A Multisite Exploration of Balance Perturbations With and Without Body Weight Support

ZeroG is an FDA-listed robotic body weight support system (BWSS). Mounted on an overhead track, patients are fitted in a harness system tethered to said track, and are able to practice gait and balance activities without the risk of falling. This compensates for ineffective postural control permitting intensive therapy sessions earlier in recovery. The purpose of this study is to determine if inducing effective and safe balance perturbations during standing and walking in the BWSS more effectively improve postural control than the BWSS without perturbations. The target population are those patients in the post-acute phase of stroke admitted for inpatient rehabilitation of balance impairments. Site investigators and/or research staff will obtain names of potential subjects from internal reporting identifying inpatients who may qualify for the study based on the inclusion criteria. Trained site investigators will meet with potential subjects to explain the study, complete a screening interview for exclusion and inclusion criteria, answer any questions, obtain informed consent and HIPAA authorization, and schedule the study therapy sessions involving the protocol. Based on the randomization scheme provided by the lead site, consented subjects will be randomized to either the BWSS with perturbations (BWSS-P) or standard BWSS control without perturbations. Subjects will perform 2 to 6 sessions in their designated intervention using a structured protocol for each session. To compare differences between treatment groups, outcome measures will be collected at baseline before any BWSS sessions are performed and within 48 hours after completing the final treatment session.

Each year, more than 795,000 people experience a stroke. Stroke, or cerebral vascular accident, is a devastating neurological event that can lead to physical and cognitive deficits, such as the inability to ambulate, impaired balance regulation, loss of coordination, and impaired communication. Due to the physical and cognitive deficits experienced following a stroke, many require admission to an inpatient rehabilitation facility with the goal of maximizing their independence before returning to the home setting. Gait and balance dysfunction are common secondary impairments to stroke, usually requiring specific rehabilitative interventions.

Following a stroke, motion analysis has observed patients navigating obstacles more conservatively and with abnormal gait patterns. One associated factor is the loss of muscle-strength secondary to stroke, which could increase the risk of falling. Within six-months of discharge, falls occur in up to 70% of patients post-stroke, highlighting the importance and urgency to improve patients' balance and gait during the rehabilitation phase.

As patients may better understand their capabilities/limitation than what the physical tests demonstrate, patient self-assessments can be important indicators of fall risk. In fact, it is estimated that over 90% of stroke survivors would report that the fear of falling negatively impacts their performance of daily living activities. Fear of falling has been shown to influence balance and gait control in older adults, supporting the theory that balance and gait should be taken into account during rehabilitative methods. These psychological factors are strong predictors of falling compared to physical factors or the presence of pathology. Patient self-assessments are important indicators of fall risk, as patients may understand their capabilities/limitation better than what physical tests can demonstrate.

The ability to walk, stand, and climb stairs are examples of mobility-related functional tasks that are critical for achieving functional independence. With those with stroke related balance and gait impairments, early and frequent balance and gait training are essential to maximizing functional ability and independence. However, it is often difficult for post-stroke patients with these impairments to safely undergo the necessary balance and gait training without putting both therapists and patients at risk for injury. It is also reasonable to suspect that any injurious falls that occur during rehabilitation would reinforce, or create, a psychological fear of falling that would impede the recovery of the patient.

Furthermore, injurious falls can prolong a patient's length of stay, increasing the economic and financial strain both to the individual and their family as the patient is out work. Any falls, but especially injurious falls, can also increase the financial burden of an institution. In some cases, patients need to be carefully examined and imaged to confirm the presence or absence of injury. If the necessary imaging equipment isn't available, a patient may need to be taken to an outside location or even emergently transferred. Improving a patient's gait and balance earlier in their stay may also prevent other injurious falls outside of therapy as well. It could also improve a patient's fall risk, meaning that resources, such as safety sitters, can be minimized, further improving the financial burden of the institution. These benefits can be achieved, in part, by focusing on and improving a patient's balance and gait status. Incorporating robotic technologies to neurological rehabilitation can play a critical role in delivering safe and effective gait and balance therapy sooner in a patient's stay.

