Spinal Stimulation Opens Door to Treating Stroke Survivors With Partial Paralysis

With epidural electrical stimulation (EES) of the cervical spine, researchers successfully improved arm and hand mobility in two stroke patients who otherwise had no treatment available for their chronic hemiparesis.

Continuous spinal cord stimulation (SCS), provided through two surgically implanted leads, improved strength, speed, and functional movements in the first two patients of this ongoing study, reported Marco Capogrosso, PhD, a biomedical engineer at the University of Pittsburgh, and colleagues.

The two stroke patients attempted movements from day 1 without training. Within 30 days, they were able to fully open and close their fist, lift their arm above their head, and use a fork and knife to cut food for the first time in years, Capogrosso and team noted in Nature Medicine.

"We discovered that electrical stimulation of specific spinal cord regions enables patients to move their arm in ways that they are not able to do without the stimulation. Perhaps even more interesting, we found that after a few weeks of use, some of these improvements endure when the stimulation is switched off, indicating exciting avenues for the future of stroke therapies," said Capogrosso in a press release.

The group's goal is for a permanent implant to be continuously switched on except for battery replacement every couple of years or so, according to co-author Elvira Pirondini, PhD, also a bioengineer at the University of Pittsburgh, during a media briefing.

Capogrosso said that a new culture is needed in which it is accepted that stroke patients have a stimulation system permanently with them. This will take convincing national stakeholders that chronic stroke patients should get long-term rehabilitation for their motor deficits.

It is well established that stroke is a leading cause of long-term disability, with the majority of patients having lasting deficits in arm and hand mobility. There are currently no treatments for chronic upper-limb paresis in stroke survivors.

To address this unmet need, Capogrosso's group tested an EES protocol adapting existing FDA-approved clinical technologies. Similar to an existing technique for analgesia, a minimally invasive device with an electric array is placed percutaneously through the person's back to enter the spinal canal and rests on top of the spinal cord. There, stimulation of sensory nerves from the arm and hand amplifies the activity of muscles that have been weakened by stroke.

Engineers are currently working on fine-tuning the intensity and location of EES to produce more fluid movements of the arm and hand, noted Douglas Weber, PhD, a biomedical engineer at Carnegie Mellon University in Pittsburgh, at the press conference.

"Clinical adoption of SCS for stroke will require the application of simple and standardized parameter optimization protocols," the investigators wrote. "Additionally, in this study we focused on the immediate assistive effects of SCS with temporary implants; future studies should focus on demonstrating the long-term safety and efficacy of a fully implanted SCS system combined with protocol-based upper-limb rehabilitation in larger randomized controlled studies."

Nevertheless, the promise of EES continues to grow, as it has previously been shown to be successful in patients with spinal cord injury and complete sensorimotor paralysis. Capogrosso suggested that there are many diseases involving paralysis that may be targeted with this therapy.

The current study detailed the progress of the first two participants of an ongoing study aiming for 15 stroke patients.

The first, a 31-year-old woman, had suffered a right thalamic hemorrhagic stroke secondary to a cavernous malformation 9 years before participation in the study. The second, a 47-year-old woman, had had a right ischemic middle cerebral artery (MCA) stroke secondary to a right carotid dissection resulting in a large MCA territory infarct 3 years before enrollment.

Both underwent surgery to implant a device for EES of the cervical spinal cord and had the implant removed within 30 days.

"Despite large differences between the two participants in terms of severity, age and time since the stroke, during SCS, both participants showed a significant improvement in strength, arm kinematics and functional task performance compared to their baselines without SCS," Capogrosso and colleagues wrote.

Chief among the limitations of the study were the very small sample and short duration of the intervention.

No serious adverse events were observed with EES, though the researchers acknowledged that their preliminary report prevents them from drawing conclusions about the safety and efficacy of EES in stroke.

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