Is recalibration more important than realignment in prism adaptation training for visuospatial neglect? A randomized controlled trial.

Prism adaptation training (PAT) as a treatment for visuospatial neglect (VSN) involves two components: recalibration and realignment. We conducted a randomized controlled trial with PAT protocols requiring different degrees of recalibration and realignment, by using a single or multi-step protocol and varying visibility of the pointing movement. Twenty-five VSN patients received an alertness treatment without prisms, followed by four PAT protocols, encompassing a multi- or single-step procedure with terminal exposure, a single-step procedure with concurrent exposure, and sham PAT, presented in random order. The primary outcome parameter was the median response time (RT) to left-sided targets in an endogenous variant of the Posner task, and we also measured the sensorimotor aftereffect. The two protocols without visibility of most of the movement trajectory produced significant aftereffects. The single-step protocol without movement visibility appeared to have a beneficial effect on non-motor leftward visuospatial attention compared to baseline, though the differences between this protocol and three other PAT protocols, includuing sham PAT, were not significant. We provide preliminary evidence that maximizing the conscious experience of movement errors may be a relevant component for remediating VSN, though the specificity of these effects remains to be further explored.Trial registration: German Clinical Trials Register identifier: DRKS00025938.