Ursula S Hofstoetter

Ursula S Hofstoetter
Medical University of Vienna | MedUni Vienna · Center for Medical Physics and Biomedical Engineering

PhD

About

55
Publications
19,452
Reads
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1,719
Citations
Citations since 2017
20 Research Items
1366 Citations
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20172018201920202021202220230100200300
Additional affiliations
August 2011 - present
Medical University of Vienna
Position
  • Human motor control of locomotion
January 2008 - July 2011
TU Wien
Position
  • Human motor control of locomotion

Publications

Publications (55)
Article
Full-text available
Recent studies of epidural electrical spinal cord stimulation have shown the enabling and, in some cases, the recovery of motor functions thought to be irreversibly lost due to severe spinal cord injury [...]
Article
Full-text available
Transcutaneous spinal cord stimulation (tSCS) is a promising intervention that can benefit spasticity control and augment voluntary movement in spinal cord injury (SCI) and multiple sclerosis. Current applications require expert knowledge and rely on the thorough visual analysis of elec-tromyographic (EMG) responses from lower-limb muscles to optim...
Article
Full-text available
Transcutaneous spinal cord stimulation is a non-invasive method for neuromodulation of sensorimotor function. Its main mechanism of action results from the activation of afferent fibers in the posterior roots—the same structures as targeted by epidural stimulation. Here, we investigated the influence of sagittal spine alignment on the capacity of t...
Article
Full-text available
Gait dysfunction and spasticity are common debilitating consequences of multiple sclerosis (MS). Improvements of these motor impairments by lumbar transcutaneous spinal cord stimulation (tSCS) have been demonstrated in spinal cord injury. Here, we explored for the first time the motor effects of lumbar tSCS applied at 50 Hz for 30 min in 16 individ...
Chapter
Recent studies combining spinal cord stimulation (SCS) with intense neurorehabilitation training have demonstrated unprecedented improvements of motor function in individuals with chronic, severe spinal cord injury (SCI). Invasive and non-invasive methods for SCS have emerged, all with the goal to augment functional activity of spared spinal circui...
Article
Full-text available
Epidural electrical stimulation (EES) applied over the human lumbosacral spinal cord provides access to afferent fibers from virtually all lower-extremity nerves. These afferents connect to spinal networks that play a pivotal role in the control of locomotion. Studying EES-evoked responses mediated through these networks can identify some of their...
Article
Full-text available
Epidural electrical stimulation of the spinal cord is an emergent strategy for the neurological recovery of lower-extremity motor function. Motoneuron pools are thought to be recruited by stimulation of posterior roots. Here, we linked electromyographic data of epidurally evoked lower-extremity responses of 34 individuals with upper motoneuron diso...
Article
Full-text available
Deficient ankle control after incomplete spinal cord injury (iSCI) often accentuates walking impairments. Transcutaneous electrical spinal cord stimulation (tSCS) has been shown to augment locomotor activity after iSCI, presumably due to modulation of spinal excitability. However, the effects of possible excitability modulations induced by tSCS on...
Article
Full-text available
Epidural spinal cord stimulation (SCS) is currently regarded as a breakthrough procedure for enabling movement after spinal cord injury (SCI), yet one of its original applications was for spinal spasticity. An emergent method that activates similar target neural structures noninvasively is transcutaneous SCS. Its clinical value for spasticity contr...
Article
Full-text available
Posterior root-muscle (PRM) reflexes are short-latency spinal reflexes evoked by epidural or transcutaneous spinal cord stimulation (SCS) in clinical and physiological studies. PRM reflexes share key physiological characteristics with the H reflex elicited by electrical stimulation of large-diameter muscle spindle afferents in the tibial nerve. Her...
Conference Paper
Full-text available
Transcutaneous spinal cord stimulation (tSCS) is a promising approach for the restoration of motor function after spinal cord injury. Yet, determining suitable electrode locations to ensure specific stimulation of target structures can be tedious due to the variability in individual patients. For the activation of afferent fibers associated with up...
Article
Full-text available
Epidural electrical stimulation of the lumbar spinal cord is currently regaining momentum as a neuromodulation intervention in spinal cord injury (SCI) to modify dysregulated sensorimotor functions and augment residual motor capacity. There is ample evidence that it engages spinal circuits through the electrical stimulation of large-to-medium diame...
