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This study compared the efficacy of a program combining
mental imagery (mental practice-MIT) and physical therapy (constraint-induced
therapy- CIT) to the efficacy of a program comprised solely of CIT
and a program comprised solely of MIT on patients' levels of upper
extremity (UE) impairment and UE functional outcomes. This study
also evaluated the effects of these different training paradigms
on cortical reorganization following stroke using functional magnetic
resonance imaging (fMRI). CIT has been shown to have a significant
positive effect on functional motor recovery in patients suffering
stroke (4). Current data suggest that mental practice improves the
performance of motor skill behaviors. Since data support that imagined
and executed actions share to some extent the same neural substrates
(5) we therefore hypothesized that mental imagery of a motor task
combined with CIT will lead to decreased UE impairment and improved
upper extremity functional outcome compared to CIT alone and that
a correlation between functional outcome and common neural structures
can be investigated using fMRI. Four stroke patients were randomly
assigned into groups: two patients received both mental imagery
and physical therapy (MIT +CIT) one patient received only mental
imagery therapy (MIT) and one only received physical therapy (CIT).
Mental imagery and functional outcome measures were used to assess
the patients’ functional ability. Blood oxygen-level dependent
(BOLD) fMRI responses were used to detect changes of cortical activity
in the brain. The MIT only patient showed no marked improvements
in motor function of the affected hand while the patients in the
CIT only and MIT +CIT groups patients did show improvements. Following
the interventions while performing finger flexion/extension of the
affected hand fMRI images of the CIT only showed bilateral BOLD
signals in the motor cortex (MC) and the MIT only patient showed
no contralateral MC activity. One of the MIT+CIT patients showed
contralateral MC activity while the other MIT + CIT patient showed
no MC activity in either hemisphere. The data collected were insufficient
in determining which intervention program was most efficient. Recommendations
for future studies include: recruiting more patients customizing
mental imagery tape to interest patients more and standardizing
the time each group spent in interventions.
Stroke survivors are often afflicted with temporary
hemiparesis where the survivor experiences weakened upper extremity
function on one side of their body. Many patients compensate for
this by using their unaffected side reinforcing the nonuse of their
hemiplegic limb. This continued non-utilizaton of the hemiplegic
limb is known as the learned-non-use concept and is thought to contribute
to possible degeneration of processes within the central nervous
system (1). Constraint Induced Therapy (CIT) is one rehabilitative
approach used to counteract the learned-non-use-concept and enhance
upper extremity motor performance of the weaker hand among patients
with stroke. CIT therapy involves restraining the stronger hand
with a mitt and then performing intensive functional task practice
with the weaker hand 5 hours/day for 10 consecutive days. This intense
repetitive task practice is expensive because it relies on individualized
interaction between the patient and rehabilitation specialist. Thus
more cost effective and possible complementary or replacement therapies
are being investigated one of which is mental imagery. Mental practice
(MIT) could be used as a means of multiplying the number of repetitions
of a movement without adding to the physical demand of training
and possibly complementing physical rehabilitation. Although mental
practice the cognitive process of repetitively imagining a task
is not accepted as a standard practice for stroke rehabilitation
the intervention has been beneficial in many situations to perfect
motor tasks especially in sports. The success of mental imagery
in these other environments have led to a few modest attempts to
apply mental practice in a rehabilitation context (3). These studies
have suggested that mental imagery helps to activate partially damaged
motor networks provides stroke patients with more skill practice
which leads to improvements in motor performance and also decreases
in levels of upper limb hemiparesis (3). Is mental imagery a possible
complement to traditional physical therapy? The primary aim of this
study is to measure the efficacy of a program combining mental and
physical practice with the efficacy of a program comprised of only
CIT or only MIT on patients' levels of upper extremity (UE) impairment
and UE functional outcomes. The secondary aim of this study is to
record changes in blood oxygen-level dependent (BOLD) fMRI response
between intervention groups. (Changes in BOLD signals are thought
to be associated with changes in regional cerebral blood flow blood
volume and the concentration of deoxyhemoglobin induced by neuronal
activation.) We hypothesized that in terms of the most effective
therapy the combined CIT + MIT would be the most effective followed
by CIT only and those patients that received MIT only training would
show the least gains in UE function. We also hypothesized that cortical
changes would correlate well with improved motor outcome. That is
those patients who showed the most functional improvement due to
their intervention would show changes in BOLD response exhibited
by a relative change in motor cortical activation from the contralateral
(damaged) hemisphere pre-therapy to the ipsilateral (unaffected)
hemisphere post- therapy. We expected to see more of this hemisphere
shift of cortical activation in the MIT + CIT group less in the
CIT only group and the least in the MIT only group.
