Longitudinal Changes in Audiometric Phenotypes of Age-Related Hearing Loss

Abstract

Presbyacusis, or age-related hearing loss, can be characterized in humans as metabolic and sensory phenotypes, based on patterns of audiometric thresholds that were established in animal models. The metabolic phenotype is thought to result from deterioration of the cochlear lateral wall and reduced endocochlear potential that decreases cochlear amplification and produces a mild, flat hearing loss at lower frequencies coupled with a gradually sloping hearing loss at higher frequencies. The sensory phenotype, resulting from environmental exposures such as excessive noise or ototoxic drugs, involves damage to sensory and non-sensory cells and loss of the cochlear amplifier, which produces a 50–70 dB threshold shift at higher frequencies. The mixed metabolic + sensory phenotype exhibits a mix of lower frequency, sloping hearing loss similar to the metabolic phenotype, and steep, higher frequency hearing loss similar to the sensory phenotype. The current study examined audiograms collected longitudinally from 343 adults 50–93 years old (n = 686 ears) to test the hypothesis that metabolic phenotypes increase with increasing age, in contrast with the sensory phenotype. A Quadratic Discriminant Analysis (QDA) was used to classify audiograms from each of these ears as (1) Older-Normal, (2) Metabolic, (3) Sensory, or (4) Metabolic + Sensory phenotypes. Although hearing loss increased systematically with increasing age, audiometric phenotypes remained stable for the majority of ears (61.5 %) over an average of 5.5 years. Most of the participants with stable phenotypes demonstrated matching phenotypes for the left and right ears. Audiograms were collected over an average period of 8.2 years for ears with changing audiometric phenotypes, and the majority of those ears transitioned to a Metabolic or Metabolic + Sensory phenotype. These results are consistent with the conclusion that the likelihood of metabolic presbyacusis increases with increasing age in middle to older adulthood.

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Influence of Glottal Fry on Acoustic Voice Assessment: A Preliminary Study

Publication date: Available online 9 November 2016
Source:Journal of Voice
Author(s): Laura W. Plexico, Mary J. Sandage
PurposeThis preliminary study examined the influence of glottal fry on measurement of speaking fundamental frequency (SF0) and whether sex differences influence the impact glottal fry has on SF0 and cepstral peak prominence (CPP). It was hypothesized that SF0 and CPP would decrease as percent glottal fry in the sample increased, with larger changes observed in the female voice.MethodsTwenty-six participants (13 men, 13 women) completed the study. Participants were recorded reading the Rainbow Passage. SF0 and CPP were determined from the original sample. Percent glottal fry SF0 was determined and semitone change was recalculated after removal of glottal fry from the sample. Regression analysis was used to determine the impact of glottal fry and sex on semitone change and CPP differences in SF0.ResultsSignificant differences were found for both sex and percent glottal fry on semitone change in SF0. A significant relationship was not found between CPP and semitone change when sex was accounted for.ConclusionsFindings from this study indicate that the measurement of SF0 for women will decline as percent of glottal fry increases. These findings have clinical implications for interpretation of SF0 measurement and evidence-based outcomes for voice therapy.



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Utilizing Infant Cry Acoustics to Determine Gestational Age

Publication date: Available online 9 November 2016
Source:Journal of Voice
Author(s): Mustafa Sahin, Suzan Sahin, Fatma N. Sari, Emel C. Tatar, Nurdan Uras, Suna S. Oguz, Mehmet H. Korkmaz
Objectives/HypothesisThe date of last menstruation period and ultrasonography are the most commonly used methods to determine gestational age (GA). However, if these data are not clear, some scoring systems performed after birth can be used. New Ballard Score (NBS) is a commonly used method in estimation of GA. Cry sound may reflect the developmental integrity of the infant. The aim of this study was to evaluate the connection between the infants' GA and some acoustic parameters of the infant cry.Study DesignA prospective single-blind study was carried out.MethodsIn this prospective study, medically stable infants without any congenital craniofacial anomalies were evaluated. During routine blood sampling, cry sounds were recorded and acoustic analysis was performed. Step-by-step multiple linear regression analysis was performed.ResultsThe data of 116 infants (57 female, 59 male) with the known GA (34.6 ± 3.8 weeks) were evaluated and with Apgar score of higher than 5. The real GA was significantly and well correlated with the estimated GA according to the NBS, F0, Int, Jitt, and latency parameters. The obtained stepwise linear regression analysis model was formulized as GA = (31.169) − (0.020 × F0) + (0.286 × GA according to NBS) − (0.003 × Latency) + (0.108 × Int) − (0.367 × Jitt). The real GA could be determined with a ratio of 91.7% using this model.ConclusionsWe have determined that after addition of F0, Int, Jitt, and latency to NBS, the power of GA estimation would be increased. This simple formula can be used to determine GA in clinical practice but validity of such prediction formulas needs to be further tested.



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Relations Between Self-Regulation Behavior and Vocal Symptoms

Publication date: Available online 9 November 2016
Source:Journal of Voice
Author(s): Anna Alice Almeida, Mara Behlau
ObjectivesThe study aimed to determine if people with vocal symptoms have different self-regulation aspects compared with vocally healthy people, and to evaluate the relationship between the number of vocal symptoms and self-regulation.Study DesignThis is a cross-sectional, prospective, multicentric study.MethodsTwo hundred ninety-eight male and female adults who are nonprofessional voice users volunteered to participate in the study. The participants answered an online survey and two self-assessment instruments: the Voice Symptom Scale (VoiSS) and the Short Self-Regulation Questionnaire (SSRQ). Individuals were classified into two groups according to VoiSS cutoff value: a vocally healthy group (total score of 15 points or lower) and a vocal symptoms group (16 points and above). The subscales of the VoiSS (impairment, emotional, and physical) were compared with the subscales of the SSRQ (goal setting and impulse control).ResultsSubjects of the vocally healthy group scored differently from subjects with vocal symptoms both in goal setting and impulse control. The results from subjects with vocal symptoms are similar to individuals with addictive behaviors. A significant negative correlation was found between the SSRQ and the VoiSS scores, indicating a strong relationship between self-regulation and vocal symptoms. A relationship between impulsivity, lack of control, and difficulty in goal setting for specific behaviors was also noted. However, caution should be taken as this is an initial exploratory study using self-assessment questionnaires.ConclusionsSubjects with vocal symptoms have a lower level of self-regulation compared to those without vocal symptoms. As the number of vocal symptoms increased, the impulse control and goal setting scores decreased.



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High-speed Imaging of Vocal Fold Vibration Onset Delay: Normal Versus Abnormal

Publication date: Available online 8 November 2016
Source:Journal of Voice
Author(s): Peak Woo
ObjectivesVocal fold vibration onset delay (VFVOD) is heard frequently in spasmodic dysphonia and in muscle tension dysphonia. VFVOD changes due to other vocal pathologies have not been investigated. VFVOD during sustained vowel production was estimated with high-speed video in 10 normal and 40 pathologic subjects (scars, vocal fold paralysis, vocal fold nodules, and polyps). Analysis of high-speed video was done using digital kymography.ResultsVFVOD can be divided into two portions. Pre-phonation delay (PPD) is the duration when the vocal folds are nearly approximated to the time of first observed oscillation. Steady state delay (SSD) is the time when vocal folds are observed to come into oscillation until steady state of oscillation is observed. Normal subjects have almost zero PPD with vocal fold oscillation observed before full vocal fold adduction. Pathologic cases showed prolonged PPD because of (1) false cord adduction, (2) prolonged true vocal fold adduction, and (3) delay to onset of vocal fold vibration. Normal subjects have SSD of three to five cycles before steady state. Pathologic states result in increased SSD. Causes for increased SSD include (1) slow ramping up to steady state, (2) partial vibration of vocal folds, and (3) diplophonia with alternating beats before achieving steady state. There are significant differences between normal and pathology groups in both PPD and SSD.ConclusionVFVOD is elevated in pathologic states. This can be due to increase in PPD or SSD. VFVOD is an under-recognized phenomenon that may contribute to complaints of vocal fatigue and dysphonia.