Body-weight support systems (BWSS) are either stationary or track-mounted suspended-harnesses that support a patient's body-weight. This permits those with significant weakness and poor coordination to ambulate and perform more intensive therapy sessions sooner in their recovery, with minimal risk of injurious fall. In addition to BWSSs, balance perturbation systems have been used to improve gait and balance-control after stroke, or other age and disease related balance impairments. Balance perturbation systems purposefully unbalance patients in order to rehabilitate their postural control. Conventional balance perturbation training, including modified treadmills, tilt-tables, or external force provided by the therapist directly, can pose an injury risk to the therapist and the patient. While incorporation of stationary BWSSs over modified treadmills can decrease the injury risk, ambulation over treadmills is not typically representative of a patients' functional ambulation in their home environment. Systems such as these may also limit the participation of patients who would otherwise benefit from balance perturbation training, but are uncomfortable or unable to ambulate on a treadmill. Direct integration of the balance perturbation modules to the BWSS can resolve many of these issues.

The goal of this multisite study is to build upon a recent pilot study and further evaluate the efficacy of this newly developed BWSS integrated balance perturbation system in rehabilitating patient gait and balance after stroke, compared to standard BWSS training without perturbations. In the pilot study, 32 participants were recruited, half of whom were unbalanced during stationary and ambulatory activities to train their balance-control and balance-reactions. Both the BWSS and BWSS with perturbation groups demonstrated significant improvements in balance-related confidence and balance performance outcome measures (Berg Balance Scale) in comparison to both their baseline and a historic control. However, when compared to the BWSS control, the outcomes of the BWSS-P group only trended in the predicted positive direction, and were not significantly different. The investigators believe this was, in part, due to the small sample size and variation in timing of the post-assessment Berg Balance scales. It is hypothesized that by increasing the sample size to achieve the appropriate power for the effect size observed in the pilot study, the BWSS with balance perturbation intervention will improve patient outcomes more than the BWSS treatment alone. Further, with the data collected from the larger sample size, it is proposed to conduct correlative analysis to determine what, if any, variables influence participant response to treatment. To address these hypotheses, these are the proposed research aims:

Research Aim 1: Conduct an unblinded multisite randomized-control trial to evaluate the effectiveness and appropriate dose requirements of a track-mounted BWSS perturbation module to improve balance and gait impairments in patients receiving inpatient rehabilitation services for stroke with a BBS score ≥21/56 (n=214). Hypothesis: Post-intervention balance and gait assessments will show that BWSS-P participants improved more than participants receiving BWSS alone.

Research Aim 2: Conduct post hoc correlative analyses to identify what affect participant variability, such as differences in stroke lesion laterality/location, age, sex, number of BWSS sessions, and time since stroke, may have on participant response to treatment. Hypothesis: Participant specific variables will impact the efficacy and participant response to treatment.

Eligibility Criteria:
Inclusion Criteria:

* Admitted to one of the listed study locations for inpatient rehabilitation following a stroke.
* Be 18 years of age or older.
* Have at least a moderate fall risk or better, shown by an admission Berg Balance Scale (BBS) score of 21/56 or greater.

  * Patients that score below 21 or are non-ambulatory will not be considered for this study.
  * Patients that are emergently re-admitted to acute care and subsequently re-admitted to the stroke rehabilitation program will be reassessed for appropriateness of continuation in the study on a case by case basis.
  * Patients that progress to a BBS score of 21 or greater during their stay, and have a set discharge date of 10 days or longer, can be approached for study recruitment.
* Appropriate cognition

  * Able to read and understand the consent, in English or a language available by translator services, based on the judgement of the clinical team, either by using outcomes measures, i.e. SLUMS greater than or equal to 20, or through clinical evaluations and team discussion. Eligibility will ultimately be decided by the treating physician in combination with the participant's clinical team.
* Ability to tolerate and actively participate in up to six, 30-minute sessions, with physical therapy while using the BWSS.
* Weigh less than 450 pounds, per the structural limitations of the ZeroG system.

Exclusion Criteria:

* Active seizures
* Spinal stabilization with the use of Halos
* Uncontrolled hypertension or hypotension
* Unstable skin structures (i.e. skin grafts)
* Chest tubes
* Unstable rib or lower extremity fractures
* Severe osteoporosis
* Participants where pressure around the abdomen, thighs, groin, or shoulders in contraindicated
* Cognitive deficits that would disrupt the ability to provide informed consent as described above
* Active enteric infection control precautions

  * Subjects would be eligible once precautions are lifted
* Ongoing orthostasis
* New limb amputations
* Vestibular disorders that may impact balance
* Premorbid conditions that may impact balance
* Patients requiring more than 50% high flow oxygen as consistent with inpatient therapy guidelines
* Anyone belonging to a vulnerable population, including inmates, individuals under the age of 18, and who are or might be pregnant