The relation between cognitive and motor dysfunction and motor imagery ability in patients with multiple sclerosis.

Abstract

Motor imagery (MI) was recently shown to be a promising tool in neurorehabilitation. The ability to perform MI, however, may be impaired in some patients with neurological dysfunction.
The objective was to assess the relation between cognitive and motor dysfunction and MI ability in patients with multiple sclerosis (MS).
Thirty patients with MS underwent cognitive and motor screening, and also performed a composite test battery to assess their MI ability. This test battery consisted of a questionnaire, a hand rotation task and a test based on mental chronometry. Patients' MI ability was compared with the MI ability of age-matched healthy controls. Moreover, their MI scores were compared between body sides and were correlated with their scores on tests of motor and cognitive functioning.
The average accuracy and temporal organization of MI significantly differed between MS patients and controls. Patients' MI accuracy significantly correlated with impairments in cognitive functioning, but was independent of motor functioning. MI duration, on the other hand, was independent of cognitive performance, but differed between the patients' most and least affected side.
These findings are of use when considering the application of MI practice in MS patients' rehabilitation.

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Multiple Sclerosis Journal
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DOI: 10.1177/1352458512437812
2012 18: 1303 originally published online 2 March 2012 Mult Scler
Elke Heremans, Anne-Marie D'hooge, Sara De Bondt, Werner Helsen and Peter Feys
multiple sclerosis
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Multiple Sclerosis Journal
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DOI: 10.1177/1352458512437812
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MULTIPLE
SCLEROSIS MSJ
JOURNAL
Introduction
Motor imagery (MI) can be defined as mental rehearsal of
a motor act in the absence of overt motor output.1 Recent
studies have shown that practice by means of MI can result
in similar neural reorganization as actual physical practice.2
Mainly in stroke patients3 and patients with Parkinson’s
disease (PD)4 the potential effect of combining MI and
physical practice was shown. However, some studies ques-
tion its applicability and effectiveness in neurological
patients, since cognitive and motor dysfunction could be
related to impairments in imagery ability. Previous research
showed that 40% of stroke patients were unable to perform
MI.3 The lack of imagery ability in these patients may be
explained by the location of their lesion. Mainly lesions in
the parietal cortex and left prefrontal area may result in a
loss of imagery ability.5,6 Moreover, studies have shown
involvement of the basal ganglia in MI.7 This was con-
firmed by behavioural studies showing impairments in MI
in patients with PD.8 Other studies, however, have shown
that, despite a severe slowness, PD patients are still able to
accurately perform MI.9 Since a relationship was shown
between imagery ability and the effectiveness of MI
The relation between cognitive and
motor dysfunction and motor imagery
ability in patients with multiple sclerosis
Elke Heremans1,3, Anne-Marie D’hooge2, Sara De Bondt2,
Werner Helsen3 and Peter Feys1,3,4
Abstract
Background: Motor imagery (MI) was recently shown to be a promising tool in neurorehabilitation. The ability to
perform MI, however, may be impaired in some patients with neurological dysfunction.
Objective: The objective was to assess the relation between cognitive and motor dysfunction and MI ability in patients
with multiple sclerosis (MS).
Methods: Thirty patients with MS underwent cognitive and motor screening, and also performed a composite test
battery to assess their MI ability. This test battery consisted of a questionnaire, a hand rotation task and a test based on
mental chronometry. Patients’ MI ability was compared with the MI ability of age-matched healthy controls. Moreover,
their MI scores were compared between body sides and were correlated with their scores on tests of motor and
cognitive functioning.
Results: The average accuracy and temporal organization of MI significantly differed between MS patients and controls.
Patients’ MI accuracy significantly correlated with impairments in cognitive functioning, but was independent of motor
functioning. MI duration, on the other hand, was independent of cognitive performance, but differed between the patients’
most and least affected side.
Conclusion: These findings are of use when considering the application of MI practice in MS patients’ rehabilitation.