Data
Individual latencies and peak-to-peak amplitudes (mean ± SD) of responses to single-pulse transcutaneous SCS applied with respective common threshold intensities. (PDF)
Data
Individual latencies and peak-to-peak amplitudes (mean ± SD) of responses to 2-Hz epidural SCS applied with respective common threshold intensities. (PDF)
Data
Threshold intensities to evoked muscle twitches in the various leg muscles normalized to the respective individually identified lowest response threshold. (PDF)
Data
Supplementary experiments confirming the effective phase of the biphasic rectangular stimulation pulses applied through transcutaneous lumbar SCS. Biphasic, symmetric rectangular pulses were applied such that the paraspinal electrodes acted as the anode for the first and the cathode for the second phase of the pulse with reference to the abdominal...
Data
Average latencies and peak-to-peak amplitudes (± SE) of responses to single-pulse transcutaneous SCS as well as 2-Hz epidural SCS applied with respective common threshold intensities. (PDF)
Chapter
Epidural spinal cord stimulation has a long history of application as a neuromodulation method for the relief of intractable pain and for improving motor control in various motor disorders. In spinal cord injury specifically, epidural stimulation of the lumbar spinal cord can effectively control severe and diffuse spasticity, without further deteri...
Article
The ability of dedicated spinal circuits, referred to as central pattern generators (CPGs), to produce the basic rhythm and neural activation patterns underlying locomotion can be demonstrated under specific experimental conditions in reduced animal preparations. The existence of CPGs in humans is a matter of debate. Equally elusive is the contribu...
Article
The mammalian lumbar spinal cord experimentally isolated from supraspinal and afferent feedback input remains capable of expressing some basic locomotor function when appropriately stimulated. This ability has been attributed to spinal neural circuits referred to as central pattern generators (CPGs). In individuals with a severe spinal cord injury,...
Article
Full-text available
The human lumbosacral spinal circuitry can generate rhythmic motor output in response to different types of inputs after motor-complete spinal cord injury. To explore spinal rhythm generating mechanisms recruited by phasic step-related sensory feedback and tonic posterior root stimulation when provided alone or in combination. We studied stepping i...
Article
Severe spinal cord injury is a devastating condition, tearing apart long white matter tracts and causing paralysis and disability of body functions below the lesion. But caudal to most injuries, the majority of neurons forming the distributed propriospinal system, the localized gray matter spinal interneuronal circuitry, and spinal motoneuron popul...
Article
Full-text available
Epidural spinal cord stimulation has a long history of application for improving motor control in spinal cord injury. This review focuses on its resurgence following the progress made in understanding the underlying neurophysiological mechanisms and on recent reports of its augmentative effects upon otherwise subfunctional volitional motor control....
Article
Full-text available
Transcutaneous stimulation of the human lumbosacral spinal cord is used to evoke spinal reflexes and to neuromodulate altered sensorimotor function following spinal cord injury. Both applications require the reliable stimulation of afferent posterior root fibers. Yet under certain circumstances, efferent anterior root fibers can be co-activated. We...
Article
Full-text available
Interest in transcutaneous electrical stimulation of the lumbosacral spinal cord is increasing in human electrophysiological and clinical studies. The stimulation effects on lower limb muscles depend on the depolarization of segmentally organized posterior root afferents and, thus, the rostro-caudal stimulation site. In previous studies, selective...
Article
Full-text available
The level of sustainable excitability within lumbar spinal cord circuitries is one of the factors deter- mining the functional outcome of locomotor therapy after motor-incomplete spinal cord injury. Here, we present initial data using noninvasive transcutaneous lumbar spinal cord stimulation (tSCS) to modulate this central state of excitability dur...
Article
Full-text available
In individuals with motor-complete spinal cord injury, epidural stimulation of the lumbosacral spinal cord at 2 Hz evokes unmodulated reflexes in the lower limbs, while stimulation at 22-60 Hz can generate rhythmic burst-like activity. Here, we elaborated on an output pattern emerging at transitional stimulation frequencies with consecutively elici...
