Assessment and rehabilitation of central sensory impairments for balance in mTBI using auditory biofeedback: a randomized clinical trial

Abstract

Background: Complaints of imbalance are common non-resolving signs in individuals with post-concussive syndrome. Yet, there is no consensus rehabilitation for non-resolving balance complaints following mild traumatic brain injury (mTBI). The heterogeneity of balance deficits and varied rates of recovery suggest varied etiologies and a need for interventions that address the underlying causes of poor balance function. Our central hypothesis is that most chronic balance deficits after mTBI result from impairments in central sensorimotor integration that may be helped by rehabilitation. Two studies are described to 1) characterize balance deficits in people with mTBI who have chronic, non-resolving balance deficits compared to healthy control subjects, and 2) determine the efficacy of an augmented vestibular rehabilitation program using auditory biofeedback to improve central sensorimotor integration, static and dynamic balance, and functional activity in patients with chronic mTBI.

Methods: Two studies are described. Study 1 is a cross-sectional study to take place jointly at Oregon Health and Science University and the VA Portland Health Care System. The study participants will be individuals with non-resolving complaints of balance following mTBI and age- and gender-matched controls who meet all inclusion criteria. The primary outcome will be measures of central sensorimotor integration derived from a novel central sensorimotor integration test. Study 2 is a randomized controlled intervention to take place at Oregon Health & Science University. In this study, participants from Study 1 with mTBI and abnormal central sensorimotor integration will be randomized into two rehabilitation interventions. The interventions will be 6 weeks of vestibular rehabilitation 1) with or 2) without the use of an auditory biofeedback device. The primary outcome measure is the daily activity of the participants measured using an inertial sensor.

Discussion: The results of these two studies will improve our understanding of the nature of balance deficits in people with mTBI by providing quantitative metrics of central sensorimotor integration, balance, and vestibular and ocular motor function. Study 2 will examine the potential for augmented rehabilitation interventions to improve central sensorimotor integration.

Trial registration: This trial is registered at clinicaltrials.gov ( NCT02748109 ).

Keywords: Balance; Biofeedback; Concussion; Gait; Sensorimotor integration; mTBI.

Fig. 1

Sensory systems contributing to static and dynamic balance

Fig. 2

CSMI methods with example data and analysis. (a) A feedback control model forms the basis for identifying model parameters (Table 2) that account for experimentally evoked body-in-space (BS) sway, representing angular tilt of the body center-of-mass (CoM), evoked by support surface (SS) and/or visual surround (VS) rotations. (b) An example of one cycle of a pseudorandom surface-tilt stimulus that evoked the CoM body sway (averaged across 5 stimulus cycles) shown in (c) for a Control subject and TBI subject. (d) Frequency domain analysis of stimulus/response data in (b) and (c) yields frequency response functions (FRFs) expressed as gain (ratio of CoM response amplitude to stimulus amplitude) and phase (timing of response relative to stimulus) measures as a function of frequency components in the pseudorandom stimulus. Parameters of the model in (a) are calculated by a fit procedure that finds parameters that optimally account for the FRF gain and phase data

Fig. 3

Flowchart illustrating the study design. Study 1 is a cross-sectional design. Study 2 recruits subjects from Study 1 for a randomized intervention