European Journal of Translational Myology, Mar 25, 2024
This article is distributed under the terms of the Creative Commons Attribution Noncommercial Lic... more This article is distributed under the terms of the Creative Commons Attribution Noncommercial License (CC BY-NC 4.0) which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
Current Directions in Biomedical Engineering, Sep 1, 2022
Introduction: Despite its central role in medicine electrical stimulation (ES) is still limited b... more Introduction: Despite its central role in medicine electrical stimulation (ES) is still limited by its selectivity. Different reports did assess effects of different waveforms, intensities, and frequency on the activation threshold of nerve fibres with different diameters. We aimed to extend this knowledge by investigating the effect of short monophasic rectangular pulses (1, 2, 5, 10, 50, 100 and 200 μs) on the recruitment order. Methods: The sciatic nerve of rats was stimulated, and the evoked compound nerve action potential (CNAP) measured at two sites on the tibialis nerve, using epineural electrodes. Changes in delay, amplitude, and the shape of the CNAP were analyzed. Results: The amplitude and delay of the CNAP were significantly affected by the pulse-width (PW). The delay and duration of the compound nerve action potential increased with longer PW, while the amplitude decreased. Discussion: Found changes are likely caused by changes in the time point of excitation of individual neuron fibres, depending on electrical field strength and exposure time. This might be of particular interest when selecting PWs for design and validation of stimulation patterns and analysis of experimental and clinical observations.
Study Design: A quasi-experimental (matched-pair-design)study. Patients received local photobiomo... more Study Design: A quasi-experimental (matched-pair-design)study. Patients received local photobiomodulation(LPBM) on one side of their body and the control group was assigned to other side, at the same locations. Objectives: To evaluate the LPBM effects on bone-mineral-density(BMD), in complete spinal-cord-injury(C.SCI) patients with osteoporosis(OP) by follow-up dual-energy X-ray-absorptiometry(DEXA). Setting: The clinic of Mazandaran University of Medical Science, Sari, Iran Methods: A total of 23 locations consisting of three-therapeutic-locations(TTLs): Forearm-MID, proximal-femur(PFe), proximal-tibia(PTib), in eight patients (except, forearm-MID with seven) were included LPBM treatment for 8 weeks. BMD were measured using DEXA in both side, at Week-8 of LPBM and at Week-15 for follow-up. Different doses were adjusted depending on the anatomical distance between the skin surface and bone depth as determined by sonography to deliver the optimal isodose at each depth for bone. This ...
Polysynaptic activity is necessary to engage the neural circuitry that controls the motor behavio... more Polysynaptic activity is necessary to engage the neural circuitry that controls the motor behaviour and is crucial to the recovery after spinal cord injury (SCI) [1]. Polysynaptic responses can be elicited with spinal cord stimulation, and there are few reports on these types of responses in human electrophysiology, most of them describing them as constant to fixed stimuli. However, we have observed that the responses fluctuate in amplitude and time. Amplitude variations can be analysed with statistical methods. However, time fluctuations are more complex due to the multiple parameters involved. This work describes a methodology to analyse the time fluctuation in the responses of each pulse. It is based on the calculation of the signal temporal centroid, representing the whole activity, weighted by its latency, in a single time value. This value is then used to model the temporal fluctuation with linear regression. The methodology was verified with an electromyography dataset from a...
This article addresses the potential clinical value of surface electrical stimulation in the acut... more This article addresses the potential clinical value of surface electrical stimulation in the acute phase of denervation after the onset of facial nerve or recurrent laryngeal nerve paralysis. These two nerve lesions are the most frequent head and neck nerve lesions. In this review, we will work out several similarities concerning the pathophysiology features and the clinical scenario between both nerve lesions, which allow to develop some general rules for surface electrical stimulation applicable for both nerve lesions. The focus is on electrical stimulation in the phase between denervation and reinnervation of the target muscles. The aim of electrostimulation in this phase of denervation is to bridge the time until reinnervation is complete and to maintain facial or laryngeal function. In this phase, electrostimulation has to stimulate directly the denervated muscles, i.e. muscle stimulation and not nerve stimulation. There is preliminary data that early electrostimulation might a...