Article
Full-text available
Constant drive provided to the human lumbar spinal cord by epidural electrical stimulation can cause local neural circuits to generate rhythmic motor outputs to lower limb muscles in people paralysed by spinal cord injury. Epidural spinal cord stimulation thus allows the study of spinal rhythm and pattern generating circuits without their configura...
Chapter
Full-text available
Transcutaneous spinal cord stimulation (SCS) is a non-invasive method to electrically stimulate afferent structures of the human lumbar spinal cord. These are the same neural targets as predominantly activated by epidural implants. Biophysical principles derived from computer simulations contributed to the identification of the directly activated n...
Chapter
Full-text available
Finite element modeling is an important computational tool in neural engineering to simulate neural excitation with implanted electrodes or with surface electrodes. Besides its importance for analyzing artificially generated neural activities, e.g., in the spinal cord, this technique is useful to interpret recorded electrical biosignals generated b...
Chapter
Full-text available
Paraspinal magnetic and electrical stimulation target deep neural structures within the vertebral canal and in-between neighboring vertebrae from a distance of several centimeters, either with magnetic coils or skin electrodes. The principal mechanism of stimulation at the neuronal level is the same for magnetic and electrical stimulation and is gi...
Article
Full-text available
Transcutaneous electrical spinal cord stimulation is a non-invasive method to stimulate afferent structures connected to the human spinal cord. Here, computer simulations are presented that aim at shedding light on why distant skin electrodes selectively activate specific groups of afferent fibers localized in the spinal canal and whether other neu...
Article
Full-text available
Lumbar posterior roots in humans can be activated by transcutaneous electrical spinal cord stimulation (tSCS). This method employs paravertebral stimulation and can be used to control spasticity and modify gait patterns in people with upper motor neuron dysfunctions. Furthermore, when single stimuli are applied reflexes are elicited in all lower li...
Article
Full-text available
Epidural spinal cord stimulation can produce rhythmic motor output to the lower limbs of motor complete spinal cord injury people. The electromyographically recorded activity consists of a series of modulated stimulus time-related compound muscle action potentials (CMAPs). Here, we investigate phase dependent modification of the CMAP latencies and...
Article
Full-text available
Non-patterned electrical spinal cord stimulation (SCS) via epidural electrodes can activate neural circuits involved in lower-limb motor control in individuals with spinal cord injury (SCI), and generate automatic, rhythmic flexion-extension movements in the paralyzed lower limbs. Here, we studied whether SCS can increase the excitability of locomo...
Article
Full-text available
Independent studies have shown that the human lumbar spinal networks below a complete spinal cord injury can produce rhythmic motor outputs in response to step-related sensory feedback or sustained electrical spinal cord stimulation (SCS). Here we present our current studies applying lumbar SCS in motor-complete spinal cord injured (SCI) individual...
Article
Full-text available
Posterior root-muscle (PRM) reflexes can be elicited by epidural as well as recently also transcutaneous electrical stimulation of the lumbar spinal cord. We tested the selectivity of transcutaneous spinal cord stimulation by eliciting PRM reflexes and recording the compound muscle action potentials of the thigh and shank. The stimulation set-up co...
Data
Full-text available
Transcutaneous stimulation of the human lumbar spinal cord: Facilitating locomotor output in spinal cord injury The lumbar spinal cord contains neural circuitry to generate motor behaviors like stepping which can be activated by tonic stimulation of supraspinal centers in animal models. Tonic activation of lumbar afferent structures with epidural...
Article
Full-text available
The concept of the neural control of human locomotion has undergone changes in the past decades. In spite of the encephalization and the erect, bipedal mode of walking, independent observations imply that unperturbed locomotor patterns can be generated by similar spinal neural circuits as in other vertebrates [1,2]. However, little is known about t...
Article
Full-text available
Context/objective: To examine the effects of transcutaneous spinal cord stimulation (tSCS) on lower-limb spasticity. Interventional pilot study to produce preliminary data. Department of Physical Medicine and Rehabilitation, Wilhelminenspital, Vienna, Austria. Three subjects with chronic motor-incomplete spinal cord injury (SCI) who could walk ≥10...
