Patients, doctors and researchers look with great expectations to epidural electrostimulation, a medical technique that could relieve the condition of subjects affected by paralysis due to spinal cord injury. Although it is still relatively rudimentary, the technique is constantly improved thanks to research. A group of scientists have published an article in the magazine Spinal cordproposing a new methodological approach based on distributing stimulation and modular the frequency of electrical impulses, which has provided good results in vitro.
Epidural electrostimulation is a medical technique that has been used for several years to help patients affected by paralysis due to spinal cord injury. It implies implanting electrodes on the roots of the dorsal nerve (which transmit “incoming” sensory “inputs) of the spinal cord below the level of trauma and the application of electrical stimuli of variable intensity and frequency. This technique, which produces or helps produce activation patterns of motor nerves (ventral, outgoing), has shown promising results, and scientists hope that one day it can help paralyzed people, for example, to stand and take some steps, as well as restore control of the sphincter and sexual function.
There is still a long way to go before achieving that goal, and for this reason the scientific community is redoubled the efforts to refine the method. “The majority of the research to date has focused on the materials and technology of the devices. Our study, on the contrary, analyzed the nature and quality of the electrical signal delivered by the electrodes,” explains Giuliano Taccola, researcher at the International School of Advanced Studies (SISSSA) of Trieste and Coordinator of the study. “The question they ask is always the same: how do we get effective motor responses? In this sense, we believe that it is important to better modulate the electrical signal and accurately identify the points where it should be applied.”
“Current techniques consist of applying a high frequency signal in a generalized way. In that way, we obtain a” cumulative “and somewhat undifferentiated stimulation of a group of nerve fibers. What we did was adopt a” multi-site “approach: electrical stimulation is applied in different points of the circuit,” he explains. In the study, Taccola and his colleagues worked with spinal neuronal circuits prepared in vitro. This allowed them to control the simulation sites with great care and record the responses of the network with great precision.
“The other novelty we present was to use a low frequency stimulation.” The combination of these two factors (signal frequency and multiple sites) produced very efficient motor patterns. “With our work, we have defined a new stimulation strategy of the spinal cord stimulation for the activation of motor neurons, which can also be imported in many of the stimulators that are used in clinical environments.”
About this neurological research
The first author of the study, carried out in collaboration with the laboratory of the spine of the Institute of Physical Medicine and Rehabilitation (IMFR) of the Gervasutta Hospital in UDINE (where the experimental data was collected) and the Luven Catholic University in Belgian, is a dose of Francesco, a young doctoral student in Sissa.
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Fountain: Sissa
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Original research: Abstract For “low frequency electrostimulation, staggered multisitio effectively induces locomotive patterns in the spinal cord of isolated rat” by dose F, the Deumenses, p forged and g taccola in in Spinal cord. Posted online on June 23, 2015 DOI: 10.1038/SC.2015.106
Abstract
Multiple low frequency steady electrostimulation effectively induces locomotive patterns in the spinal cord of isolated rat
Study design: Experimental study in animals.
Goals: Epidural stimulation has been used to activate locomotive patterns after spinal lesion and typically uses synchronous trains of high frequency stimuli delivered directly to the dorsal cord, thus recruiting multiple afferent nerve roots. Here we investigate how spinal locomotive networks integrate afferent entry and address if frequency coding is more important than amplitude to activate locomotive patterns.
Configuration: Italy and Belgium.
Methods: To investigate the importance of the intensity and frequency of the entry into obtaining the locomotive activity, we use spinal medulla of isolated neonatal rat to record episodes of fictitious locomotion (FL) induced by the electrical stimulation of simple and multiple dorsal roots (DR), which use different stimulating protocols.
Results: FL was efficiently induced through a staggered supply (delays of 0.5 to 2 s) of low frequency pulse trains (0.33 and 0.67 Hz) to three dr at sufficient intensities to activate the reflections of the ventral root. The delivery of the same trains to a single dr or synchronically to multiple DR remained ineffective. The staggered trains of several sites were more efficient than the delivery of random pulse. The weak trains delivered simultaneously to the dres failed to obtain fl. The restoration of the locomotor rhythm occurred with individual pulses applied to several distant dr.
Conclusion: Electrical stimulation recruited spinal networks that generate locomotive programs when the pulses were delivered to multiple low frequency sites. This finding could help design new protocols to optimize the increasingly common use of implantable epidural matrices to treat spinal dysfunctions.
“Steery ELECTRO -SCREENED MULTIPLE ELECTROESTIMULATION effectively induces locomotive patterns in the spinal cord of isolated rat” by dose F, the Deumenses, P forget and g taccola in Spinal cord. Published online on June 23, 2015 Doi: 10.1038/SC.2015.106
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