Rebecca J. Reed-Jones

Vision and falls: A multidisciplinary review of the contributions of visual impairment to falls among older adults

Falls are a leading cause of mortality among older adults worldwide. With the increasing aging population, falls are rapidly becoming a public health concern. Numerous internal and external factors have been associated with an older adults increased risk of falling. Most notably visual impairments are gaining recognition for their critical role in fall events, particularly related to trips, slips and falls due to environmental hazards. This review presents the issue of vision and falls from a multidisciplinary health professional perspective. Discussions include the influence of visual impairment on mobility and activities of daily living, the effects of medications on vision, visual cognitive factors on falls risk and visual training interventions. Finally, implications for multidisciplinary health professional practice and suggestions for future research are offered.

Reliability and Validity Evidence of Multiple Balance Assessments in Athletes With a Concussion

CONTEXT An estimated 300 000 sport-related concussion injuries occur in the United States annually. Approximately 30% of individuals with concussions experience balance disturbances. Common methods of balance assessment include the Clinical Test of Sensory Organization and Balance (CTSIB), the Sensory Organization Test (SOT), the Balance Error Scoring System (BESS), and the Romberg test; however, the National Collegiate Athletic Association recommended the Wii Fit as an alternative measure of balance in athletes with a concussion. A central concern regarding the implementation of the Wii Fit is whether it is reliable and valid for measuring balance disturbance in athletes with concussion. OBJECTIVE To examine the reliability and validity evidence for the CTSIB, SOT, BESS, Romberg test, and Wii Fit for detecting balance disturbance in athletes with a concussion. DATA SOURCES Literature considered for review included publications with reliability and validity data for the assessments of balance (CTSIB, SOT, BESS, Romberg test, and Wii Fit) from PubMed, PsycINFO, and CINAHL. DATA EXTRACTION We identified 63 relevant articles for consideration in the review. Of the 63 articles, 28 were considered appropriate for inclusion and 35 were excluded. DATA SYNTHESIS No current reliability or validity information supports the use of the CTSIB, SOT, Romberg test, or Wii Fit for balance assessment in athletes with a concussion. The BESS demonstrated moderate to high reliability (interclass correlation coefficient = 0.87) and low to moderate validity (sensitivity = 34%, specificity = 87%). However, the Romberg test and Wii Fit have been shown to be reliable tools in the assessment of balance in Parkinson patients. CONCLUSIONS The BESS can evaluate balance problems after a concussion. However, it lacks the ability to detect balance problems after the third day of recovery. Further investigation is needed to establish the use of the CTSIB, SOT, Romberg test, and Wii Fit for assessing balance in athletes with concussions.

WiiFit™ Plus balance test scores for the assessment of balance and mobility in older adults

The Nintendo Wii™ is becoming an increasingly popular technology for the training and assessment of balance in older adults. Recent studies have shown promising results for its use in fall prevention. However, it is not clear how scores on the WiiFit™ balance games relate to current standardized tests of balance and mobility. The purpose of this study was to evaluate the relationship between WiiFit™ Plus balance tests, and standardized tests of older adult fitness, balance, mobility, self-reported balance confidence, and visual attention and processing. Results from 34 older adult participants indicate that WiiFit™ balance tests do not correlate well with standardized functional balance, mobility and fitness tests. However, the Wii balance score, as measured by the Basic Balance Test of the WiiFit™, does correlate with visual processing speed as measured by the Useful Field of View (UFOV(®)) test. These results indicate that WiiFit™ balance tests may provide advantageous information supplementary to information obtained through standard functional mobility and balance tests; however, caution should be used when using the WiiFit™ balance tests in isolation. Further research is necessary as these technologies become widely used in clinical and home settings for balance training and assessment.

