Many
successful sports icons tout mental imagery and rehearsal as a key
component in preparing for and executing their physical
performances. One super athlete who was famous for using mental
rehearsal was the boxer Mohammad Ali. He used the power of intention
and outcome expectancy to gain victory after victory, as he noted:
"The man that has no imagination has no wings” (1). Famous golfer,
Jack Nicklaus, claimed that hitting a good golf shot is 10% swing,
40% stance and setup, and 50% the mental picture of how the swing
should occur. As studies have shown, athletes use imagery not only
to help their performance but also make their experiences more
enjoyable (2).
If mental imagery has been widely accepted and found effective in
the sports world for so many years, can an argument be made for the
incorporation of mental imagery in the physical rehabilitation of
individuals with disabilities, and specifically in individuals who
suffer strokes?
Stroke is the leading cause of disability in the United States, and
the fourth leading cause of death. It is estimated that after acute
stroke approximately 80% of the patients have some form of motor
impairment (3). About 20% of these patients regain at least part of
their lost motor functions in the subsequent months; thus, of the
patients surviving, 50-60% are left with a chronic motor disorder
(3). Therefore, much therapeutic effort is invested in functional
recovery of motor skills after stroke.
During a stroke, blood flow to the brain is compromised. This can
lead to brain anoxia and often irreversible damage results. The role
of neuroplasticity, or the ability of the brain to rewire its
pathways, is widely recognized in the physical recovery from brain
damage after stroke. Could there be a role for mental imagery in
activating the same brain centers that lead to functional recovery
and plastic changes in patients after stroke? The idea behind this
physiological phenomenon is that brain areas that are normally
involved in movement execution are also active during the
imagination of a movement. Several studies using brain-mapping
techniques have found that, during mental imagery, brain areas
related to motor execution were activated (5-10), such as the
prefrontal cortex, the pre-motor cortex, the supplemental motor
area, the cingulate cortex, the parietal cortex and the cerebellum.
The discovery of mirror neurons, which fire not only when an action
is executed, but also when one observes another person performing
the same action, also show that our action system can be used
"offline" as well as "online" (5).
Mental imagery is a cognitive task in which a function, a behavior,
or a performance is rehearsed mentally, as if the person is actually
performing it. There are two main types of mental imagery: external
and internal (4). In external imagery, an individual views himself
or herself from the perspective of an observer, "seeing" the
movement and utilizing their visual senses ("Try to see your heel
contacting the ground with each step"). Internal imagery involves a
person utilizing their kinesthetic sense to imagine oneself inside
his or her own body, "feeling" the action being performed ("Try to
feel your heel contacting the ground with each step") (4).
In the past decade, mental imagery has emerged as a promising
technique for therapists to utilize in rehabilitation of motor
skills. In 2006, Braun et al. published the first systematic review
of studies on the use of mental practice in stroke rehab, of which
included four randomized controlled trials (RCTs), one controlled
clinical trial (CCT), two patient case series, and three case
reports (11). The study designs and interventions utilized were all
highly heterogeneous, and the sample sizes were rather small and
insignificant. Because of this, there remains a great need for the
emergence of large, highly-controlled research studies to determine
"best practice guidelines" for post-stroke motor imagery.
It is widely known that rehabilitation after stroke aims to improve
range of motion, muscle strength, bowel and bladder function, and
functional and cognitive abilities. Motor recovery of ambulation is
often a major focus of physical therapy in stroke rehabilitation,
and is one of the most important factors in an individual's level of
physical independence. A study by Dickstein et al (2004)
specifically studied the effect mental imagery has on gait
rehabilitation. The first 4 weeks of the intervention period focused
on the amelioration of specific gait impairments and on improving
speed and symmetry, whereas more attention was devoted during the
last 2 weeks to the performance of functional task-oriented gait
activities (4). Mental motor imagery exercises were applied
randomly, under variable circumstances with only intermittent or
minimum oral feedback. Each session was composed of: 1. Deep muscle
relaxation (1-2 min), 2. External (visual) motor imagery practice
("See") (1-2 min), 3. Internal (kinesthetic) motor imagery practice
("Feel") (3-8 min), 4. Refocusing of attention on the immediate
surroundings and on true body position (1 min). Below is an example
of the imagery approaches and treatment progression throughout the
typical six week gait rehabilitation period (4).