Increased use of epidural Spinal Cord Stimulation (eSCS) for the rehabilitation of spinal cord in... more Increased use of epidural Spinal Cord Stimulation (eSCS) for the rehabilitation of spinal cord injury (SCI) has highlighted the need for a greater understanding of the properties of reflex circuits in the isolated spinal cord, particularly in response to repetitive stimulation. Here, we investigate the frequency-dependence of modulation of short- and long-latency EMG responses of lower limb muscles in patients with SCI at rest. Single stimuli could evoke short-latency responses as well as long-latency (likely polysynaptic) responses. The short-latency component was enhanced at low frequencies and declined at higher rates. In all muscles, the effects of eSCS were more complex if polysynaptic activity was elicited, making the motor output become an active process expressed either as suppression, tonic or rhythmical activity. The polysynaptic activity threshold is not constant and might vary with different stimulation frequencies, which speaks for its temporal dependency. Polysynaptic ...
Mit Hilfe eines nunmehr entwickelten Gate-Array ICs vereinfacht sich der Aufbau von Implantaten f... more Mit Hilfe eines nunmehr entwickelten Gate-Array ICs vereinfacht sich der Aufbau von Implantaten fur die funktionelle Elektrostimulation betrachtlich. Die Implantate werden sowohl fur die Mobilisation Querschnittgelahmter (Paraplegiker) wie auch fur die Stimulation der Nervi Phrenici im FaIle von Atemlahmung (z.B. bei hoher Tetraplegie) eingesetzt. Bis auf wenige passive Bauteile besteht die Elektronik der Implantate nur mehr aus dem entwickelten Chip. Einleitung Querschnittlahmung bedeutet fur den Betroffenen einen irreversiblen Verlust von Bewegungsfahigkeit, wobei -je nach der Hohe der erlittenen Wirbelsaulenverletzung -"nur" die Beine gelahmt sind, oder im Extremfall aIle willkurlichen Bewegungsmoglichkeiten kopfabwarts inklusive der Atemfahigkeit betroffen sind. Die Zahl der querschnittgelahmten Patienten ist wegen der erhohten Unfallzahlen standig im Steigen begriffen, immer mehr Jugendliche sind betroffen und wegen der verbesserten medizinischen Versorgung steigt die Zahl der Oberlebenden auch bei hohem Querschnitt. Abgesehen yom personlichen Leid welches mit der Querschnittlahmung verbunden ist, ist der volkswirtschaftliche Verlust betrachtlich. Querschnittlahmung ist im traditionellen Sinne medizinisch nicht heilbar, da das bei der Verletzung zerstorte Ruckenmark
Este trabajo presenta una metodologia para la extraccion de la actividad respiratoria derivada de... more Este trabajo presenta una metodologia para la extraccion de la actividad respiratoria derivada de un ECG (EDR, por sus siglas en ingles), basado en el enfoque de amplitud modulada (AM). Esto permite redefinir las metodologias actuales para obtener una senal EDR mas continua, con altos factores de correlacion y un retraso menor entre la EDR y la actividad respiratoria. Se implementaron dos algoritmos: uno utilizando la modulacion de la amplitud del pico R (EDRAM) y el otro aplicando un filtro paso-banda en el espectro de frecuencia de la respiracion. A diferencia de otros trabajos en la literatura, se utilizan filtros convencionales de bajo orden pero sin sacrificar el factor de correlacion (0.76 y 0.67) y manteniendo un retardo de ∼0.27s (con EDRAM) en un ciclo de ∼6s. Se realizo una prueba de robustez, donde se muestra una tolerancia a ruido blanco de hasta un 20% del valor maximo antes de que el factor de correlacion bajara considerablemente. El algoritmo EDRAM se aplico con exito...
Glaucoma is the second cause of world blindness after cataract. It predominantly occurs as open a... more Glaucoma is the second cause of world blindness after cataract. It predominantly occurs as open angle followed by angle closure glaucoma. Since it is silent, chronic disease with no clinical signs at the beginning of illness, it is often undiagnosed and underestimated. Prevention by early screening by gonioscopy has a great potential towards precluding the disease. Additively manufactured human eye model is a great avenue for gonioscopy training as a substitute to the currently used animal models.
