Nicole Paquet

Stroke affects the coordination and stabilization of head, thorax and pelvis during voluntary horizontal head motions performed in walking

OBJECTIVE This study was conducted to investigate and compare the coordination and stabilization of axial segments during walking with and without horizontal voluntary head turns, in healthy (n=5) and hemiparetic (n=10) subjects. METHODS Subjects were instructed to turn the head as fast and as soon as possible in the direction indicated by an illuminated arrow signal (right, left or none) that was triggered at initial contact of the right (healthy) or paretic (hemiparetic) foot. Head, thorax, and pelvis motions were obtained from a 9-segment model using retro-reflective markers and a Vicon-512 system with 6 high-resolution cameras. Coordination of axial segments in the horizontal plane was characterized using cyclographs and cross-correlation analyses. Stabilization of the segments was quantified using root mean square (RMS) values of the segments normalized acceleration profile. RESULTS The healthy subjects showed a direction-dependent modulation of axial segment coordination, with head turns toward and away from the stance limb favoring and hindering, respectively, the contra-rotational pattern of the thorax with respect to the pelvis during locomotion. Meanwhile, pelvis motions remained unaltered. This direction-specific modulation pattern was disrupted in the hemiparetic subjects, both in the spatial and temporal domains. Moreover, larger RMS values for head and thorax segments were observed in the hemiparetic groups, both with and without the superimposition of voluntary head motions. CONCLUSIONS The findings suggest that: (1) head rotations during walking modify axial segment coordination in a direction-specific manner, (2) the pelvic rotations associated with locomotion remained unaffected by head rotations and (3) stroke alters this coordination behavior, which may contribute to balance dysfunctions during locomotion.

Clinical evaluation of dynamic visual acuity in subjects with unilateral vestibular hypofunction.

Objectives: The objectives of this study are threefold: 1) to examine the effect of frequency of head motion on the clinical dynamic visual acuity (DVA) score in subjects with unilateral vestibular hypofunction (UVH); 2) to compare DVA scores between subjects with UVH and subjects with a complete unilateral vestibular deficit; and 3) to establish whether a relationship exists between the extent of the vestibular deficit and the DVA score. Design: Experimental study. Setting: Vestibular outpatient rehabilitation program. Methods: A convenience sample of 10 subjects with UVH. Main Outcome Measures: Dynamic visual acuity scores were recorded using 2 standard acuity charts: Snellen and E-chart. The DVA scores were obtained at slow (0.5 Hz), moderate (1 and 1.5 Hz), and fast (2.0 Hz) frequencies of head motion in the horizontal and the vertical planes. Percentage of caloric weakness was compared with DVA scores in each subject to test whether a relationship exists between the two. Results: As the frequency of head motion increased, the number of UVH subjects with an abnormal DVA score increased. Subjects with an abnormal DVA score at 1 Hz had the same or higher score as the frequency of the head motion was increased. Spearman correlation analyses revealed low-correlation coefficients between percentage of vestibular paresis at the caloric test and DVA scores (horizontal direction: r = 0.31, p = 0.38 for Snellen chart and r = −0.33, p = 0.35 for the E-chart; vertical: r = 0.05, p = 0.91 for the Snellen chart and r = −0.28, p = 0.50 for the E-chart). Conclusion: Subjects with UVH manifest impaired DVA. The frequency of head motion has an impact on clinical DVA scores in UVH subjects.

Optimal parameters for the clinical test of dynamic visual acuity in patients with a unilateral vestibular deficit.

OBJECTIVE To determine the influence of frequency and direction of head movement and type of vision chart on the score of a clinical test of dynamic visual acuity (DVA). METHODS The subjects were 31 healthy individuals (22 to 79 years old) and 10 patients (19 to 70 years old) with a unilateral vestibular deficit owing to surgical resection of an acoustic neuroma. They read a Snellen or an E-chart while their head was passively moved +/- 20 degrees back and forth in the horizontal or vertical direction at one of four frequencies (0.5, 1.0, 1.5, and 2.0 Hz). The DVA score was the difference in the number of lines on the vision chart that could be read with the head passively moved versus with the head immobile. RESULTS Four healthy subjects had a low DVA score during horizontal head movements at the fastest frequency (2.0 Hz) with the Snellen chart. In patients, DVA scores significantly decreased as head movement frequency increased from 0.5 to 1.0 Hz and from 1.0 to 1.5 Hz, during horizontal and vertical movements, and with both vision charts (p < .001). The DVA scores of healthy subjects were more consistent across three trials with the E-chart than with the Snellen chart at 1.0 and 0.5 Hz (horizontal movements, p < .01) and at 1.5 and 1.0 Hz (vertical movements, p < .01). CONCLUSIONS This study provides new indications on the optimal parameters for the clinical test of DVA. From the results, it is recommended that DVA be tested during horizontal and vertical head movements at a frequency of 1.5 Hz with the E-chart.

