Use of Non-Invasive Measures to Predict Cochlear Synapse Counts

Publication date: Available online 13 October 2018

Source: Hearing Research

Author(s): Naomi F. Bramhall, Garnett P. McMillan, Sharon G. Kujawa, Dawn Konrad-Martin

Abstract

Cochlear synaptopathy, the loss of synaptic connections between inner hair cells and auditory nerve fibers, has been documented in animal models of aging, noise, and ototoxic drug exposure, three common causes of acquired sensorineural hearing loss in humans. In each of these models, synaptopathy begins prior to changes in threshold sensitivity or loss of hair cells; thus, this underlying injury can be hidden behind a normal threshold audiogram. Since cochlear synaptic loss cannot be directly confirmed in living humans, non-invasive assays will be required for diagnosis. In animals with normal auditory thresholds, the amplitude of wave 1 of the auditory brainstem response (ABR) is highly correlated with synapse counts. However, synaptopathy can also co-occur with threshold elevation, complicating the use of the ABR alone as a diagnostic measure. Using an age-graded series of mice and a partial least squares regression approach to model structure-function relationships, this study shows that the combination of a small number of ABR and distortion product otoacoustic emission (DPOAE) measurements can predict synaptic ribbon counts at various cochlear frequencies to within 1-2 synapses per inner hair cell of their true value. In contrast, the model, trained using the age-graded series of mice, overpredicted synapse counts in a small sample of young noise-exposed mice, perhaps due to differences in the underlying pattern of damage between aging and noise-exposed mice. These results provide partial validation of a noninvasive approach to identify synaptic/neuronal loss in humans using ABRs and DPOAEs.

from #Audiology via ola Kala on Inoreader https://ift.tt/2OZxlN3
via IFTTT

Use of Non-Invasive Measures to Predict Cochlear Synapse Counts

Publication date: Available online 13 October 2018

Source: Hearing Research

Author(s): Naomi F. Bramhall, Garnett P. McMillan, Sharon G. Kujawa, Dawn Konrad-Martin

Abstract

Cochlear synaptopathy, the loss of synaptic connections between inner hair cells and auditory nerve fibers, has been documented in animal models of aging, noise, and ototoxic drug exposure, three common causes of acquired sensorineural hearing loss in humans. In each of these models, synaptopathy begins prior to changes in threshold sensitivity or loss of hair cells; thus, this underlying injury can be hidden behind a normal threshold audiogram. Since cochlear synaptic loss cannot be directly confirmed in living humans, non-invasive assays will be required for diagnosis. In animals with normal auditory thresholds, the amplitude of wave 1 of the auditory brainstem response (ABR) is highly correlated with synapse counts. However, synaptopathy can also co-occur with threshold elevation, complicating the use of the ABR alone as a diagnostic measure. Using an age-graded series of mice and a partial least squares regression approach to model structure-function relationships, this study shows that the combination of a small number of ABR and distortion product otoacoustic emission (DPOAE) measurements can predict synaptic ribbon counts at various cochlear frequencies to within 1-2 synapses per inner hair cell of their true value. In contrast, the model, trained using the age-graded series of mice, overpredicted synapse counts in a small sample of young noise-exposed mice, perhaps due to differences in the underlying pattern of damage between aging and noise-exposed mice. These results provide partial validation of a noninvasive approach to identify synaptic/neuronal loss in humans using ABRs and DPOAEs.

from #Audiology via ola Kala on Inoreader https://ift.tt/2OZxlN3
via IFTTT

Use of Non-Invasive Measures to Predict Cochlear Synapse Counts

Publication date: Available online 13 October 2018

Source: Hearing Research

Author(s): Naomi F. Bramhall, Garnett P. McMillan, Sharon G. Kujawa, Dawn Konrad-Martin