Purpose: We hypothesised that intercarpal K-wire fixation of adjacent carpal bones would reduce t... more Purpose: We hypothesised that intercarpal K-wire fixation of adjacent carpal bones would reduce torque and lever force within a fractured scaphoid bone. Methods: In eight cadaver wrists, a scaphoid osteotomy was stabilised using a locking nail, which also functioned as a sensor to measure isometric torque and lever forces between the fragments. The wrist was moved through 80% of full range of motion (ROM) to generate torque and force within the scaphoid. Testing was performed with and without loading of the wrist and K-wire stabilisation of the adjacent carpal bones. Results: Average torque and lever force values were 49.6 ± 25.1 Nmm and 3.5 ± 0.9 N during extension and 41 ± 26.7 Nmm and 8.1 ± 2.8 N during flexion. Torque and lever force did not depend on scaphoid size, individual wrist ROM, or deviations of the sensor versus the anatomic axis. K-wire fixation did not produce significant changes in average torque and lever force values except with wrist radial abduction (P = 0.0485). Other than wrist extension, torque direction was not predictable. In unstable scaphoid fractures, we suggest securing rotational stability with selected implants for functional postoperative care. Wrist ROM within 20% extension and radial abduction to 50% flexion limit torque and lever force exacerbation between scaphoid fragments.
Purpose This paper describes a first attempt to quantify LEMG data based on turn number calculati... more Purpose This paper describes a first attempt to quantify LEMG data based on turn number calculation. The results obtained for both healthy and ailing thyroarytenoid (TA) muscles of patients with unilateral vocal fold immobility (UVFI) were compared with the respective qualitative evaluation concerning volitional activity to determine whether the two types of analyses deliver similar results. Methods LEMG data obtained from 44 adults with UVFI were considered for the study. Semiquantitative evaluation of TA volitional activity and turn number were assessed for the ailing and the healthy TA and the difference in percentage was calculated. Paired data were compared with the Wilcoxon signed-rank test. The volitional activity assessment and the turn number evaluation were compared with the Kruskal–Wallis test, and their relationship was tested with the Kendall rank correlation. Results Datasets of 27 patients were considered compatible with turns/s calculation. The results showed that co...
The aim of this prospective study was to examine the effects of transcutaneous functional electri... more The aim of this prospective study was to examine the effects of transcutaneous functional electrical stimulation (FES) in a group of elderly women with presbyphonia. Study Design: Prospective randomized study. Methods: Fourteen participants were enrolled prospectively and attributed randomly to two different treatment groups, where one group (n = 7) received 8 weeks of training (5 days a week), whereas the other group (n = 7) received 4 weeks of ineffective stimulation, followed by 4 weeks of effective training. Stimulation protocols were established during baseline examination and confirmed with endoscopy to ensure a glottal reaction. Numerous acoustical, vocal, patient-centered, and respiratory parameters were obtained at several time points. Results: Neither 4 weeks nor 8 weeks of functional electrical transcutaneous stimulation led to changes of vocal, acoustical, or respiratory parameters, apart from patient-centered items (Voice Handicap Index 12, Voice-Related Quality of Life), which improved over time. However, there were no differences between the two arms for both items. Conclusions: Transcutaneous FES over 4 weeks and 8 weeks did not lead to significantly improved objective voice and acoustical parameters, which could be caused by the fact that the muscles of interest cannot be targeted specifically enough. However, we found a significant improvement of subjective voice perception and voice-related quality of life in both groups. We explain this finding with an observer-expectancy effect secondary to the very time-consuming and elaborate study procedures.
Predicting pathologic fractures in femora with metastatic lesions remains a clinical challenge. C... more Predicting pathologic fractures in femora with metastatic lesions remains a clinical challenge. Currently used guidelines are inaccurate, especially to predict non-impeding fractures. This study evaluated the ability of a nonlinear quantitative computed tomography (QCT)-based homogenized voxel finite element (hvFE) model to predict patient-specific pathologic fractures. The hvFE model was generated highly automated from QCT images of human femora. The femora were previously loaded in a one-legged stance setup in order to assess stiffness, failure load, and fracture location. One femur of each pair was tested in its intact state, while the contralateral femur included a simulated lesion on either the superolateral- or the inferomedial femoral neck. The hvFE model predictions of the stiffness (0.47 < R2 < 0.94), failure load (0.77 < R2 < 0.98), and exact fracture location (68%) were in good agreement with the experimental data. However, the model underestimated the failure...