Prioritizing attention on a reaction time task improves postural control and reaction time

Flexible and appropriate allocation of attention resources is important during dual-tasking to achieve task goals while maintaining postural safety. This pilot study aimed to examine the influence of explicit prioritization of attention on the dual-task paradigm by employing two levels of difficulty for the postural tasks and reaction time (RT) tasks in healthy young adults. The task entailed standing on a force platform on two feet or on one foot, attending to posture or RT, and completing a simple or choice RT task. Participants verbally responded “top” as soon as the light cue illuminated. In general, attending to RT produced faster RTs (F(1,19) = 30.9, p < 0.001) and improved center of pressure (COP) Displacement (F(1,19) = 5.1, p < 0.05) and 95% Area Ellipse (F(1,19) = 7.1, p < 0.05). These findings suggest that prioritizing attention away from posture may be beneficial for postural performance when completing a second task.

Fukuda and Babinski-Weil tests: within-subject variability and test-retest reliability in nondisabled adults.

The Fukuda Stepping Test and the Babinski-Weil test are clinical assessments that presumably reveal unilateral vestibular hypofunction. However, abnormal performances on both of these two tests have been found in nondisabled individuals. This study compared measures of lateral and longitudinal displacements and body rotation for both tests, as well as the within-subject variability and test-retest reliability of the measures. In addition, correlations between hand and foot dominance and these measures were studied. Fifty young, nondisabled participants performed three trials of the 100-step Fukuda test and three trials of the Babinski-Weil test. The testing session was repeated 7 d later (retest). Lateral displacement, body rotation, and within-subject variability of these two measures were larger on the Fukuda than the Babinski-Weil test. No difference in test-retest reliability was found between the two tests, and a significant correlation was found between body rotation on the Fukuda test and score on the Waterloo Footedness Questionnaire. There may have been smaller variability in results of the Babinski-Weil test because it contains fewer steps (36) than the 100-step Fukuda test. Future research should compare tests with an equal number of steps; but, in the meantime, the Babinski-Weil test seems to have better psychometric properties than the Fukuda test, at least in nondisabled individuals.

Reproducibility of Distance and Direction Errors Associated with Forward, Backward, and Sideway Walking in the Context of Blind Navigation

The ability to navigate without vision towards a previously seen target has been extensively studied, but its reliability over time has yet to be established. Our aims were to determine distance and direction errors made during blind navigation across four different directions involving three different gait patterns (stepping forward, stepping sideway, and stepping backward), and to establish the test – retest reproducibility of these errors. Twenty young healthy adults participated in two testing sessions separated by 7 days. They were shown targets located, respectively, 8 m ahead, 8 m behind, and 8 m to their right and left. With vision occluded by opaque goggles, they walked forward (target ahead), backward (target behind), and sideway (right and left targets) until they perceived to be on the target. Subjects were not provided with feedback about their performance. Walked distance, angular deviation, and body rotation were measured. The mean estimated distance error was similar across the four walking directions and ranged from 16 to 80 cm with respect to the 8 m target. In contrast, direction errors were significantly larger during sideway navigation (walking in the frontal plane: leftward, 10° ± 15° deviation; rightward, 18° ± 13°) than during forward and backward navigation (walking in the sagittal plane). In general, distance and direction errors were only moderately reproducible between the two sessions [intraclass correlation coefficients (ICCs) ranging from 0.682 to 0.705]. Among the four directions, rightward navigation showed the best reproducibility with ICCs ranging from 0.607 to 0.726, and backward navigation had the worst reliability with ICCs ranging from 0.094 to 0.554. These findings indicate that errors associated with blind navigation across different walking directions and involving different gait patterns are only moderately to poorly reproducible on repeated testing, especially for walking backward. The biomechanical constraints and increased cognitive loading imposed by changing the walking pattern to backward stepping may underlie the poor performance in this direction.