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Blend in Singing Ensemble Performance: Vibrato Production in a Vocal Quartet

Publication date: Available online 9 November 2016
Source:Journal of Voice
Author(s): Helena Daffern
Objectives“Blend” is a defining characteristic of good vocal ensemble performance. To achieve this, directors often consider vibrato as a feature to be controlled and consequently restrict its use. Analysis of individual voices in ensemble situations presents several challenges, including the isolation of voices for analysis from recordings. This study considers vibrato production as a feature that contributes to blend through an ecological study of a vocal quartet.MethodsA vocal ensemble was recorded using head-worn microphones and electrolaryngograph electrodes to enable fundamental frequency analysis of the individual voices. The same four-part material was recorded over several weeks of rehearsal to allow analysis of conscious and subconscious changes to vibrato production over time. Alongside the recording of their rehearsal discussions, singers were also asked for opinions on vibrato production in connection with blend.Results and ConclusionsThe results indicate that vibrato is adjusted to some extent by individual singers to improve blend, with some instances of synchrony between voice parts. Some conscious alterations to vibrato were made to improve blend; however, these are not always evident in the data, suggesting that singers' own perceptions of their performance may be influenced by other factors. These findings indicate a need for further studies of vibrato as a feature of blend, particularly in terms of the synergies between expectation and actual production, and potential synchronicity between singers; increased understanding of vibrato in an ensemble setting will lead to more efficient rehearsal techniques and vocal training, and could prevent vocal misuse leading to pathology in the future.



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Dynamic activation of basilar membrane macrophages in response to chronic sensory cell degeneration in aging mouse cochleae

Publication date: Available online 9 November 2016
Source:Hearing Research
Author(s): Mitchell D. Frye, Weiping Yang, Celia Zhang, Binbin Xiong, Bo Hua Hu
In the sensory epithelium, macrophages have been identified on the scala tympani side of the basilar membrane. These basilar membrane macrophages are the spatially closest immune cells to sensory cells and are able to directly respond to and influence sensory cell pathogenesis. While basilar membrane macrophages have been studied in acute cochlear stresses, their behavior in response to chronic sensory cell degeneration is largely unknown. Here we report a systematic observation of the variance in phenotypes, the changes in morphology and distribution of basilar membrane tissue macrophages in different age groups of C57BL/6J mice, a mouse model of age-related sensory cell degeneration. This study reveals that mature, fully differentiated tissue macrophages, not recently infiltrated monocytes, are the major macrophage population for immune responses to chronic sensory cell death. These macrophages display dynamic changes in their numbers and morphologies as age increases, and the changes are related to the phases of sensory cell degeneration. Notably, macrophage activation precedes sensory cell pathogenesis, and strong macrophage activity is maintained until sensory cell degradation is complete. Collectively, these findings suggest that mature tissue macrophages on the basilar membrane are a dynamic group of cells that are capable of vigorous adaptation to changes in the local sensory epithelium environment influenced by sensory cell status.



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Serotonin modulates response properties of neurons in the dorsal cochlear nucleus of the mouse

Publication date: Available online 9 November 2016
Source:Hearing Research
Author(s): Richard A. Felix, Cameron J. Elde, Alexander A. Nevue, Christine V. Portfors
The neurochemical serotonin (5-hydroxytryptamine, 5-HT) is involved in a variety of behavioral functions including arousal, reward, and attention, and has a role in several complex disorders of the brain. In the auditory system, 5-HT fibers innervate a number of subcortical nuclei, yet the modulatory role of 5-HT in nearly all of these areas remains poorly understood. In this study, we examined spiking activity of neurons in the dorsal cochlear nucleus (DCN) following iontophoretic application of 5-HT. The DCN is an early site in the auditory pathway that receives dense 5-HT fiber input from the raphe nuclei and has been implicated in the generation of auditory disorders marked by neuronal hyperexcitability. Recordings from the DCN in awake mice demonstrated that iontophoretic application of 5-HT had heterogeneous effects on spiking rate, spike timing, and evoked spiking threshold. We found that 56% of neurons exhibited increases in spiking rate during 5-HT delivery, while 22% had decreases in rate and the remaining neurons had no change. These changes were similar for spontaneous and evoked spiking and were typically accompanied by changes in spike timing. Spiking increases were associated with lower first spike latencies and jitter, while decreases in spiking generally had opposing effects on spike timing. Cases in which 5-HT application resulted in increased spiking also exhibited lower thresholds compared to the control condition, while cases of decreased spiking had no threshold change. We also found that the 5-HT2 receptor subtype likely has a role in mediating increased excitability. Our results demonstrate that 5-HT can modulate activity in the DCN of awake animals and that it primarily acts to increase neuronal excitability, in contrast to other auditory regions where it largely has a suppressive role. Modulation of DCN function by 5-HT has implications for auditory processing in both normal hearing and disordered states.



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A physiologically-inspired model reproducing the speech intelligibility benefit in cochlear implant listeners with residual acoustic hearing

Publication date: Available online 9 November 2016
Source:Hearing Research
Author(s): Ladan Zamaninezhad, Volker Hohmann, Andreas Büchner, Marc-René Schädler, Tim Jürgens
This study introduces a speech intelligibility model for cochlear implant users with ipsilateral preserved acoustic hearing that aims at simulating the observed speech-in-noise intelligibility benefit when receiving simultaneous electric and acoustic stimulation (EA-benefit). The model simulates the auditory nerve spiking in response to electric and/or acoustic stimulation. The temporally and spatially integrated spiking patterns were used as the final internal representation of noisy speech. Speech reception thresholds (SRTs) in stationary noise were predicted for a sentence test using an automatic speech recognition framework. The model was employed to systematically investigate the effect of three physiologically relevant model factors on simulated SRTs: (1) the spatial spread of the electric field which co-varies with the number of electrically stimulated auditory nerves, (2) the “internal” noise simulating the deprivation of auditory system, and (3) the upper bound frequency limit of acoustic hearing. The model results show that the simulated SRTs increase monotonically with increasing spatial spread for fixed internal noise, and also increase with increasing the internal noise strength for a fixed spatial spread. The predicted EA-benefit does not follow such a systematic trend and depends on the specific combination of the model parameters. Beyond 300 Hz, the upper bound limit for preserved acoustic hearing is less influential on speech intelligibility of EA-listeners in stationary noise. The proposed model-predicted EA-benefits are within the range of EA-benefits shown by 18 out of 21 actual cochlear implant listeners with preserved acoustic hearing.



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Dynamic activation of basilar membrane macrophages in response to chronic sensory cell degeneration in aging mouse cochleae

Publication date: Available online 9 November 2016
Source:Hearing Research
Author(s): Mitchell D. Frye, Weiping Yang, Celia Zhang, Binbin Xiong, Bo Hua Hu
In the sensory epithelium, macrophages have been identified on the scala tympani side of the basilar membrane. These basilar membrane macrophages are the spatially closest immune cells to sensory cells and are able to directly respond to and influence sensory cell pathogenesis. While basilar membrane macrophages have been studied in acute cochlear stresses, their behavior in response to chronic sensory cell degeneration is largely unknown. Here we report a systematic observation of the variance in phenotypes, the changes in morphology and distribution of basilar membrane tissue macrophages in different age groups of C57BL/6J mice, a mouse model of age-related sensory cell degeneration. This study reveals that mature, fully differentiated tissue macrophages, not recently infiltrated monocytes, are the major macrophage population for immune responses to chronic sensory cell death. These macrophages display dynamic changes in their numbers and morphologies as age increases, and the changes are related to the phases of sensory cell degeneration. Notably, macrophage activation precedes sensory cell pathogenesis, and strong macrophage activity is maintained until sensory cell degradation is complete. Collectively, these findings suggest that mature tissue macrophages on the basilar membrane are a dynamic group of cells that are capable of vigorous adaptation to changes in the local sensory epithelium environment influenced by sensory cell status.



