MedUni Vienna: Key mechanisms of action of spinal cord stimulation unveiled
Electrical stimulation of the spinal cord using adhesive electrodes on the skin is becoming increasingly important in the neurorehabilitation of people with spinal cord injury. The method can be used both to increase the mobility and to treat spasticity, which affects around 80 per cent of patients. Studies have already confirmed that transcutaneous spinal stimulation (TSCS) can work. How exactly it works has now been demonstrated for the first time in a research study led by MedUni Vienna. The results published in "Cell Reports Medicine" may help to further establish the procedure in clinical practice.
To gain these insights, the team led by study leader Ursula Hofstötter and first author Karen Minassian from MedUni Vienna's Center for Medical Physics and Biomedical Engineering combined clinical tests with electrophysiological measurements. The researchers analysed specific activity-inhibiting mechanisms in the spinal cord of individuals with spinal cord injury and spasticity before and after a 30-minute TSCS treatment. Comparative data was collected in a control group of volunteers with an intact spinal cord. "Until now, there were only hypotheses about the exact mechanisms of action of electrical spinal cord stimulation," reports Ursula Hofstötter. It has now been shown for the first time that TSCS specifically activates synaptic connections to inhibitory neural circuits in the spinal cord, thereby improving their natural function instead of dampening overall neuronal activity. "We have also shown that the electrical impulses target those neural networks that are associated with the development of spasticity after spinal cord injury," adds Karen Minassian.
Reducing spasticity, increasing mobility
A spinal cord injury damages the spinal cord and the nerve pathways running through it, which control essential processes in the body. In addition to paralysis of the extremities, motor, sensory and autonomic functions can also be impaired. Up to 80 per cent of those affected struggle with spasticity, i.e. a painful increase in muscle tension or muscle spasms, which further restrict the already reduced ability to consciously control movement sequences (voluntary motor control). In addition to physiotherapy and occupational therapy, the usual treatment programme also includes medication. "However, these drugs lack selectivity in their action. This means that they not only inhibit spasticity, but also suppress remaining voluntary motor activity and often result in persistent tiredness and reduced energy," emphasises Ursula Hofstötter.
Like other neuromodulative therapy approaches, spinal cord stimulation is becoming increasingly important as a treatment method in neurorehabilitation. There is no longer any need for surgery; the electrical impulses can be delivered to the spinal cord via adhesive electrodes on the skin. "The method is now also used at renowned international centres, for example in the USA and Switzerland," says Hofstötter. Studies have confirmed that electrical stimulation of the spinal cord can both reduce spasticity and improve voluntary motor control and thus the mobility of people with spinal cord injury. According to the researchers, clarifying the exact mechanisms of action can help to further establish TSCS in clinical practice.
Publication: Cell Reports Medicine
Transcutaneous spinal cord stimulation neuromodulates pre- and postsynaptic inhibition in the control of spinal spasticity.
Karen Minassian, Brigitta Freundl, Peter Lackner and Ursula S. Hofstoetter.
https://www.cell.com/cell-reports-medicine/fulltext/S2666-3791(24)00552-4
The study was funded by the Austrian Science Fund (FWF).
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