Transcutaneous auricular vagus nerve stimulation paired with task-specific training for improving walking and balance in chronic stroke: a double-blind, randomised controlled feasibility trial.
Ashraf N H Gerges, Jeric Uy, Lewis Ingram and 7 others
Both groups improved in walking and balance after six weeks of task-specific training, but the ear stimulation added no measurable benefit over a switched-off device.
The trial was too small to detect a difference, and the authors state it is not evidence the treatment works.
Key findings
1Both the active and sham groups improved in walking speed, endurance, balance, and self-efficacy over the six weeks, but no outcome showed a significant difference between the two groups.
2The intervention was feasible and safe: 93% consent rate, 96% completed all sessions, 100% found it acceptable, 16% reported mild adverse events, and no serious adverse events occurred.
3Blinding was imperfect: 57% of the active group correctly guessed their allocation versus 27% of the sham group, likely because the tingling sensation of active stimulation was detectable.
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What it does not show
Twenty-five participants is a small sample, and the authors note this may lead to type 2 errors (missing a real effect). Blinding was imperfect: participants in the active group could feel the stimulation, so 57% guessed correctly versus 27% in the sham group. This could have introduced expectancy effects on self-reported outcomes and engagement with training. The treating physiotherapist knew which group each participant was in, which could have influenced how sessions were delivered despite standardisation procedures. Training dose was not objectively measured (no step counts, walking duration, or repetition tracking), so it is unclear whether the two groups received equivalent amounts of practice. Follow-up was only about one month, so it is unknown whether any differences would have emerged or persisted over a longer period. Multiple gait and balance outcomes were examined without adjustment for multiple comparisons, increasing the chance of a false-positive finding. The authors state the study was not designed or powered for definitive hypothesis testing and that findings should be considered hypothesis-generating.
Declared interests
Funded by the Australian Government Research Training Program. No industry involvement or conflicts of interest are declared.
The easy way to misread this
The small effect sizes (Cohen's d from 0.17 to 0.42) and the trend toward more active-group participants reaching clinically important change thresholds may look like evidence of benefit. But no group-by-time interaction was statistically significant, every confidence interval crossed zero, and the authors explicitly state these findings should not be interpreted as evidence of efficacy. The trial was underpowered and not designed to test whether the treatment works.
Summarised by AI from the full paper, without a clinician reviewing it. Check it against the source before it changes what you do. Read it on PubMed →