Stroke is the largest single cause of neurological disability and individuals post-stroke are the largest consumer of rehabilitation services.1 Most individuals after a stroke will recover to some extent after the insult2; however, more than 50% of stroke survivors have residual motor deficits.3,4 Although functional ambulation is the primary goal for many individuals after stroke, many never regain this ability.5 For those who do walk after a stroke, their gait is often slow, they have poor endurance and balance, and have changes in their quality and adaptability of their walking pattern.6,7 Approximately 90% of patients with chronic stroke ambulate with impaired coordination.8 As individuals with chronic stroke continue to ambulate with a degraded pattern of coordination, they are at greater risk of falling, developing a fear of falling, and losing independence and function.7 Undeniably, rehabilitative strategies aimed at reducing stroke-related disabilities are important.
Constraint-induced movement therapy (CIMT) has been shown to substantially reduce the motor deficits of the more affected upper extremity of certain populations9,10 of individuals with stroke.11–14 CIMT is a rehabilitative strategy used primarily to increase the functional use of the neurologically weaker upper extremity through massed practice, while restraining the lesser involved upper extremity.8 The theoretical framework that supports upper extremity–based CIMT could be applied to lower extremity deficits post-stroke. CIMT capitalizes on the role of use-dependent reorganization to reverse learned nonuse. This is done by using successive approximations toward a task and increasing the demands for precision, strength, function, and coordination.15,16
There is limited evidence supporting the use of this intervention for the lower extremity.8,17 For the lower extremity application of CIMT-based principles, a somewhat different approach is used that eliminates the restraint used in upper extremity CIMT.8 It has been suggested that the restraint applied in the upper extremity intervention is simply an adjunctive technique and may not be needed for success with this therapy,8,18,19 indicating that the effective therapeutic factor in CIMT is the massed practice and forced use of the affected extremity rather than the restraint.8 A theoretical approach to CIMT was chosen over the more traditional approach, with emphasis on the access and encouragement of the affected extremity to overcome learned nonuse. This investigation focused on the massed practice and forced use of the lower extremity as the basis for the intervention. Results from a recently published study17 applying CIMT-based principles to the recovery of posture for people with chronic stroke showed that a massed practice intervention produced significant improvements in reactive balance control and anticipatory and steady-state postural control. Their results were consistent with those of others,15,20–22 indicating that the function of an affected limb post-stoke can be improved with intensive massed practice. The purpose of our pilot project was to determine the feasibility and to evaluate the effect size of an intense mobility treatment for individuals with chronic limitations in gait, balance, and mobility after stroke.
This case series is an “aabaa” design including baseline, pre-test, intervention, post-test, and follow-up evaluation. The eight individuals who participated in the intervention were recruited from the community and local physical therapy clinics. After signing an institutional review board–approved informed consent, the participants were screened to ensure they met the following inclusion/exclusion criteria: (1) they were more than 6 months post-stroke, (2) they had no serious uncontrolled medical complications; (3) they could follow directions (written, verbal, or demonstration), scoring at least 24 out of 30 on the Mini-Mental State Examination; (4) they were not currently receiving skilled therapy or treatment for the involved lower extremity; (5) they could ambulate 25 feet (with or without an assistive device); and (6) did not score higher than 45 out of 56 on the Berg Balance Scale. Table 1 describes the eight participants’ characteristics. In addition to the screening information, a descriptive entry-level lower extremity (LE) motor score was assessed before the intervention using the LE motor portion of the Fugl-Meyer Scale.23
The intense mobility training was performed 3 hours per day for 2 weeks (10 consecutive weekdays). The sessions, delivered one-on-one by senior doctoral degree–level physical therapy (PT) students and overseen by a PT, focused on encouraging the participants to use their more affected lower extremity using a massed practice schedule. A generalized activity list was constructed and used as a template for the therapy sessions. The subjects repeatedly performed activities such as gait training with and without an assistant device (over-ground walking), sit to stand, stair-climbing, various balance activities (tandem stance, single leg stance), proprioceptive activities, range of motion, stretching activities, strengthening activities, coordination tasks, and motor reeducation. The activities were documented in a daily activity log (Appendix). Tasks were patient dependent; therefore, the therapeutic intervention was not the same each day and was adapted to the participants’ performance and ability levels each day. As with traditional CIMT, only the time of the intervention was standardized. As the participants’ performance, fatigue, frustration, and interest levels changed, the therapy was modified accordingly. For example, as the participants improved in performance, the complexity and difficulty of the tasks were increased in an attempt to continue to challenge them. As they became more successful, the activities were changed in various dimensions, such as adding a time component, increasing the height or distance at which the task was performed, and increasing the pattern complexity. Throughout the therapy sessions, the participants received intermittent feedback, focusing on corrections that need to be made and acknowledging individuals’ improvements in task performance. Blood pressure and pulse were monitored before and after, and, as indicated, during, the intervention. Rest breaks were given, as needed, totaling no more than 30 minutes of the 3-hour session. Photographs of the intervention are shown in Figure 1.
A single evaluator delivered various standardized assessments and outcome measures, in a standardized order, 2 weeks before (baseline), immediately before (pre) and after (post) the intervention period, and at a 3-month follow-up, to assess change. Table 2 outlines these assessments with brief descriptions. A baseline measurement was included to serve as a no-intervention control and to attenuate practice effect.
Descriptive statistics (mean, SD) were generated for each dependent variable. Power and effect size for the intervention for this study were determined. Effect sizes were calculated for each of the dependent measures using the equation (meanpost − meanpre)/(SDpre). This is cited as the best determination for effect size for a single-group, pre-test/post-test design (no control group).30 Effect sizes were then defined by using Cohen’s classifications of effect size (d′), where a small d′ = 0.14, medium d′ = 0.36, and large d′ = 0.57.31 The effect sizes that were determined for the outcome measures were averaged to determine an overall effect size for gait, balance, and mobility following this intervention.