Keywords
multiple sclerosis, mental practice, motor imagery, rehabilitation, cognition, motor functioning
Date recieved: 28th October 2011; revised: 21st December 2011; 9th January 2012; accepted: 11th January 2012
1 Department of Rehabilitation Sciences, Katholieke Universiteit Leuven,
Belgium.
2National MS Center, Melsbroek, Belgium.
3 Department of Biomedical Kinesiology, Katholieke Universiteit Leuven,
Belgium.
4 REVAL Rehabilitation & Healthcare Research Center, PHL-University
College, and BIOMED, Universiteit Hasselt, Belgium.
Corresponding author:
Elke Heremans, K. U. Leuven, Faculty of Kinesiology and Rehabilitation
Sciences, Department of Rehabilitation Sciences, Tervuursevest 101,
3001 Leuven, Belgium.
Email: elke.heremans@faber.kuleuven.be
437812 MSJ18910.1177/1352458512437812Heremans et al.Multiple Sclerosis Journal
2012
Research Paper
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1304
Multiple Sclerosis Journal 18(9)
practice,10 a thorough evaluation of patients’ imagery abil-
ity is needed before considering using MI in rehabilitation.
In patients with multiple sclerosis (MS), MI ability has
never been examined. MS is characterized by motor as well
as cognitive symptoms.11 Cognitive impairment, present in
40–70% of the patients, mainly relates to problems in atten-
tion, information processing speed, memory, mental flexi-
bility and visuocontruction.12 These deficits may be due to
demyelination and axonal damage leading to loss of neu-
ronal synchronization and functional disconnection
amongst brain relays. Therefore, MS recently has been
described as a multiple disconnection syndrome.12,13 Recent
studies have shown that cognitive performance measured
by processing speed and executive function is significantly
associated with patients’ motor function.14 Motor symp-
toms include muscle weakness, spasticity and incoordina-
tion, leading to limitations in daily life functioning. In the
present study, we particularly focused on upper limb move-
ment capacity, since 76% of MS patients are confronted
with upper limb dysfunction during the disease course.15
The aim of this study was to investigate the relation between
these motor and cognitive problems and MS patients’ MI
ability. To determine the relation between cognitive impair-
ments and MI, the MI tests were correlated with patients’
scores on a wide set of cognitive screening tests. To assess
their relation with motor dysfunction, we correlated the MI
scores with patients’ outcome on motor tests, and compared
patients’ scores on MI tests performed with their most and
least affected body side.
Materials and methods
Participants
Thirty MS patients (14 males; 50.5±10.9 years) and 30
healthy controls (14 males; 50.2±11.1 years) were recruited
from consecutive admissions to the National MS Center
Melsbroek by a neurologist using the Poser criteria.16 They
were all right-handed as measured by the Edinburgh
Handedness Inventory Questionnaire. Exclusion criteria
were: Mini-Mental State Examination (MMSE) score <24,
neurological or psychiatric comorbidity, severe visual defi-
cit, severe orthopaedic problems of the upper limb and MS
relapse or related corticosteroid therapy within eight weeks
preceding study entry. The study was conducted in accord-
ance with the sixth revision of the ethical standards laid
down in the 1964 Declaration of Helsinki, and was approved
by the Ethics Committees of the National MS Center
Melsbroek and the Katholieke Universiteit Leuven. All par-
ticipants gave written informed consent.
Experimental procedure
Screening of disease severity and cognitive and motor func-
tions. First, patients were assessed by means of the
Expanded Disability Status Scale (EDSS). Subsequently,
patients’ cognitive functioning was evaluated by means of
the Symbol Digit Modalities Test (SDMT) and the Neuro-
psychological Screening Battery for Multiple Sclerosis
(NSBMS). The NSBMS is composed of the i) Selective
Reminding Test (SRT), ii) 7/24 Spatial Recall Test (7/24
SRT), iii) Paced Auditory Serial Addition Task (PASAT)
and iv) Controlled Oral Word Association Test (COWAT).
