A phase I study of low-pressure hyperbaric oxygen therapy for blast-induced post-concussion syndrome and post-traumatic stress disorder

Rehabilitation Treatment and Progress of Traumatic Brain Injury Dysfunction

Traumatic brain injury (TBI) is a major cause of chronic disability. Worldwide, it is the leading cause of disability in the under 40s. Behavioral problems, mood, cognition, particularly memory, attention, and executive function are commonly impaired by TBI. Spending to assist, TBI survivors with disabilities are estimated to be costly per year. Such impaired functional outcomes following TBI can be improved via various rehabilitative approaches. The objective of the present paper is to review the current rehabilitation treatment of traumatic brain injury in adults.

Treatment Perspectives Based on Our Current Understanding of Concussion

Sports-related concussion also referred to in the literature as mild traumatic brain injury remains a popular area of study for physicians, neurologists, neuropsychologists, neuroimaging, athletic trainers, and researchers across the other areas of brain sciences. Treatment for concussion is an emerging area of focus with investigators seeking to improve outcomes and protect patients from the deleterious short-term and long-term consequences which have been extensively studied and identified. Broadly, current treatment strategies for athletes recovering from concussion have remained largely unchanged since early 2000s. Knowledge of the complex pathophysiology surrounding injury should improve or advance our ability to identify processes which may serve as targets for therapeutic intervention. Clinicians working with athletes recovering from sports-related concussion should have an advanced understanding of the injury cascade and also be aware of the current efforts within the research to treat concussion. In addition, how clinicians use the word "treatment" should be carefully defined and promoted so the patient is aware of the level of intervention and what stage of recovery or healing is being affected by a specific intervention. The purpose of this review is to bring together efforts across disciplines of brain science into 1 platform where clinicians can assimilate this information before making best practices decisions regarding the treatment of patients and athletes under their care.

Hyperbaric oxygen therapy for traumatic brain injury: bench-to-bedside

Traumatic brain injury (TBI) is a serious public health problem in the United States. Survivors of TBI are often left with significant cognitive, behavioral, and communicative disabilities. So far there is no effective treatment/intervention in the daily clinical practice for TBI patients. The protective effects of hyperbaric oxygen therapy (HBOT) have been proved in stroke; however, its efficiency in TBI remains controversial. In this review, we will summarize the results of HBOT in experimental and clinical TBI, elaborate the mechanisms, and bring out our current understanding and opinions for future studies.

Treatment of persistent post-concussion syndrome due to mild traumatic brain injury: current status and future directions

Persistent post-concussion syndrome caused by mild traumatic brain injury has become a major cause of morbidity and poor quality of life. Unlike the acute care of concussion, there is no consensus for treatment of chronic symptoms. Moreover, most of the pharmacologic and non-pharmacologic treatments have failed to demonstrate significant efficacy on both the clinical symptoms as well as the pathophysiologic cascade responsible for the permanent brain injury. This article reviews the pathophysiology of PCS, the diagnostic tools and criteria, the current available treatments including pharmacotherapy and different cognitive rehabilitation programs, and promising new treatment directions. A most promising new direction is the use of hyperbaric oxygen therapy, which targets the basic pathological processes responsible for post-concussion symptoms; it is discussed here in depth.

Protein profile changes in the frontotemporal lobes in human severe traumatic brain injury

Severe traumatic brain injury (sTBI) is a serious public health issue with high morbidity and mortality rates. Previous proteomic studies on sTBI have mainly focused on human cerebrospinal fluid and serum, as well as on brain protein changes in murine models. However, human proteomic data in sTBI brain is still scarce. We used proteomic and bioinformatic strategies to investigate variations in protein expression levels in human brains after sTBI, using samples from the Department of Neurosurgery, Affiliated Hospital of Hebei University (Hebei, China). Our proteomic data identified 4031 proteins, of which 160 proteins were overexpressed and 5 proteins were downregulated. Bioinformatics analysis showed significant changes in biological pathways including glial cell differentiation, complement activation and apolipoprotein catalysis in the statin pathway. Western blot verification of protein changes in a subset of the available tissue samples showed results that were consistent with the proteomic data. This study is one of the first to investigate the whole proteome of human sTBI brains, and provide a characteristic signature and overall landscape of the sTBI brain proteome.

Sport-related structural brain injury associated with arachnoid cysts: a systematic review and quantitative analysis