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Serotonin modulates response properties of neurons in the dorsal cochlear nucleus of the mouse

Publication date: Available online 9 November 2016
Source:Hearing Research
Author(s): Richard A. Felix, Cameron J. Elde, Alexander A. Nevue, Christine V. Portfors
The neurochemical serotonin (5-hydroxytryptamine, 5-HT) is involved in a variety of behavioral functions including arousal, reward, and attention, and has a role in several complex disorders of the brain. In the auditory system, 5-HT fibers innervate a number of subcortical nuclei, yet the modulatory role of 5-HT in nearly all of these areas remains poorly understood. In this study, we examined spiking activity of neurons in the dorsal cochlear nucleus (DCN) following iontophoretic application of 5-HT. The DCN is an early site in the auditory pathway that receives dense 5-HT fiber input from the raphe nuclei and has been implicated in the generation of auditory disorders marked by neuronal hyperexcitability. Recordings from the DCN in awake mice demonstrated that iontophoretic application of 5-HT had heterogeneous effects on spiking rate, spike timing, and evoked spiking threshold. We found that 56% of neurons exhibited increases in spiking rate during 5-HT delivery, while 22% had decreases in rate and the remaining neurons had no change. These changes were similar for spontaneous and evoked spiking and were typically accompanied by changes in spike timing. Spiking increases were associated with lower first spike latencies and jitter, while decreases in spiking generally had opposing effects on spike timing. Cases in which 5-HT application resulted in increased spiking also exhibited lower thresholds compared to the control condition, while cases of decreased spiking had no threshold change. We also found that the 5-HT2 receptor subtype likely has a role in mediating increased excitability. Our results demonstrate that 5-HT can modulate activity in the DCN of awake animals and that it primarily acts to increase neuronal excitability, in contrast to other auditory regions where it largely has a suppressive role. Modulation of DCN function by 5-HT has implications for auditory processing in both normal hearing and disordered states.



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A physiologically-inspired model reproducing the speech intelligibility benefit in cochlear implant listeners with residual acoustic hearing

Publication date: Available online 9 November 2016
Source:Hearing Research
Author(s): Ladan Zamaninezhad, Volker Hohmann, Andreas Büchner, Marc-René Schädler, Tim Jürgens
This study introduces a speech intelligibility model for cochlear implant users with ipsilateral preserved acoustic hearing that aims at simulating the observed speech-in-noise intelligibility benefit when receiving simultaneous electric and acoustic stimulation (EA-benefit). The model simulates the auditory nerve spiking in response to electric and/or acoustic stimulation. The temporally and spatially integrated spiking patterns were used as the final internal representation of noisy speech. Speech reception thresholds (SRTs) in stationary noise were predicted for a sentence test using an automatic speech recognition framework. The model was employed to systematically investigate the effect of three physiologically relevant model factors on simulated SRTs: (1) the spatial spread of the electric field which co-varies with the number of electrically stimulated auditory nerves, (2) the “internal” noise simulating the deprivation of auditory system, and (3) the upper bound frequency limit of acoustic hearing. The model results show that the simulated SRTs increase monotonically with increasing spatial spread for fixed internal noise, and also increase with increasing the internal noise strength for a fixed spatial spread. The predicted EA-benefit does not follow such a systematic trend and depends on the specific combination of the model parameters. Beyond 300 Hz, the upper bound limit for preserved acoustic hearing is less influential on speech intelligibility of EA-listeners in stationary noise. The proposed model-predicted EA-benefits are within the range of EA-benefits shown by 18 out of 21 actual cochlear implant listeners with preserved acoustic hearing.



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Dynamic activation of basilar membrane macrophages in response to chronic sensory cell degeneration in aging mouse cochleae

Publication date: Available online 9 November 2016
Source:Hearing Research
Author(s): Mitchell D. Frye, Weiping Yang, Celia Zhang, Binbin Xiong, Bo Hua Hu
In the sensory epithelium, macrophages have been identified on the scala tympani side of the basilar membrane. These basilar membrane macrophages are the spatially closest immune cells to sensory cells and are able to directly respond to and influence sensory cell pathogenesis. While basilar membrane macrophages have been studied in acute cochlear stresses, their behavior in response to chronic sensory cell degeneration is largely unknown. Here we report a systematic observation of the variance in phenotypes, the changes in morphology and distribution of basilar membrane tissue macrophages in different age groups of C57BL/6J mice, a mouse model of age-related sensory cell degeneration. This study reveals that mature, fully differentiated tissue macrophages, not recently infiltrated monocytes, are the major macrophage population for immune responses to chronic sensory cell death. These macrophages display dynamic changes in their numbers and morphologies as age increases, and the changes are related to the phases of sensory cell degeneration. Notably, macrophage activation precedes sensory cell pathogenesis, and strong macrophage activity is maintained until sensory cell degradation is complete. Collectively, these findings suggest that mature tissue macrophages on the basilar membrane are a dynamic group of cells that are capable of vigorous adaptation to changes in the local sensory epithelium environment influenced by sensory cell status.



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Serotonin modulates response properties of neurons in the dorsal cochlear nucleus of the mouse

Publication date: Available online 9 November 2016
Source:Hearing Research
Author(s): Richard A. Felix, Cameron J. Elde, Alexander A. Nevue, Christine V. Portfors
The neurochemical serotonin (5-hydroxytryptamine, 5-HT) is involved in a variety of behavioral functions including arousal, reward, and attention, and has a role in several complex disorders of the brain. In the auditory system, 5-HT fibers innervate a number of subcortical nuclei, yet the modulatory role of 5-HT in nearly all of these areas remains poorly understood. In this study, we examined spiking activity of neurons in the dorsal cochlear nucleus (DCN) following iontophoretic application of 5-HT. The DCN is an early site in the auditory pathway that receives dense 5-HT fiber input from the raphe nuclei and has been implicated in the generation of auditory disorders marked by neuronal hyperexcitability. Recordings from the DCN in awake mice demonstrated that iontophoretic application of 5-HT had heterogeneous effects on spiking rate, spike timing, and evoked spiking threshold. We found that 56% of neurons exhibited increases in spiking rate during 5-HT delivery, while 22% had decreases in rate and the remaining neurons had no change. These changes were similar for spontaneous and evoked spiking and were typically accompanied by changes in spike timing. Spiking increases were associated with lower first spike latencies and jitter, while decreases in spiking generally had opposing effects on spike timing. Cases in which 5-HT application resulted in increased spiking also exhibited lower thresholds compared to the control condition, while cases of decreased spiking had no threshold change. We also found that the 5-HT2 receptor subtype likely has a role in mediating increased excitability. Our results demonstrate that 5-HT can modulate activity in the DCN of awake animals and that it primarily acts to increase neuronal excitability, in contrast to other auditory regions where it largely has a suppressive role. Modulation of DCN function by 5-HT has implications for auditory processing in both normal hearing and disordered states.



