Effect of vestibular loss on head-on-trunk stability in individuals with vestibular schwannoma.

The vestibulo-collic reflex generates neck motor commands to produce head-on-trunk movements that are essential for stabilizing the head relative to space. Here we examined the effects of vestibular loss on head-on-trunk kinematics during voluntary behavior. Head and trunk movements were measured in individuals with vestibular schwannoma before and then 6 weeks after unilateral vestibular deafferentation via surgical resection of the tumor. Movements were recorded in 6 dimensions (i.e., 3 axes of rotation and 3 axes of translation) using small light-weight inertial measurement units while participants performed balance and gait tasks. Kinematic measures differed between individuals with vestibular schwannoma (at both time points) and healthy controls for the more challenging exercises, namely those performed in tandem position or on an unstable surface without visual input. Quantitative assessment of the vestibulo-ocular reflex (VOR) revealed a reduction in VOR gain for individuals with vestibular schwannoma compared to control subjects, that was further reduced following surgery. These findings indicated that the impairment caused by either the tumor or subsequent surgical tumor resection altered head-on-trunk kinematics in a manner that is not normalized by central compensation. In contrast, we further found that head-on-trunk kinematics in individuals with vestibular schwannoma were actually comparable before and after surgery. Thus, taken together, our results indicate that vestibular loss impacts head-on-trunk kinematics during voluntary balance and gait behaviors, and suggest that the neural mechanisms mediating adaptation alter the motion strategies even before surgery in a manner that may be maladaptive for long-term compensation.

Reliability of force plate-based measures of standing balance in the sub-acute stage of post-stroke recovery.

Background: Difficulty controlling balance is one of the major contributors to the increased risk of falls among individuals with stroke. It is important to use reliable and objective measures to improve examination of balance impairments post-stroke, and to in turn inform clinical decision-making. The main objective of this study was to examine the relative and absolute reliabilities of force plate-based balance measures in quiet standing, in the sub-acute stage of stroke recovery. Methods: Twenty-four people with sub-acute stroke (mean age = 61 years) performed two trials of quiet standing, each 30 s long. Sixteen force plate-based balance measures in the time, frequency, or nonlinear domains were calculated. Within-session test-retest reliabilities were investigated using intraclass correlation coefficient (ICC), standard error of measurement, and minimal detectable change. Results: Mean speed of displacements of the centre of pressure along the anterior-posterior axis (ICC = 0.91; CI95 % = [0.83, 0.95]), and directional weight-bearing asymmetry (ICC = 0.91; CI95 % = [0.82, 0.95]) demonstrated high relative reliabilities, followed by the speed-based symmetry index and absolute weight-bearing asymmetry (both ICCs = 0.86; CI95 % = [0.74, 0.93]). Conclusions: Mean speeds of centre of pressure, directional weight-bearing asymmetry, and speed-based symmetry index are the most reliable force plate-based measures that were evaluated in our study, and can be included in the balance assessments of individuals within the sub-acute stage of post-stroke recovery. These findings can better inform clinicians about the specific balance problems experienced by people in this population.

Reliability of unconventional centre of pressure measures of quiet standing balance in people with chronic stroke.

BACKGROUND: People with stroke often have asymmetric motor impairment. Investigating asymmetries in, and dynamic properties of, centre of pressure movement during quiet standing can inform how balance is controlled. RESEARCH QUESTION: What are the test-retest reliabilities of unconventional measures of quiet standing balance control in people with chronic stroke? METHODS: Twenty people with chronic stroke (>6 months post-stroke), who were able to stand for at least 30 s without support, were recruited. Participants completed two 30-second quiet standing trials in a standardized position. Unconventional measures of quiet standing balance control included: symmetry of variability in centre of pressure displacement and velocity, between-limb synchronization, and sample entropy. Root mean square of centre of pressure displacement and velocity in the antero-posterior and medio-lateral directions were also calculated. Intraclass correlation coefficients (ICCs) were used to determine test-retest reliability, and Bland-Altman plots were created to examine proportional biases. RESULTS: ICC3,2 were between 0.79 and 0.95 for all variables, indicating 'good' to 'excellent' reliability (>0.75). However, ICC3,1 for symmetry indices and between-limb synchronization were < 0.75. Bland-Altman plots revealed possible proportional biases for root mean square of medio-lateral centre of pressure displacement and velocity and between-limb synchronization, with larger between-trial differences for participants with worse values. SIGNIFICANCE: These findings suggest that centre of pressure measures extracted from a single 30-second quiet standing trial may have sufficient reliability for some research studies in chronic stroke. However, for clinical applications, the average of at least two trials may be required.