Chapter
Full-text available
The recent years brought a growing awareness for the existence of complex neuronal structures within the spinal cord that act as movement controllers. The presented pilot study addresses an extension of pure non-invasive spinal cord stimulation by adding an afferent input from electrically stimulated peripheral nerve. The goal was to assess electro...
Article
Full-text available
One consequence of central nervous system injury or disease is the impairment of neural control of movement, resulting in spasticity and paralysis. To enhance recovery, restorative neurology procedures modify altered, yet preserved nervous system function. This review focuses on functional electrical stimulation (FES) and spinal cord stimulation (S...
Chapter
A method for transcutaneous spinal cord stimulation that can be used for noninvasive investigations of lumbar neural circuits' function in human subjects was recently developed. The same technique can be applied as a neuroaugmentative method for the control of spinal spasticity and the enhancement of the neural control of locomotion after spinal co...
Article
Full-text available
Stimulation of different spinal cord segments in humans is a widely developed clinical practice for modification of pain, altered sensation, and movement. The human lumbar cord has become a target for modification of motor control by epidural and, more recently, by transcutaneous spinal cord stimulation. Posterior columns of the lumbar spinal cord...
Article
Full-text available
Human lumbar spinal cord networks controlling stepping and standing can be activated through posterior root stimulation using implanted electrodes. A new stimulation method utilizing surface electrodes has been shown to excite lumbar posterior root fibers similarly as with implants, an unexpected finding considering the distance to these target neu...
Article
Purpose: The maintenance of body posture in humans during the execution of postural and volitional tasks relies on dynamically adjusted, continuous motor coordination. The goal of the present study was to test the underlying sensory-motor control mechanisms by assessing task-dependent modifications of short-latency spinal reflexes associated with t...
Article
Purpose: The present work describes electrophysiological methods for assessing spinal neuronal circuits’ activity in humans. Lumbosacral evoked potentials (LSEP): Electrical stimulation of primary afferents within the tibial nerve in humans elicits the H reflex that is electromyographically recorded from the calf muscle. The neuronal activity alon...
Article
Full-text available
In this report we shall review the finding that selective stimulation of tibial nerve large afferents and selective stimulation of lumbar sacral afferents to the spinal cord can elicit modification of motor output only by changing of the rate of the train of stimuli without changing the stimulus strength or site of stimulation. After a brief descri...
Article
Dynamic task-dependent regulation of reflexes controlled by the central nervous system plays an integral part in neurocontrol of locomotion. Such modifications of sensory-motor transmission can be studied by conditioning a test reflex with specific motor tasks. To elicit short-latency test reflexes, we applied a novel transcutaneous spinal cord sti...

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Project (1)
Project
Recent research of epidural and transcutaneous electrical spinal cord stimulation has demonstrated unprecedented improvements in motor function thought to be irreversibly lost due to chronic, severe spinal cord injury. Studies in parallel assess these methods for spasticity management as an alternative to medications that are often accompanied by deleterious side effects. As a noninvasive intervention, transcutaneous spinal cord stimulation holds the great potential to find its way into wide clinical application. Its firm establishment and lasting acceptance as clinical practice in spinal cord injury will not only hinge on the demonstration of safety and efficacy, but also on the delineation of a conceptual framework of the underlying physiological mechanisms. This will also require advancing our understanding of immediate and temporary effects of transcutaneous spinal cord stimulation on neuronal circuits in the intact and injured spinal cord. The purpose of the present Special Issue is to bring together peers in the field to share—and eventually fuse—their pertinent research into current neurorehabilitation practice by providing a clinical perspective and insights into underlying mechanisms. Guest Editors:Dr. Ursula S. Hofstoetter & Dr. Karen Minassian Website: https://www.mdpi.com/journal/jcm/special_issues/Spinal_Cord_Injury Deadline for manuscript submissions: 1 July 2021 LinkedIn: JCM@mdpi.com