Abstract

Cochlear synaptopathy, the loss of synaptic connections between inner hair cells and auditory nerve fibers, has been documented in animal models of aging, noise, and ototoxic drug exposure, three common causes of acquired sensorineural hearing loss in humans. In each of these models, synaptopathy begins prior to changes in threshold sensitivity or loss of hair cells; thus, this underlying injury can be hidden behind a normal threshold audiogram. Since cochlear synaptic loss cannot be directly confirmed in living humans, non-invasive assays will be required for diagnosis. In animals with normal auditory thresholds, the amplitude of wave 1 of the auditory brainstem response (ABR) is highly correlated with synapse counts. However, synaptopathy can also co-occur with threshold elevation, complicating the use of the ABR alone as a diagnostic measure. Using an age-graded series of mice and a partial least squares regression approach to model structure-function relationships, this study shows that the combination of a small number of ABR and distortion product otoacoustic emission (DPOAE) measurements can predict synaptic ribbon counts at various cochlear frequencies to within 1-2 synapses per inner hair cell of their true value. In contrast, the model, trained using the age-graded series of mice, overpredicted synapse counts in a small sample of young noise-exposed mice, perhaps due to differences in the underlying pattern of damage between aging and noise-exposed mice. These results provide partial validation of a noninvasive approach to identify synaptic/neuronal loss in humans using ABRs and DPOAEs.

from #Audiology via ola Kala on Inoreader https://ift.tt/2OZxlN3
via IFTTT

Use of Non-Invasive Measures to Predict Cochlear Synapse Counts

Publication date: Available online 13 October 2018

Source: Hearing Research

Author(s): Naomi F. Bramhall, Garnett P. McMillan, Sharon G. Kujawa, Dawn Konrad-Martin

Abstract

Cochlear synaptopathy, the loss of synaptic connections between inner hair cells and auditory nerve fibers, has been documented in animal models of aging, noise, and ototoxic drug exposure, three common causes of acquired sensorineural hearing loss in humans. In each of these models, synaptopathy begins prior to changes in threshold sensitivity or loss of hair cells; thus, this underlying injury can be hidden behind a normal threshold audiogram. Since cochlear synaptic loss cannot be directly confirmed in living humans, non-invasive assays will be required for diagnosis. In animals with normal auditory thresholds, the amplitude of wave 1 of the auditory brainstem response (ABR) is highly correlated with synapse counts. However, synaptopathy can also co-occur with threshold elevation, complicating the use of the ABR alone as a diagnostic measure. Using an age-graded series of mice and a partial least squares regression approach to model structure-function relationships, this study shows that the combination of a small number of ABR and distortion product otoacoustic emission (DPOAE) measurements can predict synaptic ribbon counts at various cochlear frequencies to within 1-2 synapses per inner hair cell of their true value. In contrast, the model, trained using the age-graded series of mice, overpredicted synapse counts in a small sample of young noise-exposed mice, perhaps due to differences in the underlying pattern of damage between aging and noise-exposed mice. These results provide partial validation of a noninvasive approach to identify synaptic/neuronal loss in humans using ABRs and DPOAEs.

from #Audiology via ola Kala on Inoreader https://ift.tt/2OZxlN3
via IFTTT

Kinematic differences between neutral and flat feet with and without symptoms as measured by the Oxford Foot Model

Publication date: Available online 13 October 2018

Source: Gait & Posture

Author(s): C.M. Kerr, A.B. Zavatsky, T. Theologis, J. Stebbins

Abstract

Background

Flatfoot is a common presentation in children. It is usually asymptomatic, though a small number of children experience pain. Foot function during flatfoot walking is rarely considered, yet as an activity that places significant demands on the feet, this could explain the differences in terms of symptoms.

Research Question

This paper investigates walking patterns in neutral and flat feet, with and without symptoms, to determine which kinematic parameters are associated with symptomatic flat feet.

Methods

This is a retrospective study in which one hundred and six children between five and 18 years old were assessed by a physiotherapist for foot posture. Each foot was classified into one of four groups, giving 98 asymptomatic neutral, 47 asymptomatic mild flat, 29 asymptomatic flat, and 38 symptomatic flat feet with complete data for analysis. Using Plug-In-Gait and Oxford-Foot-Model markers, walking kinematics were measured, along with ground reaction forces. Median values of 14 lower limb joint angles were calculated at foot strike, midstance, and foot off. Each foot was treated as an independent sample. ANOVA and ANCOVA (with the speed-related variable relative stride length as the covariate) and post-hoc tests were used to assess whether angles differed between groups.

Results

The symptomatic flat feet showed significant differences from asymptomatic groups (most commonly the neutral feet) in terms of hip flexion, knee flexion and varus, hindfoot inversion-eversion, and forefoot abduction-adduction. Increased forefoot abduction occurred throughout stance phase in symptomatic flatfooted participants compared to all asymptomatic groups.