Predictors of daily mobility skills 6 months post-discharge from acute care or rehabilitation in older adults with stroke living at home

Purpose. To determine the evolution of daily mobility skills from the timed up-and-go (TUG) upto 6 months after home return in older adults with stroke discharged from acute care or rehabilitation; and to identify the best predictive factors of the TUG at 6 months post-discharge. Methods. In this longitudinal prospective study, people with stroke aged 65 years or more and discharged home from an acute care hospital (n = 82) or a rehabilitation service (n = 109) were included. The TUG was measured at discharge (T1), and at 3 and 6 months post-discharge (T2 and T3). Correlations between the TUG at T3 and sociodemographic and clinical variables, as well as physical, cognitive, perceptual and psychological measures at T1, were used in a multiple regression model to identify the best predictors of TUG at T3. Results. TUG did not change between T1, T2 and T3 in the two groups of participants. The best predictors of TUG at T3 in participants from acute care were the use of a walking aid in daily life, age, deficits in oral expression and the presence of depressive symptoms. In participants from rehabilitation, predictors were the stage of motor recovery of the foot, the use of a walking aid in daily life, number of schooling years and memory impairments. Conclusion. Daily mobility skills, as assessed with the TUG, did not deteriorate upto 6 months after home return in older adults with stroke. The best predictor of the TUG at T3 is the use of a walking aid during daily life in participants from acute care, and motor recovery of the foot in participants from rehabilitation.

2-year review of a novel vestibular rehabilitation program in Montreal and Laval, Quebec.

OBJECTIVE To evaluate the benefits of a vestibular rehabilitation program (VRP) in the Montreal-Laval area. DESIGN The VRP was conceptualized by a panel of experts including otolaryngologists, physiotherapists, and researchers from McGill University and its teaching hospitals. From February 1999 to December 2001, 117 patients were seen, and 88 of them completed the VRP. SETTING The VRP has been established at the Jewish Rehabilitation Hospital in Laval, PQ, to provide specialized rehabilitation to clients suffering from vertigo, dizziness, and/or impaired balance owing to lesions or disorders of the vestibular system. MAIN OUTCOME MEASURES Presence or absence of nystagmus or vertigo during the Dix-Hallpike test, Dizziness Handicap Inventory (DHI), and Dynamic Gait Index (DGI). RESULTS Thirty-five patients with benign paroxysmal positional vertigo of the posterior canal were treated with canalith repositioning manoeuvres. All of the patients (100%) had absence of nystagmus or vertigo after one to four treatment sessions. Forty-six patients with vestibular deficits or dizziness-disequilibrium completed the VRP, which consisted mainly of individualized eye-head and balance home exercise programs. At the end of the VRP, there was a significant decrease in DHI score (31 vs 57; p < .01) and a significant increase in DGI score (18.4 vs 22.6; p < .01). CONCLUSIONS A range of modest to major improvements was shown by comparing initial and discharge scores of patients who had completed vestibular rehabilitation. The VRP appears to be beneficial for patients with a variety of vestibular disorders. Further research is needed to continue optimizing vestibular rehabilitation.

Engagement in Personally Valued Occupations Following Stroke and a Move to Assisted Living

ABSTRACT Research regarding valued occupations following stroke has been carried out almost exclusively with stroke survivors who have returned to their own homes following hospital discharge. We explored engagement in personally valued occupations following stroke and discharge to an assisted living facility. Four women aged 72–87 were followed at 6, 9, and 12 months post stroke. All of the women desired to engage in personally valued occupations to continue to: (1) develop skills and knowledge and contribute to others through occupations of personal interest and (2) improve their health, mobility and function. Opportunities to engage in such occupations were generally present within the AL facilities. However, there were barriers to making use of these opportunities. Challenges for AL facilities wishing to make changes that would allow for enhanced engagement in personally valued occupations included recognition of residents’ individual skills and desires to use these skills and identification of individualized information regarding residents’ interests.

Impact of age and obstacles on navigation precision and reaction time during blind navigation in dual-task conditions

Navigation without vision is a skill that is often employed in our daily lives, such as walking in the dark at night. Navigating without vision to a remembered target has previously been studied. However, little is known about the impact of age or obstacles on the attentional demands of a blind navigation task. This study examined the impacts of age and obstacles on reaction time (RT) and navigation precision during blind navigation in dual-task conditions. The aims were to determine the effects of age, obstacles, and auditory stimulus location on RT and navigation precision in a blind navigation task. Ten healthy young adults (24.5±2.5 years) and ten healthy older adults (69.5±2.9 years) participated in the study. Participants were asked to walk to a target located 8m ahead. In half the trials, the path was obstructed with hanging obstacles. Participants performed this task in the absence of vision, while executing a discrete RT task. Results demonstrated that older adults presented increased RT, linear distance travelled (LDT), and obstacle contact; that obstacle presence significantly increased RT compared to trials with no obstacles; and that an auditory stimulus emitted early versus late in the path increased LDT. Results suggest that the attentional demands of blind navigation are higher in older than young adults, as well as when obstacles are present. Furthermore, navigation precision is affected by age and when participants are distracted by the secondary task early in navigation, presumably because the secondary task interferes with path estimation.