Design: Blind randomized controlled
study, Two fMRI sessions (pre- and post- intervention) 2 weeks apart,
3 Groups were studied
For each intervention the patient
MIT only: listened to a CD recording describing 6
functional activities using the weaker arm. The patient listened
to the CD for 30 minutes three times a day for 10 consecutive days.
CIT only participated in constraint induced therapy:
10 consecutive days of therapy for up to 5 hours a day. MIT + CIT
participated in a combination of mental imagery and CIT for 10 consecutive
days for therapy 5 hours a day which included 1.5 hours of listening
to the CD recording of daily activities.
Volunteer Patients: 2 right-handed men (CIT only MIT
only) 1 left-handed man (MIT+CIT) 1 right-handed woman (MIT+ CIT)
44-67 years old (mean 54)
Exclusion criteria
Patients were excluded if they had any of the following:
Stroke was less than 3 months or more than 3 years ago, more than
one stroke excessive cognitive impairments lack of stamina pain
in the impaired extremity inability to stand and maintain balance
with arm support, implanted metal devices claustrophobia or enrollment
in other physical rehabilitation programs. All participants gave
written informed consent for the study which was approved by the
Emory University Institutional Review Board.
Parameters/Measurements
During the first testing session subjects were screened
for depression aphasia (inability to understand language) and apraxia
(loss of ability to perform purposeful actions).
Functional Evaluation
Both evaluation sessions were performed by a rater
blinded to group assignment. During both evaluation sessions upper
extremity motor function was quantitatively assessed by the:
- Motor activity log (MAL)- asks the patient to rate on a scale
of 1-5 (1 being the ability to use the affected hand entirely)
how much and how well they are able to use their affected hand
to perform a list of daily activities.
- Wolf motor function test (WMFT)- records how fast the patient
is able to functionally perform a series of separate functional
UE tasks
During both evaluation sessions upper extremity impairment
was quantitatively assessed by the:
- Fugl-Meyer Motor Assessment- rates the patient’s range
of joint motion pain proprioception and motor coordination
During both evaluation sessions mental chronometry
and mental imaging ability was measured using:
- Sirigu’s break test- test recording time it takes for
a person to imagine thumb to finger movement. The imagined movement
time is compared with the actual movement time.
- Vividness of Movement Imagery Questionnaire (VMIQ)- tests the
patient’s ability to separately imagine themselves and someone
else executing a list of tasks on a scale of 1 to 5 (1 being easily
imagined 5 hard to imagine)
- Movement Imagery Questionnaire (MIQ)- asks the patient to rate
on a scale of 0-7 (7 being very easy to see) how easily they can
imagine and feel a described movement.
Cortical Evaluation
Before each fMRI session patients were fitted with
a splint designed to position the wrist in a neutral position and
to limit the amplitude of movement. A block design was used. Per
scan the paradigm consisted of alternating four rest periods and
three task periods each lasting 30 seconds. Tasks in scanner. The
patient performed finger extensions and flexions to a steady beat
presented by a metronome
- Run1- Physically execute Flex/Ext with affected hand (70 % max
bpm)
- Run2 – Physically execute flext/Ext with unaffected hand
(70 % max bpm)
- Run3- Physically execute Flex/Ext with affected hand (60bpm)
- Run4- Physically execute Flex/Ext with unaffected hand (60bpm)
- Run 5- Mentally execute Flex/Ext with affected hand (60bpm)
- Run6- Mentally execute Flex/Ext with unaffected hand (60bpm)
To check for the absence of finger movements in the
opposite hand (mirror movements) and during mental simulation each
person had a fiber optic device that measured bending of the fingers
attached to each hand.
Calculations for each patient pre- and post-
sessions
Mean of VMIQ, MIQ, and Sirigu scores, median of WMFT
scores, and mean fMRI Beta-value ratios calculated from statistical
parametric maps (SPM99) of Beta values within the volume of interest
in the cerebral cortex from SPM software analysis.