OBJECTIVE Arachnoid cysts (ACs) are congenital lesions bordered by an arachnoid membrane. Researchers have postulated that individuals with an AC demonstrate a higher rate of structural brain injury after trauma. Given the potential neurological consequences of a structural brain injury requiring neurosurgical intervention, the authors sought to perform a systematic review of sport-related structural-brain injury associated with ACs with a corresponding quantitative analysis. METHODS Titles and abstracts were searched systematically across the following databases: PubMed, Embase, CINAHL, and PsycINFO. The review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Peer-reviewed case reports, case series, or observational studies that reported a structural brain injury due to a sport or recreational activity (hereafter referred to as sport-related) with an associated AC were included. Patients were excluded if they did not have an AC, suffered a concussion without structural brain injury, or sustained the injury during a non-sport-related activity (e.g., fall, motor vehicle collision). Descriptive statistical analysis and time to presentation data were summarized. Univariate logistic regression models to assess predictors of neurological deficit, open craniotomy, and cystoperitoneal shunt were completed. RESULTS After an initial search of 994 original articles, 52 studies were found that reported 65 cases of sport-related structural brain injury associated with an AC. The median age at presentation was 16 years (range 4-75 years). Headache was the most common presenting symptom (98%), followed by nausea and vomiting in 49%. Thirteen patients (21%) presented with a neurological deficit, most commonly hemiparesis. Open craniotomy was the most common form of treatment (49%). Bur holes and cyst fenestration were performed in 29 (45%) and 31 (48%) patients, respectively. Seven patients (11%) received a cystoperitoneal shunt. Four cases reported medical management only without any surgical intervention. No significant predictors were found for neurological deficit or open craniotomy. In the univariate model predicting the need for a cystoperitoneal shunt, the odds of receiving a shunt decreased as age increased (p = 0.004, OR 0.62 [95% CI 0.45-0.86]) and with male sex (p = 0.036, OR 0.15 [95% CI 0.03-0.88]). CONCLUSIONS This systematic review yielded 65 cases of sport-related structural brain injury associated with ACs. The majority of patients presented with chronic symptoms, and recovery was reported generally to be good. Although the review is subject to publication bias, the authors do not find at present that there is contraindication for patients with an AC to participate in sports, although parents and children should be counseled appropriately. Further studies are necessary to better evaluate AC characteristics that could pose a higher risk of adverse events after trauma.

Understanding the pathology and treatment of traumatic brain injury and posttraumatic stress disorder: a therapeutic role for hyperbaric oxygen therapy

Traumatic brain injury (TBI) is an intracranial injury caused by external trauma leading to different degrees of brain damage. TBI can cause a wide array of symptoms and range in severity from concussion to coma and death. The link between TBI and posttraumatic stress disorder (PTSD) has received increasing attention due to the high incidence of these conditions in soldiers returning from recent conflicts. TBI has been associated with an increased risk of PTSD. Additionally, TBI and PTSD often demonstrate overlapping symptoms. In this article, we discuss the different forms of TBI and their links to PTSD. We also discuss current therapies for TBI and PTSD, in particular detailing the therapeutic potential of hyperbaric oxygen therapy in the management of these conditions.

Hyperbaric oxygen therapy for the treatment of traumatic brain injury: a meta-analysis

Compelling evidence suggests the advantage of hyperbaric oxygen therapy (HBOT) in traumatic brain injury. The present meta-analysis evaluated the outcomes of HBOT in patients with traumatic brain injury (TBI). Prospective studies comparing hyperbaric oxygen therapy vs. control in patients with mild (GCS 13-15) to severe (GCS 3-8) TBI were hand-searched from medical databases using the terms "hyperbaric oxygen therapy, traumatic brain injury, and post-concussion syndrome". Glasgow coma scale (GCS) was the primary outcome, while Glasgow outcome score (GOS), overall mortality, and changes in post-traumatic stress disorder (PTSD) score, constituted the secondary outcomes. The results of eight studies (average age of patients, 23-41 years) reveal a higher post-treatment GCS score in the HBOT group (pooled difference in means = 3.13, 95 % CI 2.34-3.92, P < 0.001), in addition to greater improvement in GOS and lower mortality, as compared to the control group. However, no significant change in the PTSD score was observed. Patients undergoing hyperbaric therapy achieved significant improvement in the GCS and GOS with a lower overall mortality, suggesting its utility as a standard intensive care regimen in traumatic brain injury.

Hyperbaric oxygen therapy as a potential treatment for post-traumatic stress disorder associated with traumatic brain injury

Traumatic brain injury (TBI) describes the presence of physical damage to the brain as a consequence of an insult and frequently possesses psychological and neurological symptoms depending on the severity of the injury. The recent increased military presence of US troops in Iraq and Afghanistan has coincided with greater use of improvised exploding devices, resulting in many returning soldiers suffering from some degree of TBI. A biphasic response is observed which is first directly injury-related, and second due to hypoxia, increased oxidative stress, and inflammation. A proportion of the returning soldiers also suffer from post-traumatic stress disorder (PTSD), and in some cases, this may be a consequence of TBI. Effective treatments are still being identified, and a possible therapeutic candidate is hyperbaric oxygen therapy (HBOT). Some clinical trials have been performed which suggest benefits with regard to survival and disease severity of TBI and/or PTSD, while several other studies do not see any improvement compared to a possibly poorly controlled sham. HBOT has been shown to reduce apoptosis, upregulate growth factors, promote antioxidant levels, and inhibit inflammatory cytokines in animal models, and hence, it is likely that HBOT could be advantageous in treating at least the secondary phase of TBI and PTSD. There is some evidence of a putative prophylactic or preconditioning benefit of HBOT exposure in animal models of brain injury, and the optimal time frame for treatment is yet to be determined. HBOT has potential side effects such as acute cerebral toxicity and more reactive oxygen species with long-term use, and therefore, optimizing exposure duration to maximize the reward and decrease the detrimental effects of HBOT is necessary. This review provides a summary of the current understanding of HBOT as well as suggests future directions including prophylactic use and chronic treatment.

