Sensory-driven Motor Recovery in Poorly Recovered Subacute Stroke Patients

Lumy Sawaki, MD, PhD, University of Kentucky, Physical Medicine &Rehabilitation Department, Cardinal Hill Endowed Chair

Objectives:

The long-range goals are to: (a) maximize the restoration of hand motor function in post-stroke patients with severe motor deficits, (b) determine the impact of this intervention in activities of daily living and quality of life of these patients, and (c) collect solid data to plan a future large multicenter randomized trial.

The central hypothesis is that sub-acute stroke patients with severe motor deficit receiving PNS and intensive task-oriented therapy will have improved motor function compared to patients receiving sham PNS and task-oriented therapy and also when compared to patients receiving PNS-only. Further, the degree of this behaviorally-measured effect will correlate with the neurophysiological effect measured by TMS. Severe motor deficit for this study will be defined as subjects unable to extend the affected metacarpophalangeal joints at least 10° and the wrist 20°. We plan to accept or reject the central hypothesis by accomplishing two Specific Aims.

Specific Aim #1: Test the effect of PNS preceding intensive task-oriented therapy on hand motor function measured by Wolf Motor Function Test (WMFT). The WMTF was selected for this study because of its established validity and use in several studies to evaluate upper extremity motor function in stroke patients, especially in studies involving intensive task-oriented therapy.The working hypothesis for this aim is:

• PNS paired with task-oriented therapy will lead to a higher score on the WMFT when compared to a control stimulation group receiving sham PNS paired with task-oriented therapy
• PNS paired with task-oriented therapy will lead to a higher score on the WMFT when compared to a second control group receiving PNS-only

Specific Aim #2: Test the effect of PNS preceding intensive task-oriented therapy on motor map of a specific muscle (extensor digitorum communis muscle) measured by transcranial magnetic stimulation (TMS). The working hypothesis for this aim is:

• PNS and training of the paretic hand will lead to an increase in TMS motor map of the relevant motor cortex, in a topographically specific manner, compared to a control stimulation group receiving sham PNS and the group receiving PNS-only.
• The improved hand motor function will yield increased TMS motor map induced by hand PNS and task-oriented therapy compared to the control stimulation group receiving sham stimulation and task-oriented therapy and the PNS-only group.

Increase of TMS motor map will correlate with corticomotor reorganization of non-primary motor areas such as premotor area and sensory cortex.