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A physiologically-inspired model reproducing the speech intelligibility benefit in cochlear implant listeners with residual acoustic hearing

Publication date: Available online 9 November 2016
Source:Hearing Research
Author(s): Ladan Zamaninezhad, Volker Hohmann, Andreas Büchner, Marc-René Schädler, Tim Jürgens
This study introduces a speech intelligibility model for cochlear implant users with ipsilateral preserved acoustic hearing that aims at simulating the observed speech-in-noise intelligibility benefit when receiving simultaneous electric and acoustic stimulation (EA-benefit). The model simulates the auditory nerve spiking in response to electric and/or acoustic stimulation. The temporally and spatially integrated spiking patterns were used as the final internal representation of noisy speech. Speech reception thresholds (SRTs) in stationary noise were predicted for a sentence test using an automatic speech recognition framework. The model was employed to systematically investigate the effect of three physiologically relevant model factors on simulated SRTs: (1) the spatial spread of the electric field which co-varies with the number of electrically stimulated auditory nerves, (2) the “internal” noise simulating the deprivation of auditory system, and (3) the upper bound frequency limit of acoustic hearing. The model results show that the simulated SRTs increase monotonically with increasing spatial spread for fixed internal noise, and also increase with increasing the internal noise strength for a fixed spatial spread. The predicted EA-benefit does not follow such a systematic trend and depends on the specific combination of the model parameters. Beyond 300 Hz, the upper bound limit for preserved acoustic hearing is less influential on speech intelligibility of EA-listeners in stationary noise. The proposed model-predicted EA-benefits are within the range of EA-benefits shown by 18 out of 21 actual cochlear implant listeners with preserved acoustic hearing.



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The social-neurophysiological model of tinnitus: theory and practice.

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The social-neurophysiological model of tinnitus: theory and practice.

J Formos Med Assoc. 2015 Mar;114(3):201-3

Authors: Li Z, Gu R, Zeng X

PMID: 24083913 [PubMed - indexed for MEDLINE]

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The social-neurophysiological model of tinnitus: theory and practice.

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The social-neurophysiological model of tinnitus: theory and practice.

J Formos Med Assoc. 2015 Mar;114(3):201-3

Authors: Li Z, Gu R, Zeng X

PMID: 24083913 [PubMed - indexed for MEDLINE]

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Clinical Subgroups in Bilateral Meniere Disease.

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Clinical Subgroups in Bilateral Meniere Disease.

Front Neurol. 2016;7:182

Authors: Frejo L, Soto-Varela A, Santos-Perez S, Aran I, Batuecas-Caletrio A, Perez-Guillen V, Perez-Garrigues H, Fraile J, Martin-Sanz E, Tapia MC, Trinidad G, García-Arumi AM, González-Aguado R, Espinosa-Sanchez JM, Marques P, Perez P, Benitez J, Lopez-Escamez JA

Abstract
Meniere disease (MD) is a heterogeneous clinical condition characterized by sensorineural hearing loss, episodic vestibular symptoms, and tinnitus associated with several comorbidities, such as migraine or autoimmune disorders (AD). The frequency of bilateral involvement may range from 5 to 50%, and it depends on the duration of the disease. We have performed a two-step cluster analysis in 398 patients with bilateral MD (BMD) to identify the best predictors to define clinical subgroups with a potential different etiology to improve the phenotyping of BMD and to develop new treatments. We have defined five clinical variants in BMD. Group 1 is the most frequently found, includes 46% of patients, and is defined by metachronic hearing loss without migraine and without AD. Group 2 is found in 17% of patients, and it is defined by synchronic hearing loss without migraine or AD. Group 3, with 13% of patients, is characterized by familial MD, while group 4, that includes 12% of patients, is associated by the presence of migraine in all cases. Group 5 is found in 11% of patients and is defined by AD. This approach can be helpful in selecting patients for genetic and clinical research. However, further studies will be required to improve the phenotyping in these clinical variants for a better understanding of the diverse etiological factors contributing to BMD.

PMID: 27822199 [PubMed - in process]

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Targeting nitrative stress for attenuating cisplatin-induced downregulation of cochlear LIM domain only 4 and ototoxicity.

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Targeting nitrative stress for attenuating cisplatin-induced downregulation of cochlear LIM domain only 4 and ototoxicity.

Redox Biol. 2016 Oct 31;10:257-265

Authors: Jamesdaniel S, Rathinam R, Neumann WL

Abstract
Cisplatin-induced ototoxicity remains a primary dose-limiting adverse effect of this highly effective anticancer drug. The clinical utility of cisplatin could be enhanced if the signaling pathways that regulate the toxic side-effects are delineated. In previous studies, we reported cisplatin-induced nitration of cochlear proteins and provided the first evidence for nitration and downregulation of cochlear LIM domain only 4 (LMO4) in cisplatin ototoxicity. Here, we extend these findings to define the critical role of nitrative stress in cisplatin-induced downregulation of LMO4 and its consequent ototoxic effects in UBOC1 cell cultures derived from sensory epithelial cells of the inner ear and in CBA/J mice. Cisplatin treatment increased the levels of nitrotyrosine and active caspase 3 in UBOC1 cells, which was detected by immunocytochemical and flow cytometry analysis, respectively. The cisplatin-induced nitrative stress and apoptosis were attenuated by co-treatment with SRI110, a peroxynitrite decomposition catalyst (PNDC), which also attenuated the cisplatin-induced downregulation of LMO4 in a dose-dependent manner. Furthermore, transient overexpression of LMO4 in UBOC1 cells prevented cisplatin-induced cytotoxicity while repression of LMO4 exacerbated cisplatin-induced cell death, indicating a direct link between LMO4 protein levels and cisplatin ototoxicity. Finally, auditory brainstem responses (ABR) recorded from CBA/J mice indicated that co-treatment with SRI110 mitigated cisplatin-induced hearing loss. Together, these results suggest that cisplatin-induced nitrative stress leads to a decrease in the levels of LMO4, downregulation of LMO4 is a critical determinant in cisplatin-induced ototoxicity, and targeting peroxynitrite could be a promising strategy for mitigating cisplatin-induced hearing loss.

PMID: 27821327 [PubMed - as supplied by publisher]

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Age equivalence in the benefit of repetition for speech understanding

Although repetition is the most commonly used conversational repair strategy, little is known about its relative effectiveness among listeners spanning the adult age range. The purpose of this study was to identify differences in how younger, middle-aged, and older adults were able to use immediate repetition to improve speech recognition in the presence of different kinds of maskers. Results suggest that all groups received approximately the same amount of benefit from repetition. Repetition benefit was largest when the masker was fluctuating noise and smallest when it was competing speech.

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The influence of a user-adaptive prosthetic knee across varying walking speeds: a randomized cross-over trial

Publication date: Available online 9 November 2016
Source:Gait & Posture
Author(s): E.C. Prinsen, M.J. Nederhand, H.S. Sveinsdóttir, M.R. Prins, F. van der Meer, HFJM Koopman, J.S. Rietman
Previously conducted trials comparing the gait pattern of individuals with a transfemoral amputation using a user-adaptive and a non-microprocessor-controlled prosthetic knee (NMPK) found mixed and conflicting results. Few trials, however, have compared user-adaptive to non-adaptive prosthetic knees across different walking speeds. Because of the ability of variable damping, the effect of user-adaptive knees might be more pronounced at lower or higher walking speeds. Our aim was to compare the Rheo Knee II (a microprocessor-controlled prosthetic knee) with NMPKs across varying walking speeds. In addition, we studied compensatory mechanisms associated with non-optimal prosthetic knee kinematics, such as intact ankle vaulting and vertical acceleration of the pelvis. Nine persons with a transfemoral amputation or knee disarticulation were included and measured with their own NMPK and with the Rheo Knee II. Measurements were performed at three walking speeds: preferred walking speed, 70% preferred walking speed and 115% preferred walking speed. No differences on peak prosthetic knee flexion during swing were found between prosthetic knee conditions. In addition, prosthetic knee flexion increased significantly with walking speed for both prosthetic knee conditions. At 70% preferred walking speed we found that vaulting of the intact ankle was significantly decreased while walking with the Rheo Knee II compared to the NMPK condition (P=0.028). We did not find differences in peak vertical acceleration of the pelvis during initial and mid-swing of the prosthetic leg. In conclusion, comparison of walking with the Rheo Knee II to walking with a NMPK across different walking speeds showed limited differences in gait parameters.