In addition, we evaluated patients’ verbal and visuospatial
working memory by means of the Digit Span and Corsi
Block Tapping, respectively. Finally, patients’ fine motor
function was assessed by means of the Nine Hole Peg Test
(9HPT) (Table 1).
Kinesthetic and Visual Imagery Questionnaire. The short ver-
sion of the KVIQ (KVIQ-10) was used to evaluate partici-
pants’ MI vividness. This questionnaire was specifically
developed for assessing imagery ability in populations with
restricted mobility.17 The subjects first physically executed
and then imagined doing the movements. Subjects who
were unable to physically perform the movement were
requested to use the other limb, or, in case both limbs were
too severely impaired, to observe the experimenter per-
forming the movement before imagining it. The KVIQ-10
comprises five visual and five kinesthetic items, scored on
a five-point visual analogue scale (1 = very clear image or
intensity and 5 = no image or sensations at all). Lateralized
items were performed at both body sides.
Hand rotation task. The hand rotation task was applied to
measure imagery accuracy. Ninety-six successive line
drawings of hands (48 left and 48 right) were shown on a
computer screen in four different views (back, palm, ulnar,
radial) and 12 different rotations (30 degree steps).18 Sub-
jects were asked to judge as accurately as possible whether
a left or right hand was shown without moving or seeing
their own hands. This test requires mental rotation of their
own hand and is as such an implicit MI test. Six practice
pictures were given. Sharma et al.18 described previously
that a score below 75% indicates inability to perform
accurate MI.
Mental chronometry. We applied mental chronometry on
the Box and Block Test (BBT).19,20 Mental chronometry is
based on the comparison between the duration of physical
execution and imagery of a task, with a close temporal rela-
tionship indicating correct MI. During the BBT, 2.5 cm2
wooden blocks are transported from one part of a box to
another. We measured the time needed to transport 20
blocks.9 After one practice trial, three trials of imagery and
physical execution (in random order) were performed for
each hand. During the imagery trials, participants were
instructed to use visual imagery from a first person per-
spective. They were instructed to imagine the task in the
same way as if they had performed it physically.
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Table 1. Patients’ characteristics.
Patient
number

Age
(years)/
gender
Years
since
diagnosis
Type of
MS
EDSS
score
(/10)
MMSE
(/30)
SDMT
NSBMS
(/4)
SRT
(/96)
7/24
SRT
(/35)
PASAT
(/60)
COWAT
Digit
Span
(/12)
Corsi Block
Tapping
(/12)
9HPT
right side
(s)
9HPT
left side
(s)
1
41/F
1
PP
7
30
55
4
51
26
54
47
8
8
31.2
26.8
2
77/M
41
SP
7
25
30
1
3
19
1
36
6
5
26.5
23.9
3
56/M
11
PP
6.5
29
27
4
45
33
29
29
6
5
49.6
105.0
4
41/F
2
RR
6.5
29
39
4
38
34
35
30
4
5
21.4
26.7
5
51/F
28
RR
6.5
30
31
1
15
18
1
20
7
5
29.3
25.2
6
62/F
15
RP
3
29
48
4
16
30
38
45
7
6
21.9
27.2
7
62/M
25
SP
6.5
27
26
4
24
19
35
32
1
3
34.5
42.8
8
52/F
4
SP
4
30
47
3
21
32
1
30
4
5
37.2
17.2
9
53/M
7
SP
7.5
28
29
2
22
26
1
28
3
5
27.0
29.7
10
50/F
17
RR
7
30
25
3
18
7
26
26
8
6
41.6
138.0
11
59/M
14
SP
7
28
31
3
8
25
40
43
5
6
193.0
63.0
12
45/F
16
PP
8
30
37
3
26
18
26
38
5
5
35.2
85.0
13
58/M
8
PP
7.5
30
47
4
21
30