The relationship between postural stability and virtual environment adaptation

Currently little is known about how adaptive responses to virtual environments are different between individuals who experience sickness related symptoms and those who do not. It is believed that sensory interactions between visually perceived self-motion and static inertial cues from vestibular and/or proprioceptive sensory systems contribute to the development of adaptation symptoms. The aim of this study was to evaluate the relationship between adaptation symptoms and postural stability in a virtual environment (VE) driving simulator. In addition, the role of sensory interaction was assessed using direct electrical stimulation techniques of the vestibular and cutaneous sensory systems. Posture performance was measured using centre of pressure measures of single leg stance tests during eyes open and eyes closed conditions. Correlation analysis of postural measures and symptom scores were conducted, as well as analysis of variance of posture performance between SICK and WELL individuals. Results indicate that posture stability is negatively correlated to symptom reporting. WELL individuals displayed the greatest decrease in postural stability during eyes open single leg stance following VE simulation. Application of a secondary sensory stimulation (vestibular or cutaneous) resulted in increased visual dependency for postural control following simulation. Combined, these results suggest that sensory interactions drive postural changes that are observed following VE simulation and are related to how visual information is used to control posture.

Vision and agility training in community dwelling older adults: incorporating visual training into programs for fall prevention.

This study aimed to examine the effect of visual training on obstacle course performance of independent community dwelling older adults. Agility is the ability to rapidly alter ongoing motor patterns, an important aspect of mobility which is required in obstacle avoidance. However, visual information is also a critical factor in successful obstacle avoidance. We compared obstacle course performance of a group that trained in visually driven body movements and agility drills, to a group that trained only in agility drills. We also included a control group that followed the American College of Sports Medicine exercise recommendations for older adults. Significant gains in fitness, mobility and power were observed across all training groups. Obstacle course performance results revealed that visual training had the greatest improvement on obstacle course performance (22%) following a 12 week training program. These results suggest that visual training may be an important consideration for fall prevention programs.

Assessment of oculomotor control and balance post-concussion: A preliminary study for a novel approach to concussion management

Abstract Primary objective: Balance disturbances occur in ∼30% of concussion injuries, with vestibular dysfunction reported as the main contributor. However, few have studied oculomotor control post-concussion to assess vestibular dysfunction. Research design: The current research measured the differences in oculomotor control between athletes post-concussion (PC) and athletes without concussion (NC) during an active balance control task. Methods: Nine PC and nine NC athletes wore a monocular eye tracking device, while balance tests were performed using the Nintendo WiiFit® soccer heading game. Average game scores, eye deviations from centre (Gaze Deviations) and gaze fixation (Percentage Time on Centre) were measured. Results: PC made significantly greater Gaze Deviations from centre compared to NC (p < 0.001), however Percentage Time on Centre and game scores were not significantly different between groups. Correlations between gaze and balance within groups revealed a significant positive correlation in NC, while a significant negative correlation in PC. Conclusions: Results from this exploratory examination of oculomotor behaviour post-concussion revealed significant differences in gaze stability between athletes with a concussion and those without, suggesting vestibular involvement post-concussion. Assessment of oculomotor control during balance activities may provide further insight into dysfunction of the vestibular system following a concussion injury.

Kinematics and muscular responses to a ramp descent in the ACL deficient knee

BACKGROUND AND PURPOSE Descent of a ramp has been shown to induce large anterior shear forces on the knee joint. Compensatory muscle responses observed in individuals following an anterior cruciate ligament (ACL) injury are believed to be adopted for the purpose of reducing these forces at the knee, in the absence of the mechanical restraint previously provided by the ACL. As such, examining the kinematics and muscle responses of ACL deficient individuals during ramp descent may provide further insight into strategies used by this population to compensate for anterior shear forces at the knee. METHODS Eight ACL deficient individuals were studied, in comparison to a healthy CONTROL group (N=8), during the descent of a 20 degrees ramp. Kinematics and electromyography were recorded for the injured lower limb of ACLD and matched limb of healthy control individuals. RESULTS ACLD individuals produced altered knee kinematics at heel contact only. Knee motion through stance and swing were similar to CONTROL individuals. ACLD individuals produced significantly greater vastus lateralis and gastrocnemius total muscle activity, but decreased total biceps femoris activity. No significant differences were observed for the timing of peak muscle activity or the magnitude at this point between ACLD and CONTROL. DISCUSSION AND CONCLUSION Greater total muscle activity of vastus lateralis implies that greater force contributions from this muscle were used by ACLD in comparison to CONTROL in response to the ramp. These observations reinforce that quadriceps avoidance is not used by ACLD individuals to reduce anterior shear forces at the knee joint. Rather, vastus lateralis may be used to reduce internal tibial rotation in extreme loading situations.