Current Directions in Biomedical Engineering, 2016
Neuromodulation using electrical stimulation is able to enhance motor control of individuals suff... more Neuromodulation using electrical stimulation is able to enhance motor control of individuals suffering an upper motor neuron disorder. This work examined the effect of sustained electrical stimulation to modify spasticity in the leg muscles. We applied transcutaneous spinal cord stimulation with a pulse rate of 50 Hz for 30 min. The subjects were assessed before and after the intervention using in a pendulum test setup. The motion of the free swinging leg was acquired through video tracking and goniometer measurements. The quantification was done through the R2n index which shows consistency identifying the spasticity levels. In all incomplete SCI subjects having severe spasticity, the results show that electrical stimulation is effective to modify the increased muscle tone.
Long-term permanent denervation (LT-PD) induces severe atrophy of skeletal muscle accompanied by ... more Long-term permanent denervation (LT-PD) induces severe atrophy of skeletal muscle accompanied by apoptotic loss of myonuclei. Morphologic characteristics of the long-term denervated muscle suggest that the original fibers are lost and those seen are the results of repeated cycles of cell death and regeneration. Myoblasts and myotubes express peculiar myosins. Light and heavy chains of embryonic myosin are sensitive indicators of myogenic events in adult muscles. Electrical stimulation of permanent denervated muscle increases the mean size of the myofibers, maintains the sarcomeres and possibly prevents secondary degeneration and apoptosis/necrosis. Mechanisms underlying the recruitment of satellite cells for regenerative or hypertrophic processes have not been established, but cytokine interactions among macrophages and satellite cells seem to be essential. Here we show that long-term denervated muscles increase in size and change their myosin content after full regeneration is induced by bupivacaine treatment. After transient expression of embryonic myosin, fast myosins prevail in all the experimental muscles. In spite of a severe atrophy (around 90%), ten days after injury the regenerated muscles have twice the area at the muscle belly of the respective long-term denervated muscles. Since satellite cells activity is required for extreme hypertrophy of overloaded adult muscles or eutrophy after severe atrophy in recovering muscles, positive regulation of activation, division and fusion of myoblasts could be an important tool to understand limits of recovery of neurogenic muscle myopathies by functional electrical stimulation (FES). Pilot studies in humans show that standing up with denervated muscles using functional electrical stimulation is a reality in permanent complete denervation.
✓ The left sciatic nerve of 36 rats was exposed and four ring-shaped stainless steel wire electro... more ✓ The left sciatic nerve of 36 rats was exposed and four ring-shaped stainless steel wire electrodes were sutured to the epineurium of each nerve in the same manner as performed clinically for “carousel stimulation” in man. The rats were sacrificed 10 days (Group 1), 3 weeks (Group 2), or 3 months (Group 3) after implantation. The electrodes were excised, the nerves were embedded in Epon, and semithin sections were obtained for histological and planimetric assessment of lesions caused by the epineurially sutured electrodes. The right sciatic nerves served as controls. The total area of neural tissue within the perineurium was determined at three levels: at the site of the electrodes, 8 mm proximal, and 8 mm distal. The area of neural tissue damaged by the surgical procedure was expressed as a percentage of the total area. In Group 1, nine of 12 nerves showed lesions ranging from 0.39% to 25.39% of the total area of neural tissue, in Group 2 eight of 11 sciatic nerves showed lesions ...
Journal of Neuropathology & Experimental Neurology, 2014
The histologic features of aging muscle suggest that denervation contributes to atrophy, that imm... more The histologic features of aging muscle suggest that denervation contributes to atrophy, that immobility accelerates the process, and that routine exercise may protect against loss of motor units and muscle tissue. Here, we compared muscle biopsies from sedentary and physically active seniors and found that seniors with a long history of high-level recreational activity up to the time of muscle biopsy had 1) lower loss of muscle strength versus young men (32% loss in physically active vs 51% loss in sedentary seniors); 2) fewer small angulated (denervated) myofibers; 3) a higher percentage of fiber-type groups (reinnervated muscle fibers) that were almost exclusive of the slow type; and 4) sparse normal-size muscle fibers coexpressing fast and slow myosin heavy chains, which is not compatible with exercise-driven muscle-type transformation. The biopsies from the old physically active seniors varied from sparse fiber-type groupings to almost fully transformed muscle, suggesting that coexpressing fibers appear to fill gaps. Altogether, the data show that long-term physical activity promotes reinnervation of muscle fibers and suggest that decades of high-level exercise allow the body to adapt to age-related denervation by saving otherwise lost muscle fibers through selective recruitment to slow motor units. These effects on size and structure of myofibers may delay functional decline in late aging. Trial registration: ClinicalTrials.gov (NCT01679977).