42
46
9
6
24.3
47.4
14
46/M
13
SP
6.5
30
28
3
40
33
19
38
8
6
91.0
137.0
15
59/M
17
PP
6.5
30
42
4
29
35
23
50
8
5
26.7
34.6
16
42/M
2
RR
5.5
30
19
4
56
30
34
40
7
4
25.4
40.4
17
47/F
10
SP
7
28
34
2
4
32
34
18
8
7
27.5
44.9
18
51/F
5
PP
4
29
38
3
10
29
24
33
8
3
60.0
63.0
19
53/M
9
RR
6.5
30
31
4
23
32
24
32
4
6
39.6
77.3
20
65/F
16
RR
6.5
25
8
0
11
21
1
22
4
4
37.1
43.3
21
29/F
8
RR
7
30
42
4
18
31
49
39
8
7
55.7
28.9
22
56/M
14
SP
7
29
40
4
56
34
32
38
7
8
42.4
22.0
23
29/F
3
RR
4.5
29
54
4
65
35
54
39
7
6
20.9
23.5
24
34/M
9
RR
5.5
29
20
3
16
33
1
51
3
6
27.2
60.1
25
60/F
21
SP
6
29
53
4
58
27
47
43
8
7
24.9
26.8
26
40/F
18
RP
7.5
30
29
4
58
31
25
34
3
5
47.3
27.2
27
55/F
23
SP
5.5
27
30
2
13
26
1
48
6
5
32.8
31.3
28
52/F
7
RR
6
29
55
4
48
33
42
62
5
5
17.9
19.7
29
56/F
17
SP
6
30
54
4
63
28
26
26
9
4
24.2
34.0
30
35/M
12
SP
6.5
30
52
4
35
28
41
41
7
6
23.9
28.6
Abbreviations: PP, Primary Progressive; SP, Secundary Progressive; RR, Relapse Remitting; RP, Relapsing Progressive; EDSS, Expanded Disability Status Scale; MMSE, Mini Mental State Examination; SDMT, Sym-
bol Digit Modalities Test; NSBMS, Neuropsychological Screening Battery for Multiple Sclerosis; SRT, Selective Reminding Test; 7/24 SRT, 7/24 Spatial Recall Test; PASAT, Paced Auditory Serial Addition Task;
COWAT, Controlled Oral Word Association Test, 9HPT, Nine Hole Peg Test
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Multiple Sclerosis Journal 18(9)
Statistical analyses
We calculated the mean score on the KVIQ-10, mean hand
rotation accuracy and mean duration of imagined and exe-
cuted conditions of the BBT. After establishing normality
assumptions for data distribution (Shapiro–Wilk test),
patients’ and controls’ KVIQ scores were compared with an
independent t-test. For the hand rotation task and BBT, a
repeated measures analysis of variance (ANOVA) with
group (MS, controls) as between-subject factor was used.
As within-subject factor, dominant body side was included
for the BBT and hand rotation task (left side, right side) and
condition (physical execution, MI) for the BBT only. For
significant effects at α=0.05, post hoc Tukey HSD tests
were applied.
Pearson correlation coefficients were calculated to cor-
relate the disease characteristics (EDSS, type of MS, years
since diagnosis) and scores on cognitive (SDMT, NSBMS
and its subcomponents, Digit Span, Corsi Block Tapping)
and motor (9HPT) screening tests with scores on the
imagery tasks. Finally, for the asymmetrically affected
patients, subgroups were made for their most and least
affected body sides. The most affected side was defined as
the body side for which physical execution of the BBT was
at least 10% slower than for the other side. For all variables,
dependent t-tests were performed to compare the most and
least affected sides. For the KVIQ-10, only the asymmetri-
cal items were included in this analysis.
Results
KVIQ-10
Both groups rated their imagery vividness as good and no
differences were found between groups (Table 2).
Hand rotation task
MS patients had a significantly lower accuracy score than
controls (F(1,58)=4.398, p=0.04) (Table 2). For both
groups, there were no significant differences in judging pic-
tures from left or right hands. Nine MS patients failed to
reach the 75% limit to define accurate MI, while for the
control group this was the case for three persons.