Determinants of ligand binding and catalytic activity in the myelin enzyme 2',3'-cyclic nucleotide 3'-phosphodiesterase

2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) is an enzyme highly abundant in the central nervous system myelin of terrestrial vertebrates. The catalytic domain of CNPase belongs to the 2H phosphoesterase superfamily and catalyzes the hydrolysis of nucleoside 2',3'-cyclic monophosphates to nucleoside 2'-monophosphates. The detailed reaction mechanism and the essential catalytic amino acids involved have been described earlier, but the roles of many amino acids in the vicinity of the active site have remained unknown. Here, several CNPase catalytic domain mutants were studied using enzyme kinetics assays, thermal stability experiments, and X-ray crystallography. Additionally, the crystal structure of a perdeuterated CNPase catalytic domain was refined at atomic resolution to obtain a detailed view of the active site and the catalytic mechanism. The results specify determinants of ligand binding and novel essential residues required for CNPase catalysis. For example, the aromatic side chains of Phe235 and Tyr168 are crucial for substrate binding, and Arg307 may affect active site electrostatics and regulate loop dynamics. The β5-α7 loop, unique for CNPase in the 2H phosphoesterase family, appears to have various functions in the CNPase reaction mechanism, from coordinating the nucleophilic water molecule to providing a binding pocket for the product and being involved in product release.

Hyperbaric oxygen therapy for post concussion symptoms: issues may affect the results

Post concussion syndrome (PCS) is a set of symptoms succeeding in 25 % of mild traumatic brain injury (mTBI) patients. Hyperbaric oxygen therapy (HBOT) has been demonstrated as an effective method for treating acute and severe TBI, but its efficacy in PCS remains controversial. In this editorial, we reviewed the clinical studies of HBOT in PCS, summarized the limitations of these studies, and discussed the limitations: inappropriate Sham group using room air at 1.2 or 1.3 ATA; delayed HBO administration; subjective assessment methods; time point for outcome assessment and small sample size. We hope that our concerns will be helpful for future clinical studies of HBO therapy in TBI or other neurological disorders.

Effects of hyperbaric oxygen on eye tracking abnormalities in males after mild traumatic brain injury

The effects of hyperbaric oxygen (HBO2) on eye movement abnormalities in 60 military servicemembers with at least one mild traumatic brain injury (TBI) from combat were examined in a single-center, randomized, double-blind, sham-controlled, prospective study at the Naval Medicine Operational Training Center. During the 10 wk of the study, each subject was delivered a series of 40, once a day, hyperbaric chamber compressions at a pressure of 2.0 atmospheres absolute (ATA). At each session, subjects breathed one of three preassigned oxygen fractions (10.5%, 75%, or 100%) for 1 h, resulting in an oxygen exposure equivalent to breathing either surface air, 100% oxygen at 1.5 ATA, or 100% oxygen at 2.0 ATA, respectively. Using a standardized, validated, computerized eye tracking protocol, fixation, saccades, and smooth pursuit eye movements were measured just prior to intervention and immediately postintervention. Between and within groups testing of pre- and postintervention means revealed no significant differences on eye movement abnormalities and no significant main effect for HBO2 at either 1.5 ATA or 2.0 ATA equivalent compared with the sham-control. This study demonstrated that neither 1.5 nor 2.0 ATA equivalent HBO2 had an effect on postconcussive eye movement abnormalities after mild TBI when compared with a sham-control.

Hyperbaric oxygen in chronic traumatic brain injury: oxygen, pressure, and gene therapy

Hyperbaric oxygen therapy is a treatment for wounds in any location and of any duration that has been misunderstood for 353 years. Since 2008 it has been applied to the persistent post-concussion syndrome of mild traumatic brain injury by civilian and later military researchers with apparent conflicting results. The civilian studies are positive and the military-funded studies are a mixture of misinterpreted positive data, indeterminate data, and negative data. This has confused the medical, academic, and lay communities. The source of the confusion is a fundamental misunderstanding of the definition, principles, and mechanisms of action of hyperbaric oxygen therapy. This article argues that the traditional definition of hyperbaric oxygen therapy is arbitrary. The article establishes a scientific definition of hyperbaric oxygen therapy as a wound-healing therapy of combined increased atmospheric pressure and pressure of oxygen over ambient atmospheric pressure and pressure of oxygen whose main mechanisms of action are gene-mediated. Hyperbaric oxygen therapy exerts its wound-healing effects by expression and suppression of thousands of genes. The dominant gene actions are upregulation of trophic and anti-inflammatory genes and down-regulation of pro-inflammatory and apoptotic genes. The combination of genes affected depends on the different combinations of total pressure and pressure of oxygen. Understanding that hyperbaric oxygen therapy is a pressure and oxygen dose-dependent gene therapy allows for reconciliation of the conflicting TBI study results as outcomes of different doses of pressure and oxygen.

Factors Associated with Word Memory Test Performance in Persons with Medically Documented Traumatic Brain Injury

OBJECTIVES

(1) To examine the rate of poor performance validity in a large, multicenter, prospectively accrued cohort of community dwelling persons with medically documented traumatic brain injury (TBI), (2) to identify factors associated with Word Memory Test (WMT) performance in persons with TBI.