Proprioceptive deficits of the lower limb following anterior cruciate ligament deficiency affect whole body steering control

The role of lower limb proprioception in the steering control of locomotion is still unclear. The purpose of the current study was to determine whether steering control is altered in individuals with reduced lower limb proprioception. Anterior cruciate ligament deficiency (ACLD) results in a decrease in proprioceptive information from the injured knee joint (Barrack et al. 1989). Therefore the whole body kinematics were recorded for eight unilateral ACLD individuals and eight CONTROL individuals during the descent of a 20° incline ramp followed by either a redirection using a side or cross cutting maneuver or a continuation straight ahead. Onset of head and trunk yaw, mediolateral displacement of a weighted center of mass (COMHT) and mediolateral displacement of the swing foot were analyzed to evaluate differences in the steering control. Timing analyses revealed that ACLD individuals delayed the reorientation of body segments compared to CONTROL individuals. In addition, ACLD did not use a typical steering synergy where the head leads whole body reorientation; rather ACLD individuals reoriented the head, trunk and COMHT in the new direction at the same time. These results suggest that when lower limb proprioceptive information is reduced, the central nervous system (CNS) may delay whole body reorientation to the new travel direction, perhaps in order to integrate existing sensory information (vision, vestibular and proprioception) with the reduced information from the injured knee joint. This control strategy is maintained when visual information is present or reduced in a low light environment. Additionally, the CNS may move the head and trunk segments as, effectively, one segment to decrease the number of degrees of freedom that must be controlled and increase whole body stability during the turning task.

Is the size of the useful field of view affected by postural demands associated with standing and stepping

The useful field of view (UFOV) is the visual area from which information is obtained at a brief glance. While studies have examined the effects of increased cognitive load on the visual field, no one has specifically looked at the effects of postural control or locomotor activity on the UFOV. The current study aimed to examine the effects of postural demand and locomotor activity on UFOV performance in healthy young adults. Eleven participants were tested on three modified UFOV tasks (central processing, peripheral processing, and divided-attention) while seated, standing, and stepping in place. Across all postural conditions, participants showed no difference in their central or peripheral processing. However, in the divided-attention task (reporting the letter in central vision and target location in peripheral vision amongst distracter items) a main effect of posture condition on peripheral target accuracy was found for targets at 57° of eccentricity (p=.037). The mean accuracy reduced from 80.5% (standing) to 74% (seated) to 56.3% (stepping). These findings show that postural demands do affect UFOV divided-attention performance. In particular, the size of the useful field of view significantly decreases when stepping. This finding has important implications for how the results of a UFOV test are used to evaluate the general size of the UFOV during varying activities, as the traditional seated test procedure may overestimate the size of the UFOV during locomotor activities.

Clinical assessment of balance in adults with concussion

Balance is a key component to the assessment of concussion injury; however, the efficacies of clinical tests used are currently under debate. It is questionable whether currently accepted methods of standing balance assessment quantify balance disturbances sufficiently to support decisions on recovery and return to play. Recent evidence of balance abnormalities postconcussion that linger beyond the typical 3- to 5-day recovery period support arguments that currently available standing balance tests are not sensitive enough to determine recovery of function. This article discusses the current clinical tests used in the assessment of concussion in adults and their limitations and the evidence supporting continued balance dysfunction. Implications for the future of balance assessment in concussed adults and recommendations to clinicians for best practices are presented.