San Raffaele Hospital (Milan, Italy): new, promising results from the first patients implanted with the spinal neurostimulator. A new, high-frequency spinal stimulation protocol gives hope for motor recovery and reduced muscular spasticity

The study, published in Science Translational Medicine, bears the signature of doctors and researchers from the IRCCS San Raffaele Hospital, the Vita-Salute San Raffaele University of Milan and the Scuola Superiore Sant'Anna of Pisa.

MILAN, Jan. 15, 2025 /PRNewswire/ -- A team of doctors and researchers from the IRCCS San Raffaele Hospital and Vita-Salute San Raffaele University of Milan and of bioengineers from the Scuola Superiore Sant'Anna of Pisa, has obtained promising results in the treatment of spinal cord injuries, thanks to an innovative protocol based on high-frequency, epidural electric stimulation. The study, published in Science Translational Medicine, has shown that this technique significantly reduces muscle spasticity and improves motor functions in patients with spinal cord injury.

The research has focused on two patients with incomplete spinal cord injuries that during 2023 had recovered their motor skills. This was possible thanks to the implantation of the spinal cord neurostimulator, a device already used in pain therapy. Researchers have applied targeted, high-frequency stimulations that, together with specific rehabilitation programs, have significantly improved muscular strength, walking ability and motor control of the patients. The applied stimulation protocol has also reduced the pathological reflexes and the involuntary contractions at the basis of muscular spasticity, thus promoting more fluid and natural movements.

Muscle spasticity

Central nervous system diseases, such as traumatic spinal cord injuries that interrupt communication with the brain can cause difficulty in walking, limb paralysis as well as muscle spasticity— that is, the intermittent or sustained activation of muscle contraction leading to involuntary muscular stiffness and spasms. Muscle spasticity significantly reduces motor functions, and affects nearly 70% of patients with spinal cord injury. Recent studies have shown that applying an electrical stimulation to an injured spinal cord is a promising strategy for restoring the ability to walk. Low-frequency stimulation protocols are currently applied to mitigate spasticity, but they have a limited effect in patients suffering from muscle spasms.

The study

The two patients examined in the current study had a traumatic spinal cord injury: in 2023, they had received an innovative implantation of the spinal cord electrostimulator that, after a long period of rehabilitation at the Unit directed by Dr. Sandro Iannaccone, has enabled the recovery of their walking ability. Both patients have shown significant improvements in their functional abilities, and one of them has also walked for 175 meters without active stimulation.

The two patients have participated in an intense rehabilitation program, which has integrated low and high-frequency stimulations with motor exercises. The research team has observed that high-frequency spinal cord stimulation is a safe technique to inhibit pathological hyperreactivity of spinal circuits without causing discomfort in patients.

"Spinal cord is naturally hyperreactive to stimuli. This is necessary to favor normal rapid reflexes. This hyperreactivity is usually balanced by the brain, which inhibits motor circuits when their activation is not required. However, in the case of spinal cord injury, patients lose the inhibitory messages coming from the brain that regulate spinal hyperreactivity – explains Simone Romeni, first author of the study and researcher at the at the IRCCS San Raffaele Hospital  and at the École Polytechnique Federale of Losanna (EPFL) and, who adds – we believe that the frequencies in the order of kiloHertz (much higher than those used in previous studies) applied in our protocol interfere with this pathological spinal hyperactivity, thus inhibiting the transmission to muscles and consequently reducing spasms".

Conclusions

"The spinal cord protocol developed and tested in this study represents a significant example of the extraordinary potential of neuroengineering applied to neurorehabilitation. This first result, thanks to the advantageous collaboration with the colleagues from San Raffaele, lays the basis for the future development of new technologies aimed at improving the quality of life of people with motor disabilities as well as potentiating the use of existing therapeutic opportunities" explains Silvestro Micera, Professor at the Scuola Superiore Sant'Anna and at the Ecole Polytechnique Federale of Losanna (EPFL) and coordinator of the study.

"This is a safe and efficient surgery procedure that offers a new perspective in the treatment of patients suffering from severe spinal cord injuries. The combination of advanced technologies with personalized approaches to rehabilitation offers new perspectives for motor recovery, thus revolutionizing the treatment of spinal injuries, reducing the side effects associated with the pharmacological and surgical therapies currently in use" adds Pietro Mortini, Full Professor of Neurosurgery at the Vita-Salute San Raffaele University and Head of Neurosurgery at the IRCCS San Raffaele Hospital and coordinator of the study.

"The next steps will involve further clinical studies on a higher number of patients, with the aim to confirm the preliminary results. We are planning to extend these indications to different clinical conditions that will be defined in the upcoming months. We are at the beginning of a new, promising era for motor neurorehabilitation. We would like to express our deep gratitude to the patients who have trusted us" concludes Professor Mortini.

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