysis masking procedure (CHAMP) in diagnosis of M e ni e re ' s disease. Design: Retrospective case review from a tertiary referral center. Study sample: Thirty patients suspected to have M e ni e re ' s disease were assessed by ECochG and CHAMP tests. Results: Positivity of ECochG with SP/AP amplitude ratio .40 or .35 was compared with CHAMP V-delay or CHAMP R D. Positive ECochG results were found in 43% (>.40 SP/ AP ratio) and 63% (>.35 SP/AP ratio) of patients, comparing to positive CHAMP V delay in 27% and CHAMP R D in 30% of patients. A signifi cant difference ( p

This study describes the use of triphasic electrical stimulation pulses with an adjustable phase amplitude ratio (PAR) for the reduction of electrical stimulus artifacts. It is hypothesized that the setting of a certain PAR can facilitate a nearly artifact-free recording of electrically evoked compound action potentials (ECAP) in the cochlea. Artifact reduction with triphasic pulses using single epochs is expected to prevent latency or polarity effects, which are seen in standard forward masking or alternating polarity strategies. Although the application of a third phase is already implemented in implants manufactured by MED-EL (Zierhofer, 2003) and Cochlear (Sydney, Nucleus 5 System; van Dijk et al. (2007)) for the reduction of stimulation artifacts generated with these stimulators in ECAP measurements, an elaborate systematic evaluation of PAR for artifact reduction has not yet been conducted (compare evaluation for one subject Schoesser et al. (2001)). In the present paper, the effect of PAR variation on human ECAP recording and the feasibility of amplitude growth function recording with triphasic pulses and an optimized PAR are evaluated. Measurements were accomplished in five subjects, whereby more detailed test series were carried out in one subject. All subjects were implanted with devices from the company MED-EL, Innsbruck. A comparison of PAR optimized triphasic pulses was carried out against two other measurement techniques (biphasic alternating polarity stimulation and biphasic stimulation according to Miller) for apical, middle, and basal electrodes. ECAP thresholds were estimated by means of amplitude growth functions. However, recording of ECAP with triphasic pulses showed drawbacks: additional artifacts depending on stimulation and/or recording parameters are introduced, the ratio between the additional artifact and improved detectability of neural responses is dependent on PAR, and response thresholds obtained with triphasic pulses--although similar in shape--are in most cases substantially higher compared to thresholds measured with the Miller method. Higher thresholds most probably occur because the triphasic pulse patterns seem to less effectively stimulate neural structures compared to biphasic pulses since measured response thresholds are higher. For certain electrode groups threshold profiles obtained with triphasic pulses were found to be similar compared to stimulation with biphasic pulses.

Triphasic electrical stimulation pulses with an adjustable phase amplitude ratio (PAR) can reduce stimulus artifacts in electrically evoked compound actions potentials (ECAPs) recording in the cochlea (see companion paper Bahmer and Baumann, submitted for publication ). The present study describes the application of triphasic pulses in forward masking paradigms for recording recovery functions. Masking was found to be most effective using equal masker-probe PAR settings. Results were compared with data applying artifact cancellation strategy for biphasic pulses according to Miller et al. (2000) . Measurements were accomplished in five subjects (S1–S5) with an equal masker-probe PAR setting, whereby more detailed test series were carried out in one subject (S1). All subjects were users of MED-EL SONATAti100 or PULSARci100 cochlear implants (Innsbruck, Austria). Parameters like asymptote level, absolute refractory period and time constant were determined by fitting exponential functions to the recovery functions. Detailed measurements collected on 11 electrode locations in subject S1 showed similar parameter profiles on basal electrode contacts for both triphasic and Miller artifact cancellation methods, whereas apical/middle electrode contacts differed in part largely. Compared to Miller's artifact cancellation method estimated asymptote levels were lower with triphasic stimulation; the estimated absolute refractory period and time constants were estimated higher on apical electrodes. Results obtained in subjects S2–S5 showed considerable variances and a proper parametrization of the recovery function was possible only very selectively for triphasic pulse stimulation. In these cases, congruencies in estimated asymptote levels and time constants were found when triphasic stimulation and biphasic stimulation according to Miller were compared.