METHOD

This was a prospective cohort, observational study of 491 persons with medically documented TBI. Participants were administered a battery of cognitive tests, questionnaires on emotional distress and post-concussive symptoms, and a performance validity test (WMT). Additional data were collected by interview and review of medical records.

RESULTS

One hundred and seventeen participants showed poor performance validity using the standard cutoff. Variable cluster analysis was conducted as a data reduction strategy. Findings revealed that the 10 cognitive tests and questionnaires could be summarized as 4 indices of emotional distress, speed of cognitive processing, verbal memory, and verbal fluency. Regression models revealed that verbal memory, emotional distress, age, and injury severity (time to follow commands) made unique contribution to prediction of poor performance validity.

CONCLUSIONS

Poor performance validity was common in a research sample of persons with medically documented TBI who were not evaluated in conjunction with litigation, compensation claims, or current report of symptoms. Poor performance validity was associated with poor performance on cognitive tests, greater emotional distress, lower injury severity, and greater age. Many participants expected to have residual deficits based on initial injury severity showed poor performance validity.

All the right moves: the need for the timely use of hyperbaric oxygen therapy for treating TBI/CTE/PTSD

Background

The modern age of hyperbaric medicine began in 1937; however, today few know about hyperbaric oxygen’s effects on the body and medical conditions outside of diving medicine and wound care centers - a serious ethical issue as there are 20 US military veterans committing suicide every day directly related to Traumatic Brain Injury/Post Traumatic Stress Disorder. The problem is not whether hyperbaric oxygen is effective for treating brain injuries, but why the interference in offering this therapy to those who need it.

Discussion

Up against black-boxed anti-depressants that are not efficacious, it should be a “no-brainer” to use a safe, off-label drug, but in the case of military veterans, every suicide might be seen as a tremendous cost saving to certain technocrats. The unspoken rationale is that if the military were to embrace hyperbaric oxygen as the efficacious therapy that it is then current active troops that have suffered injuries will come forward and seek treatment and benefits for their Traumatic Brain Injuries now that they know there is a viable therapy and in so doing troop strength will be decimated. So, to attempt to delay the acceptance of hyperbaric oxygen the Department of Defense has funded faux-studies claiming low pressure room air to be a placebo or sham, and then proclaiming there is no statistical difference between treatment arms and sham or placebo treatment arms. With few who understand hyperbaric medicine there is almost no one to call them on this subterfuge and prevarication. Many peer-reviewed articles have been published in the last decade that demonstrate hyperbaric oxygen is effective in repairing an injured brain even long after that injury took place. One of the most notable showed that blast-induced brain injured war veterans experienced a 15 point IQ increase (p < 0.001).

Summary

Hyperbaric oxygen is an efficacious, benign and humanitarian way to affect brain repair but it has not been adopted because it lacks patent protection and has no large corporate sponsors. It has also met interference because other agendas are present be they the protection of the status quo, myopic budgetary constraints, or perceived liability issues.

What's New in Traumatic Brain Injury: Update on Tracking, Monitoring and Treatment

Traumatic brain injury (TBI), defined as an alteration in brain functions caused by an external force, is responsible for high morbidity and mortality around the world. It is important to identify and treat TBI victims as early as possible. Tracking and monitoring TBI with neuroimaging technologies, including functional magnetic resonance imaging (fMRI), diffusion tensor imaging (DTI), positron emission tomography (PET), and high definition fiber tracking (HDFT) show increasing sensitivity and specificity. Classical electrophysiological monitoring, together with newly established brain-on-chip, cerebral microdialysis techniques, both benefit TBI. First generation molecular biomarkers, based on genomic and proteomic changes following TBI, have proven effective and economical. It is conceivable that TBI-specific biomarkers will be developed with the combination of systems biology and bioinformation strategies. Advances in treatment of TBI include stem cell-based and nanotechnology-based therapy, physical and pharmaceutical interventions and also new use in TBI for approved drugs which all present favorable promise in preventing and reversing TBI.

When physics meets biology: low and high-velocity penetration, blunt impact, and blast injuries to the brain

The incidence of traumatic brain injuries (TBI) in the US has reached epidemic proportions with well over 2 million new cases reported each year. TBI can occur in both civilians and warfighters, with head injuries occurring in both combat and non-combat situations from a variety of threats, including ballistic penetration, acceleration, blunt impact, and blast. Most generally, TBI is a condition in which physical loads exceed the capacity of brain tissues to absorb without injury. More specifically, TBI results when sufficient external force is applied to the head and is subsequently converted into stresses that must be absorbed or redirected by protective equipment. If the stresses are not sufficiently absorbed or redirected, they will lead to damage of extracranial soft tissue and the skull. Complex interactions and kinematics of the head, neck and jaw cause strains within the brain tissue, resulting in structural, anatomical damage that is characteristic of the inciting insult. This mechanical trauma then initiates a neuro-chemical cascade that leads to the functional consequences of TBI, such as cognitive impairment. To fully understand the mechanisms by which TBI occurs, it is critically important to understand the effects of the loading environments created by these threats. In the following, a review is made of the pertinent complex loading conditions and how these loads cause injury. Also discussed are injury thresholds and gaps in knowledge, both of which are needed to design improved protective systems.

