Neurotrophin Gene Therapy in Deafened Ears with Cochlear Implants: Long-term Effects on Nerve Survival and Functional Measures

Abstract

Because cochlear implants function by stimulating the auditory nerve, it is assumed that the condition of the nerve plays an important role in the efficacy of the prosthesis. Thus, considerable research has been devoted to methods of preserving the nerve following deafness. Neurotrophins have been identified as a potential contributor to neural health, but most of the research to date has been done in young animals and for short periods (less than 3 to 6 months) after the onset of treatment. The first objective of the current experiment was to examine the effects of a neurotrophin gene therapy delivery method on spiral ganglion neuron (SGN) preservation and function in the long term (5 to 14 months) in mature guinea pigs with cochlear implants. The second objective was to examine several potential non-invasive monitors of auditory nerve health following the neurotrophin gene therapy procedure. Eighteen mature adult male guinea pigs were deafened by cochlear perfusion of neomycin and then one ear was inoculated with an adeno-associated viral vector with an Nft3-gene insert (AAV.Ntf3) and implanted with a cochlear implant electrode array. Five control animals were deafened and inoculated with an empty AAV and implanted. Data from 43 other guinea pig ears from this and previous experiments were used for comparison: 24 animals implanted in a hearing ear, nine animals deafened and implanted with no inoculation, and ten normal-hearing non-implanted ears. After 4 to 21 months of psychophysical and electrophysiological testing, the animals were prepared for histological examination of SGN densities and inner hair cell (IHC) survival. Seventy-eight percent of the ears deafened and inoculated with AAV.Ntf3 showed better SGN survival than the 14 deafened-control ears. The degree of SGN preservation following the gene therapy procedure was variable across animals and across cochlear turns. Slopes of psychophysical multipulse integration (MPI) functions were predictive of SGN density, but only in animals with preserved IHCs. MPI was not affected by the AAV.Ntf3 treatment, but there was a minor improvement in temporal integration (TI). AAV.Ntf3 treatment had significant effects on ECAP and EABR amplitude growth func-tion (AGF) slopes; the reduction in slope in deafened ears was ameliorated by the AAV.Ntf3 treatment. Slopes of the ECAP and EABR AGFs were predictive of SGN density in a broad area near and just apical to the implant. The highest ensemble spontaneous activity (ESA) values were seen in animals with surviving IHCs, but AAV.Ntf3 treatment in deafened ears resulted in slightly higher ESA values compared to deafened untreated ears. Overall, a combination of the psychophysical and electrophysiological measures can be useful for monitoring the health of the implanted cochlea in guinea pigs. These measures should be applicable for assessing cochlear health in human subjects.

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Biomechanical Description of Phonation in Children Affected by Williams Syndrome

Publication date: Available online 2 August 2017
Source:Journal of Voice
Author(s): Irene Hidalgo de la Guía, Pedro Gómez Vilda, Elena Garayzábal Heinze
The voice of persons with Williams syndrome (WS) is described as hoarse with a deep and unstable fundamental frequency (f0). These observations may be justified by the deficit of elastin due to a haplo-insufficiency in the ELN gene characteristic of the syndrome. In view of the possible relationship between elastin deficit and dysphonia, a study of the dynamic function of WS phonation was conducted by means of biomechanical analysis. In order to assess the presence of dysphonic symptoms and their degree of severity, the biomechanical description of WS phonation has been evaluated in terms of dynamic mass and viscoelasticity estimates. Glottal biomechanical features such as vocal fold dynamic mass, stiffness, unbalances, and laryngeal tremor of 12 children with WS aged 3 to 8 years (five girls and seven boys) have been estimated and compared with the normative phonation of 97 children with typical development (53 girls and 44 boys). The results show that WS children show differences in f0, vocal fold mass and stiffness, phonation stability, glottal contact defects, and laryngeal tremor. The conclusions may help to make a more complete view of the connection between WS and dysphonia based on objective assessments.