Week 1: Motor Imagery Practice
Example: "Try to imagine hearing the sound of your footsteps on the
floor."
Week 2: Emphasis on Gait Impairments
Example: "Try to 'see' your left knee flex as high as your right
knee."
"Try to 'feel' your left knee flex as high as your right knee."
Week 3: Emphasis on Affected Side and Increased Gait Speed
Example: "Feel that you stand on your paretic leg longer."
"Feel that you move each of your feet farther ahead."
Week 4: Emphasis on Increasing Symmetry
Example: "Try to 'see' both of your legs making the same movements."
"Feel each foot going up the same height as the other."
Week 5 & 6: Imagery Practice for Different Environments
Example: "Imagine that you are walking on a sidewalk at normal
speed, just as you used to walk before the stroke." "While walking
in the street, try to feel the same self-confidence that you always
had."
These progressions can be used in clinical practice, and tailored to
each patient based on their functional and cognitive status,
learning preferences, and overall motivation. There is no denying
that proper rehabilitation is essential for functional recovery
after stroke. Of all the varying approaches to stroke
rehabilitation, supplementing traditional treatments with mental
imagery techniques may prove to be a safe and effective way to
increase patient recovery.
Mohammed Ali utilized mental imagery to prepare for and expect
victory. Patients who suffer from strokes can utilize mental imagery
in much the same way: to practice and prepare to spread their wings
towards their own personal victories. It just may be that thought
can be transformed into action, that mental imagery can be a
powerful player in a patient’s road to recovery.
Last revised: September 18, 2012
by Jennifer Werwie, DPT
References:
1) Kim Bryan, BH. (2006). Use of
exercise-related mental imagery by middle-aged adults. Graduate thesis:
University of Florida. (1): 1.
2) Hall, CR. (1995). The motivational function of mental imagery for
participation in sport and exercise. In J. Annett, B. Cripps, & H. Steinberg
(Eds.), Exercise Addiction:
Motivation for participation in sport and exercise (pp. 15-21). Leicester
England:
British Psychological Society.
3) "Stroke Facts." (2011). Centers for Disease Control and Prevention:
Division for Heart Disease and Stroke Prevention. <http://www.cdc.gov/stroke/facts.htm>
4) Dickstein R, Dunsky A, Marcovitz E. (2004). Motor imagery for gait
rehabilitation in post-stroke hemiparesis. Physical Therapy (84)12;
1167-1177.
5) Vries, SD, Mulder, T. (2007). Motor imagery and stroke rehabilitation: a
critical discussion. Centre for Human Movement Sciences, University Medical
Centre Groningen, J Rehabil Med; 39: 5–13.
6) Malouin F, Richards CL, Jackson PL, Dumas F, Doyon J. (2003). Brain
activations during motor imagery of locomotor-related tasks: a PET study.
Hum Brain Mapp. 19: 47-62.
7) Gerardin E, Sirigu A, Lehericy S, Poline JB, Gaymard B, Marsault C, et
al. (2000). Partially overlapping neural networks for real and imagined hand
movements. Cereb Cortex. 10: 1093–1104.
8) Porro CA, Cettolo V, Francescato MP, Baraldi P. (2000). Ipsilateral
involvement of primary motor cortex during motor imagery. Eur J Neurosci;
12: 3059–3063.
9) Hanakawa T, Immisch I, Toma K, Dimyan MA, Van Gelderen P, Hallett M.
(2003). Functional properties of brain areas associated with motor execution
and imagery. J Neurophysiol; 89: 989–1002.
10) de Lange FP, Hagoort P, Toni I. (2005). Neural topography and content of
movement representations. J Cogn Neurosci; 17: 97–112.
11) Braun SM, Beurskens AJ, Borm PJ, Schack T, Wade DT. (2006). The effects
of mental practice in stroke rehabilitation: a systematic review. Arch Phys
Med Rehabil. 87(6):842-52.