Pre-Post Intervention changes in Motor function
MIT
- Single patient did not show improvements in the affected hand
as expressed by decreased Fugl-Meyer but showed slight improvements
on the MAL and WMFT
- CIT- Single patient showed improvement of affected hand as exhibited
by decreased times on the MAL and WMFT
- MIT + CIT- one patient showed improvements on both the MAL and
Fugl-Meyer but did not show improvement on the WMFT; the other
patient showed improvement as exhibited by decreased times on
the WMFT increased usage of the affected hand (MAL) and increased
motor function as shown on the Fugl-Meyer
Pre-Post Intervention changes in Mental Imagery
- MIT-Single patient showed no improvement in ability to mentally
image as exhibited by a decreased self-perception of imaging abilities
on the VMIQ and MIQ; showed improvement in Sirigu times with the
affected hand.
- CIT-not trained to image therefore data were not collected.
- MIT + CIT- one patient had decreased self-perception of imaging
abilities but improved on the Sirigu test of the affected hand;
the other patient showed improvement on the MIQ but no improvement
on the VMIQ or Sirigu
Slight or inconsistent improvement in functional outcomes in each
group did not provide conclusive evidence for the efficacy of one
interventional program over another. The individual undergoing CIT
only intervention did show improvement in certain measures. The
functional improvement of the two patients in the MIT +CIT were
inconsistent. For example MIT +CIT #2 showed improvement in the
WMFT while MIT +CIT #1 did not. The MIT intervention did lead to
slight improvement in certain functional and mental imagery measures
(Sirigu MAL WMFT) but did not result in a clinically significant
improvement. No improvements in mental imagery ability were observed
with a two week intervention although patients with stroke have
the ability to mentally imagine an upper extremity motor task. This
lack of improvement may be due to many contributing factors such
as: site of lesion duration of intervention mode of stimulus. Future
studies will address these issues. The fMRI data suggested that
patients in all three groups were able to mentally imagine moving
their affected hand. After 2 weeks of MIT only the patient showed
increased contralateral cortical activation in motor areas during
execution of the flexion/extension task. This activation may be
due to the patient’s lack of physical intervention causing
the brain to recruit the same motor pathways used before the stroke.
However bilateral cortical activation was observed during the mental
imagery runs. This suggests that the MIT intervention helped recruit
the healthy ipsilateral hemisphere to some extent. Following 2 weeks
of CIT only our patient showed increased bilateral cortical activation
in both the motor and pre-motor areas during execution of the flexion/extension
task. Activation of these areas is probably due to the recruitment
of the healthy (left) hemisphere to complete the task. (Note we
observed no mirror movement of the right hand during these tasks).
Interestingly following CIT alone we observed motor occipital and
inferior parietal activation mainly in the contralateral hemisphere
during the imagined flexion/extension task. This contralateral activation
may be due to the lack of mental imagery training and the use of
pre-stroke motor pathways. The pattern of activation after 2 weeks
of CIT + MIT in one individual led to more focal contralateral activation
when performing the flexion/extension task. Ipsilateral activation
in occipital temporal-occipital and temporal areas were noticeably
concentrated while the patient imagined the flexion/extension task.
These activations part of the ventral processing stream were related
to the patients “Visual imagery” of the task and were
probably due to the shifting cortical reorganization to the healthy
ipsilateral hemisphere. Though the MIT intervention did cause changes
in the brain no significant functional improvements were noticed
between the CIT only and MIT +CIT groups perhaps because both patients
in the MIT +CIT group had parietal lobe strokes. Patients affected
by parietal strokes are known to be impaired at predicting the time
necessary to perform differentiated finger movements and visually
guided pointing gestures through mental imagery (2). Recommendations
for future studies include: including more patients excluding patients
with parietal lobe strokes extending the period of therapy for more
than 2 weeks customizing mental imagery tape to interest patients
more and standardizing the time each group spent with interventions.
Sponsored by the Howard Hughes Medical Institute Grant No. 52003727;
National Institute of Health Grant No. NIH HD40984; Emory Center
for Complementary and Alternative Medicine Grant No. NIH-NCAM AT00609;
Atlanta VA Rehab R&D Grant No. 508-D3 5012; and Emory General
Science Committee of the Faculty Science Council.
Stroke survivors are often afflicted with temporary
hemiparesis where the survivor experiences weakened upper extremity
function on one side of their body. There are many rehabilitation
methods to help the patient regain function in their arms and hands.
This study investigates the efficacy of three different types of
rehabilitation methods using fMRI and functional outcome measures.
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