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Multiscale and Shannon entropies during gait as fall risk predictors—A prospective study

Publication date: Available online 9 November 2016
Source:Gait & Posture
Author(s): Lucia Bizovska, Zdenek Svoboda, Nicolas Vuillerme, Miroslav Janura
Although entropy-based measurements of gait dynamics are becoming widely used tools for fall risk assessment, their relationship to fall occurrence is still unclear. The aim of this study was hence to compare fallers and non-fallers in terms of gait dynamics assessed by the multiscale and Shannon entropy. This study included 139 participants, aged 60–80 years, divided into two groups according to fall occurrence during a 6-month prospective observation (38 fallers, 101 non-fallers). The methodology involved the use of the Tinetti balance assessment tool (TBAT) and 5minutes of overground walking with 3D accelerometers located near the L5 vertebra and shanks. We analyzed 150 strides for gait complexity, an index of complexity (CI), computed from multiscale entropy (MSE) and Shannon entropy (ShE) derived from the recurrence quantification analysis. We found no significant differences between groups in MSE and CI. The TBAT total score was significantly higher in non-fallers (P=0.033), however, both groups showed low risk of falls. ShE in the anterior-posterior direction from trunk and in the mediallateral direction from the shanks were both significantly higher in fallers (P=0.020; P=0.024). ShE was negatively correlated with CI, the shank ShE in the vertical direction was positively correlated with TBAT. Taken together, our findings suggest that MSE is not able to distinguish between highly functional groups, whereas Shannon entropy seems to be sufficient in fall risk prediction.



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Interpreting sources of variation in clinical gait analysis: a case study

Publication date: Available online 8 November 2016
Source:Gait & Posture
Author(s): Stephanie L. King, Gabor J. Barton, Lakshminarayan R. Ranganath
Objective: To illustrate and discuss sources of gait deviations (experimental, genuine and intentional) during a gait analysis and how these deviations inform clinical decision making.MethodsA case study of a 24-year old male diagnosed with Alkaptonuria undergoing a routine gait analysis. A 3D motion capture with the Helen-Hayes marker set was used to quantify lower-limb joint kinematics during barefoot walking along a 10m walkway at a self-selected pace. Additional 2D video data were recorded in the sagittal and frontal plane. The patient reported no aches or pains in any joint and described his lifestyle as active.ResultsTemporal-spatial parameters were within normal ranges for his age and sex. Three sources of gait deviations were identified; the posteriorly rotated pelvis was due to an experimental error and marker misplacement, the increased rotation of the pelvis in the horizontal plane was genuine and observed in both 3D gait curves and in 2D video analysis, finally the inconsistency in knee flexion/extension combined with a seemingly innocuous interest in the consequences of abnormal gait suggested an intentional gait deviation.ConclusionsGait analysis is an important analytical tool in the management of a variety of conditions that negatively impact on movement. Experienced gait analysts have the ability to recognise genuine gait adaptations that forms part of the decision-making process for that patient. However, their role also necessitates the ability to identify and correct for experimental errors and critically evaluate when a deviation may not be genuine.



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Novel dynamic peak and distribution plantar pressure measures on diabetic patients during walking

Publication date: Available online 9 November 2016
Source:Gait & Posture
Author(s): Haitham M. Al-Angari, Ahsan H. Khandoker, Sungmun Lee, Wael Almahmeed, Habiba S. Al Safar, Herbert F. Jelinek, Kinda Khalaf
Diabetic peripheral neuropathy (DPN) is a common complication leading to foot ulceration and amputation. Several kinematic, kinetic and plantar pressure measures have been proposed for DPN detection, however findings have been inconsistent. In this work, we present new shape features that capture variations in the plantar pressure using shape and entropy measures to the study of patients with retinopathy, DPN and nephropathy, and a control diabetic group with no complications. The change in the peak plantar pressure (PPP) position with each step for both feet was represented as a convex polygon, asymmetry index, area of the convex polygon, 2nd wavelet moment (WM2) and sample entropy (SamEn). WM2 and the SamEn were more sensitive in capturing variations due to presence of complications than the area and asymmetry measures. WM2 of the left heel (median: 1stIQ, 3rdIQ): 8.27 (4.6,14.8) and left forefoot: 9.2 (2.4,16) were significantly lower for the DPN group compared to the control (CONT) group (heel 11.9 (5.0,16.4); forefoot: 10.3 (4.4,21.3), p<0.05). SamEn for the DPN group was significantly lower in the right foot compared to the left foot (1.3 (1.26, 1.37) and 1.33 (1.26,1.4), p<0.01) compared to CONT (right foot: 1.37 (1.24,1.45) and left foot: 1.34 (1.25,1.42), P<0.05). These new shape and regularity features have shown promising results in detecting diabetic peripheral neuropathy and warrant further investigation.



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How far do stabilometric and clinical parameters correlate in peripheral neuropathies?

Publication date: Available online 9 November 2016
Source:Gait & Posture
Author(s): Ana Flavia Gomes Paiva, Philippe Thoumie, Besma Missaoui
Peripheral neuropathies are characterized by the impairment of motor and sensitive nervous fibers. We aimed to investigate the correlation between proprioception, force and the limits of equilibrium parameter (LOE), by assessing 38 patients diagnosed with characterized bilateral neuropathy and 11 healthy subjects. Clinical evaluation, based on a motor and pallesthesic score, enabled their classification into groups corresponding to motor, sensitive or mixed neuropathies. Balance measures on a stabilometric platform allowed differentiation between the patients and healthy subjects but not between the groups of patients. The parameter limits of equilibrium (LOE) calculated as percentage of foot length allowed not only the differentiation between patients and healthy subjects but also between patients showing motor and sensitive forms. ROC analysis gave a threshold of 15% for LOE to discriminate between motor and sensory neuropathies with a 75% of sensitivity and 72% of specificity. Consequently, we propose a simple experimental procedure to carry out an accurate assessment of balance disorders in order to identify future rehabilitation modalities recommended to these patients.



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Predicting postoperative gait in cerebral palsy

Publication date: Available online 9 November 2016
Source:Gait & Posture
Author(s): Omar A. Galarraga C., Vincent Vigneron, Bernadette Dorizzi, Néjib Khouri, Eric Desailly
In this work, postoperative lower limb kinematics are predicted with respect to preoperative kinematics, physical examination and surgery data. Data of 115 children with cerebral palsy that have undergone single-event multilevel surgery were considered. Preoperative data dimension was reduced utilizing principal component analysis. Then, multiple linear regressions with 80% confidence intervals were performed between postoperative kinematics and bilateral preoperative kinematics, 36 physical examination variables and combinations of 9 different surgical procedures. The mean prediction errors on test vary from 4° (pelvic obliquity and hip adduction) to 10° (hip rotation and foot progression), depending on the kinematic angle. The unilateral mean sizes of the confidence intervals vary from 5° to 15°. Frontal plane angles are predicted with the lowest errors, however the same performance is achieved when considering the postoperative average signals. Sagittal plane angles are better predicted than transverse plane angles, with statistical differences with respect to the average postoperative kinematics for both plane’s angles except for ankle dorsiflexion. The mean prediction errors are smaller than the variability of gait parameters in cerebral palsy. The performance of the system is independent of the preoperative state severity of the patient. Even if the system is not yet accurate enough to define a surgery plan, it shows an unbiased estimation of the most likely outcome, which can be useful for both the clinician and the patient. More patients’ data are necessary for improving the precision of the model in order to predict the kinematic outcome of a large number of possible surgeries and gait patterns.



