scholarly journals Neurophysiology of epidurally evoked spinal cord reflexes in clinically motor-complete posttraumatic spinal cord injury

2021 ◽  
Author(s):  
Jose Luis Vargas Luna ◽  
Justin Brown ◽  
Matthias J. Krenn ◽  
Barry McKay ◽  
Winfried Mayr ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Short Latency ◽  
Low Frequencies ◽  
Complex Behaviour ◽  
Lower Limb Muscles ◽  
Long Latency ◽  
Cord Injury ◽  
Epidural Spinal Cord Stimulation ◽  
Spinal Cord Reflexes

AbstractIncreased 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 components can be observed as direct responses, neuromodulation of monosynaptic responses or driving the muscle activity by themselves, depending on the frequency level. We suggest that the presence of polysynaptic activity could be a potential predictor for appropriate stimulation conditions. This work studies the complex behaviour of spinal circuits deprived of voluntary motor control from the brain and in the absence of any other inputs. This is done by describing the monosynaptic responses, polysynaptic activity, and its interaction through its input–output interaction with sustain stimulation that, unlike single stimuli used to study the reflex pathway, can strongly influence the interneuron circuitry and reveal a broader spectrum of connectivity.

scholarly journals Spasms after spinal cord injury show low-frequency intermuscular coherence

2018 ◽  
Vol 120 (4) ◽  
pp. 1765-1771
Author(s):  
Stefane A. Aguiar ◽  
Stuart N. Baker ◽  
Katie Gant ◽  
Jorge Bohorquez ◽  
Christine K. Thomas
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Lower Limb ◽  
Low Frequency ◽  
Low Frequencies ◽  
First Report ◽  
Lower Limb Muscles ◽  
Cord Injury ◽  
Limb Muscles ◽  
Intermuscular Coherence

Intermuscular coherence allows the investigation of common input to muscle groups. Although beta-band (15–30 Hz) intermuscular coherence is well understood as originating from the cortex, the source of intermuscular coherence at lower frequencies is still unclear. We used a wearable device that recorded electromyographic (EMG) signals during a 24-h period in four lower limb muscles of seven spinal cord injury patients (American Spinal Cord Injury Association impairment scale: A, 6 subjects; B, 1 subject) while they went about their normal daily life activities. We detected natural spasms occurring during these long-lasting recordings and calculated intermuscular coherence between all six possible combinations of muscle pairs. There was significant intermuscular coherence at low frequencies, between 2 and 13 Hz. The most likely source for this was the spinal cord and its peripheral feedback loops, because the spinal lesions in these patients had interrupted connections to supraspinal structures. This is the first report to demonstrate that the spinal cord is capable of producing low-frequency intermuscular coherence with severely reduced or abolished descending drive. NEW & NOTEWORTHY This is the first report to demonstrate that intermuscular coherence between lower limb muscles at low frequencies can be produced by the spinal cord with severely reduced or abolished descending drive.

scholarly journals Effects of a Contusive Spinal Cord Injury on Spinal Motor Neuron Activity and Conduction Time in Rats

2020 ◽  
Author(s):  
Jordan A. Borrell ◽  
Dora Krizsan-Agbas ◽  
Randolph J. Nudo ◽  
Shawn B. Frost
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Spike Activity ◽  
Short Latency ◽  
Neuron Activity ◽  
Emg Activity ◽  
Conduction Time ◽  
Dorsal Midline ◽  
Cord Injury ◽  
Contusion Injury

AbstractObjectiveThe purpose of this study was to determine the effects of spinal cord injury (SCI) on spike activity evoked in the hindlimb spinal cord of the rat from cortical electrical stimulation.ApproachAdult, male, Sprague Dawley rats were randomly assigned to a Healthy or SCI group. SCI rats were given a 175 kDyn dorsal midline contusion injury at the level of the T8 vertebrae. At four weeks post-SCI, intracortical microstimulation (ICMS) was delivered at several sites in the hindlimb motor cortex of anesthetized rats, and evoked neural activity was recorded from corresponding sites throughout the dorsoventral depths of the spinal cord and EMG activity from hindlimb muscles.Main resultsIn healthy rats, post-ICMS spike histograms showed reliable, evoked spike activity during a short-latency epoch 10-12 ms after the initiation of the ICMS pulse train (short). Longer latency spikes occurred between ~20-60 ms, generally following a Gaussian distribution, rising above baseline at time LON, followed by a peak response (Lp), and then falling below baseline at time LOFF. EMG responses occurred between LON and Lp (25-27 ms). In SCI rats, short-latency responses were still present, long-latency responses were disrupted or eliminated, and EMG responses were never evoked. The retention of the short-latency responses indicates that spared descending spinal fibers, most likely via the cortico-reticulospinal pathway, can still depolarize spinal cord motor neurons after a dorsal midline contusion injury.SignificanceThis study provides novel insights into the role of alternate pathways for voluntary control of hindlimb movements after SCI that disrupts the corticospinal tract in the rat.

