CRITICALLY APPRAISED PAPER (CAP) Padula, W. V., Nelson, C. A., Padula, W. V., Benabib, R., Yilmaz, T., & Krevisky, S. (2009). Modifying postural adaptation following a CVA through prismatic shift of visuo-spatial egocenter. Brain Injury, 23(6), 566 576. http://dx.doi.org/10.1080/02699050902926283 CLINICAL BOTTOM LINE: Individuals experiencing hemiparesis after a cerebrovascular accident (CVA) tend to have a postural shift out of midline toward the weakened side. Compensation strategies used in the first weeks of recovery cause a postural shift away from the hemiparetic side. This improper body-space orientation shifts an individual s weightbearing laterally. In addition to possible decreased visual spatial awareness, lateral weight shift causes postural imbalance. Yoked prisms have improved posture and visual perception in individuals post-cva by compensating for deviations in eye alignment. Prisms also have been found to have potential to trigger brain functions correlated to multisensory integration. This study uses yoked prisms as an intervention for visual spatial dysfunction. In individuals post CVA, this visual spatial dysfunction shifts their postural orientation out of midline. Yoked prisms are already used by occupational therapists to increase a client s functional performance. This quasi-experimental study found that yoked prisms are effective at realigning and reducing the visual spatial shift post CVA. (See the results section below for statistical values.) Realignment back to midline affects balance and posture for these individuals and corrects their learning strategies. The directions of the base-end of the yoked prisms are opposite the direction of the individual s postural lean. All individuals in this study were 1 to 3 years post CVA, which demonstrates the prisms ability to improve posture and balance when misalignment of midline occurs in a client. Because of yoked prisms influence on improving postural alignment 1 3 years post CVA, it is hypothesized that this intervention can positively affect functional performance for individuals who are in the initial stages of recovery post CVA due to the possibility of neural plasticity. Occupational therapists used yoked prisms after the acute intervention phase with clients experiencing a shift in visual spatial relations to improve posture and in turn positively affect functional performance. Clinically this study shows that lean or drift away from the hemiparetic side correlates with a shift in visual midline, but this visual shift can be reduced using yoked prisms. Limitations to this study were the statistical testing measures that were used. 1
RESEARCH OBJECTIVE(S) List study objectives. Analyze the presence and direction of visual midline shift (VMS) to the non-affected side after a CVA, and determine whether yoked prisms are an effective way to realign visual midline and postural orientation when hemiparesis is present. DESIGN TYPE AND LEVEL OF EVIDENCE: Level II: Quasi-experimental. Subjects in both the experimental and control groups were randomly assigned left- or right-based prisms and all subjects participated in 4 aspects of testing. SAMPLE SELECTION How were subjects recruited and selected to participate? Please describe. The authors of the study selected participants in a sequential order when the participants met the inclusion criteria. Inclusion Criteria All participants in the study had binocular vision with refractive correction equal or less than - /+2.00 dioptres. Communication and independent ambulatory abilities were also required for all participants. Exclusion Criteria Subjects who had a -/+. 50 dioptres anisometropia (unequal refractive power), used refractive correction during the testing, or had scotomas were not allowed to participate in the study. SAMPLE CHARACTERISTICS N= (Number of participants taking part in the study) 60 #/ (%) Male 33/(55%) #/ (%) Female 27/(45%) Ethnicity Experimental Group Control Group 30 adults with CVA (7 females and 10 males in the right CVA group; 8 females and 5 males in the left CVA group); occurrence of CBA ranged from 1to 3 years. 30 adults with unknown neurological impairment. 2
INTERVENTION(S) AND CONTROL GROUPS Add groups if necessary Group 1: Participants with a diagnosis of a right CVA Brief description of the intervention How many participants in the group? Where did the intervention take place? Who delivered? How often? For how long? The subjects in this group received evaluation of visual midline shift (VMS) and postural orientation with and without yoked prisms while standing and walking. This group of participants consisted of 17 subjects 1 3 years post CVA. The intervention took place in a clinical setting, but no other details on the setting were reported. Clinicians carried out each part of the 4 aspects of testing. Group 2: Participants with a diagnosis of a left CVA Brief description of the intervention How many participants in the group? Where did the intervention take place? Who delivered? How often? For how long? The subjects in this group received evaluation of VMS and postural orientation with and without yoked prisms. This group of participants consisted of 13 subjects 1 3 years post CVA. The intervention took place in a clinical setting, but no other details on the setting were reported. Clinicians carried out each part of the 4 aspects of testing. Group 3: Healthy individuals with no known neurological impairments Brief description of the intervention How many participants in the group? Where did the intervention take place? Who delivered? How often? For how long? The subjects in this group received evaluation of VMS and postural orientation with and without yoked prisms. There were 30 participants in this group, none of whom had a known neurological condition. The intervention took place in a clinical setting, but no other details on the setting were reported. Clinicians carried out each part of the 4 aspects of testing. Intervention Biases: Check yes, no, or and explain, if needed. 3
