Research Article: Evaluating the Effect of Cognitive Dysfunction on Mental Imagery in Patients with Stroke Using Temporal Congruence and the Imagined ‘Timed Up and Go’ Test (iTUG)

Date Published: January 26, 2017

Publisher: Public Library of Science

Author(s): Maxime Geiger, Céline Bonnyaud, Yves-André Fery, Bernard Bussel, Nicolas Roche, Jean-Claude Baron.


Motor imagery (MI) capacity may be altered following stroke. MI is evaluated by measuring temporal congruence between the timed performance of an imagined and an executed task. Temporal congruence between imagined and physical gait-related activities has not been evaluated following stroke. Moreover, the effect of cognitive dysfunction on temporal congruence is not known.

To assess temporal congruence between the Timed Up and Go test (TUG) and the imagined TUG (iTUG) tests in patients with stroke and to investigate the role played by cognitive dysfunctions in changes in temporal congruence.

TUG and iTUG performance were recorded and compared in twenty patients with chronic stroke and 20 controls. Cognitive function was measured using the Montreal Cognitive Assessment (MOCA), the Frontal Assessment Battery at Bedside (FAB) and the Bells Test.

The temporal congruence of the patients with stroke was significantly altered compared to the controls, indicating a loss of MI capacity (respectively 45.11 ±35.11 vs 24.36 ±17.91, p = 0.02). Furthermore, iTUG test results were positively correlated with pathological scores on the Bells Test (r = 0.085, p = 0.013), likely suggesting that impairment of attention was a contributing factor.

These results highlight the importance of evaluating potential attention disorder in patients with stroke to optimise the use of MI for rehabilitation and recovery. However further study is needed to determine how MI should be used in the case of cognitive dysfunction.

Partial Text

In clinical practice, functional motor activity is routinely assessed using the ‘Timed Up and Go’ (TUG) test. The TUG test involves the patient standing up from a chair, walking 3m, turning around, walking 3m back to the chair and sitting down [1]. It has been validated for use in patients with stroke and several studies have shown that TUG test performance is altered in these patients [2–4] [5,6]. Cognitive dysfunction, which is common after stroke, may have an impact on motor capacity and can interfere with gait-related activities. Correlations have been found between cognitive impairments and activity restrictions in stroke patients [5,7]. Several studies also showed that performance on the TUG test is altered in subjects with cognitive impairments compared with matched, cognitively intact subjects (patients with stroke and elderly patients) [5,6].

Twenty patients with stroke and twenty control subjects were included in this study (see Table 1). The control group were volunteers with no history of neurological or orthopaedic pathology that could interfere with the task, they were recruited from the staff of the University Hospital. Patients were recruited from the University Hospital during routine consultations and were eligible for inclusion if they: i) were over eighteen years old, ii) had hemiparesis due to a single stroke more than six months previously, iii) were able to perform the TUG test independently with or without walking aids. Exclusion criteria included: i) bilateral cortical lesions, ii) cerebellar syndrome, iii) severe comprehensive deficit or severe aphasia (score = 0 on the SOFMER’ scale of aphasia severity), iv) apraxia and v) musculoskeletal surgery less than six months previously. All subjects gave written consent before participation. The study was performed in accordance with the ethical codes of the World Medical Association (Declaration of Helsinki) and was approved by the local Ethics Committee (Comité de protection des personnes Ile de France XI, Ref 13005. CNIL, Ref DR-2013-283)

The characteristics of patients with stroke and healthy controls are shown in Table 1. There was no difference in the mean age of the two groups (p = 0.54).

This study is the first to explore temporal congruence between the TUG and iTUG in patients with stroke. Although a previous study explored gait related activities, they did not involve such complex tasks and did not use the same paradigm [22]. The results of the present study showed that: i) the patients with stroke performed both the iTUG and TUG significantly more slowly than the healthy controls; ii) temporal congruence was weaker in the patients with stroke (indicating reduced MI capacity) than healthy controls; iii) both the patients and healthy controls performed the iTUG significantly faster than the TUG, and iv) performance-time on the bells test was significantly correlated with the iTUG, suggesting that attentional disorders may affect MI capacity to perform the TUG test. These results confirm our first hypothesis that the MI capacity of patients with stroke would be reduced compared to healthy controls for the TUG task, and partially confirm our second hypothesis of a relationship between reduced MI capacity and cognitive impairment. Indeed, although the temporal congruence alterations was not correlated with cognitive disorders, it can be noticed that iTUG performance time was correlated with attentional impairment suggesting that MI is partially altered.

There are a few points which might constitute limitations in the interpretations of the present data.

This study showed that the direction of alteration of temporal congruence depends on the task being assessed in both patients with stroke and healthy subjects. Disparities likely reflect differences in the nervous control of simple, voluntary movements compared with the control of complex tasks (semi-automatic and voluntary), however this remains to be tested using fMRI.