Keywords
rhythmic auditory stimulation - mirror therapy - stroke - the action research arm
test - grip strength
Introduction
Stroke can be defined as evolving medical symptoms of principal disruption of cerebral
function of which the symptoms can continue for 24 hours or more and can lead to death.[1] The neurological presentations relate to the extent of injury, site of the part
engaged, as well as fundamental causes of brain dysfunction.[2] Globally, stroke results in 12.6 million individuals having a disability of which
8.9 million people belong to lower middle–income countries.[3]
Stroke accounted for 41% of deaths and 72% of disabilities in our country.[4] In India, the second leading cause of death is stroke, the most significant cause
of disability.[5]
[6] Upper extremity function is damaged in approximately 70% of these individuals.[7] Damage to the upper extremity function of hemiplegic patients critically disrupts
their ability to perform daily tasks independently.[8]
Following the onset of stroke, motor paralysis appears, and the recovery of finger
extension function takes the longest period.[9] Given that many daily activities require using movements of fingers and hands, patients,
who are not able to use their hands after the onset of stroke, experience a certain
level of physical and mental pain.[10]
Mirror therapy is an easy and feasible intervention for upper limb training. The purpose
is restoring the upper limb dexterity while asking the patient to emphasis on uninvolved
extremity movements.[11]
Rhythmic auditory stimulation (RAS) is another treatment intervention that has shown
to be beneficial in enhancing upper limb movements.[12] RAS enhances motor control by promoting organization and accomplishment by powerful
entrainment and integrated outcomes of repeated rhythmic sensory signals on the motor
system.[13]
Park et al stated stroke survivors accounting for 85%, undergo paralysis, and 69%
of patients account for disrupted functioning of upper limbs.[8] The hand and digits dexterity recovery makes a crucial contribution to the rehabilitation
of hemiplegic patients.[11] Because of the limited evidence of RAS on hand functions in hemiplegic patients,
a need arises for looking into its uses together with mirror therapy in improving
the hand functions, as well as strength, of the hemiparetic hand. The framed null
hypothesis was that there would be no significant effect of RAS and mirror therapy
on the hand functions and grip strength of the stroke patients. The alternate hypothesis
was there would be a significant effect of RAS and mirror therapy on the hand functions
and grip strength of the stroke patients.
Objective
This study aimed to evaluate the (1) effect of conventional therapy on hand functions
and grip strength of stroke patients, (2) combined effects of RAS and mirror therapy
on the hand functions and grip strength of the stroke patients, and (3) compare the
effects of conventional therapy against the combined effects of RAS and mirror therapy
on the hand functions and grip strength of the stroke patients
Materials and Methods
The study design is a pre–post quasiexperimental study involving patients clinically
diagnosed with a stroke, duration of 6 months from onset, both the genders, aged 50
to 65 years for 4 weeks.[8]
[11] A total of 30 patients were conveniently selected as per the inclusion criteria.
Patients with anterior cerebral artery (ACA) and middle cerebral artery (MCA) involvement
with the affected side being the dominant side and those with Brunnstrom's recovery
stages of 3 and 4 took part.[8] Patients with dementia, depression, or productive psychosis were not included.[2] Patients having any visual or auditory impairments were excluded.[14] The patients were grouped into the following: the control group receiving traditional
physiotherapy and the experimental group receiving exclusively mirror therapy plus
RAS. The purposive sampling technique was used to group the patients into control
and experimental group.
Procedure
[Fig. 1] shows the flowchart for the procedure. Overall, 20 treatment sessions were given
for 1 month for both the groups. Assessments were made before and after the treatment
sessions using hand-held dynamometer and ARAT. Conventional physiotherapy was provided
for 20 minutes to the control group in each session.
Fig. 1 Flowchart for the procedure. ARAT, action research arm test.
Conventional Physiotherapy
Tone Normalization of Spastic Muscles
Slow sustained stretching of the agonist spastic muscles through range of motion (ROM).
Active exercises focused on the activation of the weak antagonist muscles using slow
and controlled movements were performed. Local facilitation techniques, such as stretching,
tapping, and light resistance, were added to enhance the action of the weak antagonist
muscles.[15] Tapping to the antagonist muscle was given to facilitate voluntary movement out
of synergy pattern which caused reciprocal inhibition of the spastic muscle. Tone
normalization was provided for 5 minutes.
To maintain Range of Motion
ROM exercises were given for 5 minutes.
