A spinal implant device developed by scientists and doctors in Switzerland has enabled three paralyzed men to walk again. The men, aged 30, 35, and 48, participated in a trial conducted by research institute École Polytechnique Fédérale de Lausanne (EPFL) wherein the device was first surgically implanted in the cervical (neck) part of their spines followed by rehabilitative therapy. Within one week, all of the men were able to regain motion in their lower limbs, and after three months, they were able to walk hands-free with hip support in a gravity-assist mechanism.

Spinal cord injury interferes with the cell communication essential in the nervous system for enabling neurological functions. When a human or animal wants to move a limb, the brain sends electrical signals down the spinal cord which trigger, or “innervate”, nerve cells connected to muscles to move as instructed. In the case of severe or complete paralysis, as was the case with the three men treated, the signals from the brain are too weak to reach the areas that are paralyzed. The implant used in the trial provided a targeted boost to the signals used for lower limb movement.

The device, an “implantable pulse generator” which delivers epidural electrical stimulation (EES) to the spinal cord, is commonly used for deep brain stimulation but was modified to enable wireless commands to meet the trial’s needs. To achieve the necessary types of impulses to the spine, researchers studied the bodies’ electrical activity behavior when motion was attempted by participants. That information was used to develop algorithms which would control electrical pulses sent from the device.

As detailed in the research paper reporting the experiments and results for the implant, different types of muscle movements involve different groups of nerve cells being activated. The three men who participated in the trial were able choose the types of motion they wanted to attempt, i.e., standing or walking, via a tablet with a mobile app. The app would then communicate with the implant to direct the types of pulses sent to match the signals for the nerve cell groups associated with the movement desired.

Surprisingly for researchers, the trial also resulted in limited repair of the previously damaged spinal cord nerve connections responsible for participants’ paralysis. One of the participants was even able to walk a few paces without the device’s signals after a few months of therapy. Additionally, the animal portion of the trial showed nerve fibers growing back and connecting to the brain again.

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There are many positive potential treatment developments indicated by the success of this trial, but certain limitations should be noted. First, the electrical pulses cause discomfort for participants and thus can’t be maintained for long periods of time. This initial trial was only able to enable walking for approximately one hour. Second, the treatment carries a high price tag. The cost of the device and therapy together puts the paralysis treatment out of reach for many of its would-be beneficiaries.  As more research continues along with expended trials planned to take place in the next three years, it’s possible for it to be available on a wide scale.