Mental chronometry
For BBT duration, a significant interaction between condi-
tion and group was found (F(1,58)=5.79, p=0.02). During
both imagery and execution, the task was performed faster
by controls than by patients (execution: F(1,58)=66.02,
p<0.01; imagery: F(1,58)=20.31, p<0.01) (Table 2). In the
control group, imagery was performed significantly slower
than physical execution (F(1,58)=23.82, p<0.01) and both
conditions were performed significantly faster with the
right than with the left hand (F(1,58)=5.99, p<0.01). In the
MS group, however, no significant differences for condi-
tion and dominant body side were found.
Correlations between screening and MI tests
There were no significant correlations between patients’
EDSS score, type of MS and years since diagnosis with
their performance on the MI tests. None of the cognitive
tests correlated with the KVIQ-10 and with imagery of the
BBT, but all of them showed a significant correlation with
the hand rotation task (SDMT: r=0.54; NSBMS: r=0.58;
SRT: r=0.52; 7/24 SRT: r=0.39; PASAT: r=0.40; COWAT:
r=0.55; Digit Span: r=0.44; Corsi Block Tapping: r=0.48)
(Figure 1). The 9HPT for fine motor function did not cor-
relate significantly with the imagery tests.
Comparison between most and least
affected sides
Twenty-one out of 30 patients showed an asymmetry in
upper limb function. Subgroups of the most and least
affected sides were significantly different, shown by differ-
ences in physical execution of the BBT and the 9HPT
Table 2. Test scores (group mean and standard deviation) per variable.
Task VariablesMS patientsControlsBetween-groups
difference
KVIQ-10
Hand rotation


Vividness score
Accuracy
Right side subscore
Left side subscore
40.0 ± 18.2
82.1% ± 13.5%
81.8% ± 13.8%
82.4% ± 14.4%
39.2 ± 15.1
88.4% ± 9.2%
88.9% ± 9.7%
87.8% ± 10.4%
p = 0.85
p < 0.05
p < 0.05
p = 0.10
BBT





Duration execution
Duration imagery
Right side duration execution
Right side duration imagery
Left side duration execution
Left side duration imagery
27.9s ± 7.8s
26.4s ± 8.5s
26.6s ± 10.1s
25.7s ± 9.7s
29.2s ± 8.3s
27.2s ± 9.0s
15.9s ± 1.9s
18.6s ± 4.4s
15.3s ± 1.9s
17.4s ± 4.2s
16.6s ± 2.0s
19.7s ± 4.5s
p < 0.01
p < 0.01
p < 0.01
p < 0.01
p < 0.01
p < 0.01
Abbreviations: KVIQ-10, Kinesthetic and Visual Imagery Questionnaire; BBT, Box and Block Test
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Heremans et al.
1307
(Table 3). Dependent t-tests showed, in line with physical
execution, a significant difference between patients’ most
and least affected body sides in imagery duration of the
BBT. No differences were found between the most and
least affected body sides for the KVIQ-10 and the hand
rotation task (Table 3).
Discussion
Recently, promising results were shown with regard to MI
practice in the rehabilitation of stroke patients,3 but very
limited research examined its potential for patients with
MS. Before considering using MI-based exercises as a ther-
apy tool for these patients, however, it is important to con-
sider to what extent patients’ motor and cognitive
impairments are related to their ability to generate correct
motor images. Therefore, we evaluated the MI ability of 30
MS patients in comparison to 30 controls. Several aspects
of MI ability were assessed, including vividness, accuracy
and temporal organization. We expected these aspects to be
differentially affected in patients showing different degrees
of cognitive and/or motor impairments.
As main results, it was found that imagery vividness did
not differ between groups. Imagery accuracy, however, was
significantly lower in patients than controls. Moreover, sig-
nificant correlations were found between imagery accuracy
and patients’ cognitive functioning. Furthermore, differ-
ences between groups were found in imagery duration. In
general, patients were slower than controls during both
execution and imagery. Whereas, in controls, imagery was
performed slower than physical execution, no differences
were found in MS patients. In the patients, imagery dura-
tion significantly differed between their most and least
affected body sides, indicating an association with motor
functioning.