A post hoc power analysis using the determined effect size was conducted to determine the average power for the sample size and the power for each dependent measure. Finally, the number of participants needed to reach a power of 0.80, to limit type II errors, was determined for each dependent variable and across the intervention.
The average effect size for gait, balance, and mobility after this intervention is 0.72. Using this effect size (n = 8 participants) and an α = 0.05, the average power was 0.58. In order to reach an acceptable power of 0.80, 14 participants would be needed. Table 3 itemizes the effect size, power, and number of participants needed to reach a power of 0.80 for the intervention and for each of the dependent measures.
Table 4 shows the participants’ changes across testing sessions for time and distance parameters of gait. The cycle time and stride length are reported for the hemiparetic side. Table 5 itemizes the participants’ scores across the balance and mobility assessments.
The purpose of this study was to determine feasibility and evaluate the effect size of an intense mobility treatment for individuals with chronic disabilities and impairments after stroke. While the effect size of this intervention is large, the small sample size results in a power of 0.58. An acceptable power to minimize type II errors is 0.80.32 In order to reach this power, a sample of 14 individuals would be needed. This intervention demonstrated much stronger effect sizes for balance than gait or mobility. Incorporating more gait-specific focus, possibly locomotor training, into the 3-hour intervention may be appropriate to focus more directly on task-specific training for gait.
There is a definite link between balance and falls,33 and many standardized assessments have been given generalized cutoff scores that link the patient’s ability to perform the test to the their risk of falls. Individuals with a score of less than 45 out of 56 on the Berg Balance Scale are identified as having an increased risk of falling.34,35 In this study, half of the participants surpassed the cutoff score, decreasing their risk of falls. In addition, all the participants demonstrated a minimum detectable change score of at least 6 points. This means that there is a 90% likelihood that the change seen is true and not due to measurement error.36
To date, two laboratories have reported using CIMT-based principles to treat the lower extremity of patients with chronic stroke.8,17 Limited results, however, were published about the trial performed by Taub et al,8 as it was only mentioned in a review article that the effort was under way. The recently published second study by Vearrier et al17 applied an intensive massed practice intervention for 10 patients, following a traditional CIMT time frame of 6 hr/day for 10 consecutive weekdays. The Vearrier et al study examined the effects of massed practice for retraining of postural control for people with chronic disability from stroke. Results showed that the intensive massed practice intervention produced significant improvements in reactive balance control and anticipatory and steady-state postural control.17
Similarly, our research study examined the effects of an intense mobility treatment, based on the theories that support CIMT. Our intervention, however, was given 3 hours per day for 2 consecutive weeks. While traditional CIMT is performed for 6 hours per day for 2 weeks, a recent study found that 3 hours of CIMT significantly improves motor function in individuals with chronic stroke.37 Although the treatment effects for this cited upper extremity–based study were not as significant as the 6-hour training, significant positive results were obtained with reduced cost and time requirements. Therefore, the 3-hour per day intervention was used for our study. In addition, this design was used to decrease the fatigue factor associated with repetitive use of the lower extremities. The investigators believe that 6 hours per day would cause undue fatigue for these individuals translating to a decreased capacity for motor learning.38–41
Using the published research of Vearrier et al17 as a comparison, this study that included 3 hours per day produced clinically meaningful improvements in balance when compared to their 6 hours per day. For example, on the Berg Balance Scale, the average change from the pre- to post-test score for the Vearrier et al study was 48.5 to 51.2, where the average change in this study was 31 to 43. Important to note, however, when compared to the 10 subjects who participated in the Vearrier et al study, the eight participants in this research were lower functioning individuals, therefore having more room for improvement. The Vearrier et al17 study used a cutoff score of a 30 out of 56 minimum on the Berg Balance Scale (only half of our participants met this level). In our research study, no minimal balance criterion was used.
The changes in the scores in this study could be due to a variety of factors. The scores could reflect actual improvements in gait, balance, balance confidence, and mobility. The participants may have performed better after the intervention simply because they had performed these tests previously, demonstrating a practice effect; however, an attempt was made to attenuate this by performing a baseline testing session. The lack of a true control group was a limitation of our study; however, the goal was to establish feasibility of the intervention, not to look at statistical changes between two groups. Another limitation to this study was that the evaluator was not blind to test sessions. This was done, however, to avoid introducing interrater reliability issues. This case series was also limited by the amount of time chosen for the follow-up. A longer follow-up would have allowed for better observations of maintained improvement. Finally, there was no set schedule for delivery of feedback to participants; difference in feedback among participants could be a potential limitation.
Overall, this intense mobility training resulted in large effect sizes for balance with smaller effect sizes for gait and mobility for individuals with chronic impairments after stroke. Future studies incorporating more participants would provide insight into the effectiveness for a larger population. The addition of a control group in which the intervention was administered in a distributed manner, such as a traditional outpatient schedule, keeping the practice time the same, would help to further determine the clinical relevance of this intense massed intervention. The addition of more task-specific activities to address gait, such as locomotor training, should be considered as a component to this intervention. This may address the limited effect sizes observed for gait with this intervention.
The authors are grateful to all the students who helped with the intervention, especially Kristi W. Haynes. This project was funded by the Research and Productive Scholarship Awards Program at the University of South Carolina.
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Keywords:© 2007 Neurology Section, APTA
stroke outcome; motor activity; physical therapy techniques; rehabilitation