Significance

The results suggest that foot motion in the transverse plane is closely associated with the presence of symptoms in flat feet and that this is accompanied by changes in the kinematics of the ankle, knee, and hip.

from #Audiology via ola Kala on Inoreader https://ift.tt/2RORIva
via IFTTT

Kinematic differences between neutral and flat feet with and without symptoms as measured by the Oxford Foot Model

Publication date: Available online 13 October 2018

Source: Gait & Posture

Author(s): C.M. Kerr, A.B. Zavatsky, T. Theologis, J. Stebbins

Abstract

Background

Flatfoot is a common presentation in children. It is usually asymptomatic, though a small number of children experience pain. Foot function during flatfoot walking is rarely considered, yet as an activity that places significant demands on the feet, this could explain the differences in terms of symptoms.

Research Question

This paper investigates walking patterns in neutral and flat feet, with and without symptoms, to determine which kinematic parameters are associated with symptomatic flat feet.

Methods

This is a retrospective study in which one hundred and six children between five and 18 years old were assessed by a physiotherapist for foot posture. Each foot was classified into one of four groups, giving 98 asymptomatic neutral, 47 asymptomatic mild flat, 29 asymptomatic flat, and 38 symptomatic flat feet with complete data for analysis. Using Plug-In-Gait and Oxford-Foot-Model markers, walking kinematics were measured, along with ground reaction forces. Median values of 14 lower limb joint angles were calculated at foot strike, midstance, and foot off. Each foot was treated as an independent sample. ANOVA and ANCOVA (with the speed-related variable relative stride length as the covariate) and post-hoc tests were used to assess whether angles differed between groups.

Results

The symptomatic flat feet showed significant differences from asymptomatic groups (most commonly the neutral feet) in terms of hip flexion, knee flexion and varus, hindfoot inversion-eversion, and forefoot abduction-adduction. Increased forefoot abduction occurred throughout stance phase in symptomatic flatfooted participants compared to all asymptomatic groups.

Significance

The results suggest that foot motion in the transverse plane is closely associated with the presence of symptoms in flat feet and that this is accompanied by changes in the kinematics of the ankle, knee, and hip.

from #Audiology via ola Kala on Inoreader https://ift.tt/2RORIva
via IFTTT

Sling-based infant carrying affects lumbar and thoracic spine neuromechanics during standing and walking

Publication date: Available online 12 October 2018

Source: Gait & Posture

Author(s): Stefan Schmid, Michèle Stauffer, Judit Jäger, Renate List, Silvio Lorenzetti

Abstract

Background

Regular infant carrying might be a contributing factor for the development and progression of low back and pelvic girdle pain in mothers after childbirth. However, the neuromechanical adaptations of the spine due to different sling-based carrying techniques are not sufficiently well understood in order to provide evidence-based carrying recommendations.

Research question

What are the immediate effects of different sling-based infant carrying techniques on trunk neuromechanics?

Methods

Using a Vicon motion capture and a wireless surface electromyography system, three-dimensional pelvis and spinal kinematics as well as activation patterns of eight trunk muscles were derived from fifteen healthy young women during upright standing and level walking without carrying a load and while carrying a 6 kg-dummy with a sling in front and on either side. Data were analyzed using Statistical Parametric Mapping, allowing group comparisons of discrete parameters (standing) as well as continuous data (walking). To distinguish between clinically relevant and clinically not relevant kinematic findings, statistically significant differences were only considered in case of ≥5°.

Results

Compared to unloaded walking, carrying the dummy in front was mainly associated with increased lumbar lordosis (standing: (Δ8.8°, p = 0.006; walking: (Δ≥8.2°, 1-100% of gait cycle [%GC], p < 0.001). When carrying the dummy on the preferred side, increased thoracic kyphosis (standing: ≥6.4°, p ≤ 0.003; walking: Δ≥5.6°, 1-100%GC, p < 0.001) and axial rotation towards the ipsilateral side (standing: Δ5.3°, p = 0.003; walking: Δ≥5.0°, 46-58%GC, p = 0.002) were observed. All three conditions entailed increased paraspinal muscle activity during walking, although only unilaterally in side carrying (lumbar, preferred condition: Δ≥13.2%maxMVIC, 49-57%GC, p < 0.001; thoracic, non-preferred condition: Δ≥5.3%maxMVIC, 47-58%GC, p < 0.001).

Significance

Carrying an infant alternating on both sides using a sling could be advantageous for preventing musculoskeletal pain resulting from excessive lumbar hyperextension and paraspinal muscle hyperactivation in women after childbirth.

from #Audiology via ola Kala on Inoreader https://ift.tt/2A7MH9Y
via IFTTT