Attention Deficits After Aneurysmal Subarachnoid Hemorrhage Measured Using the Test of Variables of Attention

Background and Purpose—

The aim of this pilot study was to assess attention deficits in patients with aneurysmal subarachnoid hemorrhage using the test of variables of attention (TOVA). This is a computer-based continuous performance test providing objective measures of attention. We also compared the TOVA results with the attention and concentration domains of Montgomery Åsberg Depression Rating Scale and Montreal cognitive assessment, 2 examiner-administrated neuropsychological instruments.

Methods—

Nineteen patients with moderate to good recovery (Glasgow outcome scale, 4–5) were assessed using the TOVA, Montgomery Åsberg Depression Rating Scale, and Montreal cognitive assessment. The measurements were done when the patients visited the hospital for a routine magnetic resonance imaging control of the aneurysm.

Results—

TOVA performance was pathological in 58%. The dominating pattern was a worsening of performance in the second half of the test, commonly a failing to react to correct stimuli. We found no correlation between TOVA and the performance in concentration and attention domains of Montgomery Åsberg Depression Rating Scale and Montreal cognitive assessment.

Conclusions—

Attention deficits, measured by the TOVA, were common after subarachnoid hemorrhage. This should be further studied to improve outcome.

A terrorist bomb blast, a real challenge for any tertiary care health provider

Multiple casualties and the complex set of injuries in survivors of a terrorist bomb blast poses a real challenge to health care providers. We are presenting three such cases, first case suffered a fracture of both bone lower limb bilaterally along with head injury (foreign bodies were impacted in the scalp and brain parenchyma). Following primary resuscitation, patient shifted to operation theatre after a quick computerized tomography scan and external fixator applied in general anesthesia using the rapid sequence induction. No active neurosurgical intervention was done. As this patient had acute post-traumatic stress response, he was subjected to low pressure hyperbaric oxygen therapy (pressure of 1.5 ATA for 60 min a day for 10 days) and group counseling. He had good recovery except one lost a limb because of extensive neurovascular damage due to blast. Second case had much more extensive damage involving multiple organ systems. He had blast lung, big cerebrovascular hemorrhage along with gut perforation. Despite best possible surgical and intensive care interventions, patent developed multiple organ failure and unfortunately we lost our patient. Third case was of a right sided globe rupture resulted from blast induced flying foreign bodies. After primary survey and initial resuscitation evisceration done for the damaged eye and patient later on discharged with necessary instruction (including warning signs) for follow-up.

The neuropathology of traumatic brain injury

Traumatic brain injury, a leading cause of mortality and morbidity, is divided into three grades of severity: mild, moderate, and severe, based on the Glasgow Coma Scale, the loss of consciousness, and the development of post-traumatic amnesia. Although mild traumatic brain injury, including concussion and subconcussion, is by far the most common, it is also the most difficult to diagnose and the least well understood. Proper recognition, management, and treatment of acute concussion and mild traumatic brain injury are the fundamentals of an emerging clinical discipline. It is also becoming increasingly clear that some mild traumatic brain injuries have persistent, and sometimes progressive, long-term debilitating effects. Evidence indicates that a single traumatic brain injury can precipitate or accelerate multiple age-related neurodegenerations, increase the risk of developing Alzheimer's disease, Parkinson's disease, and motor neuron disease, and that repetitive mild traumatic brain injuries can provoke the development of a tauopathy, chronic traumatic encephalopathy. Clinically, chronic traumatic encephalopathy is associated with behavioral changes, executive dysfunction, memory loss, and cognitive impairments that begin insidiously and progress slowly over decades. Pathologically, chronic traumatic encephalopathy produces atrophy of the frontal and temporal lobes, thalamus, and hypothalamus, septal abnormalities, and abnormal deposits of hyperphosphorylated tau (τ) as neurofibrillary tangles and disordered neurites throughout the brain. The incidence and prevalence of chronic traumatic encephalopathy and the genetic risk factors critical to its development are currently unknown. Chronic traumatic encephalopathy frequently occurs as a sole diagnosis, but may be associated with other neurodegenerative disorders, including Alzheimer's disease, Lewy body disease, and motor neuron disease. Currently, chronic traumatic encephalopathy can be diagnosed only at autopsy; however, promising efforts to develop imaging, spinal fluid, and peripheral blood biomarkers are underway to diagnose and monitor the course of disease in living subjects.

Effects of low-level blast exposure on the nervous system: is there really a controversy?

