The effects of constraint-induced therapy on precision grip: a preliminary study

Abstract

Objective: This preliminary study examines the effects of a 2-week constraint-induced therapy (CIT) intervention on the force-producing capabilities of the hemiparetic hand during the performance of a functional dexterous manipulation task.

Methods: A 6-degree-of-freedom force/torque transducer that was embedded into the handle of a key allowed for the quantification of grasping forces and torques produced during the performance of a functional key-turning task. Clinical and kinetic data were collected from 10 subacute patients (3-9 months poststroke) who were participating in an ongoing national clinical study (EXCITE trial) examining the effects of CIT on upper extremity motor performance. Investigators were blinded to treatment designation. Five patients receiving treatment immediately completed 2 weeks of intensive CIT, whereas a group randomized to treatment 1 year later did not receive any therapy during a similar 2-week span.

Results: . Results indicated that 4 of the 5 patients in the CIT group, compared to the delayed group, showed significant clinical improvements in hand function, increased maximum precision grip force, improved force and torque regulation, and reduced variability in rate of force production during task performance.

Conclusions: Improved force control may be a mechanism contributing to the observed improvements in dexterous function in those patients undergoing CIT.

Figure 1

Illustration of participant grasping the force/torque transducer with the key in the neutral position. The cross-hatch arrow represents initial transducer position (1), solid arrow represents the clockwise turn of the key to the 90-degree position (2), and the open arrow represents the counterclockwise turn to the 90-degree position (3). Figure B depicts the forces and torques about each axis that were being measured. Figure C contains representative grasping force and torque data from a healthy control participant while performing the key-turning task.

Figure 2

Representative grasping force (grip = solid lines; load = dotted lines) and torque profiles (Tx = solid lines; Ty = dotted lines) for an individual trial for 2 patients in the immediate group (upper plots) and 2 patients (lower plots) in the delayed group during the pretest session.

Figure 3

Representative grip and load forces and torque profiles for an individual trial from the posttest session for the same patients shown in Figure 2.

Figure 4

Representative grasping forces (grip = solid lines; load = dotted lines) for an individual trial for 2 patients in the immediate group after constraint-induced therapy (CIT) completion.

Figure 5

Individual rate of grip force profiles from grip force onset to completion of key-turning for a patient in the delayed (left plots) and immediate group (right plots) under pre- and posttest conditions.