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Gait patterns in association with underlying impairments in polio survivors with calf muscle weakness

Publication date: October 2017
Source:Gait & Posture, Volume 58
Author(s): Hilde E. Ploeger, Sicco A. Bus, Frans Nollet, Merel-Anne Brehm
The objective was to identify gait patterns in polio survivors with calf muscle weakness and associate them to underlying lower extremity impairments, which are expected to help in the search for an optimal orthosis.Unilaterally affected patients underwent barefoot 3D-gait analyses. Gait pattern clusters were created based on the ankle and knee angle and ankle moment shown in midstance of the affected limb. Impairment clusters were created based on plantarflexor and knee-extensor strength, and ankle and knee joint range-of-motion. The association between gait patterns and underlying impairments were examined descriptively. The Random Forest Algorithm and regression analyses were used to predict gait patterns and parameters.Seven gait patterns in 73 polio survivors were identified, with two dominant patterns: one with a mildly/non-deviant ankle angle, ankle moment and knee angle (n=23), and one with a strongly deviant ankle angle and a mildly/non-deviant ankle moment and knee angle (n=18). Gait pattern prediction from underlying impairments was 49% accurate with best prediction performance for the second dominant gait pattern (sensitivity 78% and positive predictive value 74%). The underlying impairments explained between 20 and 32% of the variance in individual gait parameters.Polio survivors with calf muscle weakness who present a similar impairment profile do not necessarily walk the same. From physical examination alone, the gait pattern nor the individual gait parameters could be accurately predicted. The patient’s gait should therefore be measured to help in the prescription and evaluation of orthoses for these patients.



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Gait patterns in association with underlying impairments in polio survivors with calf muscle weakness

Publication date: October 2017
Source:Gait & Posture, Volume 58
Author(s): Hilde E. Ploeger, Sicco A. Bus, Frans Nollet, Merel-Anne Brehm
The objective was to identify gait patterns in polio survivors with calf muscle weakness and associate them to underlying lower extremity impairments, which are expected to help in the search for an optimal orthosis.Unilaterally affected patients underwent barefoot 3D-gait analyses. Gait pattern clusters were created based on the ankle and knee angle and ankle moment shown in midstance of the affected limb. Impairment clusters were created based on plantarflexor and knee-extensor strength, and ankle and knee joint range-of-motion. The association between gait patterns and underlying impairments were examined descriptively. The Random Forest Algorithm and regression analyses were used to predict gait patterns and parameters.Seven gait patterns in 73 polio survivors were identified, with two dominant patterns: one with a mildly/non-deviant ankle angle, ankle moment and knee angle (n=23), and one with a strongly deviant ankle angle and a mildly/non-deviant ankle moment and knee angle (n=18). Gait pattern prediction from underlying impairments was 49% accurate with best prediction performance for the second dominant gait pattern (sensitivity 78% and positive predictive value 74%). The underlying impairments explained between 20 and 32% of the variance in individual gait parameters.Polio survivors with calf muscle weakness who present a similar impairment profile do not necessarily walk the same. From physical examination alone, the gait pattern nor the individual gait parameters could be accurately predicted. The patient’s gait should therefore be measured to help in the prescription and evaluation of orthoses for these patients.



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Gait patterns in association with underlying impairments in polio survivors with calf muscle weakness

Publication date: October 2017
Source:Gait & Posture, Volume 58
Author(s): Hilde E. Ploeger, Sicco A. Bus, Frans Nollet, Merel-Anne Brehm
The objective was to identify gait patterns in polio survivors with calf muscle weakness and associate them to underlying lower extremity impairments, which are expected to help in the search for an optimal orthosis.Unilaterally affected patients underwent barefoot 3D-gait analyses. Gait pattern clusters were created based on the ankle and knee angle and ankle moment shown in midstance of the affected limb. Impairment clusters were created based on plantarflexor and knee-extensor strength, and ankle and knee joint range-of-motion. The association between gait patterns and underlying impairments were examined descriptively. The Random Forest Algorithm and regression analyses were used to predict gait patterns and parameters.Seven gait patterns in 73 polio survivors were identified, with two dominant patterns: one with a mildly/non-deviant ankle angle, ankle moment and knee angle (n=23), and one with a strongly deviant ankle angle and a mildly/non-deviant ankle moment and knee angle (n=18). Gait pattern prediction from underlying impairments was 49% accurate with best prediction performance for the second dominant gait pattern (sensitivity 78% and positive predictive value 74%). The underlying impairments explained between 20 and 32% of the variance in individual gait parameters.Polio survivors with calf muscle weakness who present a similar impairment profile do not necessarily walk the same. From physical examination alone, the gait pattern nor the individual gait parameters could be accurately predicted. The patient’s gait should therefore be measured to help in the prescription and evaluation of orthoses for these patients.



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