Sensory Reeducation
Stroking through thenar, as well as hypothenar, eminences five times to achieve purposeful
muscular contractions. Superficial and deep pressure were applied. Localization to
touch was to allowing patients to touch objects of various sizes, shapes, and materials.
Sensory re-education was given for 5 minutes.
Encouraging Voluntary Movement
Patients were encouraged to make use of their involved hand for performing daily activities
such as grooming and dressing. The patients performed all the voluntary activities
for 5 minutes. Integrated mirror therapy and RAS for 20 minutes were rendered to the
experimental group in each session.
Rhythmic Auditory Stimulation
Participants were made to sit in a back-supported chair, with the affected hand placed
on the desk.[14] RAS using an electronic smartphone-based metronome was given. Patients performed
hand movements such as grasping a ball and releasing it, rolling the ball from the
tip of fingers to the palm, pinching a ball, stacking coins, and other physiological
movements of the hand. Patients executed the repeated movement sequence with the metronome
beats in time.[14] To find out the preferred auditory stimulation frequency, each patient was asked
to perform a repetition of each task for 1 minute using the affected hand.[14] The advantage of using a smartphone is that it can be easily operated and is instantly
available ([Table 1]).[16]
Table 1
Duration, frequency, and activities for the treatment interventions
|
Treatment interventions
|
Duration
|
Frequency
|
Activities to be performed
|
|
Rhythmic auditory stimulation
|
10 minutes
|
5 days/week
|
• Grasping a ball and releasing it
• Rolling the ball from the tip of the fingers to the palm
• Pinching a ball
• Stacking coins
• Other physiological movements of the hand
|
|
Mirror therapy
|
10 minutes
|
5 days/week
|
• Supination and pronation
• Flexion–extension of wrist and finger, finger movements
• Sponge squeezing
• Swiping a table with a towel etc.
|
Mirror Therapy
A mirror box training session followed this. The involved hand of the patient was
asked to place at the back of the box while the uninvolved extremity ahead of the
box. Participants performed various physiological forearm and hand movements, viewing
the uninvolved extremity image, thereby watching the reflection of movements of the
hand projected over the affected hand.[10]
[16] The patients performed the same physiological activities simultaneously using the
paretic hand ([Table 1]).[17]
Outcome Measures
Statistical Analysis
Statistical analyses are listed in [Tables 2]
[3]
[4]
[5]
[6]
[7].
Table 2
Comparison of the groups by age
|
Variable
|
Paired differences
|
t
|
df
|
Significance (two-tailed)
|
|
Mean
|
Standard deviation
|
Standard error mean
|
95% confidence interval of the difference
|
|
Lower
|
Upper
|
|
AGE_E
AGE_C
|
0.800
|
7.022
|
1.813
|
−3.089
|
4.689
|
0.441
|
14
|
0.666
|
Note: Notable distinctions were not present among the two groups (experimental group
and control group) in age distribution and mean age (t = 0.441 and p = 0.666; [Table 2]).
Table 3
Comparison of the groups by gender
|
Variable
|
Paired differences
|
t
|
df
|
Significance (two-tailed)
|
|
Mean
|
Standard deviation
|
Standard error mean
|
95% confidence interval of the difference
|
|
Lower
|
Upper
|
|
Gender
|
0.067
|
0.704
|
0.182
|
−0.323
|
0.456
|
0.367
|
14
|
0.719
|
Note: Notable distinctions were not present among the two groups (experimental and
control group) in gender distribution and mean age (t = 0.367 and p = 0.719; [Table 3]).
Table 4
Pre–post action research arm test (ARAT) scores
|
Variable
|
Paired differences
|
t
|
df
|
Significance (two-tailed)
|
|
Mean
|
Standard deviation
|
Standard error mean
|
95% confidence interval of the difference
|
|
Lower
|
Upper
|
|
Pair 1: experimental group
|
Pre–post scores of ARAT
|
−11.73
|
4.35
|
1.123
|
−14.14
|
−9.324
|
−10.45
|
14
|
0.000
|
|
Pair 2: control group
|
Pretest scores of ARAT, posttest scores of ARAT
|
−5.133
|
1.685
|
0.435
|
−6.066
|
−4.2
|
−11.8
|
14
|
0.000
|
Note: The mean of paired difference of pre-post ARAT scores in the control group was
−5.133 with standard deviation of 1.685, which is statistically significant (p <0.0001; [Table 4]).