The amplitude change of cortical responses to repeated stimulation with respect to different interstimulus intervals (ISIs) is considered as an index of sensory memory. To determine the effect of aging on lifetime of auditory sensory memory, N100m responses were recorded in young, middle-aged, and elderly healthy volunteers (n=15 for each group). Trains of 5 successive tones were presented with an inter-train interval of 10 s. In separate sessions, the within-train ISIs were 0.5, 1, 2, 4, and 8 s. The amplitude ratio between N100m responses to the first and fifth stimuli (S5/S1 N100m ratio) within each ISI condition was obtained to reflect the recovery cycle profile. The recovery function time constant (τ) was smaller in the elderly (1.06±0.26 s, p

Neuroimaging studies have revealed dramatic asymmetries between the responses to temporally regular and irregular sounds in the antero-lateral part of Heschl’s gyrus. For example, the magnetoencephalography (MEG) study of Krumbholz et al. [Cereb. Cortex 13, 765-772 (2003)] showed that the transition from a noise to a similar noise with sufficient temporal regularity to provoke a pitch evoked a pronounced temporal-regularity onset response (TRon response), whereas a comparable transition in the reverse direction revealed essentially no temporal-regularity offset response (TRoff response). The current paper presents a follow-up study in which the asymmetry is examined with much greater power, and the results suggest an intriguing reinterpretation of the onset/offset asymmetry. The TR-related activity in auditory cortex appears to be composed of a transient (TRon) and a TR-related sustained response (TRsus), with a highly variable TRon/TRsus amplitude ratio. The TRoff response is generally dominated by the break-down of the TRsus activity, which occurs so rapidly as to preclude the involvement of higher-level cortical processing. The time course of the TR-related activity suggests that TR processing might be involved in monitoring the environment and alerting the brain to the onset and offset of behaviourally relevant, animate sources.

BACKGROUND The purpose of this study was to investigate the association between mylohyoid motor-evoked potentials (MH-MEP) and swallowing function and determine the value of MH-MEP for predicting aspiration 3 months poststroke. METHODS Subacute patients within a month of their first stroke were enrolled up for 2 consecutive years. Videofluoroscopic swallowing studies (VFSS) were performed twice. Patients were evaluated during VFSS using the penetration aspiration scale (PAS) and videofluoroscopic dysphagia scale (VDS). MH-MEP was recorded in the mylohyoid muscles. The active electrode was positioned submentally, 2 cm lateral to midline. Magnetic stimulation was performed on the contralateral motor cortex, 2-4 cm anterior and 4-6 cm lateral to the cranial vertex. The resting motor threshold (rMT), latency, and amplitude stimulation at 120% (amp120) and 150% (amp150) of the rMT were assessed. The ratio of each parameter was also estimated. The relationship between MH-MEP and VFSS findings was analyzed. KEY RESULTS Sixty-eight patients completed the study. On VFSS at 3 months poststroke, 24 (35.3%) patients showed aspiration. The rMT, rMT ratio, amp120 and amp120 ratio were significantly correlated with the PAS and VDS (P

Respiratory sensory gating is evidenced by decreased respiratory-related-evoked potentials (RREP) amplitude of the N1 peak for the second stimulus (S2) when two occlusions are separated by a 500-millisecond interval. The RREP N1 peak amplitude ratio of the S2 and the first occlusion (S1), S2/S1, is usually

To evaluate the prognostic value of interocular amplitude ratio of flicker electroretinogram (ERG) in determining the development of neovascularization in patients with central retinal vein occlusion (CRVO).We retrospectively reviewed the data obtained from flicker ERG in 51 CRVO patients. Of these, 22 eyes which had enough follow-up to differentiate ischemic CRVO from nonischemic CRVO were included for data analysis. The flicker ERG was recorded at a 30 Hz frequency after dark adaptation, and ten sweeps were averaged.Eleven eyes were ischemic and 11 eyes were nonischemic. Three amplitude parameters had the potential to explain the type of CRVO. They were amplitude of lesion eye (p = 0.0001), interocular difference of amplitude (p0.0001), and interocular ratio of amplitude (p0.0001). Both an interocular amplitude difference of -23 microV and interocular amplitude ratio of 60% were very good cutoff points to differentiate ischemic from nonischemic CRVO. Receiver operating characteristic curve analysis revealed that each of the two cutoff values had a sensitivity and specificity of 100%.Interocular comparison of amplitude is a good solution for avoiding the variability of ERG. An interocular amplitude ratio of flicker ERG of 60% is a succinct, useful parameter in clinical practices for differentiating ischemic from nonischemic CRVO.