Immediate effects of spinal cord stimulation in spinal spasticity

1985 ◽  
Vol 62 (4) ◽  
pp. 558-562 ◽  
Author(s):  
Giancarlo Barolat-Romana ◽  
Joel B. Myklebust ◽  
David C. Hemmy ◽  
Barbara Myklebust ◽  
William Wenninger
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Spinal Cord Stimulation ◽  
Content Type ◽  
Clinical Observations ◽  
Cord Injury ◽  
Epidural Spinal Cord Stimulation ◽  
Stimulation System ◽  
Fine Print

✓ Six patients with intractable spasms after spinal cord injury underwent implantation of an epidural spinal cord stimulation system. All the patients experienced good relief postoperatively. In three patients spinal cord stimulation consistently produced immediate inhibition of the spasms. This was evident within less than 1 minute of stimulation. Conversely, the spasms reappeared within less than 1 minute after cessation of the stimulation. The clinical observations were confirmed by polygraphic electromyographic recordings.

scholarly journals Strategies and performances of Functional Electrical Stimulation Cycling using the BerkelBike with Spinal Cord Injury in a competition context (CYBATHLON)

2017 ◽  
Vol 27 (4) ◽  
Author(s):  
Rik Berkelmans ◽  
Billy Woods
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Electrical Stimulation ◽  
Functional Electrical Stimulation ◽  
Lower Limb ◽  
Imperial College ◽  
Surface Electrode ◽  
Arm Cranking ◽  
Lower Limb Muscles ◽  
Cord Injury

The functional electrical stimulation (FES) bicycle race was an event at the Cybathlon, held in Zurich October 2016. BerkelBike BV (The Netherlands) in collaboration with Imperial College London entered a spinal cord injury pilot who had tetraplegia to compete in this event. The BerkelBike Pro is a commercially available FES capable recumbent which is normally driven by the arm- and leg power. The arm cranking part was disabled. Now the tricycle must be driven using the pilots own lower limb muscles through stimulation in accordance with race rules. The bike used during the race was also adapted with a fixed gear for improved efficiency. The pilot who represented this team come second place overall in the event and attained the fastest race time of all pilots who utilised surface electrode FES. Steps can be taken to increase the race efficiency of the BerkelBikes and its FES capabilities even further.

Epidural spinal cord stimulation as an intervention for motor recovery after motor complete spinal cord injury

2021 ◽  
Author(s):  
Jan T Hachmann ◽  
Andrew Yousak ◽  
Josephine J Wallner ◽  
Parag N. Gad ◽  
V. Reggie Edgerton ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Spinal Cord Stimulation ◽  
Large Diameter ◽  
Motor Units ◽  
Clinical Results ◽  
Neural Pathways ◽  
Epidural Stimulation ◽  
Cord Injury ◽  
Epidural Spinal Cord Stimulation

Spinal cord injury (SCI) commonly results in permanent loss of motor, sensory, and autonomic function. Recent clinical studies have shown that epidural spinal cord stimulation may provide a beneficial adjunct for restoring lower extremity and other neurological functions. Herein, we review the recent clinical advances of lumbosacral epidural stimulation for restoration of sensorimotor function in individuals with motor complete SCI and we discuss the putative neural pathways involved in this promising neurorehabilitative approach. We focus on three main sections: review recent clinical results for locomotor restoration in complete SCI; discuss the contemporary understanding of electrical neuromodulation and signal transduction pathways involved in spinal locomotor networks; review current challenges of motor system modulation and future directions towards integrative neurorestoration. The current understanding is that initial depolarization occurs at the level of large diameter dorsal root proprioceptive afferents that when integrated with interneuronal and latent residual supraspinal translesional connections can recruit locomotor centers and augment downstream motor units. Spinal epidural stimulation can initiate excitability changes in spinal networks and supraspinal networks. Different stimulation parameters can facilitate standing or stepping, and it may also have potential for augmenting myriad other sensorimotor and autonomic functions. More comprehensive investigation of the mechanisms that mediate the transformation of dysfunctional spinal networks to higher functional states with a greater focus on integrated systems based control system may reveal the key mechanisms underlying neurological augmentation and motor restoration after severe paralysis.

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