High-pressure blast waves can cause extensive CNS injury in human beings. However, in combat settings, such as Iraq and Afghanistan, lower level exposures associated with mild traumatic brain injury (mTBI) or subclinical exposure have been much more common. Yet controversy exists concerning what traits can be attributed to low-level blast, in large part due to the difficulty of distinguishing blast-related mTBI from post-traumatic stress disorder (PTSD). We describe how TBI is defined in human beings and the problems posed in using current definitions to recognize blast-related mTBI. We next consider the problem of applying definitions of human mTBI to animal models, in particular that TBI severity in human beings is defined in relation to alteration of consciousness at the time of injury, which typically cannot be assessed in animals. However, based on outcome assessments, a condition of "low-level" blast exposure can be defined in animals that likely approximates human mTBI or subclinical exposure. We review blast injury modeling in animals noting that inconsistencies in experimental approach have contributed to uncertainty over the effects of low-level blast. Yet, animal studies show that low-level blast pressure waves are transmitted to the brain. In brain, low-level blast exposures cause behavioral, biochemical, pathological, and physiological effects on the nervous system including the induction of PTSD-related behavioral traits in the absence of a psychological stressor. We review the relationship of blast exposure to chronic neurodegenerative diseases noting the paradoxical lowering of Abeta by blast, which along with other observations suggest that blast-related TBI is pathophysiologically distinct from non-blast TBI. Human neuroimaging studies show that blast-related mTBI is associated with a variety of chronic effects that are unlikely to be explained by co-morbid PTSD. We conclude that abundant evidence supports low-level blast as having long-term effects on the nervous system.

The effect of hyperbaric oxygen on persistent postconcussion symptoms

BACKGROUND

The high incidence of persistent postconcussion symptoms in service members with combat-related mild traumatic brain injury has prompted research in the use of hyperbaric oxygen (HBO2) for management.

OBJECTIVE

The effects of HBO2 on persistent postconcussion symptoms in 60 military service members with at least 1 combat-related mild traumatic brain injury were examined in a single-center, double-blind, randomized, sham-controlled, prospective trial at the Naval Medicine Operational Training Center at Naval Air Station Pensacola.

METHODS

Over a 10-week period, subjects received a series of 40, once-daily, hyperbaric chamber compressions at 2.0 atmospheres absolute (ATA). During each session, subjects breathed 1 of 3 preassigned oxygen fractions (10.5%, 75%, or 100%) for 60 minutes, resulting in an oxygen exposure equivalent to breathing surface air, 100% oxygen at 1.5 ATA, or 100% oxygen at 2.0 ATA, respectively. Individual, subscale and total item responses on the Rivermead Postconcussion Symptom Questionnaire and individual and total Posttraumatic Disorder Checklist-Military Version were measured just prior to intervention and immediately postintervention.

RESULTS

Between-group testing of pre- and postintervention means revealed no significant differences on individual or total scores on the Posttraumatic Disorder Checklist-Military Version or Rivermead Postconcussion Symptom Questionnaire, demonstrating a successful randomization and no significant main effect for HBO2 at 1.5 or 2.0 ATA equivalent compared with the sham compression. Within-group testing of pre- and postintervention means revealed significant differences on several individual items for each group and difference in the Posttraumatic Disorder Checklist-Military Version total score for the 2.0 ATA HBO2 group.

DISCUSSION

The primary analyses of between group differences found no evidence of efficacy for HBO2. The scattered within group differences are threatened by Type 2 errors and could be explained by nonspecific effects.

CONCLUSION

This study demonstrated that HBO2 at either 1.5 or 2.0 ATA equivalent had no effect on postconcussion symptoms after mild traumatic brain injury when compared with sham compression.

Hyperbaric medicine for the hospital-based physician

Hyperbaric oxygen (HBO2) is the inhalation of 100% oxygen at pressures > 1.4 times atmospheric pressure. Hyperbaric oxygen can be delivered in monoplace (single person) or multiplace (multi-person) chambers. Most clinical HBO2 exposures are between 2 and 2.4 atm abs for approximately 2 hours. Hyperbaric oxygen causes the blood and tissue oxygen levels to increase, reduces the volume of intravascular and tissue bubbles (to treat decompression sickness [DCS] and arterial gas embolism [AGE]), and accelerates wash-out of other gases, such as nitrogen or carbon monoxide (CO), which is important for DCS, AGE, and CO poisoning. Hyperbaric oxygen favorably modulates ischemia-reperfusion injury by transiently inhibiting neutrophil-endothelial interactions, which is important for patients with DCS, AGE, CO poisoning, and potentially other acute ischemic conditions. Because of enhanced oxygen delivery, HBO2 is used for acute crush injury, ischemic flaps and grafts, acute central retinal arterial occlusion, other acute arterial occlusions, and idiopathic sudden sensorineural hearing loss. Hyperbaric oxygen has antimicrobial effects and is offered for patients with limb- or life-threatening infections, such as clostridial gas gangrene and necrotizing fasciitis. The most common US indication for HBO2 is the treatment of ischemic wounds (eg, diabetic lower extremity wounds, late effects of radiation, and refractory osteomyelitis). In ischemic wounds, HBO2 can deliver sufficient oxygen to the nonhealing wound to stimulate angiogenesis and healing through multiple mechanisms, including increased collagen production, increased growth factor receptor numbers, upregulation of vascular endothelial growth factor, increased circulating endothelial progenitor cells, and improvement in neutrophil-mediated host defense. Clinical trials support efficacy of HBO2 for acute CO poisoning, diabetic lower extremity wounds, crush injury, and radiation necrosis. Most hyperbaric chambers are associated with wound care centers and may be hospital based or nonhospital based. We review some of the disorders treated with HBO2 that hospital-based clinicians may be asked to evaluate.

