Effect of vagus nerve stimulation paired with rehabilitation for upper limb function improvement after stroke: a systematic review and meta-analysis of randomized controlled trials.
Kehong Zhao, Jiaen Yang, Jiapeng Huang and 2 others
PMID 34839304WHAT IT FOUND
VNS added to rehabilitation produced a 3.59-point gain on the FMA-UE, below the 4.25-to-7.25 range one study sets as clinically meaningful.
The Wolf Motor Function Test gain met its threshold. Hand function, grip, and dexterity did not differ from rehabilitation alone.
Key findings
01The FMA-UE improved by 3.59 points (95% CI 2.55 to 4.63) with VNS plus rehabilitation compared with control, but the authors note this falls below the 4.25-to-7.25-point range one study sets as the minimum for a clinically meaningful change in chronic stroke.
02The Wolf Motor Function Test showed a significant gain in the invasive VNS subgroup (0.30 points, 95% CI 0.18 to 0.43) and in the transcutaneous VNS subgroup (3.59 points, 95% CI 1.97 to 5.21), both meeting the 0.2-to-0.4-point threshold cited from another study.
03Stroke Impact Scale hand function, Box and Block, and Nine-Hole Peg scores showed no significant difference between the VNS and control groups.
STILL TO COME
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What it does not show
Only five trials with 178 participants in total, so the effect estimates are imprecise and the authors note the sample may not provide sufficient statistical power. Outcomes were measured only at the end of the intervention. There is no follow-up data, so it is unknown whether any gain is maintained. Only English-language studies were included. Only two of the five trials concealed who received the real versus sham stimulation, and only three blinded the participants, which could inflate the apparent effect. Publication bias could not be assessed because there were fewer than ten studies. No trial directly compared invasive VNS to transcutaneous VNS, so the two delivery methods cannot be contrasted.
Declared interests
The authors declare no conflicts of interest.
The easy way to misread this
Do not read the 3.59-point FMA-UE gain as a clinically meaningful improvement. The authors themselves note it falls below the 4.25-to-7.25-point range one study sets as the minimum for a meaningful change, and the hand function, grip, and dexterity measures showed no difference at all.
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