European Journal of Translational Myology, Mar 25, 2024
This article is distributed under the terms of the Creative Commons Attribution Noncommercial Lic... more This article is distributed under the terms of the Creative Commons Attribution Noncommercial License (CC BY-NC 4.0) which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
Current Directions in Biomedical Engineering, Sep 1, 2022
Introduction: Despite its central role in medicine electrical stimulation (ES) is still limited b... more Introduction: Despite its central role in medicine electrical stimulation (ES) is still limited by its selectivity. Different reports did assess effects of different waveforms, intensities, and frequency on the activation threshold of nerve fibres with different diameters. We aimed to extend this knowledge by investigating the effect of short monophasic rectangular pulses (1, 2, 5, 10, 50, 100 and 200 μs) on the recruitment order. Methods: The sciatic nerve of rats was stimulated, and the evoked compound nerve action potential (CNAP) measured at two sites on the tibialis nerve, using epineural electrodes. Changes in delay, amplitude, and the shape of the CNAP were analyzed. Results: The amplitude and delay of the CNAP were significantly affected by the pulse-width (PW). The delay and duration of the compound nerve action potential increased with longer PW, while the amplitude decreased. Discussion: Found changes are likely caused by changes in the time point of excitation of individual neuron fibres, depending on electrical field strength and exposure time. This might be of particular interest when selecting PWs for design and validation of stimulation patterns and analysis of experimental and clinical observations.
Study Design: A quasi-experimental (matched-pair-design)study. Patients received local photobiomo... more Study Design: A quasi-experimental (matched-pair-design)study. Patients received local photobiomodulation(LPBM) on one side of their body and the control group was assigned to other side, at the same locations. Objectives: To evaluate the LPBM effects on bone-mineral-density(BMD), in complete spinal-cord-injury(C.SCI) patients with osteoporosis(OP) by follow-up dual-energy X-ray-absorptiometry(DEXA). Setting: The clinic of Mazandaran University of Medical Science, Sari, Iran Methods: A total of 23 locations consisting of three-therapeutic-locations(TTLs): Forearm-MID, proximal-femur(PFe), proximal-tibia(PTib), in eight patients (except, forearm-MID with seven) were included LPBM treatment for 8 weeks. BMD were measured using DEXA in both side, at Week-8 of LPBM and at Week-15 for follow-up. Different doses were adjusted depending on the anatomical distance between the skin surface and bone depth as determined by sonography to deliver the optimal isodose at each depth for bone. This ...
Polysynaptic activity is necessary to engage the neural circuitry that controls the motor behavio... more Polysynaptic activity is necessary to engage the neural circuitry that controls the motor behaviour and is crucial to the recovery after spinal cord injury (SCI) [1]. Polysynaptic responses can be elicited with spinal cord stimulation, and there are few reports on these types of responses in human electrophysiology, most of them describing them as constant to fixed stimuli. However, we have observed that the responses fluctuate in amplitude and time. Amplitude variations can be analysed with statistical methods. However, time fluctuations are more complex due to the multiple parameters involved. This work describes a methodology to analyse the time fluctuation in the responses of each pulse. It is based on the calculation of the signal temporal centroid, representing the whole activity, weighted by its latency, in a single time value. This value is then used to model the temporal fluctuation with linear regression. The methodology was verified with an electromyography dataset from a...
This article addresses the potential clinical value of surface electrical stimulation in the acut... more This article addresses the potential clinical value of surface electrical stimulation in the acute phase of denervation after the onset of facial nerve or recurrent laryngeal nerve paralysis. These two nerve lesions are the most frequent head and neck nerve lesions. In this review, we will work out several similarities concerning the pathophysiology features and the clinical scenario between both nerve lesions, which allow to develop some general rules for surface electrical stimulation applicable for both nerve lesions. The focus is on electrical stimulation in the phase between denervation and reinnervation of the target muscles. The aim of electrostimulation in this phase of denervation is to bridge the time until reinnervation is complete and to maintain facial or laryngeal function. In this phase, electrostimulation has to stimulate directly the denervated muscles, i.e. muscle stimulation and not nerve stimulation. There is preliminary data that early electrostimulation might a...