BACKGROUND AND RESEARCH OBJECTIVE Precordial electrode misplacement is an important source of error in electrocardiogram (ECG) interpretation. Previous studies have shown important changes affecting P wave morphology when V1 and V2 electrodes are placed in higher intercostal spaces. We aimed to identify ECG signs that could alert professionals performing or interpreting the ECG about the incorrect placement of V1 and V2 electrodes. SUBJECTS AND METHODS This cross-sectional study included 101 apparently healthy individuals. Five P wave patterns were compared, placing electrodes V1 and V2 on the fourth (correct position), third, and second intercostal spaces (incorrect position). RESULTS Incorrect V1-V2 electrode placement produced statistically significant differences in 3 of 5 ECG patterns. The presence of a negative component of the P wave in V2 (P < .001), negative P wave in V1 (P < .001), and rSr' preceded by negative P wave (P < .001) was strongly indicative of high placement. Patterns where the amplitude ratio between the positive and negative components of the P wave in V1 was less than or equal to 1 were observed in 27 of 101 cases with correct placement. However, on comparing correct and incorrect electrode placement, significant differences were found (P < .001) CONCLUSION Patterns that indicate high placement of V1 and V2 were (1) negative component of the P wave in V2 lead recorded in either second and third intercostal spaces, (2) negative P wave in V1 lead recorded in either second and third intercostal spaces, and (3) rSr' preceded by negative P wave recorded only when V1 is placed on the second but not on the third intercostal space.

CONCLUSIONS: Our results suggest that summating potential/action potential (SP/AP) area ratio may not necessarily have higher sensitivity in the diagnosis of endolymphatic hydrops of Meniere's disease (MD) than SP/AP amplitude ratio in transtympanic electrocochleography (ECochG). OBJECTIVE: Recent studies suggested that SP/AP area curve ratio was more sensitive to endolymphatic hydrops in comparison with SP/AP amplitude ratio in extratympanic ECochG. The purpose of the present study was to evaluate the utility of the SP/AP area curve ratio in transtympanic ECochG for the diagnosis of MD. PATIENTS AND METHODS: A retrospective chart review of 198 patients (209 ears) was conducted in cases of MD. RESULTS: With regard to SP/AP amplitude ratio, 57.1% in definite cases of MD (group 1), 39.6% in probable cases of MD (group 2), and 50.0% in the cases who had transformed from probable MD to definite MD (group 3) showed abnormally high values, respectively. Abnormally high values were observed in 43.9%, 27.7%, and 30.0% in SP/AP area ratio in groups 1, 2, and 3, respectively, indicating that abnormal values were observed more frequently in the amplitude ratio than in the area ratio in all three groups., Acta oto-laryngologica, 129(1), pp.25-29; 2009

We suggest that 1/0.5 kHz FPA would be clinically useful in the diagnosis of Ménière's disease.To determine whether clinically useful VEMP parameters could be identified using different tone burst stimuli for the diagnosis of Ménière's disease.The Ménière's group included 24 affected ears from definite Ménière's disease and 26 affected ears from probable Ménière's disease. The control group included 20 normal ears. Using tone bursts of 0.5 and 1 kHz, two parameters were examined: 1) the frequency peak amplitude ratio (1/0.5 kHz FPA), where the peak amplitude was determined by the difference in amplitude between peak p13 and peak n23 ipsilaterally; and 2) the interaural amplitude difference (IAD) ratio, defined as the difference in amplitude between peaks p13 and n23 (p13-n23) in the right and left ears divided by the sum of p13-p23 in both ears.Data showed that the 1/0.5 kHz FPA ratios in the Ménière's group were significantly elevated compared with those of the control group (p0.001) and the recommendable cut-off value for the diagnosis of Ménière's symptoms using 1/0.5 kHz FPA was0.7. However, the IAD ratio did not show significant differences in either the 0.5 or 1 kHz stimulus conditions.

