The role of action observation in rehabilitation of motor deficits

Traditional bottom-up neurorehabilitative approaches to the treatment of motor deficits after stroke are of proven value and have their established place in the treatment schemas. Experimental data suggest that motor observation is capable of activation of the same cortical motor areas that are involved in the performance of the observed actions, constituting a physiologically based top-down mechanism of motor activation. Action observation along with reinforcement by actual action execution combines both bottom-up and top-down approaches and provides a potentially powerful tool for neurorehabilitation.

In this ongoing study the treatment consists of focused observation of video sequences showing daily life hand and arm actions that are followed by repetitive practice of the observed actions. Every video sequence (lasting 6min.) contains object oriented upper limb actions presented from different angels for each hand. After watching the sequence, the patients are asked to perform the observed movement for 6min. with their paretic upper limb. The duration of the treatment lasts for 20 consecutive workdays (4 w) with ca. 90min. training per day.

8 patients with ischemic median artery infarction at the chronic stage and a moderate hemiparesis affecting the arm have up to now completed the study. The study was approved by the local ethic committee and patients gave their written consent. The effects of treatment were assessed by standardized clinical scales: Stroke Impact Scale (SIS), Frenchay Arm Test (FAT) and Wolf Motor Function Test (WMFT).

Two baseline measurements lying three weeks apart confirmed a stable neurological status of each participant. Functional motor improvement of the patients in the course of the treatment could be demonstrated as a significant difference in the pre-test and the post-test measurements of all three tests using the Wilcoxon Signed Ranks Test (WMFT: Z=-2,5, AS(2t)=0,014; FMT: Z=-2,4, AS(2t)=0,017; SIS: Z=-2,2, AS(2t)=0,025). The comparison of the post-test- and follow-up-measurements showed additionally that the treatment had a significant long-term effect.

The preliminary results of this study confirm our hypothesis, that motor observation ameliorates the neurorehabilitative treatment of motor functions. However, further investigation of a greater number of patients and investigation of a control group performing only motor tasks without motor observation is necessary. Both points are subject of the ongoing study.