A feasibility Study of Prisms And Therapy In Attention Loss after stroke (SPATIAL feasibility)

Stroke is the most common cause of UK adult disability. National stroke service audits and service user surveys consistently report inadequate psychological support e.g. for cognitive impairments such as unilateral spatial neglect. Neglect is a syndrome of impaired spatial awareness, sometimes known as sensory inattention or hemi-inattention. At its core is a difficulty directing attention contra-lesionally. This affects awareness of the left side of the body, looking, listening and making leftward movements. It limits the person’s ability to participate in NHS therapies and is a confusing and distressing condition for survivors and families. There are several possible rehabilitation interventions for neglect and the Cochrane systematic review of rehabilitation for neglect includes 23 randomised controlled trials. This concluded that effectiveness is unproven but the review requires updating (only included trials to 2011).

One promising intervention is prism adaptation training. The underlying impairment in neglect is an attentional bias (usually) to the right side causing neglect of the left. During a 5 minute prism adaptation training session (pointing at a visual target wearing rightward prisms) the patient initially misreaches to right of target (direct effect), over the next few minutes they progressively compensate for this error recalibrating to point leftwards (adaptation). This adaptation persists after removal of the prisms, continuing to mis-reach leftwards (compensatory after effect). Most importantly this after effect persists beyond the training session. It has been demonstrated to extend to spatial cognition tests and behavioural tasks such as reading and wheel-chair navigation hours and days later. Directional specificity in neglect patients has been demonstrated i.e. (in contrast to healthy controls) patients with left neglect adapt only to right-deviating prisms (not to left-deviating prisms). A leading international team reviewed over 40 papers on prism adaptation training concluding there is consistent ‘proof of concept’ but acknowledging the need to translate this into a pragmatic clinical trial. In addition, our collaborators in Bristol have conducted limited feasibility studies in the clinical setting.

The component studies proposed for this PhD will systematically examine the strength of the current evidence for rehabilitation of neglect with a specific meta-analysis of trials of prism adaptation training, finalise development of prism adaptation training for implementation and evaluation in the clinical setting and design and conduct a feasibility multi-centre randomised controlled trial of prism adaptation training.