Neck muscle vibration and prism adaptation fail to improve balance disturbances after stroke: A multicentre randomised controlled study

•Cumulative sessions of neck muscle vibration do not improve postural balance.•Cumulative sessions of prism adaptation do not improve postural balance.•Combining vibration and prisms does not produce a synergistic effect. Pilot studies suggest potential effects of neck muscle vibration (NMV) and prism adaptation (PA) on postural balance disturbances related to spatial cognition. To evaluate the effect of 10 sessions of NMV and/or PA on ML deviation. We used the mediolateral centre of pressure position (ML deviation) as a biomarker for spatial cognition perturbation, hypothesising that PA and NMV would improve ML deviation, with a potential synergistic impact when used together. We conducted a multicentre, single-blind, randomised controlled study. Participants within 9 months of a right-hemisphere supratentorial stroke and with less than 40% body weight supported on the paretic side in standing were randomised into 4 groups (PA, NMV, PA+NMV, or control). ML deviation at Day 14. Secondary outcomes: force platform data, balance abilities, autonomy, and ML deviation, measured just after the first session (Day 1), at Day 90, and Day 180. A generalised linear mixed model (GLMM) assessed intervention effects on these outcomes, adjusting for initial ML deviation and incorporating other relevant factors. 89 participants were randomised and data from 80 participants, mean (SD) age 59.2 (10.2) years, mean time since stroke 94 (61) days were analysed. At Day 14, a weak time x group interaction (P = .001, omega-squared = 0.08) was found, with no significant between-group differences in ML deviation (P = .12) or in secondary outcomes (P = .08). Between-group differences were found on Day 1 (P = .03), Day 90 (P = .001) and Day 180 (P < .0001) regardless of age and stroke-related data. On Day 1, ML deviation improved in both the PA and NMV groups (P = .03 and P = .01). In contrast, ML deviation deteriorated in the NMV+PA group on Day 90 and Day 180 (P = .01 and P = .01). The study found no evidence of any beneficial effects of repeated unimodal or combined sessions of NMV and/or PA on ML deviation after stroke. ClinicalTrials.gov identifier NCT01677091