Olivia Liu – Department of Neuroscience
Stroke is one of the most damaging neurologic emergencies worldwide. One of the most common sequelae is life-long motor impairment and paralysis due to damage to the corticospinal tract. Many studies in the past have attempted to use a technology called spinal cord stimulation (SCS) to amplify inputs to leg spinal motor neurons. When combined with behavioral therapy, some participants regained a fraction of their walking capabilities, even when they’re not hooked to the SCS. Despite this promising data, very little research has been done to explore SCS’s effects on upper limb paresis.
In the March 2023 Nature Medicine edition, Powell and his colleagues hypothesized that if we stimulate what’s left of the un-lesioned corticospinal tract, we could drive voluntary movement in the arms. Two middle-aged Caucasian females with histories of strokes and chronic upper limb deficits were involved in Powell’s research. First, brain mapping (“tractography”) was done to help determine the correct stimulation parameters. Next, leads are implanted along C4-T1 on the same side as the patient’s affected arm. Results showed that elbow flexion strength and grip strength both increased, and noticeable improvement was documented with regard to movement smoothness. Despite not having any follow-up physical therapy, both patients only had 1 point decreases in their Fugl Meyer Assessment Scores (measurement of sensorimotor impairment after stroke) 4 weeks after being off of the SCS.
In summary, Powell has conducted a great preliminary study that shows how neuromodulation can improve the quality of life of stroke patients. And though motor strength still decreased after SCS detachment, there’s much hope for recovering sensorimotor defects that are thought to be lost forever. His team suspects it will be years before a larger-scale clinical trial can be conducted. When this comes to fruition, it may give more credibility to these wonderful findings.
References:
Powell, M.P., Verma, N., Sorensen, E. et al. Epidural stimulation of the cervical spinal cord for post-stroke upper-limb paresis. Nat Med 29, 689–699 (2023). https://doi.org/10.1038/s41591-022-02202-6
Edited By: Firas Batrash, Editor-in-Chief
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