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Lateral trunk lean and medializing the knee as gait strategies for knee osteoarthritis

Publication date: Available online 8 November 2016
Source:Gait & Posture
Author(s): T.A. Gerbrands, M.F. Pisters, P.J.R. Theeven, S. Verschueren, B. Vanwanseele
Objective: To determine (1) if Medial Thrust or Trunk Lean reduces the knee adduction moment (EKAM) the most during gait in patients with medial knee osteoarthritis, (2) if the best overall strategy is the most effective for each patient and (3) if these strategies affect ankle and hip kinetics.DesignThirty patients with symptomatic medial knee osteoarthritis underwent 3-dimensional gait analysis. Participants received verbal instructions on two gait strategies (Trunk Lean and Medial Thrust) in randomized order after comfortable walking was recorded. The peaks and impulse of the EKAM and strategy-specific kinematic and kinetic variables were calculated for all conditions.ResultsEarly stance EKAM peak was significantly reduced during Medial Thrust (-29%). During Trunk Lean, early and late stance EKAM peak and EKAM impulse reduced significantly (38%, 21% and −25%, respectively). In 79% of the subjects, the Trunk Lean condition was significantly more effective in reducing EKAM peak than Medial Thrust. Peak ankle dorsi and plantar flexion, knee flexion and hip extension and adduction moments were not significantly increased.ConclusionsMedial Thrust and Trunk Lean reduced the EKAM during gait in patients with knee osteoarthritis. Individual selection of the most effective gait modification strategy seems vital to optimally reduce dynamic knee loading during gait. No detrimental effects on external ankle and hip moments or knee flexion moments were found for these conditions.



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The influence of a user-adaptive prosthetic knee across varying walking speeds: a randomized cross-over trial

Publication date: Available online 9 November 2016
Source:Gait & Posture
Author(s): E.C. Prinsen, M.J. Nederhand, H.S. Sveinsdóttir, M.R. Prins, F. van der Meer, HFJM Koopman, J.S. Rietman
Previously conducted trials comparing the gait pattern of individuals with a transfemoral amputation using a user-adaptive and a non-microprocessor-controlled prosthetic knee (NMPK) found mixed and conflicting results. Few trials, however, have compared user-adaptive to non-adaptive prosthetic knees across different walking speeds. Because of the ability of variable damping, the effect of user-adaptive knees might be more pronounced at lower or higher walking speeds. Our aim was to compare the Rheo Knee II (a microprocessor-controlled prosthetic knee) with NMPKs across varying walking speeds. In addition, we studied compensatory mechanisms associated with non-optimal prosthetic knee kinematics, such as intact ankle vaulting and vertical acceleration of the pelvis. Nine persons with a transfemoral amputation or knee disarticulation were included and measured with their own NMPK and with the Rheo Knee II. Measurements were performed at three walking speeds: preferred walking speed, 70% preferred walking speed and 115% preferred walking speed. No differences on peak prosthetic knee flexion during swing were found between prosthetic knee conditions. In addition, prosthetic knee flexion increased significantly with walking speed for both prosthetic knee conditions. At 70% preferred walking speed we found that vaulting of the intact ankle was significantly decreased while walking with the Rheo Knee II compared to the NMPK condition (P=0.028). We did not find differences in peak vertical acceleration of the pelvis during initial and mid-swing of the prosthetic leg. In conclusion, comparison of walking with the Rheo Knee II to walking with a NMPK across different walking speeds showed limited differences in gait parameters.



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Multiscale and Shannon entropies during gait as fall risk predictors—A prospective study

Publication date: Available online 9 November 2016
Source:Gait & Posture
Author(s): Lucia Bizovska, Zdenek Svoboda, Nicolas Vuillerme, Miroslav Janura
Although entropy-based measurements of gait dynamics are becoming widely used tools for fall risk assessment, their relationship to fall occurrence is still unclear. The aim of this study was hence to compare fallers and non-fallers in terms of gait dynamics assessed by the multiscale and Shannon entropy. This study included 139 participants, aged 60–80 years, divided into two groups according to fall occurrence during a 6-month prospective observation (38 fallers, 101 non-fallers). The methodology involved the use of the Tinetti balance assessment tool (TBAT) and 5minutes of overground walking with 3D accelerometers located near the L5 vertebra and shanks. We analyzed 150 strides for gait complexity, an index of complexity (CI), computed from multiscale entropy (MSE) and Shannon entropy (ShE) derived from the recurrence quantification analysis. We found no significant differences between groups in MSE and CI. The TBAT total score was significantly higher in non-fallers (P=0.033), however, both groups showed low risk of falls. ShE in the anterior-posterior direction from trunk and in the mediallateral direction from the shanks were both significantly higher in fallers (P=0.020; P=0.024). ShE was negatively correlated with CI, the shank ShE in the vertical direction was positively correlated with TBAT. Taken together, our findings suggest that MSE is not able to distinguish between highly functional groups, whereas Shannon entropy seems to be sufficient in fall risk prediction.



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Interpreting sources of variation in clinical gait analysis: a case study

Publication date: Available online 8 November 2016
Source:Gait & Posture
Author(s): Stephanie L. King, Gabor J. Barton, Lakshminarayan R. Ranganath
Objective: To illustrate and discuss sources of gait deviations (experimental, genuine and intentional) during a gait analysis and how these deviations inform clinical decision making.MethodsA case study of a 24-year old male diagnosed with Alkaptonuria undergoing a routine gait analysis. A 3D motion capture with the Helen-Hayes marker set was used to quantify lower-limb joint kinematics during barefoot walking along a 10m walkway at a self-selected pace. Additional 2D video data were recorded in the sagittal and frontal plane. The patient reported no aches or pains in any joint and described his lifestyle as active.ResultsTemporal-spatial parameters were within normal ranges for his age and sex. Three sources of gait deviations were identified; the posteriorly rotated pelvis was due to an experimental error and marker misplacement, the increased rotation of the pelvis in the horizontal plane was genuine and observed in both 3D gait curves and in 2D video analysis, finally the inconsistency in knee flexion/extension combined with a seemingly innocuous interest in the consequences of abnormal gait suggested an intentional gait deviation.ConclusionsGait analysis is an important analytical tool in the management of a variety of conditions that negatively impact on movement. Experienced gait analysts have the ability to recognise genuine gait adaptations that forms part of the decision-making process for that patient. However, their role also necessitates the ability to identify and correct for experimental errors and critically evaluate when a deviation may not be genuine.



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Novel dynamic peak and distribution plantar pressure measures on diabetic patients during walking

Publication date: Available online 9 November 2016
Source:Gait & Posture
Author(s): Haitham M. Al-Angari, Ahsan H. Khandoker, Sungmun Lee, Wael Almahmeed, Habiba S. Al Safar, Herbert F. Jelinek, Kinda Khalaf
Diabetic peripheral neuropathy (DPN) is a common complication leading to foot ulceration and amputation. Several kinematic, kinetic and plantar pressure measures have been proposed for DPN detection, however findings have been inconsistent. In this work, we present new shape features that capture variations in the plantar pressure using shape and entropy measures to the study of patients with retinopathy, DPN and nephropathy, and a control diabetic group with no complications. The change in the peak plantar pressure (PPP) position with each step for both feet was represented as a convex polygon, asymmetry index, area of the convex polygon, 2nd wavelet moment (WM2) and sample entropy (SamEn). WM2 and the SamEn were more sensitive in capturing variations due to presence of complications than the area and asymmetry measures. WM2 of the left heel (median: 1stIQ, 3rdIQ): 8.27 (4.6,14.8) and left forefoot: 9.2 (2.4,16) were significantly lower for the DPN group compared to the control (CONT) group (heel 11.9 (5.0,16.4); forefoot: 10.3 (4.4,21.3), p<0.05). SamEn for the DPN group was significantly lower in the right foot compared to the left foot (1.3 (1.26, 1.37) and 1.33 (1.26,1.4), p<0.01) compared to CONT (right foot: 1.37 (1.24,1.45) and left foot: 1.34 (1.25,1.42), P<0.05). These new shape and regularity features have shown promising results in detecting diabetic peripheral neuropathy and warrant further investigation.



