Severities in persistent mild traumatic brain injury related headache is associated with changes in supraspinal pain modulatory functions.

Emerging evidence suggests mild traumatic brain injury related headache (MTBI-HA) is a form of neuropathic pain state. Previous supraspinal mechanistic studies indicate patients with MTBI-HA demonstrate a dissociative state with diminished levels of supraspinal prefrontal pain modulatory functions and enhanced supraspinal sensory response to pain in comparison to healthy controls. However, the relationship between supraspinal pain modulatory functional deficit and severity of MTBI-HA is largely unknown. Understanding this relationship may provide enhanced levels of insight about MTBI-HA and facilitate the development of treatments. This study assessed pain related supraspinal resting states among MTBI-HA patients with various headache intensity phenotypes with comparisons to controls via functional magnetic resonance imaging (fMRI). Resting state fMRI data was analyzed with self-organizing-group-independent-component-analysis in three MTBI-HA intensity groups (mild, moderate, and severe) and one control group (n = 16 per group) within a pre-defined supraspinal pain network based on prior studies. In the mild-headache group, significant increases in supraspinal function were observed in the right premotor cortex (T = 3.53, p < 0.001) and the left premotor cortex (T = 3.99, p < 0.0001) when compared to the control group. In the moderate-headache group, a significant (T = -3.05, p < 0.01) decrease in resting state activity was observed in the left superior parietal cortex when compared to the mild-headache group. In the severe-headache group, significant decreases in resting state supraspinal activities in the right insula (T = -3.46, p < 0.001), right premotor cortex (T = -3.30, p < 0.01), left premotor cortex (T = -3.84, p < 0.001), and left parietal cortex (T = -3.94, p < 0.0001), and an increase in activity in the right secondary somatosensory cortex (T = 4.05, p < 0.0001) were observed when compared to the moderate-headache group. The results of the study suggest that the increase in MTBI-HA severity may be associated with an imbalance in the supraspinal pain network with decline in supraspinal pain modulatory function and enhancement of sensory/pain decoding.

fMRI findings in MTBI patients with headaches following rTMS.

Mild Traumatic Brain Injury (MTBI) patients with persistent headaches are known to have diminished supraspinal modulatory connectivity from their prefrontal cortices. Repetitive transcranial magnetic stimulation (rTMS) is able to alleviate MTBI-related headache (MTBI-HA). This functional magnetic resonance imaging (fMRI) study assessed supraspinal correlates associated with the headache analgesic effect of rTMS at left prefrontal cortex (LPFC), hypothesizing real rTMS would significantly increase modulatory functions at LPFC in comparison to sham treatment. Subjects with MTBI-HA were randomized to receive either real or sham rTMS treatments and subjected to pre- and post-treatment resting state and evoked heat-pain fMRI as described in a prior study. Real rTMS consisted of 2000 pulses delivered at 10 Hz and 80% of the resting motor threshold at left dorsolateral prefrontal cortex, whereas sham treatment was delivered with same figure-of-eight coil turned 180 degrees. Follow-up fMRI was performed one-week post-treatment. All fMRI data was processed using BrainVoyager QX Software. 14 subjects receiving real and 12 subjects receiving sham treatments completed the study. The REAL group demonstrated significant (P < 0.02) decreases in headache frequency and intensity at one week following treatment. fMRI scans in the REAL group showed increased evoked heat pain activity (P < 0.002) and resting functional connectivity (P < 0.0001) at the LPFC after rTMS. Neither this significant analgesic effect nor these fMRI findings were seen in the sham group. Sham treatment was, however, associated with a decrease in resting state activity at the LPFC (P < 0.0001). This study correlates the demonstrated analgesic effect of rTMS in the treatment of MTBI-HA with enhanced supraspinal functional connectivity in the left prefrontal cortex, which is known to be involved in "top-down" pain inhibition along the descending midbrain-thalamic-cingulate pathway. Trial Registration: This study was registered on September 24, 2013, on ClinicalTrials.gov with the identifier: NCT01948947. https://clinicaltrials.gov/ct2/show/NCT01948947 .

Diminished corticomotor excitability in Gulf War Illness related chronic pain symptoms; evidence from TMS study.