On the one hand, the results of the KVIQ may indicate
that imagery vividness is well preserved in MS patients.
However, caution is warranted when interpreting the results
of questionnaires. First, it was previously shown that vivid-
ness measures predict performance on other imagery tasks
rather weakly or not at all.21 Besides, when using question-
naires participants perform an auto-evaluation of their MI
ability, implying that they may overestimate their compe-
tence and that answers are subject to the individual’s mood
and to social desirability.22 Furthermore, previous studies in
MS have shown that patients’ self-reports correlate with
cognitive functioning and depression.23 This is an impor-
tant issue, since most studies on MI limit the assessment of
imagery ability to self-evaluation questionnaires. More
objective methods such as hand rotation and mental chro-
nometry tasks should be considered in addition.
In contrast to imagery vividness, clear differences
between groups were found in imagery accuracy. On aver-
age, patients were less accurate than controls and their
imagery accuracy significantly correlated with their cogni-
tive screening scores. Interestingly, the correlation of the
hand rotation task with the total NSBMS score was higher
than with each of its subcomponents. This indicates that MI
involves several aspects of cognition. The hand rotation
scores also significantly correlated with tests on working
memory. This is in accordance with previous findings,24
showing an influence of working memory on MI in stroke
patients. Imagery accuracy did not depend on patients’
motor functioning, as shown by the lack of differences on
the hand rotation task between patients’ least and most
affected sides and the lack of correlation with the 9HPT.
A significant relation between imagery and motor func-
tioning, however, was found with regard to patients’ tempo-
ral organization of MI, which significantly differed between
patients’ most and least affected body sides. In the control
group, imagery was performed slower than physical execu-
tion, which was not the case in the MS group. This can be
interpreted in two ways. On the one hand, previous studies
suggested that a close match between the duration of
Figure 1. Correlations between cognitive tests (Symbol Digit
Modalities Test (SDMT) in the left panel and Neuropsychological
Screening Battery for Multiple Sclerosis (NSBMS) in the right
panel) and the accuracy score of the hand rotation task for the
MS patients.
Table 3. MS patients’ scores (group mean and standard deviation) per test for the most and least affected side.
Test Most affected sideLeast affected side Between-groups difference
9HPT
BBT execution duration
BBT imagery duration
Asymmetric items KVIQ-10
Hand rotation accuracy
61.5s ± 46.3s
32.5s ± 10.7s
28.0s ± 11.4s
20.0 ± 9.0
83.2% ± 12.4%
35.7s ± 18.6s
23.3s ± 6.1s
23.6s ± 7.3s
19.3 ± 8.9
83.5% ± 11.9%
p < 0.01
p < 0.01
p = 0.03
p = 0.20
p = 0.88
Abbreviations: 9HPT, Nine Hole Peg Test; BBT, Box and Block Test; KVIQ-10, Kinesthetic and Visual Imagery Questionnaire
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Multiple Sclerosis Journal 18(9)
imagery and execution indicates correct MI.20 As such, the
BBT data show that patients were able to perform the task
with good temporal organization. On the other hand, other
studies stated that if imagery is performed in accordance to
the principles of motor control, it may not be performed
faster than physical execution.18 In healthy controls, on
average, imagery was slightly slower than physical execu-
tion. In the patient group, however, there was on average no
difference and some patients performed MI even faster than
physical execution. This might indicate that these patients
had an impaired temporal organization of MI, called ‘cha-
otic motor imagery’. Chaotic MI is defined as an inability
to perform MI accurately or, if having preserved accuracy,
the demonstration of temporal uncoupling.18 Another
explanation for the altered ratio between the duration of MI
and execution in these patients might be that, instead of MI
being abnormally speeded up, it may not include errors in
patients’ physical execution of the BBT. As such, we advise
caution when interpreting mental chronometry data in neu-
rological patients, since these data might be affected by
patients’ disease symptoms.