The Effect of Reactive Balance Training on Falls in Daily Life: An Updated Systematic Review and Meta-Analysis.

OBJECTIVE: Reactive balance training (RBT) is an emerging approach to reducing falls risk in people with balance impairments. The purpose of this study was to determine the effect of RBT on falls in daily life among individuals at increased risk of falls and to document associated adverse events. METHODS: Databases searched were Ovid MEDLINE (1946 to March 2022), Embase Classic and Embase (1947 to March 2022), Cochrane Central Register of Controlled Trials (2014 to March 2022), and Physiotherapy Evidence Database (PEDro; searched on 22 March 2022). Randomized controlled trials of RBT were included. The literature search was limited to the English language. Records were screened by 2 investigators separately. Outcome measures were number of participants who reported falls after training, number of falls reported after training, and the nature, frequency, and severity of adverse events. Authors of included studies were contacted to obtain additional information. RESULTS: Twenty-nine trials were included, of which 17 reported falls and 21 monitored adverse events. Participants assigned to RBT groups were less likely to fall compared with control groups (fall risk ratio = 0.76; 95% CI = 0.63-0.92; I2 = 32%) and reported fewer falls than control groups (rate ratio = 0.61; 95% CI = 0.45-0.83; I2 = 81%). Prevalence of adverse events was higher in RBT (29%) compared with control groups (20%). CONCLUSION: RBT reduced the likelihood of falls in daily life for older adults and people with balance impairments. More adverse events were reported in RBT than control groups. IMPACT: Balance training that evokes balance reactions can reduce falls among people at increased risk of falls. Older adults and individuals with balance problems were less likely to fall in daily life after participating in RBT compared with traditional balance training. LAY SUMMARY: If you are an older adult and/or have balance problems, your physical therapist may prescribe reactive balance training rather than traditional balance training in order to reduce your likelihood of falling in daily life.

Publication Rate and Consistency of Registered Trials of Motor-Based Stroke Rehabilitation.

OBJECTIVE: To determine the publication rate of motor-rehabilitation trials poststroke and the consistency between registry records and their corresponding main publications in trial design, primary objectives and outcomes, eligibility criteria, and sample size. METHODS: We searched 18 clinical trial registries to identify randomized controlled trials of motor-based stroke rehabilitation registered after July 2005 and completed before April 2017. Eligible trials included adults with stroke, with at least one outcome measure related to motor function. Information in the registry records was compared with that of their main publications, if any. RESULTS: Three hundred twenty-three trials met our eligibility criteria; we were unable to find a peer-reviewed publication reporting the main findings for 46% (150/323) of these. Of the 169 trials with peer-reviewed articles published in English, 141 (83%) were consistent with the registry record in trial design, 100 (59%) were consistent in primary objectives, 71 (42%) were consistent in primary outcomes, 28 (17%) were consistent in eligibility criteria, and 74 (44%) were consistent in sample size. CONCLUSIONS: Approximately half of motor-based stroke rehabilitation trials were not published, even more than 3 years after the end of the trial. When main publications were found, they substantially deviated from information in the registry record. These findings highlight the importance of trial registries for identifying unpublished stroke rehabilitation trials and of searching trial registries when conducting systematic reviews and meta-analysis to help ensure that reviews are unbiased.

Does Perturbation Training Prevent Falls after Discharge from Stroke Rehabilitation? A Prospective Cohort Study with Historical Control.

BACKGROUND: Individuals with stroke fall frequently, and no exercise intervention has been shown to prevent falls post stroke. Perturbation-based balance training (PBT), which involves practicing reactions to instability, shows promise for preventing falls in older adults and individuals with Parkinson's disease. This study aimed to determine if PBT during inpatient stroke rehabilitation can prevent falls after discharge into the community. METHODS: Individuals with subacute stroke completed PBT as part of routine inpatient rehabilitation (n = 31). Participants reported falls experienced in daily life for up to 6 months post discharge. Fall rates were compared to a matched historical control group (HIS) who did not complete PBT during inpatient rehabilitation. RESULTS: Five of 31 PBT participants, compared to 15 of 31 HIS participants, reported at least 1 fall. PBT participants reported 10 falls (.84 falls per person per year) whereas HIS participants reported 31 falls (2.0 falls per person per year). When controlled for follow-up duration and motor impairment, fall rates were lower in the PBT group than the HIS group (rate ratio: .36 [.15, .79]; P = .016). CONCLUSIONS: These findings suggest that PBT is promising for reducing falls post stroke. While this was not a randomized controlled trial, this study may provide sufficient evidence for implementing PBT in stroke rehabilitation practice.