Contamination: Co-intervention: Timing: YES Site: Comment: Based on the study design, all subjects received the same treatment as part of the study. The tests may have been given out of order. Comment: No other interventions affecting the results of the tested intervention were stated. Comment: The duration of the testing and when the effects were measured were not reported by the researchers. Comment: Participants in both groups received their testing in a clinical setting. Use of different therapists to provide intervention: Comment: The researchers did not state that the testers were different clinicians. MEASURES AND OUTCOMES Complete for each measure relevant to occupational therapy: Measure 1: Influence of yoked prisms on postural orientation Name/type of measure used: Each subject was fitted with 12 dioptres of yoked prisms and observations were measured while the subject stood and walked. What outcome was measured? The presence or absence of a lean or drift away from the hemiparetic side was measured. Is the measure reliable? Is the measure valid? When is the measure used? This measure is used to determine how yoked prisms influences postural orientation. 4
Measurement Biases Were the evaluators blind to treatment status? Check yes, no, or, and if no, explain. Comment: Evaluators used the same treatment for both groups. Evaluators were not blinded to the experimental or control group. Recall or memory bias. Check yes, no, or, and if yes, explain. Others (list and explain): Comment: It was not stated whether the tester and researcher were the same person or group of people. This has potential for bias because researchers may interpret findings to lead toward significance if they are invested in the study. RESULTS List key findings based on study objectives Include statistical significance where appropriate (p < 0.05) Include effect size if reported The researchers hypothesis of yoked prisms correcting the visual midline shift of midline and improving postural orientation was supported. Yoked prisms with the base positioned opposite the visual shift of midline are effective at realigning posture post-cva. At baseline, it was determined that in the experimental group, VMS away from the hemiparetic side was significantly present (right CVA p < 0.001, left CVA p = 0.001). This indicates the presence of postural disorientation away from the hemiparetic side in subjects with a CVA. When testing the placement of the base of the prisms (right or left), researchers found a statistically significant correlation between subjects with right CVA and base-right yoked prisms (p 0.001). In conjunction, base-left prisms had a statistically significant effect on individuals with left CVA (p = 0.001). These findings indicate that the base (right or left) of the prisms used for the intervention should correspond to the hemisphere of the brain where the CVA occurs. When using the yoked prisms to correct the lean, statistical significance was found in the experimental group (right CVA p < 0.001, left CVA p < 0.001). These findings show that yoked prisms are an effective intervention for correcting VMS. All results from subjects in the control group showed to no statistical significance. The researchers did not report the effect size when recording the results. Was this study adequately powered (large enough to show a difference)? Check yes, no, or, and if no, explain. 5
YES Comment: It appears the number of participants (60) along with only looking at one factor s (CVA) effects give this enough power. Were appropriate analytic methods used? Check yes, no, or, and if no, explain. Comment: The researchers only used a test of proportion and descriptive statistics to measure results. Inferential statistics could have been used when analyzing the data. No correlational statistics were used even though the researchers stated they were looking for correlational relationships (p. 570). Were statistics appropriately reported (in written or table format)? Check yes or no, and if no, explain. YES Comment: Was the percent/number of subjects/participants who dropped out of the study reported? Limitations: What are the overall study limitations? The limitations to this study are the statistical measures that are used. When testing subjects in part 1, it was reported that the evaluator sat ~30 degrees from the subject and moved the wand at ~4 cm per second at ~70 degree arc. It was not stated whether the same tester gave each participant this part of the procedure; different testers could have sat at different angles from the subject or moved the wand at varying speeds. Postural orientation also was measured by observation, with the angle of a positive lean being stated as ~10 degrees. These measures are subjective in nature. The statistical measurements were stated as descriptive statistics but the measures were not stated clearly. The authors of this study state that they looked to demonstrate a correlation in the results. However, there was not a statistical measure used to measure the correlation. CONCLUSIONS State the authors conclusions related to the research objectives. Results of this study indicated that subjects post-cva typically have a VMS of perceived midline opposite their hemiplegic side. With the use of yoked prisms, the shift can be clinically reduced and directed back to a subject s physical midline. The researchers state that other neurological diagnoses may affect visual spatial orientation similar to the subjects of this study. However, further research is needed to determine whether yoked prisms could be used as an effective intervention in these differing populations. 6
This work is based on the evidence-based literature review completed by Keely Meagher, OTS, and Kelly Erickson, PhD, OTR/L, Faculty Advisor, College of Saint Scholastica. CAP Worksheet adapted from Critical Review Form--Quantitative Studies. Copyright 1998, by M. Law, D. Stewart, N. Pollack, L. Letts, J. Bosch, & M. Westmorland, McMaster University. Used with permission. For personal or educational use only. All other uses require permission from AOTA. Contact: www.copyright.com 7