Transcranial Electrical Stimulation for mTBI

Mild traumatic brain injury (mTBI) is a leading cause of sustained physical, cognitive, emotional, and behavioral deficits in OEF/OIF/OND Veterans and the general public. However, the underlying pathophysiology is not completely understood, and there are few effective treatments for post-concussive symptoms (PCS). In addition, there are substantial overlaps between PCS and post-traumatic stress disorder (PTSD) symptoms in mTBI. Furthermore, a substantial number of studies have shown higher (nearly double) rates of comorbid PTSD in individuals with mTBI, observed in military and civilian settings. IASIS is among a class of passive neurofeedback treatments that combine low-intensity pulses for transcranial electrical stimulation (LIP-tES) with electroencephalography (EEG) monitoring. Nexalin is another tES technique , with FDA approvals for treating insomnia, depression, and anxiety. LIP-tES techniques have shown promising results in alleviating PCS in individuals with TBI. However, the neural mechanisms underlying the effects of LIP-tES treatment in TBI are unknown, owing to the dearth of neuroimaging investigations of this therapeutic intervention. Conventional neuroimaging techniques such as MRI and CT have limited sensitivity in detecting physiological abnormalities caused by mTBI, or in assessing the efficacy of mTBI treatments. In acute and chronic phases, CT and MRI are typically negative even in mTBI patients with persistent PCS. In contrast, evidence is mounting in support of resting-state magnetoencephalography (rs-MEG) slow-wave source imaging as a non-invasive imaging marker for neuronal abnormalities in mTBI. Using region of interest (ROI) and voxel-wise approaches, the investigators demonstrated that MEG slowwave source imaging detects abnormal slow-waves (delta-band, 1-4 Hz) with \~85% sensitivity in chronic and sub-acute mTBI patients with persistent PCS. The primary goal of the present application is to use rs- MEG to identify the neural underpinnings of behavioral changes associated with IASIS treatment in Veterans with mTBI. Using a double-blind placebo controlled design, the investigators will study changes in abnormal MEG slowwaves before and after IASIS treatment (relative to a 'sham' treatment group), and for a subset, before and after additional Nexalin treatment, in Veterans with mTBI. In addition, the investigators will examine treatment-related changes in PCS, PTSD symptoms, neuropsychological test performances, and their association with changes in MEG slow-waves. Pre-treatment baseline and posttreatment rs-MEG exams, symptoms assessments, and neuropsychological tests will be performed. The investigators for the first time will address a fundamental question about the mechanism of slow-waves in brain injury, namely whether slow-wave generation in wakefulness is merely a negative consequence of neuronal injury or if it is a signature of ongoing neuronal rearrangement and healing that occurs at the site of the injury. Specific Aim 1: To detect the loci of injury in Veterans with mTBI and assess the mechanisms underlying functional neuroimaging changes related to IASIS treatment, and for a subset of Veterans with remaining symptoms, additional Nexalin treatment, using rs-MEG slow-wave source imaging. The investigators' voxel-wise rs-MEG source-imaging technique will be used to identify abnormal slow-wave generation (delta band) in the baseline and post-treatment MEG exams to assess treatment-related changes on a single-subject basis. Healthy control (HC) Veterans, matched for combat exposure, will be used to establish an MEG normative database. Test-retest reliability of MEG slow-wave source imaging for mTBI will also be examined. Hypothesis 1: Veterans with mTBI will generate abnormal MEG slow-waves during the baseline MEG exam. Voxel-wise MEG slow-wave source imaging will show significantly higher sensitivity than conventional MRI in identifying the loci of injury on a single-subject basis. The test-retest reliability of MEG slow-wave source imaging is expected to be high, with intra-class correlation coefficient (ICC) 0.75 between two sequential MEG exams. Hypothesis 2: In wakefulness, slow-wave generation is a signature of ongoing neural rearrangement/ healing, rather than a negative consequence of neuronal injury. IASIS treatment will enhance neural rearrangement/healing by initially potentiating slow-wave generation immediately after each treatment session. Hypothesis 3: IASIS will ultimately reduce abnormal MEG slow-wave generation in mTBI by the end of the treatment course, owing to the accomplishment of neural rearrangement / healing. In Veterans with mTBI who finish IASIS treatment, but not in the sham group, MEG source imaging will show a significant decrease in abnormal slow-waves at post-treatment exam. Such significant decreases will also be evident in both the voxel-wise and overall abnormal MEG slow-wave measures. Specific Aim 2: To examine treatment-related changes in PCS and PTSD symptoms in Veterans with mTBI. PCS and PTSD symptoms will be assessed at the baseline and post-treatment follow-up visits. Hypothesis 4: Compared with the sham group, mTBI Veterans in the IASIS treatment group will show significantly greater decreases in PCS symptoms between baseline and post-treatment assessments. Hypothesis 5: Compared with the sham group, mTBI Veterans in the IASIS treatment group will also show significantly greater decreases in PTSD symptoms between baseline and post-treatment assessments. Specific Aim 3: To study the relationship among IASIS treatment-related changes in rs-MEG slow-wave imaging, PCS, and neuropsychological measures in Veterans with mTBI. The investigators will correlate changes between baseline and post-IASIS abnormal rs-MEG slow-wave generation (i.e., total abnormal rs-MEG slow-wave and voxel-wise source imaging measures) with changes in PCS and neuropsychological tests performance. Hypothesis 6: Reduced MEG slow-wave generation will correlate with reduced total PCS score, individual PCS scores (e.g., sleep disturbance, post-traumatic headache, photophobia, and memory problem symptoms), and improved neuropsychological exam scores between post-IASIS and baseline exams.