Is it possible to use the Structural Dimension Analysis of Motor Memory (SDA-M) to investigate representations of motor actions in stroke patients?

Objective: To determine the feasibility of the Structural Dimension Analysis of Motor Memory (SDA-M), a method derived from sports psychology, in establishing the mental representations of complex movements in patients after stroke. Design: Case series of patients, with age-matched healthy controls. Setting: A rehabilitation nursing home. Subjects: Sixteen patients 3—26 weeks after their stroke, and 16 controls. Intervention: Each control had the SDA-M performed within a 10-day period. Each stroke patient had the SDA-M performed once. In the SDA-M the subject was asked to state for each of 10 actions involved in drinking from a cup whether it is functionally close to each of the other nine or not. Main measures: The raw data from the SDA-M were transformed through cluster analysis into Euclidean distances and tree diagrams to illustrate the internal representation of the action. Results: All subjects were able to perform the assessment. Healthy controls all had a similar set of Euclidean distances and tree diagrams that were `normal'. The tree diagrams remained very similar on the three occasions. Four stroke patients had tree diagrams that were `normal'. The remaining twelve had tree diagrams that differed greatly both from the `normal' and from each other, with much less clustering of actions. Patients with more severe stroke appeared to have more disordered tree diagrams. Conclusion: The Structural Dimension Analysis of Motor Memory (SDA-M) is a feasible method for investigating the mental representation of internal motor action plans in stroke patients, giving similar data in stable healthy people and revealing abnormal patterns in patients after stroke.