The myelin membrane-associated enzyme 2',3'-cyclic nucleotide 3'-phosphodiesterase: on a highway to structure and function

The membrane-anchored myelin enzyme 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) was discovered in the early 1960s and has since then troubled scientists with its peculiar catalytic activity and high expression levels in the central nervous system. Despite decades of research, the actual physiological relevance of CNPase has only recently begun to unravel. In addition to a role in myelination, CNPase is also involved in local adenosine production in traumatic brain injury and possibly has a regulatory function in mitochondrial membrane permeabilization. Although research focusing on the CNPase phosphodiesterase activity has been helpful, several open questions concerning the protein function in vivo remain unanswered. This review is focused on past research on CNPase, especially in the fields of structural biology and enzymology, and outlines the current understanding regarding the biochemical and physiological significance of CNPase, providing ideas and directions for future research.

Delayed hyperbaric oxygen therapy promotes neurogenesis through reactive oxygen species/hypoxia-inducible factor-1α/β-catenin pathway in middle cerebral artery occlusion rats

BACKGROUND AND PURPOSE

Hyperbaric oxygen (HBO) has been reported to be neuroprotective and to improve neurofunctional outcomes in acute stroke. However, it is not clear whether delayed HBO enhances endogenous neurogenesis and promotes neurofunctional recovery. The aim of this study is to evaluate the effects of delayed HBO therapy on neurogenesis and its potential mechanisms.

METHODS

One hundred eleven male Sprague-Dawley rats that survived for 7 days from 2 hours of middle cerebral artery occlusion and reperfusion were used. Delayed and multiple HBO were administrated beginning at 7 days after middle cerebral artery occlusion and lasting for 42 days with 3 HBO-free intervals (5 days each). Motor sensory deficits were measured by foot-fault test, and learning and memory abilities were evaluated by Morris water maze. Neurogenesis was examined by double immunostaining of bromodeoxyuridine and doublecortin, bromodeoxyuridine and neuronal nuclei at day 42. For mechanism studies, inhibitors for reactive oxygen species (ROS), hypoxia-inducible factor (HIF)-1α, and β-catenin were administrated, and the levels of ROS, HIF-1α, β-catenin, lymphoid enhancer-binding factor-1, T-cell factor-1, neurogenin-1, doublecortin, and synapsin-1 were assessed by ELISA or Western blot at day 14.

RESULTS

Delayed HBO treatment promoted neurogenesis and improved neurofunctional recovery at day 42, and the improvements were reversed by inhibition of ROS and HIF-1α. Delayed HBO significantly increased ROS and HIF-1α, and upregulated the expression of neurogenin-1, doublecortin, and synapsin-1. Inhibition of ROS and HIF-1α removed the effects of delayed HBO.

CONCLUSIONS

Delayed HBO enhanced endogenous neurogenesis and improved neurofunctional recovery in the late-chronic phase of stroke possibly mediated by ROS/HIF-1α/β-catenin pathway. Delayed HBO may serve as an alternative treatment to improve long-term recovery of stroke survivors.

Hyperbaric oxygen therapy for chronic post-concussive syndrome

In this editorial, the value of hyperbaric oxygen therapy in the management of chronic post-concussive syndrome following mild traumatic brain injury is discussed.

Clinical utility of SPECT neuroimaging in the diagnosis and treatment of traumatic brain injury: a systematic review

Purpose

This systematic review evaluated the clinical utility of single photon emission computed tomography (SPECT) in traumatic brain injury (TBI).

Methods

After defining a PICO Statement (Population, Intervention, Comparison and Outcome Statement), PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) criteria were applied to identify 1600 articles. After screening, 374 articles were eligible for review. Inclusion for review was focus on SPECT in the setting of mild, moderate, or severe TBI with cerebral lobar specificity of SPECT findings. Other inclusion criteria were comparison modalities in the same subjects and articles in English. Foreign language articles, SPECT studies that did not include comparison modalities, and case reports were not included for review.

Results

We identified 19 longitudinal and 52 cross-sectional studies meeting inclusion criteria. Three longitudinal studies examined diagnostic predictive value. The first showed positive predictive value increases from initial SPECT scan shortly after trauma to one year follow up scans, from 59% to 95%. Subsequent work replicated these results in a larger cohort. Longitudinal and cross sectional studies demonstrated SPECT lesion localization not detected by CT or MRI. The most commonly abnormal regions revealed by SPECT in cross-sectional studies were frontal (94%) and temporal (77%) lobes. SPECT was found to outperform both CT and MRI in both acute and chronic imaging of TBI, particularly mild TBI. It was also found to have a near 100% negative predictive value.

Conclusions

This review demonstrates Level IIA evidence (at least one non-randomized controlled trial) for the value of SPECT in TBI. Given its advantages over CT and MRI in the detection of mild TBI in numerous studies of adequate quality, and given its excellent negative predictive value, it may be an important second test in settings where CT or MRI are negative after a closed head injury with post-injury neurological or psychiatric symptoms.