To assess the realistic yield of lower leg sensory nerve action potential amplitudes (SNAP) and the sural/radial nerve amplitude ratio (SRAR) in the routine evaluation of suspected distal axonal polyneuropathy. Investigated were 721 people. In 393 referents without and 328 patients with chronic distal symmetrical polyneuropathy the SRAR, sural, superficial peroneal and dorsal sural SNAP were determined. The dorsal sural SNAP could not be elicited in 26 % of referents. Axonal polyneuropathy was confirmed by an abnormally low value of the sural or superficial peroneal SNAP or SRAR in 70 % of patients, and most often (68 %) by an absent sural or superficial peroneal SNAP. In 9 % of patients there was a normal sural but abnormal superficial peroneal SNAP, and 11 % had an abnormal sural but normal superficial peroneal SNAP. ROC curve analysis demonstrated equal accuracy of the sural and superficial peroneal SNAP. To confirm distal axonal polyneuropathy in routine clinical practice the sural and superficial peroneal SNAP had equal and complementary yield, whereas the SRAR and dorsal sural SNAP had limited additional yield.

The electrodiagnostic yield of the medial plantar nerve action potential (NAP) amplitude versus the sural/radial amplitude ratio (SRAR) was determined in 110 consecutive patients with clinically diagnosed distal sensory polyneuropathy (SN) and normal sural responses. Forty-five consecutive patients with clinically diagnosed lumbosacral radiculopathy served as disease controls. Of the 110 SN patients, 32 were classified clinically as SN with large-fiber involvement (SN-LFI), whereas 78 had clinically pure small-fiber SN. Plantar NAP amplitudes were abnormal in 18 of 32 patients (56%) with SN-LFI, and 15 of 78 (19%) with small-fiber SN. A SRAR0.21 (fifth percentile of normal) was found in 7 of 32 patients (22%) with SN-LFI and 8 of 78 (10%) with small-fiber SN. In the control group, the medial plantar NAP was normal in all 45 subjects (100%), whereas the SRAR was0.21 in 43 subjects (96%). Thus, for a 50% pretest probability of SN-LFI, the positive predictive value of an abnormal medial plantar was 100% versus 85% for a SRAR0.21. The medial plantar NAP amplitude is a more useful measure of SN, than is the SRAR, in patients under age 70, with suspected SN-LFI. The yield of the SRAR and plantar NAP amplitude is poor when clinical signs of large-fiber sensory dysfunction are lacking.

Objective To define the optimal nerve conduction study (NCS) method of lower subscapular nerve and evaluate its clinical utility. Methods Thirty healthy adults (8 males) with a mean age of 45.2 ± 16.5 (range, 21–75) years were recruited in this study. A total of sixty nerves were studied using the Dantec Counterpoint EMG machine (Dantec, Skovlunde, Denmark). 6 patients with clinical and electrodiagnostic evidence of brachial plexopathy were also evaluated. Results The mean ± 2 standard deviation values of the distal latencies, base-to-peak amplitudes and inter-side amplitude ratio were 2.38 ± 0.52 (range, 1.80–2.90) ms, 13.10 ± 5.10 (range, 8.70–21.10) mV and 0.93 ± 0.12 (range, 0.67–1.00), respectively. There was a significant correlation between the subject age and the base-to-peak amplitudes. All 6 patients with brachial plexopathy had reduced base-to-peak amplitudes as well as inter-side amplitude ratio of less than 0.67 (the normal limits for control). Conclusion The lower subscapular NCS were satisfactorily recordable and well tolerated. It was useful in evaluation of patients with brachial plexopathy.

Purpose: To describe a normative database for the multifocal VEP (mfVEP) and to evaluate specificity for a range of cluster criteria. Methods: One hundred persons (62 females and 38 males) with normal visual fields and ranging in age from 21.6 to 92.4 years participated in this study. Self-reported race in 80 of these 100 persons was `White or Caucasian,' eight were `Black or African-American,' eight were `Asian,' and four were `Hispanic or Latino.' Pattern-reversal mfVEPs were obtained using a dartboard stimulus pattern in VERISTM and two 8-min runs per eye were averaged. A bootstrap technique was used to estimate the normal range of mfVEP response signal-to-noise ratio (SNR) and inter-ocular amplitude ratio at each location. Specificity (1 – false alarm rate) was evaluated for a range of cluster criteria, whereby the number and probability level of the points defining a cluster were varied. Results: There was no overall effect of age on SNR (r2=0.16, p=0.22) nor was the interaction between age and location significant (F=0.83, p=0.82, ANOVA). The location with the largest age effect had an r2 of only 0.13. There was a small but significant effect of sex (t=2.1, p=0.04) such that SNR was slightly (11) larger in females than males, but there was no significant interaction between sex and age (t=0.82, p=0.41). There was a slight trend toward higher SNR in the Asian group and lower SNR in the African-American group, but the overall effect of race was not significant (F=1.99, p=0.12). Specificity depended on the number and probability level of the points defining a cluster. Specificity did not vary by age group in a simple monotonic manner. False positive rates were slightly higher in females than males, and slightly higher in the African-American group as compared with the Asian group. Conclusions: Excellent specificity can be achieved for the mfVEP by using particular cluster criteria for monocular and inter-ocular tests. The effects of age, sex, and race were all very small and only the effect of sex was statistically significant. This normative database can be used for analyses of mfVEP results from individual patients with little risk that demographic factors such as age and sex will confound diagnostic accuracy.