Table 5
Pre–post grip strength scores
|
Variable
|
Paired differences
|
t
|
df
|
Significance (two-tailed)
|
|
Mean
|
Standard deviation
|
Standard error mean
|
95% confidence interval of the difference
|
|
Lower
|
Upper
|
|
Experimental group
|
Pretest scores of grip strength (kg), posttest scores of grip strength
|
−5.667
|
2.289
|
0.591
|
−6.934
|
−4.399
|
−9.589
|
14
|
0.000
|
|
Control group
|
Pretest scores of grip strength, posttest scores of grip strength
|
−2.8
|
1.612
|
0.416
|
−3.693
|
−1.907
|
−6.725
|
14
|
0.000
|
Note: The mean of paired difference of pre–post grip strength scores in the control
group was −2.880 with standard deviation of 1.612 which is statistically significant
(p <0.0001; [Table 5]).
Table 6
Paired differences of pretest scores of action research arm test (ARAT) and grip strength
|
Variable
|
Paired differences
|
t
|
df
|
Significance (two-tailed)
|
|
Mean
|
Standard deviation
|
Standard error mean
|
95% confidence interval of the difference
|
|
Lower
|
Upper
|
|
Pretest scores of ARAT between the experimental and control group
|
0.267
|
12.87
|
3.323
|
−6.861
|
7.394
|
0.08
|
14
|
0.937
|
|
Pretest scores of grip strength (kg) between the experimental and control group
|
0.467
|
5.643
|
1.457
|
−2.658
|
3.591
|
0.32
|
14
|
0.753
|
Note: The values obtained show that the subjects were homogenous in both groups ([Table 6]).
Table 7
Paired differences of posttest scores of ARAT and grip strength
|
Variable
|
Paired differences
|
t
|
df
|
Significance (two-tailed)
|
|
Mean
|
SD
|
Standard error mean
|
95% confidence interval of the difference
|
|
Lower
|
Upper
|
|
Posttest scores of ARAT between the experimental and control group
|
6.867
|
10.19
|
2.631
|
1.224
|
12.51
|
2.61
|
14
|
0.021
|
|
Posttest scores of grip strength between the experimental and control group
|
3.333
|
6.275
|
1.62
|
−0.142
|
6.809
|
2.057
|
14
|
0.059
|
Abbreviations: ARAT, action research arm test; SD, standard deviation.
Note: The mean of paired differences of scores of ARAT posttest was 6.867 with SD = 10.19
(p = 0.021). The mean of paired differences in grip strength score was 3.333 with SD = 6.275
(p = 0.059), which is statistically significant ([Table 7]).
Results
Notable changes among the groups were not found: control (57.07 ± 4.079) and experimental
(57.87 ± 4.824) groups with the distribution of age and mean age (p = 0.666) and gender distribution and mean (p = 0.719).
A notable difference in ARAT scores between the groups was not seen: control (27.07 ± 8.852)
and experimental (27.33 ± 10.560) groups with mean pretest scores (p = 0.937). But notable changes in ARAT results were present in the groups: control
(32.20 ± 8.986), and experimental (39.07 ± 8.345) groups with mean posttest scores
(p = 0.021) and change from pretest to posttest (p = 0.0001) scores.
This shows that the experimental group is showing maximum changes in ARAT results
compared with the control group.
No notable distinctions in grip strength results were observed among groups: control
(14.20 ± 4.329) and experimental (14.67 ± 3.773) groups with mean pretest scores (p = 0.753). Notable distinction was observed: control (17.00 ± 4.375) and experimental
(20.33 ± 4.923) groups with mean posttest scores (p = 0.059); change from pretest to posttest was noted (p = 0.0001).
It shows that the experimental group shows maximum changes or improvement in grip
strength scores than the control group.
Thus, it shows that the integrated visual and auditory stimulation (RAS and mirror
therapy) improved functions of the hand and grip strength among hemiparetic patients.
Statistically significant values were observed for the experimental group.
Discussion
Stroke often results in a paretic hand. After 6 months from the duration of stroke,
patients regaining dexterity in manipulative tasks accounted for 38%, while only 11.6%
achieved complete functional recovery in hand dexterity.[18]
Differences in hand functions and grip strengths were evaluated and compared. The
application of RAS by a smartphone-based metronome application showed improvements
in grip strength, as well as various physiological hand functions, while mirror therapy
provided the appropriate visual feedback.