In general, our results show that patients’ cognitive and
motor dysfunctions are related to their MI ability. When
considering using MI-based exercises in MS, a thorough
screening of each patient’s MI ability is needed, since it
was shown that a relationship exists between imagery abil-
ity and the effectiveness of MI practice.10 This does not
necessarily mean that patients with diminished MI ability
could not benefit from MI practice, but these patients might
need additional training in using this technique first. For the
patients who are able to successfully perform MI, imagery
could be a valuable exercise method. Recent studies have
shown that exercise training can induce positive effects in
patients with MS. For example, Dalgas et al.25,26 showed
that progressive resistance training leads to improvements
in lower limb muscle strength and functional capacity in
moderately disabled patients with relapsing–remitting MS.
Up until now, it has been unclear if exercise training is also
feasible and has similar effects in more severely disabled
patients, and patients with other types of MS. Studies in
gerontology suggest that exercise training might also have
a beneficial effect on cognitive function. However, this
requires further research in patients with MS.27 A potential
problem in severely affected MS patients, however, may be
that physical exercise might be limited by the presence of
motor fatigue, temporary decreasing physical performance
and training intensity. Motor fatigue has been defined as a
decline in motor performance during sustained or repetitive
muscle activity.28 We hypothesize that MI practice may
serve as an alternative strategy to continue training at
moments that motor fatigue hampers a patient from per-
forming physical practice. On the other hand, MI requires
mental resources, which may not be constantly present suf-
ficiently in the case of cognitive fatigue, defined as a slow-
ing in mental ability during the performance of repeated
cognitive tasks.29 The presence of primary fatigue, includ-
ing cognitive fatigue, is high with approximately 65% of
the MS patients reporting limitations in functioning due to
fatigue.30 The feasibility to efficiently perform physical and
MI practice in patients with fatigue should be examined in
the future.31
The present study is the first study investigating the
applicability of MI in patients with MS with motor and/or
cognitive impairments. Previously, Bovend’Eerdt et al.32
investigated MI in 30 patients with various neurological
pathologies, but only one of them suffered from MS. Also,
no definitive conclusions could be drawn from this study
since patients’ compliance with the MI intervention was too
low. These results point out that future studies are needed to
explore the barriers and facilitators to uptake an MI inter-
vention. Moreover, future research should examine strate-
gies to further optimize the quality of the MI process,
especially in patients with diminished MI ability. In healthy
persons,33 PD34 and stroke patients35, providing them with
external cues during MI was shown to enhance MI quality.
Although this approach seems promising, we should avoid
generalizing results from studies investigating other types
of neurological patients, since the etiology, affected ana-
tomical areas, course of the disease and type of cognitive
deficits can widely differ between patients. Even within a
group of patients with the same pathology, potentially a
wide variation in MI quality can be found. The present
study was limited to hospitalized patients who showed, on
average, more severe motor symptoms than community-
based MS patients. Also, we excluded patients with very
severe cognitive dysfunctions. More research on a larger
sample, consisting of patients with mild as well as severe
motor and cognitive problems, should be performed in the
future. In addition, further research is needed to specifically
validate the assessment battery that was used in the present
study in patients with MS.
In summary, the current study showed that the MI vivid-
ness of patients with MS did not differ from healthy controls.
However, MS patients did show significant differences in
imagery accuracy and temporal organization. Patients’ MI
accuracy significantly correlated with impairments in cogni-
tive functioning, but was independent of motor functioning.
MI duration, on the other hand, differed between body sides,
implying an association with impaired motor functioning.
Acknowledgements
We would like to express our profound gratitude to the MS patients
and healthy controls who participated in this study. The authors
would like to thank the staff of the National MS Center Melsbroek
Belgium, in particular Dr. M.B. D’Hooghe, Dr. G. Nagels, Dr. A.
Symons and B. Gebara, who helped to realise this study.
Funding
Elke Heremans was supported by the Research Foundation –
Flanders (FWO) and by a PDM grant of the K. U. Leuven.
at Katholieke Univ Leuven on November 26, 2012msj.sagepub.comDownloaded from

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Heremans et al.
1309
Conflict of interest statement
None declared.
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