Chronic diffuse body pain is unequivocally highly prevalent in Veterans who served in the 1990-91 Persian Gulf War and diagnosed with Gulf War Illness (GWI). Diminished motor cortical excitability, as a measurement of increased resting motor threshold (RMT) with transcranial magnetic stimulation (TMS), is known to be associated with chronic pain conditions. This study compared RMT in Veterans with GWI related diffuse body pain including headache, muscle and joint pain with their military counterparts without GWI related diffuse body pain. Single pulse TMS was administered over the left motor cortex, using anatomical scans of each subject to guide the TMS coil, starting at 25% of maximum stimulator output (MSO) and increasing in steps of 2% until a motor response with a 50 µV peak to peak amplitude, defined as the RMT, was evoked at the contralateral flexor pollicis brevis muscle. RMT was then analyzed using Repeated Measures Analysis of Variance (RM-ANOVA). Veterans with GWI related chronic headaches and body pain (N = 20, all males) had a significantly (P < 0.001) higher average RMT (% ± SD) of 77.2% ± 16.7% compared to age and gender matched military controls (N = 20, all males), whose average was 55.6% ± 8.8%. Veterans with GWI related diffuse body pain demonstrated a state of diminished corticomotor excitability, suggesting a maladaptive supraspinal pain modulatory state. The impact of this observed supraspinal functional impairment on other GWI related symptoms and the potential use of TMS in rectifying this abnormality and providing relief for pain and co-morbid symptoms requires further investigation.Trial registration: This study was registered on January 25, 2017, on ClinicalTrials.gov with the identifier: NCT03030794. Retrospectively registered. https://clinicaltrials.gov/ct2/show/NCT03030794 .

The prevalence of headaches, pain, and other associated symptoms in different Persian Gulf deployment periods and deployment durations.

OBJECTIVES: This study aims to assess (1) the difference in the prevalence of headaches, pain, and other associated symptoms between Gulf War I (1990-1991) and Post-Gulf War I (1992-2015) veterans who served as active military personnel in the Persian Gulf and (2) how the durations of deployment may affect the prevalence of those symptoms. METHODS: With institutional human subject committee approval, veterans who were accepted to the Gulf War Registry at the VA San Diego Healthcare System between July 2013 and June 2015 (N = 367) were included in this retrospective chart review study and grouped according to the Gulf War period they served under or how long they were deployed to the Persian Gulf. Chi-square was used for categorical data analyses and analysis of variance was conducted for continuous outcomes. All analyses were two-tailed, where applicable, with α = 0.05 and Bonferroni for pairwise group comparisons. RESULTS: Veterans who served during Post-Gulf War I or both Gulf War I and Post-Gulf War I exhibited more pain and neurological symptoms than Gulf War I veterans (p = 0.005, p = 0.003). In addition, veterans who served ⩾12 months reported more overall pain symptoms and analgesic use than those who served less time (p < 0.001, p = 0.024). CONCLUSION: The findings suggest that the length of deployment and Persian Gulf deployment period may play a role in acquiring headaches, pain, and other associated symptoms with increased analgesic consumption.

Pain-related white matter tract abnormalities in mild traumatic brain injury patients with persistent headache.

BACKGROUND: The occurrence of debilitating chronic persistent (24/7) headache after mild traumatic brain injury represents a central neuropathic pain state. Previous studies suggest that this chronic headache state can be attributed to altered supraspinal modulatory functional connectivity in both resting and evoked pain states. Abnormalities in the myelin sheaths along the supraspinal superior longitudinal fasciculus and anterior thalamic radiation are frequently associated with alteration in pain modulation related to functional connectivity deficit with the prefrontal cortex. This study assessed the correlated axonal injury-related white matter tract abnormality underlying these previously observed prefrontal functional connectivity deficits by comparing the fractional anisotropy, axial diffusivity, and radial diffusivity of brain white matter in patients with mild traumatic brain injury-related headache to healthy controls. RESULT: Diffusion tensor imaging data from patients ( N = 12, average age ± SD = 35.0 ± 8.0 years old, 10 male) with mild traumatic brain injury-headache were compared with images acquired from healthy controls. The mild traumatic brain injury cohort demonstrated two areas of significant ( P < 0.01, F value >16, cluster size >50 voxels) white matter tract abnormalities closely related to pain affective and modulatory functions in (1) the left superior longitudinal fasciculus which connects the prefrontal cortices with the parietal cortices and (2) the right anterior thalamic radiation connecting the prefrontal cortices with the anterior cingulate cortex. In addition, a significant ( P < 0.01) decrease in axial diffusivity and increase in radial diffusivity at the superior longitudinal fasciculus cluster were noted in the mild traumatic brain injury cohort. CONCLUSION: The identified white matter tract abnormalities may represent a state of Wallerian degeneration which correlates with the functional connectivity deficit in pain modulation and can contribute to the development of the chronic persistent headache in the patients with mild traumatic brain injury.

Left Dorsolateral Prefrontal Cortex rTMS in Alleviating MTBI Related Headaches and Depressive Symptoms.

