Evaluating Sensory Acuity as a Marker of Balance Dysfunction After a Traumatic Brain Injury: A Psychophysical Approach

Enhancing Anticipatory and Compensatory Postural Responses to Improve Balance in Individuals with TBI

Traumatic Brain Injury (TBI) is one of the leading causes of sensorimotor deficits in adults and often results in balance impairments. Two types of postural mechanisms are employed to achieve balance during perturbations: Anticipatory Postural Adjustments (APA) and Compensatory Postural Adjustments (CPA). People with TBI have reduced APA/CPA responses due to sensory-motor deficits from the injury. The objective of this feasibility study was to evaluate a Perturbation-based Balance Training program with visual cues (PBTvc) to target both APA/CPA responses to improve balance. The evaluation included biomechanical (reactive balance during random perturbation) and functional (Berg Balance Scale, Timed Up and Go and Falls Efficacy Scale) metrics. Preliminary data is presented for two participants with chronic TBI who received 16 sessions of PBTvc. The results show an improved range of trunk oscillation and time to stability during random perturbation tasks with corresponding improvements in Berg Balance Scale, Timed Up & Go, and Falls Efficacy Scale. The results suggest that PBTvc has the potential to improve APA/CPA mechanisms for functional recovery.Clinical Relevance- Preliminary data provides initial evidence for PBTvc as a therapeutic intervention for balance rehabilitation in adults with TBI.

Objective evaluation of the risk of falls in individuals with traumatic brain injury: feasibility and preliminary validation. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021;2021:4658-4661. [PMID: 34892252 DOI: 10.1109/embc46164.2021.9630020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Falls are a significant health concern for individuals with traumatic brain injury (TBI). For developing effective preemptive strategies to reduce falls, it is essential to get an accurate and objective assessment of fall-risk. The current investigation evaluates the feasibility of a robotic, posturography-based fall-risk assessment to objectively quantify the risk of falls in individuals with TBI. Five individuals with chronic TBI (age: 56.2 ± 4.7 years, time since injury: 13.09±11.95 years) performed the fall-risk assessment on hunova- a commercial robotic platform for assessing and training balance. The unique assessment considers multifaceted fall-driving components, including static and dynamic balance, sit-to-stand, limits of stability, responses to perturbations, gait speed, and history of previous falls and provides a composite score for risk of falls, called silver index (SI), a number between 0 (no risk) and 100 (high risk) based on a machine learning-based predictive model. The SI score for individuals with TBI was 66±32.1 (min: 32, max: 100) - categorized as medium-to-high risk of falls. The construct validity of SI outcome was performed by evaluating its relationship with clinical outcomes of functional balance and mobility (Berg Balance Scale (BBS), Timed-Up and Go (TUG), and gait speed) as well as posturography outcomes (Center of Pressure (CoP) area and velocity). The bivariate Pearson correlation coefficient, although not statistically significant, suggested the presence of linear relationships (0.52 > r > 0.84) between SI and functional and posturography outcomes, supporting the construct validity of SI. A large sample is needed to further prove the validity of the SI outcome before it is used for meaningful interpretations of the risk of falls in individuals with TBI.Clinical Relevance- Clinical assessments of risk of falls are traditionally based on questionnaires that may lack objectivity, consistency, and accuracy. The current work tests the feasibility of using a robotic platform-based assessment to objectively quantify the risk of falls in individuals with TBI.

Balance Control Strategies during Perturbed Standing after a Traumatic Brain Injury: Kinematic Analysis. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021;2021:4855-4858. [PMID: 34892296 DOI: 10.1109/embc46164.2021.9630258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

The objective of the current investigation was to examine the presence, absence or alteration of fundamental postural control strategies in individuals post traumatic brain injury (TBI) in response to base of support perturbations in the anterior-posterior (AP) direction. Four age-matched healthy controls (age: 46.50 ± 5.45 years) and four individuals diagnosed with TBI (age: 48.50 ± 9.47 years, time since injury: 6.02 ± 4.47 years) performed standing on instrumented balance platform with integrated force plates while 3D motion capture data was collected at 60 Hz. The platform was programmed to move in the AP direction, during a sequence of 5 perturbations delivered in a sinusoidal pattern at a frequency of 1 Hz, with decreasing amplitudes of 10, 8, 6, 4, and 2 mm respectively. The sagittal plane peak-to-peak range and root mean square (RMS) of the hip, knee, and ankle joint angles during the 5 seconds of perturbation were computed from optical motion capture data. The TBI group had a higher mean range (5.17 ± 1.91°) about the ankle compared to the HC group (4.17 ± 0.81°) for the 10mm perturbation, but their mean range was smaller than the HCs for the other 4 conditions. About the hip, the TBI group's mean range was larger than the HC's for all conditions. For both groups, the mean range decreased with perturbation amplitude for all conditions. The TBI group showed larger changes in mean range and RMS values as the amplitude of the perturbation changed, while the HC group showed smaller intertrial changes. The results suggest that the TBI group was substantially more reliant on the hip strategy to maintain balance during the perturbations and this reliance was well linked with perturbation amplitude.Clinical Relevance- Existing information regarding changes in postural control strategies in individuals post TBI is limited. The current work demonstrates lower limb kinematic differences between HC and TBI and some preliminary evidence on increased hip movement in the TBI group.