Increased use of epidural Spinal Cord Stimulation (eSCS) for the rehabilitation of spinal cord in... more Increased use of epidural Spinal Cord Stimulation (eSCS) for the rehabilitation of spinal cord injury (SCI) has highlighted the need for a greater understanding of the properties of reflex circuits in the isolated spinal cord, particularly in response to repetitive stimulation. Here, we investigate the frequency-dependence of modulation of short- and long-latency EMG responses of lower limb muscles in patients with SCI at rest. Single stimuli could evoke short-latency responses as well as long-latency (likely polysynaptic) responses. The short-latency component was enhanced at low frequencies and declined at higher rates. In all muscles, the effects of eSCS were more complex if polysynaptic activity was elicited, making the motor output become an active process expressed either as suppression, tonic or rhythmical activity. The polysynaptic activity threshold is not constant and might vary with different stimulation frequencies, which speaks for its temporal dependency. Polysynaptic ...
Mit Hilfe eines nunmehr entwickelten Gate-Array ICs vereinfacht sich der Aufbau von Implantaten f... more Mit Hilfe eines nunmehr entwickelten Gate-Array ICs vereinfacht sich der Aufbau von Implantaten fur die funktionelle Elektrostimulation betrachtlich. Die Implantate werden sowohl fur die Mobilisation Querschnittgelahmter (Paraplegiker) wie auch fur die Stimulation der Nervi Phrenici im FaIle von Atemlahmung (z.B. bei hoher Tetraplegie) eingesetzt. Bis auf wenige passive Bauteile besteht die Elektronik der Implantate nur mehr aus dem entwickelten Chip. Einleitung Querschnittlahmung bedeutet fur den Betroffenen einen irreversiblen Verlust von Bewegungsfahigkeit, wobei -je nach der Hohe der erlittenen Wirbelsaulenverletzung -"nur" die Beine gelahmt sind, oder im Extremfall aIle willkurlichen Bewegungsmoglichkeiten kopfabwarts inklusive der Atemfahigkeit betroffen sind. Die Zahl der querschnittgelahmten Patienten ist wegen der erhohten Unfallzahlen standig im Steigen begriffen, immer mehr Jugendliche sind betroffen und wegen der verbesserten medizinischen Versorgung steigt die Zahl der Oberlebenden auch bei hohem Querschnitt. Abgesehen yom personlichen Leid welches mit der Querschnittlahmung verbunden ist, ist der volkswirtschaftliche Verlust betrachtlich. Querschnittlahmung ist im traditionellen Sinne medizinisch nicht heilbar, da das bei der Verletzung zerstorte Ruckenmark
Este trabajo presenta una metodologia para la extraccion de la actividad respiratoria derivada de... more Este trabajo presenta una metodologia para la extraccion de la actividad respiratoria derivada de un ECG (EDR, por sus siglas en ingles), basado en el enfoque de amplitud modulada (AM). Esto permite redefinir las metodologias actuales para obtener una senal EDR mas continua, con altos factores de correlacion y un retraso menor entre la EDR y la actividad respiratoria. Se implementaron dos algoritmos: uno utilizando la modulacion de la amplitud del pico R (EDRAM) y el otro aplicando un filtro paso-banda en el espectro de frecuencia de la respiracion. A diferencia de otros trabajos en la literatura, se utilizan filtros convencionales de bajo orden pero sin sacrificar el factor de correlacion (0.76 y 0.67) y manteniendo un retardo de ∼0.27s (con EDRAM) en un ciclo de ∼6s. Se realizo una prueba de robustez, donde se muestra una tolerancia a ruido blanco de hasta un 20% del valor maximo antes de que el factor de correlacion bajara considerablemente. El algoritmo EDRAM se aplico con exito...
Glaucoma is the second cause of world blindness after cataract. It predominantly occurs as open a... more Glaucoma is the second cause of world blindness after cataract. It predominantly occurs as open angle followed by angle closure glaucoma. Since it is silent, chronic disease with no clinical signs at the beginning of illness, it is often undiagnosed and underestimated. Prevention by early screening by gonioscopy has a great potential towards precluding the disease. Additively manufactured human eye model is a great avenue for gonioscopy training as a substitute to the currently used animal models.