A stimulator array is described which can deliver a wide range of displacement waveforms from each contactor, allowing vibratory stimuli to be targeted towards different populations of mechanoreceptors in the skin. The array has a working bandwidth of 20-400 Hz and 100 moving contactors covering an area of 1 cm2 on the fingertip. The array was validated with two experiments on the perception of moving vibratory targets within a uniform background vibration. In the first experiment, with target and background at the same frequency, equivalent discrimination of target movement was obtained at higher values of target/background amplitude ratio for 40-Hz stimuli than for 320-Hz stimuli. In the second experiment, discrimination of target movement within a different-frequency background (320-Hz target and 40-Hz background, or vice versa) was found to be much easier than within a same-frequency background. These results suggest that tactile spatial acuity is better at 320 Hz than 40 Hz and that it is possible to target different receptor populations in the skin by using these frequencies. However, there are problems with this interpretation: on the basis of characterization of touch receptors in previous studies, spatial acuity is expected to be worse at 320 Hz than at 40 Hz.

The study was performed to investigate the relationship between perceived muscle tension and electromyographic hyperactivity and to what extent electromyographic (EMG) hyperactivity relates to personality traits in fibromyalgics. Thirty-six females with fibromyalgia performed isokinetic maximal forward flexions of the shoulder combined with surface EMG recordings of the trapezius and infraspinatus muscles. Signal amplitude ratio and peak torque were calculated in the initial and endurance test phases. Pain intensity, perceived general and local shoulder muscle tension, and personality traits using the Karolinska Scales of Personality were assessed pre-test. Neither perceived muscle tension nor muscular tension personality trait correlated with EMG muscle hyperactivity. Perceived general muscle tension correlated with aspects of anxiety proneness (including muscle tension) of the Karolinska Scales of Personality. Pain intensity interacted with many of the variables. We propose that when patients with fibromyalgia report muscle tension that they may be expressing something other than physiological muscle tension.

To evaluate the characteristics of pattern visual evoked potentials (PVEPs) in traumatic optic neuropathy (TON) compared with optic neuritis (ON), we retrospectively studied 47 patients with TON and 64 patients with unilateral ON. PVEPs elicited by the stimulation with 3 reversals/s were recorded in all patients. A PVEP could be recorded in 29.8% of the TON patients and 49.6% of the ON patients at their first visit. In the 14 patients with TON and recordable PVEPs, the mean amplitude ratio (affected/fellow eye) was 0.29 ± 0.03 (SE) and the mean delay of the peak latency was 17.9 ± 2.9 ms. In the 30 patients with ON and recordable PVEPs, the mean amplitude ratio was 0.48 ± 0.04 (SE) and the mean delay of the peak latency was 23.5 ± 2.5 ms. The amplitude ratio was significantly lower in patients with TON than in those with ON.

We studied the Erb's point potential with supramaximal stimulation of the median nerve in 14 consecutive patients with clinical and electrophysiological evidence of unilateral brachial plexopathy and in normal controls. Both arms were studied in each individual. In each patient, the ratio of amplitude of recorded Erb's point potential from the affected arm to the normal arm was calculated. In controls the side with a recorded potential of a lower amplitude was used as the numerator to calculate a similar ratio. Eleven out of 14 patients had a Erb's point amplitude ratio less than that of controls. This method is a simple and useful adjunct in the electrophysiological assessment of brachial plexopathy.