Impact of time on quality of motor control of the paretic upper limb after stroke

Abstract

Objective: To establish the time course of recovery regarding smoothness of upper limb movements in the first 6 months poststroke.

Design: Cohort study with 3-dimensional kinematic measurements in weeks 1, 2, 3, 4, 5, 8, 12, and 26 poststroke.

Setting: Onsite 3-dimensional kinematic measurements in stroke units, rehabilitation centers, nursing homes, and patients' homes.

Participants: Patients (N=44; 19 women, 25 men; mean age ± SD, 58±12y) with a first-ever unilateral ischemic stroke and incomplete upper limb paresis (27 left sided, 17 right sided) were included.

Interventions: Not applicable.

Main outcome measures: In each measurement, an electromagnetic motion tracker acquired hand and finger trajectories during a reach-to-grasp task. Movement duration was determined, and smoothness of hand transport and grasp aperture was quantified by normalized jerk. With the use of random coefficient analysis, the effect of progress of time on smoothness of hand transport and grasp aperture was investigated.

Results: During the first 5 weeks poststroke, there was a significant contribution of progress of time to reductions in movement duration and normalized jerk of hand transport and grasp aperture (P<.01).

Conclusions: The present longitudinal 3-dimensional kinematic study showed that smoothness of paretic upper limb movements improves in the first 8 weeks poststroke. This improvement suggests that motor control normalizes in the first 8 weeks poststroke and can be mostly explained by spontaneous neurologic recovery that occurs typically in the first weeks poststroke. Future 3-dimensional kinematic studies should investigate whether therapies starting early after stroke can improve the quality of motor control beyond spontaneous neurologic recovery.

Keywords: Biomechanics; MD; NJ; Rehabilitation; Stroke; Upper extremity; movement duration; normalized jerk.