OBJECTIVE: Persistent mild traumatic brain injury related headache (MTBI-HA) represents a neuropathic pain state. This study tested the hypothesis that repetitive transcranial magnetic stimulation (rTMS) at the left prefrontal cortex can alleviate MTBI-HA and associated neuropsychological dysfunctions. METHODS AND MATERIALS: Veterans with MTBI-HA were randomized to receive four sessions of either real (REAL group) or sham (SHAM group) high frequency rTMS delivered at 10 Hz, 80% of resting motor threshold and 2000 pulses per session at >24 and <72 hours apart. Pre-treatment, post-treatment 1-week and 4-week headache and neuropsychological assessments were conducted. RESULTS: Twenty nine out of forty-four consented subjects completed the study. A two-factor (visit × treatment) repeated measures ANOVA showed a significant (p = 0.002, F = 11.63, df = 1) interaction for the average daily persistent headache intensity with the REAL group exhibiting a significant (p < 0.0001) average reduction (±SD) of 25.3 ± 16.8% and 23.0 ± 17.7% reduction in their numerical rating scale at the one-week and four-week post-treatment assessments in comparison to <1 ± 11.7% and 2.3 ± 14.5% reduction found in the SHAM group. In addition, a significant (p < 0.01) 50% and 57% reduction was found in the prevalence of persistent headache in the REAL group at the one-week and four-week assessments in comparison to 7% and 20% reduction found in the SHAM group. Furthermore, the REAL group demonstrated a significant (p = 0.033) improvement (from 22.3 ± 6.4 at pre-treatment to 19.0 ± 5.0 at post-treatment one-week) in the Hamilton Rating Scale for Depression score, while the SHAM group's score remained largely unchanged (from 25.33 ± 8.43 to 24.64 ± 5.03) in the same time frame. This trend of improvement, although not statistically significant, continues to the post-treatment four-week assessment. CONCLUSION: A short-course rTMS at the left DLPFC can alleviate MTBI-HA symptoms and provide a transient mood enhancing benefit. Further studies are required to establish a clinical protocol balancing both treatment efficacy and patient compliance.

Exposure reporting disparity in Gulf War Registry-related clinical assessments.

OBJECTIVES: The Gulf War Registry monitors related health conditions of veterans returning from the Persian Gulf Region. Enrollment consists of two phases: Phase I-veterans meet with their local VA Environmental Health Coordinator and complete the self-reported Gulf War Phase I Worksheet (VA Form 10-9009A). Phase II involves a physical exam, medical history review, and laboratory test analysis conducted by a licensed physician. The providers' documentations are frequently referred for exposure assessment and benefit claim. We conducted an initial comparison assessment to ascertain any potential disparity in exposure reporting between the applicants in Phase I and the providers in Phase II. METHODS: With institutional human subject committee approval, a list of veterans with a Gulf War Registry electronic medical note from the VA San Diego Healthcare System (2013-2015) was obtained. Comparing Phase I with Phase II reports allows three distinct reporting group combinations for each of the 21 exposure categories. Group I: both the patients and the healthcare personnel provided the same report for the respective exposure. Group II: healthcare personnel but not the patients reported the exposure. Group III: only the patients but not the healthcare personnel reported the exposure. RESULTS: A total of 178 (of 367) subjects had both the medical note from the healthcare provider and a physical copy of their Phase I Worksheet available, and therefore were eligible to be included in the overall one-way and subsequent pair-wise chi-square analyses. The results indicate that Group I reporting pattern had a significantly (p < 0.01) lower prevalence in nine exposure categories compared to Group III. CONCLUSION: The findings suggest that the medical documentation from the healthcare providers does not consistently and accurately reflect the patients' report in near 50% (9/21) of assessed exposure categories. Potential remedies addressing this exposure reporting disparity, such as a standardized template or electronic upload, are further discussed.

Effect of low frequency transcutaneous magnetic stimulation on sensory and motor transmission.

Peripheral nerve injury diminishes fast conducting large myelinated afferent fibers transmission but enhances smaller pain transmitting fibers firing. This aberrant afferent neuronal behavior contributes to development of chronic post-traumatic peripheral neuropathic pain (PTP-NP). Non-invasive dynamic magnetic flux stimulation has been implicated in treating PTP-NP, a condition currently not adequately addressed by other therapies including transcutaneous electrical nerve stimulation (TENS). The current study assessed the effect of low frequency transcutaneous magnetic stimulation (LFTMS) on peripheral sensory thresholds, nerve conduction properties, and TENS induced fast afferent slowing effect as measured by motor and sensory conduction studies in the ulnar nerve. Results indicated sham LFTMS with TENS (Sham + TENS) significantly (P = 0.02 and 0.007, respectively) reduces sensory conduction velocity (CV) and increases sensory onset latency (OL), and motor peak latency (PL) whereas, real LFTMS with TENS (Real + TENS) reverses effects of TENS on sensory CV and OL, and significantly (P = 0.036) increases the sensory PL. LFTMS alone significantly (P < 0.05) elevates sensory PL and onset-to-peak latency. LFTMS appears to reverse TENS slowing effect on fast conducting fibers and casts a selective peripheral modulatory effect on slow conducting pain afferent fibers.