Scientists from Lausanne and Italy have discovered a promising method for reducing muscle spasticity in people affected by an incomplete spinal cord injury. They can thus benefit from techniques aimed at restoring walking.
To restore walking after spinal cord injury, electrically stimulating the spinal cord represents a promising strategy, as recent studies have shown. But for people affected by muscle spasms, stimulation protocols have only limited effectiveness.
An obstacle due to the fact that spasticity induces unpredictable behavior of involuntary muscle rigidity. However, this symptom concerns almost 70% of people suffering from spinal cord injuries, the Federal Polytechnic School of Lausanne (EPFL) said in a press release on Wednesday.
At EPFL, the Università San Raffaele in Milan and the Scuola Sant’Anna in Pisa, scientists have found a way to reduce this muscular spasticity. This involves electrically stimulating the cord, at high frequency, in order to block abnormal muscle contractions, according to this work published in the journal Science Translational Medicine.
Safe and effective procedure
“We found that high-frequency electrical stimulation of the spinal cord, combined with classical low-frequency continuous stimulation, is effective during rehabilitation,” explains Silvestro Micera, professor at EPFL and Scuola Sant’Anna. It counteracts the rigidity and muscle spasms of paralyzed patients and assists them functionally during locomotion.
“It is a safe and effective surgical procedure, which offers new perspectives in the treatment of people affected by severe spinal cord injuries,” adds Pietro Mortini, professor of neurosurgery at the Università San Raffaele. “We plan to extend the indications to various clinical conditions, which we will define in the coming months,” adds the researcher, quoted in the press release.
Electrical stimulation of the spinal cord makes it possible to indirectly reach the motor neurons responsible for muscular movements. Indeed, the posterior part of the cord includes sensory neurons, which in turn communicate with motor neurons.
Hyperreactive circuit
In cases of muscular spasticity, we know that this sensorimotor circuit is hyperreactive: the spinal cord itself is hyperreactive to stimuli, an excellent thing, as this allows for rapid reflexes.
Normally, this hyperreactivity is tempered by the brain, which inhibits motor circuits. However, in patients with spinal cord injury, these messages from the brain are lost, and with them the inhibition mechanism.
By indirectly stimulating motor circuits, scientists were able to establish that high-frequency stimulation is an effective way to stop hyperreactivity, without causing discomfort for the patient. However, further experiments will be required to confirm the potential of this approach, concludes EPFL.
This article was automatically published. Source: ats