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How far do stabilometric and clinical parameters correlate in peripheral neuropathies?

Publication date: Available online 9 November 2016
Source:Gait & Posture
Author(s): Ana Flavia Gomes Paiva, Philippe Thoumie, Besma Missaoui
Peripheral neuropathies are characterized by the impairment of motor and sensitive nervous fibers. We aimed to investigate the correlation between proprioception, force and the limits of equilibrium parameter (LOE), by assessing 38 patients diagnosed with characterized bilateral neuropathy and 11 healthy subjects. Clinical evaluation, based on a motor and pallesthesic score, enabled their classification into groups corresponding to motor, sensitive or mixed neuropathies. Balance measures on a stabilometric platform allowed differentiation between the patients and healthy subjects but not between the groups of patients. The parameter limits of equilibrium (LOE) calculated as percentage of foot length allowed not only the differentiation between patients and healthy subjects but also between patients showing motor and sensitive forms. ROC analysis gave a threshold of 15% for LOE to discriminate between motor and sensory neuropathies with a 75% of sensitivity and 72% of specificity. Consequently, we propose a simple experimental procedure to carry out an accurate assessment of balance disorders in order to identify future rehabilitation modalities recommended to these patients.



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Predicting postoperative gait in cerebral palsy

Publication date: Available online 9 November 2016
Source:Gait & Posture
Author(s): Omar A. Galarraga C., Vincent Vigneron, Bernadette Dorizzi, Néjib Khouri, Eric Desailly
In this work, postoperative lower limb kinematics are predicted with respect to preoperative kinematics, physical examination and surgery data. Data of 115 children with cerebral palsy that have undergone single-event multilevel surgery were considered. Preoperative data dimension was reduced utilizing principal component analysis. Then, multiple linear regressions with 80% confidence intervals were performed between postoperative kinematics and bilateral preoperative kinematics, 36 physical examination variables and combinations of 9 different surgical procedures. The mean prediction errors on test vary from 4° (pelvic obliquity and hip adduction) to 10° (hip rotation and foot progression), depending on the kinematic angle. The unilateral mean sizes of the confidence intervals vary from 5° to 15°. Frontal plane angles are predicted with the lowest errors, however the same performance is achieved when considering the postoperative average signals. Sagittal plane angles are better predicted than transverse plane angles, with statistical differences with respect to the average postoperative kinematics for both plane’s angles except for ankle dorsiflexion. The mean prediction errors are smaller than the variability of gait parameters in cerebral palsy. The performance of the system is independent of the preoperative state severity of the patient. Even if the system is not yet accurate enough to define a surgery plan, it shows an unbiased estimation of the most likely outcome, which can be useful for both the clinician and the patient. More patients’ data are necessary for improving the precision of the model in order to predict the kinematic outcome of a large number of possible surgeries and gait patterns.



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Lateral trunk lean and medializing the knee as gait strategies for knee osteoarthritis

Publication date: Available online 8 November 2016
Source:Gait & Posture
Author(s): T.A. Gerbrands, M.F. Pisters, P.J.R. Theeven, S. Verschueren, B. Vanwanseele
Objective: To determine (1) if Medial Thrust or Trunk Lean reduces the knee adduction moment (EKAM) the most during gait in patients with medial knee osteoarthritis, (2) if the best overall strategy is the most effective for each patient and (3) if these strategies affect ankle and hip kinetics.DesignThirty patients with symptomatic medial knee osteoarthritis underwent 3-dimensional gait analysis. Participants received verbal instructions on two gait strategies (Trunk Lean and Medial Thrust) in randomized order after comfortable walking was recorded. The peaks and impulse of the EKAM and strategy-specific kinematic and kinetic variables were calculated for all conditions.ResultsEarly stance EKAM peak was significantly reduced during Medial Thrust (-29%). During Trunk Lean, early and late stance EKAM peak and EKAM impulse reduced significantly (38%, 21% and −25%, respectively). In 79% of the subjects, the Trunk Lean condition was significantly more effective in reducing EKAM peak than Medial Thrust. Peak ankle dorsi and plantar flexion, knee flexion and hip extension and adduction moments were not significantly increased.ConclusionsMedial Thrust and Trunk Lean reduced the EKAM during gait in patients with knee osteoarthritis. Individual selection of the most effective gait modification strategy seems vital to optimally reduce dynamic knee loading during gait. No detrimental effects on external ankle and hip moments or knee flexion moments were found for these conditions.



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The influence of a user-adaptive prosthetic knee across varying walking speeds: a randomized cross-over trial

Publication date: Available online 9 November 2016
Source:Gait & Posture
Author(s): E.C. Prinsen, M.J. Nederhand, H.S. Sveinsdóttir, M.R. Prins, F. van der Meer, HFJM Koopman, J.S. Rietman
Previously conducted trials comparing the gait pattern of individuals with a transfemoral amputation using a user-adaptive and a non-microprocessor-controlled prosthetic knee (NMPK) found mixed and conflicting results. Few trials, however, have compared user-adaptive to non-adaptive prosthetic knees across different walking speeds. Because of the ability of variable damping, the effect of user-adaptive knees might be more pronounced at lower or higher walking speeds. Our aim was to compare the Rheo Knee II (a microprocessor-controlled prosthetic knee) with NMPKs across varying walking speeds. In addition, we studied compensatory mechanisms associated with non-optimal prosthetic knee kinematics, such as intact ankle vaulting and vertical acceleration of the pelvis. Nine persons with a transfemoral amputation or knee disarticulation were included and measured with their own NMPK and with the Rheo Knee II. Measurements were performed at three walking speeds: preferred walking speed, 70% preferred walking speed and 115% preferred walking speed. No differences on peak prosthetic knee flexion during swing were found between prosthetic knee conditions. In addition, prosthetic knee flexion increased significantly with walking speed for both prosthetic knee conditions. At 70% preferred walking speed we found that vaulting of the intact ankle was significantly decreased while walking with the Rheo Knee II compared to the NMPK condition (P=0.028). We did not find differences in peak vertical acceleration of the pelvis during initial and mid-swing of the prosthetic leg. In conclusion, comparison of walking with the Rheo Knee II to walking with a NMPK across different walking speeds showed limited differences in gait parameters.



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Multiscale and Shannon entropies during gait as fall risk predictors—A prospective study

Publication date: Available online 9 November 2016
Source:Gait & Posture
Author(s): Lucia Bizovska, Zdenek Svoboda, Nicolas Vuillerme, Miroslav Janura
Although entropy-based measurements of gait dynamics are becoming widely used tools for fall risk assessment, their relationship to fall occurrence is still unclear. The aim of this study was hence to compare fallers and non-fallers in terms of gait dynamics assessed by the multiscale and Shannon entropy. This study included 139 participants, aged 60–80 years, divided into two groups according to fall occurrence during a 6-month prospective observation (38 fallers, 101 non-fallers). The methodology involved the use of the Tinetti balance assessment tool (TBAT) and 5minutes of overground walking with 3D accelerometers located near the L5 vertebra and shanks. We analyzed 150 strides for gait complexity, an index of complexity (CI), computed from multiscale entropy (MSE) and Shannon entropy (ShE) derived from the recurrence quantification analysis. We found no significant differences between groups in MSE and CI. The TBAT total score was significantly higher in non-fallers (P=0.033), however, both groups showed low risk of falls. ShE in the anterior-posterior direction from trunk and in the mediallateral direction from the shanks were both significantly higher in fallers (P=0.020; P=0.024). ShE was negatively correlated with CI, the shank ShE in the vertical direction was positively correlated with TBAT. Taken together, our findings suggest that MSE is not able to distinguish between highly functional groups, whereas Shannon entropy seems to be sufficient in fall risk prediction.



