Motor Imagery ability in adults with neurological conditions compared to healthy individuals: A systematic review and meta-analysis

Background and Purpose: Growing evidence suggests effects of motor imagery interventions in neurorehabilitation. However, neurological impairment may be related to deficits in motor imagery ability. We aimed to summarize the evidence on differences across motor imagery ability components following Stroke, Traumatic Brain Injury (TBI), Parkinson’s disease (PD), or Multiple Sclerosis (MS).Methods: Six databases were searched up to February 2024. Studies comparing adults with these conditions to healthy individuals were included. Two reviewers independently selected studies and assessed Risk of Bias. Quantitative and qualitative analyses were applied. Motor imagery generation, maintenance, and manipulation, assessed through questionnaires, mental chronometry, and mental rotation tasks respectively, were the outcomes. Results: Fifty-two studies with low or moderate bias were included (Stroke: n=26; TBI: n=1; PD: n=14; MS: n=11). Meta-analyses revealed a moderate difference in Stroke for generation of kinesthetic motor imagery and a moderate difference in PD for visual motor imagery. For imagery maintenance, qualitative syntheses indicated contradictory evidence for Stroke (although it was stronger towards a difference), with PD and MS showing differences with moderate to strong evidence. Meta-analyses showed a large and moderate difference in the accuracy measures of imagery manipulation in Stroke and PD, respectively; qualitative analysis also supported this in MS. For TBI, a limited number of studies impeded performing a formal synthesis of the evidence. Discussion and Conclusions: Differences in specific motor imagery ability domains may be present in people with neurological conditions of different aetiologies. Clinicians should consider assessing all three components before applying motor imagery interventions.