The results obtained after the paired t-test analysis showed that there was a recommendable improvement in both the outcome
measures in the experimental group: ARAT score (39.07 ± 8.345) and grip strength score
(20.33 ± 4.923). The findings matched the results of Street et al where significant
mean values of ARAT (29.80 ± 18.75) were observed on the application of auditory stimulation
which was designed for home-purpose for stroke patients with hemiparesis of the arm.[13]
[19] Raglio et al found recommendable recovery in grip strength (24.91 ± 11.55) in their
study.[20] The improvements in the strength of grip functions observed are similar to the improvements
observed in El Shemy and Abd El-Maksoud in which strength of grip functions improved
profoundly (10.63 ± 1.49 vs. 5.7 ± 1.42, p < 0.05) were observed.[21] The obtained results also come in agreement with Sathian et al.[22]
After the analysis of the paired t-test, the results showed improvement in both the outcome measures in the control
group: ARAT score (32.20 ± 8.986) and grip strength score (17.00 ± 4.375).
Recommendable improvement in ARAT scores postassessment was noted. A significantly
higher effect in ARAT scores was seen among the experimental group. The positive results
in the ARAT scores were due to the improvement of considerable dexterity which emphasized
four aspects, that is, pinch, grip, grasp, and gross movements of the hand.
A significantly higher effect in grip strength scores was seen in the experimental
group than in the control group. Grip strength improvement is related to improvements
in complicated motor functions which shows that grip strength can be used as an indicator
of the functional recovery of the hand and arm.
Conventional physiotherapeutic approaches are influenced by the ability of central
nervous system (CNS) to reorganize itself to relearn and perform various cognitive
and motor functions. Hence, the results can be ascribed to repetitions of specific
tasks and exercises, local facilitation techniques, and motor relearning strategies.[23]
The outcomes show the improvement in quality of movement and enhanced motor control
using RAS in stroke patients. The programmed movements produced by RAS were smooth,
effective, and bought about wider ROM. The study results show that rhythmic cueing
improves the quality of movement and motor control in stroke patients. RAS allowed
for a programmed movement that was more efficient and smoother and had wider ROM.
The results are likely the result of auditory rhythms transmitted to the motor system
which provided constant feedback while performing the various exercises. The auditory
and motor system have rich connectivity across various cortical, subcortical, and
spinal levels. The auditory system projects into motor structures in the brain, creating
entrainment between the rhythmic signal and the motor response.
Rhythmic auditory cueing has three advantages. First, holding frequency constant ensures
that the same movement is actually repeated. The auditory cueing may entrain the motor
system to its beat. Second, matching the sound with full extension or flexion of fingers
provides an attentional goal for the patient. Goal setting is also known to promote
motor learning. Third, receiving feedback is fundamental to motor learning. In this
study, sensory information from the audio cues and visual and somatosensory sources
provided intrinsic feedback to the patient regarding the movement goal.[14] The profound effects of RAS on movement have been explained by the auditory-motor
entrainment which means innate synchronization of movement rhythm to the regular beat
of music/sounds.[24]
The experimental group demonstrated better results in accomplishing the daily tasks
of living compared with the control group. These results support the study of Stevens
and Stoykov[25] study, stating that observing movements through mirror therapy generates positive
feedback. Observation of normal movement provided positive visual feedback and improved
the function of their affected limb without it being moved. Normal movement is thought
to be induced due to activating the premotor cortex by recalling the proprioception
(individual perception) that was reduced or removed when normal visual feedback was
provided.[19] Mirror therapy, when used with daily functional activities, enhanced the motor recovery
of the paretic upper extremity in stroke patients. Mirror therapy provides sustained
regular visual input of movement which may better promote central brain remodeling.[26]
Limitations and Recommendations
Limitations and Recommendations
Stroke patients within 6 months from onset were taken into account, hence the homogeneity
among the patients hence the homogeneity among the patients were maintained. The long-term
effect of the interventions is not known as the research was conducted only for a
month without follow-ups. Also, patients with Brunnstrom's stages 3 and 4 were included
in the study, leading to nonuniformity in the pre–post test scores between and among
the groups. Interventions according to various Brunnstrom's stages and individualized
to the patients' functional needs should be developed.
Conclusion
The study can be concluded by stating that integrated visual and auditory stimulation
has beneficial effects on hand functions and strength in hemiparetic stroke patients.
However, when compared with the conventional approach, the results of research conclude
that combined effects of RAS and mirror therapy have beneficial effects on restoration
and improvement of the hand functions. Both these treatment interventions can be used
as suitable adjuncts along with conventional physiotherapy to encourage and facilitate
the restoration of hand functions in hemiparetic patients.
