More than six months after a stroke, the arm and hand are usually treated as a settled account: whatever function returned has returned. A University of Pittsburgh and Carnegie Mellon team has been testing whether electricity delivered to the cervical spinal cord could reopen that account — at least while the current is on. Their two-patient first-in-human report appeared in Nature Medicine in 2023; this is the seven-patient feasibility follow-on.
In the new trial, also in Nature Medicine, seven participants with profound, chronic upper-limb deficits — baseline Fugl-Meyer Assessment scores of 15–35 out of 66 — were implanted with two leads placed unilaterally in the cervical spinal cord for four weeks, then explanted. (The registered eligibility window was broader, Fugl-Meyer above 7 and below 50; 15–35 describes the cohort that actually enrolled, not the cutoff.) Per the registry (NCT04512690), the primary endpoints were safety and tolerability — serious adverse events, and stimulation-related discomfort or pain — not efficacy. On that score it cleared: no serious adverse events occurred. Fugl-Meyer was a secondary outcome.
The motor signals were the headline. With stimulation switched on, function improved immediately regardless of severity — an average +32% in strength and +5.6 Fugl-Meyer points versus each participant’s own baseline. Three of the seven, all with residual corticospinal connectivity to finger muscles, regained some hand and finger movement under stimulation.
Despite just 8.6 hours of motor activity over the month (5.5 with stimulation on), participants gained an average of +6.6 Fugl-Meyer points at the end of the study versus baseline — and spasticity eased in all seven. The published report gives point estimates only; no confidence intervals, standard deviations or p-values are reported for these aggregate effects.
What this is, and isn’t
This is a seven-person, single-arm feasibility study with a temporary implant — the authors call it “preliminary evidence” of safety, feasibility and efficacy. There is no control group, the gains were measured during stimulation, the implant came out within 30 days, and the headline figures are reported without dispersion or significance testing. The end-of-study Fugl-Meyer change of +6.6 points sits within the 4.25–7.25-point range usually considered clinically meaningful (the MCID) and above the 5.2-point minimal detectable change the registry cites — but with n=7, no comparator and no reported confidence interval, the estimate carries wide uncertainty. What the trial establishes is feasibility and a safety signal — the foundation, the authors note, for larger efficacy studies of a potentially fully implantable neuroprosthetic.