scholarly journals Low-Intensity and Short-Duration Continuous Cervical Transcutaneous Spinal Cord Stimulation Intervention Does Not Prime the Corticospinal and Spinal Reflex Pathways in Able-Bodied Subjects

2021 ◽  
Vol 10 (16) ◽  
pp. 3633
Author(s):  
Atsushi Sasaki ◽  
Roberto M. de Freitas ◽  
Dimitry G. Sayenko ◽  
Yohei Masugi ◽  
Taishin Nomura ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Short Duration ◽  
Upper Limb ◽  
Spinal Cord Stimulation ◽  
Spinal Reflex ◽  
Therapeutic Effects ◽  
Low Intensity ◽  
Reflex Excitability ◽  
Cord Injury ◽  
Transcutaneous Spinal Cord Stimulation

Cervical transcutaneous spinal cord stimulation (tSCS) has been utilized in applications for improving upper-limb sensory and motor function in patients with spinal cord injury. Although therapeutic effects of continuous cervical tSCS interventions have been reported, neurophysiological mechanisms remain largely unexplored. Specifically, it is not clear whether sub-threshold intensity and 10-min duration continuous cervical tSCS intervention can affect the central nervous system excitability. Therefore, the purpose of this study was to investigate effects of sub-motor-threshold 10-min continuous cervical tSCS applied at rest on the corticospinal and spinal reflex circuit in ten able-bodied individuals. Neurophysiological assessments were conducted to investigate (1) corticospinal excitability via transcranial magnetic stimulation applied on the primary motor cortex to evoke motor-evoked potentials (MEPs) and (2) spinal reflex excitability via single-pulse tSCS applied at the cervical level to evoke posterior root muscle (PRM) reflexes. Measurements were recorded from multiple upper-limb muscles before, during, and after the intervention. Our results showed that low-intensity and short-duration continuous cervical tSCS intervention applied at rest did not significantly affect corticospinal and spinal reflex excitability. The stimulation duration and/or intensity, as well as other stimulating parameters selection, may therefore be critical for inducing neuromodulatory effects during cervical tSCS.

scholarly journals Successful application of burst spinal cord stimulation for refractory upper limb pain: a case series

2021 ◽  
Vol 49 (3) ◽  
pp. 030006052110040
Author(s):  
Kuen Su Lee ◽  
Yoo Kyung Jang ◽  
Gene Hyun Park ◽  
In Jae Jun ◽  
Jae Chul Koh
Keyword(s):  
Spinal Cord ◽  
Upper Limb ◽  
Spinal Cord Stimulation ◽  
Therapeutic Potential ◽  
Case Series ◽  
Limb Amputation ◽  
Intractable Pain ◽  
Limb Pain ◽  
Cord Injury ◽  
Upper Limb Pain

Spinal cord stimulation (SCS) has been used to treat sustained pain that is intractable despite various types of treatment. However, conventional tonic waveform SCS has not shown promising outcomes for spinal cord injury (SCI) or postamputation pain. The pain signal mechanisms of burst waveforms are different to those of conventional tonic waveforms, but few reports have presented the therapeutic potential of burst waveforms for the abovementioned indications. This current case report describes two patients with refractory upper limb pain after SCI and upper limb amputation that were treated with burst waveform SCS. While the patients could not obtain sufficient therapeutic effect with conventional tonic waveforms, the burst waveforms provided better pain reduction with less discomfort. However, further studies are necessary to better clarify the mechanisms and efficacy of burst waveform SCS in patients with intractable pain.

scholarly journals Modification of spasticity by transcutaneous spinal cord stimulation in individuals with incomplete spinal cord injury

2013 ◽  
Vol 37 (2) ◽  
pp. 202-211 ◽  
Author(s):  
Ursula S. Hofstoetter ◽  
William B. McKay ◽  
Keith E. Tansey ◽  
Winfried Mayr ◽  
Helmut Kern ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Spinal Cord Stimulation ◽  
Incomplete Spinal Cord Injury ◽  
Cord Injury ◽  
Transcutaneous Spinal Cord Stimulation

Selectivity and excitability of upper-limb muscle activation during cervical transcutaneous spinal cord stimulation in humans

2021 ◽  
Author(s):  
Roberto M. de Freitas ◽  
Atsushi Sasaki ◽  
Dimitry G. Sayenko ◽  
Yohei Masugi ◽  
Taishin Nomura ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Upper Limb ◽  
Spinal Cord Stimulation ◽  
Muscle Activation ◽  
Anterior Neck ◽  
Hand Muscles ◽  
Ia Afferents ◽  
Arm Muscles ◽  
Muscle Responses ◽  
Transcutaneous Spinal Cord Stimulation