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Interpreting sources of variation in clinical gait analysis: a case study

Publication date: Available online 8 November 2016
Source:Gait & Posture
Author(s): Stephanie L. King, Gabor J. Barton, Lakshminarayan R. Ranganath
Objective: To illustrate and discuss sources of gait deviations (experimental, genuine and intentional) during a gait analysis and how these deviations inform clinical decision making.MethodsA case study of a 24-year old male diagnosed with Alkaptonuria undergoing a routine gait analysis. A 3D motion capture with the Helen-Hayes marker set was used to quantify lower-limb joint kinematics during barefoot walking along a 10m walkway at a self-selected pace. Additional 2D video data were recorded in the sagittal and frontal plane. The patient reported no aches or pains in any joint and described his lifestyle as active.ResultsTemporal-spatial parameters were within normal ranges for his age and sex. Three sources of gait deviations were identified; the posteriorly rotated pelvis was due to an experimental error and marker misplacement, the increased rotation of the pelvis in the horizontal plane was genuine and observed in both 3D gait curves and in 2D video analysis, finally the inconsistency in knee flexion/extension combined with a seemingly innocuous interest in the consequences of abnormal gait suggested an intentional gait deviation.ConclusionsGait analysis is an important analytical tool in the management of a variety of conditions that negatively impact on movement. Experienced gait analysts have the ability to recognise genuine gait adaptations that forms part of the decision-making process for that patient. However, their role also necessitates the ability to identify and correct for experimental errors and critically evaluate when a deviation may not be genuine.



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Novel dynamic peak and distribution plantar pressure measures on diabetic patients during walking

Publication date: Available online 9 November 2016
Source:Gait & Posture
Author(s): Haitham M. Al-Angari, Ahsan H. Khandoker, Sungmun Lee, Wael Almahmeed, Habiba S. Al Safar, Herbert F. Jelinek, Kinda Khalaf
Diabetic peripheral neuropathy (DPN) is a common complication leading to foot ulceration and amputation. Several kinematic, kinetic and plantar pressure measures have been proposed for DPN detection, however findings have been inconsistent. In this work, we present new shape features that capture variations in the plantar pressure using shape and entropy measures to the study of patients with retinopathy, DPN and nephropathy, and a control diabetic group with no complications. The change in the peak plantar pressure (PPP) position with each step for both feet was represented as a convex polygon, asymmetry index, area of the convex polygon, 2nd wavelet moment (WM2) and sample entropy (SamEn). WM2 and the SamEn were more sensitive in capturing variations due to presence of complications than the area and asymmetry measures. WM2 of the left heel (median: 1stIQ, 3rdIQ): 8.27 (4.6,14.8) and left forefoot: 9.2 (2.4,16) were significantly lower for the DPN group compared to the control (CONT) group (heel 11.9 (5.0,16.4); forefoot: 10.3 (4.4,21.3), p<0.05). SamEn for the DPN group was significantly lower in the right foot compared to the left foot (1.3 (1.26, 1.37) and 1.33 (1.26,1.4), p<0.01) compared to CONT (right foot: 1.37 (1.24,1.45) and left foot: 1.34 (1.25,1.42), P<0.05). These new shape and regularity features have shown promising results in detecting diabetic peripheral neuropathy and warrant further investigation.



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How far do stabilometric and clinical parameters correlate in peripheral neuropathies?

Publication date: Available online 9 November 2016
Source:Gait & Posture
Author(s): Ana Flavia Gomes Paiva, Philippe Thoumie, Besma Missaoui
Peripheral neuropathies are characterized by the impairment of motor and sensitive nervous fibers. We aimed to investigate the correlation between proprioception, force and the limits of equilibrium parameter (LOE), by assessing 38 patients diagnosed with characterized bilateral neuropathy and 11 healthy subjects. Clinical evaluation, based on a motor and pallesthesic score, enabled their classification into groups corresponding to motor, sensitive or mixed neuropathies. Balance measures on a stabilometric platform allowed differentiation between the patients and healthy subjects but not between the groups of patients. The parameter limits of equilibrium (LOE) calculated as percentage of foot length allowed not only the differentiation between patients and healthy subjects but also between patients showing motor and sensitive forms. ROC analysis gave a threshold of 15% for LOE to discriminate between motor and sensory neuropathies with a 75% of sensitivity and 72% of specificity. Consequently, we propose a simple experimental procedure to carry out an accurate assessment of balance disorders in order to identify future rehabilitation modalities recommended to these patients.



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Predicting postoperative gait in cerebral palsy

Publication date: Available online 9 November 2016
Source:Gait & Posture
Author(s): Omar A. Galarraga C., Vincent Vigneron, Bernadette Dorizzi, Néjib Khouri, Eric Desailly
In this work, postoperative lower limb kinematics are predicted with respect to preoperative kinematics, physical examination and surgery data. Data of 115 children with cerebral palsy that have undergone single-event multilevel surgery were considered. Preoperative data dimension was reduced utilizing principal component analysis. Then, multiple linear regressions with 80% confidence intervals were performed between postoperative kinematics and bilateral preoperative kinematics, 36 physical examination variables and combinations of 9 different surgical procedures. The mean prediction errors on test vary from 4° (pelvic obliquity and hip adduction) to 10° (hip rotation and foot progression), depending on the kinematic angle. The unilateral mean sizes of the confidence intervals vary from 5° to 15°. Frontal plane angles are predicted with the lowest errors, however the same performance is achieved when considering the postoperative average signals. Sagittal plane angles are better predicted than transverse plane angles, with statistical differences with respect to the average postoperative kinematics for both plane’s angles except for ankle dorsiflexion. The mean prediction errors are smaller than the variability of gait parameters in cerebral palsy. The performance of the system is independent of the preoperative state severity of the patient. Even if the system is not yet accurate enough to define a surgery plan, it shows an unbiased estimation of the most likely outcome, which can be useful for both the clinician and the patient. More patients’ data are necessary for improving the precision of the model in order to predict the kinematic outcome of a large number of possible surgeries and gait patterns.



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Lateral trunk lean and medializing the knee as gait strategies for knee osteoarthritis

Publication date: Available online 8 November 2016
Source:Gait & Posture
Author(s): T.A. Gerbrands, M.F. Pisters, P.J.R. Theeven, S. Verschueren, B. Vanwanseele
Objective: To determine (1) if Medial Thrust or Trunk Lean reduces the knee adduction moment (EKAM) the most during gait in patients with medial knee osteoarthritis, (2) if the best overall strategy is the most effective for each patient and (3) if these strategies affect ankle and hip kinetics.DesignThirty patients with symptomatic medial knee osteoarthritis underwent 3-dimensional gait analysis. Participants received verbal instructions on two gait strategies (Trunk Lean and Medial Thrust) in randomized order after comfortable walking was recorded. The peaks and impulse of the EKAM and strategy-specific kinematic and kinetic variables were calculated for all conditions.ResultsEarly stance EKAM peak was significantly reduced during Medial Thrust (-29%). During Trunk Lean, early and late stance EKAM peak and EKAM impulse reduced significantly (38%, 21% and −25%, respectively). In 79% of the subjects, the Trunk Lean condition was significantly more effective in reducing EKAM peak than Medial Thrust. Peak ankle dorsi and plantar flexion, knee flexion and hip extension and adduction moments were not significantly increased.ConclusionsMedial Thrust and Trunk Lean reduced the EKAM during gait in patients with knee osteoarthritis. Individual selection of the most effective gait modification strategy seems vital to optimally reduce dynamic knee loading during gait. No detrimental effects on external ankle and hip moments or knee flexion moments were found for these conditions.



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