Targeted engagement of a dorsal premotor circuit in the treatment of post-stroke paresis

Abstract

Background: Good motor outcome after stroke has been found to correlate with increased activity in a dorsal premotor (PMd) brain circuit, suggesting that therapeutic strategies targeting this circuit might have a favorable, causal influence on motor status.

Objective: This study addressed the hypothesis that a Premotor Therapy that exercises normal PMd functions would provide greater behavioral gains than would standard Motor Therapy; and that Premotor Therapy benefits would be greatest in patients with greater preservation of PMd circuit elements.

Methods: Patients with chronic hemiparetic stroke (n = 15) were randomized to 2-weeks of Premotor Therapy or Motor Therapy, implemented through a robotic device.

Results: Overall, gains were modest but significant (change in FM score, 2.1 ± 2.8 points, p < 0.02) and did not differ by treatment assignment. However, a difference between Therapies was apparent when injury to the PMd circuit was considered, as the interaction between treatment assignment and degree of corticospinal tract injury was significantly related to the change in FM score (p = 0.018): the more the corticospinal tract was spared, the greater the gains provided by Premotor Therapy. Similar results were obtained when looking at the interaction between treatment assignment and PMd function (p = 0.03).

Conclusions: Targeted engagement of a brain circuit is a feasible strategy for stroke rehabilitation. This approach has maximum impact when there is less stroke injury to key elements of the targeted circuit.