Cervical transcutaneous spinal cord stimulation (tSCS) efficacy for rehabilitation of upper-limb motor function was suggested to depend on recruitment of Ia afferents. However, selectivity and excitability of motor activation with different electrode configurations remains unclear. In this study, activation of upper-limb motor pools was examined with different cathode and anode configurations during cervical tSCS in 10 able-bodied individuals. Muscle responses were measured from six upper-limb muscles simultaneously. First, post-activation depression was confirmed with tSCS paired pulses (50 ms interval) for each cathode configuration (C6, C7, and T1 vertebral levels), with anode on the anterior neck. Selectivity and excitability of activation of the upper-limb motor pools were examined by comparing the recruitment curves (10-100 mA) of first evoked responses across muscles and cathode configurations. Our results showed that hand muscles were preferentially activated when the cathode was placed over T1 compared to the other vertebral levels, while there was no selectivity for proximal arm muscles. Furthermore, higher stimulation intensities were required to activate distal hand muscles than proximal arm muscles, suggesting different excitability thresholds between muscles. In a separate protocol, responses were compared between anode configurations (anterior neck, shoulders, iliac crests, and back), with one selected cathode configuration. The level of discomfort was also assessed. Largest muscle responses were elicited with the anode configuration over the anterior neck, while there were no differences in the discomfort. Our results therefore inform methodological considerations for electrode configuration to help optimize recruitment of Ia afferents during cervical tSCS.

scholarly journals Transcutaneous spinal cord stimulation of the cervical cord modulates lumbar networks

2020 ◽  
Vol 123 (1) ◽  
pp. 158-166 ◽  
Author(s):  
Trevor S. Barss ◽  
Behdad Parhizi ◽  
Vivian K. Mushahwar
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Stimulation ◽  
Cervical Spinal Cord ◽  
H Reflex ◽  
Cervical Cord ◽  
Arm Cycling ◽  
Cord Injury ◽  
Walking Capacity ◽  
Transcutaneous Spinal Cord Stimulation ◽  
Lumbar Cord

It has been established that coordinated arm and leg (A&L) cycling facilitates corticospinal drive and modulation of cervico-lumbar connectivity and ultimately improves overground walking in people with incomplete spinal cord injury or stroke. This study examined the effect of noninvasive transcutaneous spinal cord stimulation (tSCS) on the modulation of cervico-lumbar connectivity. Thirteen neurologically intact adults participated in the study. The excitability of the Hoffmann (H) reflex elicited in the soleus muscle was examined under multiple conditions involving either the arms held in a static position or rhythmic arm cycling while tSCS was applied to either the cervical or lumbar cord. As expected, soleus H-reflex amplitude was significantly suppressed by 19.2% during arm cycling (without tSCS) relative to arms static (without tSCS). Interestingly, tSCS of the cervical cord with arms static significantly suppressed the soleus H-reflex (−22.9%), whereas tSCS over the lumbar cord did not suppress the soleus H-reflex (−3.8%). The combination of arm cycling with cervical or lumbar tSCS did not yield additional suppression of the soleus H-reflex beyond that obtained with arm cycling alone or cervical tSCS alone. The results demonstrate that activation of the cervical spinal cord through both rhythmic arm cycling and tonic tSCS significantly modulates the activity of lumbar networks. This highlights the potential for engaging cervical spinal cord networks through tSCS during rehabilitation interventions to enhance cervico-lumbar connectivity. This connectivity is influential in facilitating improvements in walking function after neurological impairment. NEW & NOTEWORTHY This is the first study to investigate the modulatory effects of transcutaneous spinal cord stimulation (tSCS) on cervico-lumbar connectivity. We report that both rhythmic activation of the cervical spinal cord through arm cycling and tonic activation of the cervical cord through tSCS significantly modulate the activity of lumbar networks. This suggests that engaging cervical spinal cord networks through tSCS during locomotor retraining interventions may not only enhance cervico-lumbar connectivity but also further improve walking capacity.

scholarly journals On the reflex mechanisms of cervical transcutaneous spinal cord stimulation in human subjects