Graph-theoretical analysis of EEG functional connectivity during balance perturbation in traumatic brain injury: A pilot study

Traumatic brain injury (TBI) often results in balance impairment, increasing the risk of falls, and the chances of further injuries. However, the underlying neural mechanisms of postural control after TBI are not well understood. To this end, we conducted a pilot study to explore the neural mechanisms of unpredictable balance perturbations in 17 chronic TBI participants and 15 matched healthy controls (HC) using the EEG, MRI, and diffusion tensor imaging (DTI) data. As quantitative measures of the functional integration and segregation of the brain networks during the postural task, we computed the global graph-theoretic network measures (global efficiency and modularity) of brain functional connectivity derived from source-space EEG in different frequency bands. We observed that the TBI group showed a lower balance performance as measured by the center of pressure displacement during the task, and the Berg Balance Scale (BBS). They also showed reduced brain activation and connectivity during the balance task. Furthermore, the decrease in brain network segregation in alpha-band from baseline to task was smaller in TBI than HC. The DTI findings revealed widespread structural damage. In terms of the neural correlates, we observed a distinct role played by different frequency bands: theta-band modularity during the task was negatively correlated with the BBS in the TBI group; lower beta-band network connectivity was associated with the reduction in white matter structural integrity. Our future studies will focus on how postural training will modulate the functional brain networks in TBI.

Oculomotor Deficits and Symptom Severity Are Associated With Poorer Dynamic Mobility in Chronic Mild Traumatic Brain Injury

Oculomotor deficits, vestibular impairments, and persistent symptoms are common after a mild traumatic brain injury (mTBI); however, the relationship between visual-vestibular deficits, symptom severity, and dynamic mobility tasks is unclear. Twenty-three individuals (mean age 55.7 ± 9.3 years) with persistent symptoms after mTBI, who were between 3 months to 2 years post-injury were compared with 23 age and sex-matched controls. Oculomotor deficits [depth perception, near-point convergence, baseline visual acuity (BLVA), perception time], vestibular deficits (dynamic visual acuity in the pitch and yaw planes), dynamic mobility measured by the Functional Gait Assessment (FGA), and symptoms measured by the Post-Concussion Symptom Scale (PCSS) and Dizziness Handicap Inventory (DHI) were compared between groups. Participants with mTBI had poorer performance on the FGA (p < 0.001), higher symptom severity on the PCSS (p < 0.001), and higher DHI scores (p < 0.001) compared to controls. Significant differences were seen on specific items of the FGA between individuals with mTBI and controls during walking with horizontal head turns (p = 0.002), walking with vertical head tilts (p < 0.001), walking with eyes closed (p = 0.003), and stair climbing (p = 0.001). FGA performance was correlated with weeks since concussion (r = −0.67, p < 0.001), depth perception (r = −0.5348, p < 0.001), near point convergence (r = −0.4717, p = 0.001), baseline visual acuity (r = −0.4435, p = 0.002); as well as with symptoms on the PCSS (r = −0.668, p < 0.001), and DHI (r = −0.811, p < 0.001). Dynamic balance deficits persist in chronic mTBI and may be addressed using multifaceted rehabilitation strategies to address oculomotor dysfunction, post-concussion symptoms, and perception of handicap due to dizziness.

Enhancing sensory acuity and balance function using near-sensory biofeedback-based perturbation intervention for individuals with traumatic brain injury

BACGROUND

Interventions addressing balance dysfunction after traumatic brain injury (TBI) only target compensatory aspects and do not investigate perceptual mechanisms such as sensory acuity.

OBJECTIVE

To evaluate the efficacy of a novel intervention that integrates sensory acuity with a perturbation-based approach for improving the perception and functional balance after TBI.

METHODS

A two-group design was implemented to evaluate the effect of a novel, perturbation-based balance intervention. The intervention group (n = 5) performed the intervention with the sinusoidal (0.33, 0.5, and 1 Hz) perturbations to the base of support with amplitudes derived using our novel outcome of sensory acuity - perturbation perception threshold (PPT). The efficacy is evaluated using changes in PPT and functional outcomes (Berg Balance Scale (BBS), Timed-up and Go (TUG), 5-meter walk test (5MWT), and 10-meter walk test (10MWT)).

RESULTS

There was a significant post-intervention change in PPT for 0.33 Hz (p = 0.021). Additionally, clinically and statistically significant improvements in TUG (p = 0.03), 5MWT (p = 0.05), and 10MWT (p = 0.04) were observed.

CONCLUSIONS

This study provides preliminary efficacy of a novel, near-sensory balance intervention for individuals with TBI. The use of PPT is suggested for a comprehensive understanding and treatment of balance dysfunction. The promising results support the investigation in a larger cohort.