Purpose: We hypothesised that intercarpal K-wire fixation of adjacent carpal bones would reduce t... more Purpose: We hypothesised that intercarpal K-wire fixation of adjacent carpal bones would reduce torque and lever force within a fractured scaphoid bone. Methods: In eight cadaver wrists, a scaphoid osteotomy was stabilised using a locking nail, which also functioned as a sensor to measure isometric torque and lever forces between the fragments. The wrist was moved through 80% of full range of motion (ROM) to generate torque and force within the scaphoid. Testing was performed with and without loading of the wrist and K-wire stabilisation of the adjacent carpal bones. Results: Average torque and lever force values were 49.6 ± 25.1 Nmm and 3.5 ± 0.9 N during extension and 41 ± 26.7 Nmm and 8.1 ± 2.8 N during flexion. Torque and lever force did not depend on scaphoid size, individual wrist ROM, or deviations of the sensor versus the anatomic axis. K-wire fixation did not produce significant changes in average torque and lever force values except with wrist radial abduction (P = 0.0485). Other than wrist extension, torque direction was not predictable. In unstable scaphoid fractures, we suggest securing rotational stability with selected implants for functional postoperative care. Wrist ROM within 20% extension and radial abduction to 50% flexion limit torque and lever force exacerbation between scaphoid fragments.
Purpose This paper describes a first attempt to quantify LEMG data based on turn number calculati... more Purpose This paper describes a first attempt to quantify LEMG data based on turn number calculation. The results obtained for both healthy and ailing thyroarytenoid (TA) muscles of patients with unilateral vocal fold immobility (UVFI) were compared with the respective qualitative evaluation concerning volitional activity to determine whether the two types of analyses deliver similar results. Methods LEMG data obtained from 44 adults with UVFI were considered for the study. Semiquantitative evaluation of TA volitional activity and turn number were assessed for the ailing and the healthy TA and the difference in percentage was calculated. Paired data were compared with the Wilcoxon signed-rank test. The volitional activity assessment and the turn number evaluation were compared with the Kruskal–Wallis test, and their relationship was tested with the Kendall rank correlation. Results Datasets of 27 patients were considered compatible with turns/s calculation. The results showed that co...
The aim of this prospective study was to examine the effects of transcutaneous functional electri... more The aim of this prospective study was to examine the effects of transcutaneous functional electrical stimulation (FES) in a group of elderly women with presbyphonia. Study Design: Prospective randomized study. Methods: Fourteen participants were enrolled prospectively and attributed randomly to two different treatment groups, where one group (n = 7) received 8 weeks of training (5 days a week), whereas the other group (n = 7) received 4 weeks of ineffective stimulation, followed by 4 weeks of effective training. Stimulation protocols were established during baseline examination and confirmed with endoscopy to ensure a glottal reaction. Numerous acoustical, vocal, patient-centered, and respiratory parameters were obtained at several time points. Results: Neither 4 weeks nor 8 weeks of functional electrical transcutaneous stimulation led to changes of vocal, acoustical, or respiratory parameters, apart from patient-centered items (Voice Handicap Index 12, Voice-Related Quality of Life), which improved over time. However, there were no differences between the two arms for both items. Conclusions: Transcutaneous FES over 4 weeks and 8 weeks did not lead to significantly improved objective voice and acoustical parameters, which could be caused by the fact that the muscles of interest cannot be targeted specifically enough. However, we found a significant improvement of subjective voice perception and voice-related quality of life in both groups. We explain this finding with an observer-expectancy effect secondary to the very time-consuming and elaborate study procedures.
Predicting pathologic fractures in femora with metastatic lesions remains a clinical challenge. C... more Predicting pathologic fractures in femora with metastatic lesions remains a clinical challenge. Currently used guidelines are inaccurate, especially to predict non-impeding fractures. This study evaluated the ability of a nonlinear quantitative computed tomography (QCT)-based homogenized voxel finite element (hvFE) model to predict patient-specific pathologic fractures. The hvFE model was generated highly automated from QCT images of human femora. The femora were previously loaded in a one-legged stance setup in order to assess stiffness, failure load, and fracture location. One femur of each pair was tested in its intact state, while the contralateral femur included a simulated lesion on either the superolateral- or the inferomedial femoral neck. The hvFE model predictions of the stiffness (0.47 < R2 < 0.94), failure load (0.77 < R2 < 0.98), and exact fracture location (68%) were in good agreement with the experimental data. However, the model underestimated the failure...