2019 ◽  
Vol 121 (5) ◽  
pp. 1672-1679 ◽  
Author(s):  
Matija Milosevic ◽  
Yohei Masugi ◽  
Atsushi Sasaki ◽  
Dimitry G. Sayenko ◽  
Kimitaka Nakazawa
Keyword(s):  
Spinal Cord ◽  
Muscle Contraction ◽  
Upper Limb ◽  
Spinal Cord Stimulation ◽  
Presynaptic Inhibition ◽  
Tendon Vibration ◽  
Muscle Stretching ◽  
Muscle Tendon Vibration ◽  
Passive Muscle ◽  
Transcutaneous Spinal Cord Stimulation

Transcutaneous and epidural electrical spinal cord stimulation techniques are becoming more valuable as electrophysiological and clinical tools. Recently, remarkable recovery of the upper limb sensorimotor function during cervical spinal stimulation was demonstrated. In the present study, we sought to elucidate the neural mechanisms underlying the effects of transcutaneous spinal cord stimulation (tSCS) of the cervical spine. We hypothesized that cervical tSCS can be used to selectively activate the sensory route entering the spinal cord and transsynaptically converge on upper limb motor pools. To test this hypothesis, we applied cervical tSCS using paired stimuli (homosynaptic depression) and during passive muscle stretching of the wrist flexor (presynaptic inhibition via Ia afferents), voluntary hand muscle contraction (descending facilitation of motoneuron pool), and muscle-tendon vibration of the wrist (presynaptic inhibition via afferent occlusion). Our results demonstrate significant inhibition of the second evoked response during paired stimulus delivery, inhibition of responses during passive muscle stretching and muscle-tendon vibration, and facilitation during voluntary muscle contraction, which share similarities with responses evoked during lumbosacral tSCS. These results indicate that the route of the stimulation current transmission passes via afferents in the dorsal roots through the spinal cord to activate the motor pools and potentially interneuronal networks projecting to upper limb muscles. Using a novel stimulation paradigm, our study is the first to present evidence of the sensory neuronal pathway of the cervical tSCS propagation. Overall, our work demonstrates the utility and sensitivity of cervical tSCS to engage the sensory pathway projecting to the upper limbs. NEW & NOTEWORTHY Despite therapeutic effects that have been demonstrated previously using noninvasive cervical spinal stimulation, it has been unclear whether, and to what degree, the stimulation can activate the sensory afferent system. Our study presents evidence that cervical transcutaneous spinal cord stimulation can engage the sensory pathways and transsynaptically converge on motor pools projecting to upper limb muscles, demonstrating the utility and sensitivity of cervical spinal stimulation for electrophysiological assessments and neurorehabilitation.

scholarly journals Posteroanterior Cervical Transcutaneous Spinal Cord Stimulation: Interactions with Cortical and Peripheral Nerve Stimulation

2021 ◽  
Vol 10 (22) ◽  
pp. 5304
Author(s):  
Jaclyn R. Wecht ◽  
William M. Savage ◽  
Grace O. Famodimu ◽  
Gregory A. Mendez ◽  
Jonah M. Levine ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Motor Cortex ◽  
Motor Neurons ◽  
Nerve Stimulation ◽  
Spinal Cord Stimulation ◽  
Cervical Spinal Cord ◽  
Hand Function ◽  
Median Nerve Stimulation ◽  
Cord Injury ◽  
Transcutaneous Spinal Cord Stimulation

Transcutaneous spinal cord stimulation (TSCS) has demonstrated potential to beneficially modulate spinal cord motor and autonomic circuitry. We are interested in pairing cervical TSCS with other forms of nervous system stimulation to enhance synaptic plasticity in circuits serving hand function. We use a novel configuration for cervical TSCS in which the anode is placed anteriorly over ~C4–C5 and the cathode posteriorly over ~T2–T4. We measured the effects of single pulses of TSCS paired with single pulses of motor cortex or median nerve stimulation timed to arrive at the cervical spinal cord at varying intervals. In 13 participants with and 15 participants without chronic cervical spinal cord injury, we observed that subthreshold TSCS facilitates hand muscle responses to motor cortex stimulation, with a tendency toward greater facilitation when TSCS is timed to arrive at cervical synapses simultaneously or up to 10 milliseconds after cortical stimulus arrival. Single pulses of subthreshold TSCS had no effect on the amplitudes of median H-reflex responses or F-wave responses. These findings support a model in which TSCS paired with appropriately timed cortical stimulation has the potential to facilitate convergent transmission between descending motor circuits, segmental afferents, and spinal motor neurons serving the hand. Studies with larger numbers of participants and repetitively paired cortical and spinal stimulation are needed.

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