Our central hypothesis is that chronic balance deficits after mild traumatic brain injury (mTBI) result from impairments in central sensorimotor integration (CSMI) that may be helped by rehabilitation. There are two objectives of this proposal; the first objective is to characterize balance deficits in people with mTBI. The second objective is to use a novel auditory bio-feedback (ABF) device to improve measures central sensorimotor integration and balance control.

Objectives: This study as two parts: 1) Cross-sectional study (Aim I: Balance Assessment) to identify and characterize maladaptive balance control strategies after mTBI compared to healthy controls and 2) Interventional randomized pilot study (Aim II: Balance Rehabilitation) using a novel ABF rehabilitation technique to ameliorate maladaptive balance control strategies after TBI. Subjects in Aim II will be a subset from Aim I and studies will occur simultaneously.

Plan: The proposed 4-year study has two parts: 1) Cross-sectional study (Aim I: Balance Assessment) to identify and characterize maladaptive balance control strategies after mTBI compared to healthy controls and 2) Interventional randomized pilot study (Aim II: Balance Rehabilitation) using a novel ABF rehabilitation technique to ameliorate maladaptive balance control strategies after TBI. Subjects in Aim II will be a subset from Aim I and studies will occur simultaneously.

Methods: I) Balance Assessment: To characterize balance deficits in people with mTBI who have chronic, non-resolving balance deficits compared to healthy control subjects without a history of mTBI. We hypothesize that a) objective measures of central sensorimotor integration, static and dynamic balance will better distinguish people with mTBI from control subjects than clinical measures, b) a subset of people with mTBI will have abnormal central sensori-motor integration (CSMI) test measures, even without peripheral vestibular or ocular motor deficits c) the relationship between poorer static/dynamic balance performance and mTBI is regulated/mediated by CSMI. We will test 130 subjects between the ages of 18 and 60; 65 with chronic (> 3 months) mTBI and non-resolving balance deficits and 65 healthy age and gender matched control subjects without a history of mTBI. We will obtain objective measures of static and dynamic balance using wearable inertial sensors and determine how these measures relate to central sensorimotor integration. We will also obtain laboratory measures of peripheral vestibular function and ocular motor function to help classify people and to consider as potential covariates in rehabilitation efficacy.

II) Balance Rehabilitation: To determine the efficacy of a novel, ABF balance rehabilitation program to improve central sensorimotor integration, static and dynamic balance, and functional activity in patients with chronic mTBI. We hypothesize that a) CSMI scores will improve with rehabilitation and ABF will increase the improvement of CSMI scores beyond the standard of care, b) ABF intervention will improve objective summary measures of balance and c) people with central sensorimotor integration impairment will show sustained improvement in CSMI scores and balance after rehabilitation. We will randomize 40 subjects between the ages of 18 and 60; 65 with chronic (> 3 months) mTBI and non-resolving balance deficits from Aim I who have abnormal CSMI into either the ABF rehabilitation group or the standard of care group. People will be tested before and after a 6-week intervention period and again 6 week later to determine long-term changes. Normal/abnormal vestibular and ocular motor function will be used as covariates to determine if peripheral deficits affect the efficacy of ABF rehabilitation.

Inclusion Criteria:

• have a diagnosis of mTBI based upon Veterans Health Administration (VHA)/Department of Defense (DoD) criteria with persisting symptoms >3 months post injury
• have minimal cognitive impairment; a score between 0 and 8 on the Short Blessed test for cognitive function
• may have or not had a loss of consciousness (LOC) with their initial injury

-OR-

• have no recent history of mTBI or brain injury and related complaints

Exclusion Criteria:

• have had or currently have any other injury, medical, substance or neurological illness that could potentially explain balance deficits (e.g., Central Nervous System disease, stroke, moderate TBI, lower extremity amputation)
• meet criteria for moderate to severe substance use disorder within the past month, as defined by Diagnostic and Statistical Manual (DSM-V)
• display behavior that would significantly interfere with validity of data collection or safety during study
• be in significant pain during the evaluation (5/10 by patient subjective report)
• be a pregnant female (balance considerations)
• have past history of peripheral vestibular pathology or ocular motor deficits
• have significant hearing loss that would interfere with the use of an auditory biofeedback device; hearing loss no worse than 30 decibel (dB) HL (PTA 0.5-3 kHz), in better ear, with the difference in ears being less than 15 dB PTA
• be unable to abstain for 24 hours in advance of testing in the use medications that might impair their balance (meclizine, scopolamine, benzodiazepines such as Valium, sedatives such as Ambien, narcotic pain medications, and antihistamines)