Current Directions in Biomedical Engineering, 2016
Neuromodulation using electrical stimulation is able to enhance motor control of individuals suff... more Neuromodulation using electrical stimulation is able to enhance motor control of individuals suffering an upper motor neuron disorder. This work examined the effect of sustained electrical stimulation to modify spasticity in the leg muscles. We applied transcutaneous spinal cord stimulation with a pulse rate of 50 Hz for 30 min. The subjects were assessed before and after the intervention using in a pendulum test setup. The motion of the free swinging leg was acquired through video tracking and goniometer measurements. The quantification was done through the R2n index which shows consistency identifying the spasticity levels. In all incomplete SCI subjects having severe spasticity, the results show that electrical stimulation is effective to modify the increased muscle tone.
Long-term permanent denervation (LT-PD) induces severe atrophy of skeletal muscle accompanied by ... more Long-term permanent denervation (LT-PD) induces severe atrophy of skeletal muscle accompanied by apoptotic loss of myonuclei. Morphologic characteristics of the long-term denervated muscle suggest that the original fibers are lost and those seen are the results of repeated cycles of cell death and regeneration. Myoblasts and myotubes express peculiar myosins. Light and heavy chains of embryonic myosin are sensitive indicators of myogenic events in adult muscles. Electrical stimulation of permanent denervated muscle increases the mean size of the myofibers, maintains the sarcomeres and possibly prevents secondary degeneration and apoptosis/necrosis. Mechanisms underlying the recruitment of satellite cells for regenerative or hypertrophic processes have not been established, but cytokine interactions among macrophages and satellite cells seem to be essential. Here we show that long-term denervated muscles increase in size and change their myosin content after full regeneration is induced by bupivacaine treatment. After transient expression of embryonic myosin, fast myosins prevail in all the experimental muscles. In spite of a severe atrophy (around 90%), ten days after injury the regenerated muscles have twice the area at the muscle belly of the respective long-term denervated muscles. Since satellite cells activity is required for extreme hypertrophy of overloaded adult muscles or eutrophy after severe atrophy in recovering muscles, positive regulation of activation, division and fusion of myoblasts could be an important tool to understand limits of recovery of neurogenic muscle myopathies by functional electrical stimulation (FES). Pilot studies in humans show that standing up with denervated muscles using functional electrical stimulation is a reality in permanent complete denervation.
✓ The left sciatic nerve of 36 rats was exposed and four ring-shaped stainless steel wire electro... more ✓ The left sciatic nerve of 36 rats was exposed and four ring-shaped stainless steel wire electrodes were sutured to the epineurium of each nerve in the same manner as performed clinically for “carousel stimulation” in man. The rats were sacrificed 10 days (Group 1), 3 weeks (Group 2), or 3 months (Group 3) after implantation. The electrodes were excised, the nerves were embedded in Epon, and semithin sections were obtained for histological and planimetric assessment of lesions caused by the epineurially sutured electrodes. The right sciatic nerves served as controls. The total area of neural tissue within the perineurium was determined at three levels: at the site of the electrodes, 8 mm proximal, and 8 mm distal. The area of neural tissue damaged by the surgical procedure was expressed as a percentage of the total area. In Group 1, nine of 12 nerves showed lesions ranging from 0.39% to 25.39% of the total area of neural tissue, in Group 2 eight of 11 sciatic nerves showed lesions ...
Journal of Neuropathology & Experimental Neurology, 2014
The histologic features of aging muscle suggest that denervation contributes to atrophy, that imm... more The histologic features of aging muscle suggest that denervation contributes to atrophy, that immobility accelerates the process, and that routine exercise may protect against loss of motor units and muscle tissue. Here, we compared muscle biopsies from sedentary and physically active seniors and found that seniors with a long history of high-level recreational activity up to the time of muscle biopsy had 1) lower loss of muscle strength versus young men (32% loss in physically active vs 51% loss in sedentary seniors); 2) fewer small angulated (denervated) myofibers; 3) a higher percentage of fiber-type groups (reinnervated muscle fibers) that were almost exclusive of the slow type; and 4) sparse normal-size muscle fibers coexpressing fast and slow myosin heavy chains, which is not compatible with exercise-driven muscle-type transformation. The biopsies from the old physically active seniors varied from sparse fiber-type groupings to almost fully transformed muscle, suggesting that coexpressing fibers appear to fill gaps. Altogether, the data show that long-term physical activity promotes reinnervation of muscle fibers and suggest that decades of high-level exercise allow the body to adapt to age-related denervation by saving otherwise lost muscle fibers through selective recruitment to slow motor units. These effects on size and structure of myofibers may delay functional decline in late aging. Trial registration: ClinicalTrials.gov (NCT01679977).
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Papers by Winfried Mayr