Hyperbaric oxygen for blast-related postconcussion syndrome: three-month outcomes

OBJECTIVE

Mild traumatic brain injury (mTBI) and postconcussion syndrome (PCS) are common among military combatants. Hyperbaric oxygen (HBO2 ) is a proposed treatment for these conditions, but it has not been rigorously studied. The objective of this study was to determine the effects of HBO2 by 3 months post compression at 2 commonly employed dosing levels to treat PCS; whether specific subgroups may have benefited; and if no overall effect was found, whether benefit is masked by other conditions.

METHODS

This randomized, double-blind, sham-controlled study was conducted at the Naval Air Station in Pensacola, Florida on 61 male Marines with a history of mTBI and PCS. Intervention consisted of 40 once daily 60-minute hyperbaric chamber compressions at 2.0 atmospheres absolute (ATA) at 1 of 3 randomly preassigned oxygen fractions, resulting in respective blinded groups with an oxygen-breathing exposure equivalent to (1) surface air (sham), (2) 100% oxygen at 1.5ATA, or (3) 100% oxygen at 2.0ATA. The main outcome measure was the Rivermead Post-Concussion Questionnaire-16 (RPQ-16) collected before compressions and at 2 later points.

RESULTS

The interaction of time by intervention group was not significant for improvement on the RPQ-16. Nor was there evidence of efficacy on the RPQ-16 for any subgroup. No significant time by intervention interaction was found for any functional, cognitive, or psychomotor secondary outcome measure at an unadjusted 0.05 significance level.

INTERPRETATION

Using a randomized control trial design and analysis including a sham, results showed no evidence of efficacy by 3 months post-compression to treat the symptomatic, cognitive, or behavioral sequelae of PCS after combat-related mTBI.

Traumatic Brain Injury pathophysiology and treatments: early, intermediate, and late phases post-injury

Traumatic Brain Injury (TBI) affects a large proportion and extensive array of individuals in the population. While precise pathological mechanisms are lacking, the growing base of knowledge concerning TBI has put increased emphasis on its understanding and treatment. Most treatments of TBI are aimed at ameliorating secondary insults arising from the injury; these insults can be characterized with respect to time post-injury, including early, intermediate, and late pathological changes. Early pathological responses are due to energy depletion and cell death secondary to excitotoxicity, the intermediate phase is characterized by neuroinflammation and the late stage by increased susceptibility to seizures and epilepsy. Current treatments of TBI have been tailored to these distinct pathological stages with some overlap. Many prophylactic, pharmacologic, and surgical treatments are used post-TBI to halt the progression of these pathologic reactions. In the present review, we discuss the mechanisms of the pathological hallmarks of TBI and both current and novel treatments which target the respective pathways.

Randomized, Sham-Controlled, Feasibility Trial of Hyperbaric Oxygen for Service Members With Postconcussion Syndrome: Cognitive and Psychomotor Outcomes 1 Week Postintervention

Background Mild traumatic brain injury (mTBI) and residual postconcussion syndrome (PCS) are common among combatants of the recent military conflicts in Iraq and Afghanistan. Hyperbaric oxygen (HBO2) is a proposed treatment but has not been rigorously studied for this condition. Objectives In a secondary analysis, examine for possible effects on psychomotor (balance and fine motor) and cognitive performance 1 week after an HBO2 intervention in service members with PCS after mTBI. Methods A randomized, double-blind, sham control, feasibility trial comparing pretreatment and posttreatment was conducted in 60 male active-duty marines with combat-related mTBI and PCS persisting for 3 to 36 months. Participants were randomized to 1 of 3 preassigned oxygen fractions (10.5%, 75%, or 100%) at 2.0 atmospheres absolute (ATA), resulting in respective groups with an oxygen exposure equivalent to (1) breathing surface air (Sham Air), (2) 100% oxygen at 1.5 ATA (1.5 ATAO2), and (3) 100% oxygen at 2.0 ATA (2.0 ATAO2). Over a 10-week period, participants received 40 hyperbaric chamber sessions of 60 minutes each. Outcome measures, including computerized posturography (balance), grooved pegboard (fine motor speed/dexterity), and multiple neuropsychological tests of cognitive performance, were collected preintervention and 1-week postintervention. Results Despite the multiple sensitive cognitive and psychomotor measures analyzed at an unadjusted 5% significance level, this study demonstrated no immediate postintervention beneficial effect of exposure to either 1.5 ATAO2 or 2.0 ATAO2 compared with the Sham Air intervention. Conclusions These results do not support the use of HBO2 to treat cognitive, balance, or fine motor deficits associated with mTBI and PCS.

Hyperbaric oxygen therapy can improve post concussion syndrome years after mild traumatic brain injury - randomized prospective trial

Background

Traumatic brain injury (TBI) is the leading cause of death and disability in the US. Approximately 70-90% of the TBI cases are classified as mild, and up to 25% of them will not recover and suffer chronic neurocognitive impairments. The main pathology in these cases involves diffuse brain injuries, which are hard to detect by anatomical imaging yet noticeable in metabolic imaging. The current study tested the effectiveness of Hyperbaric Oxygen Therapy (HBOT) in improving brain function and quality of life in mTBI patients suffering chronic neurocognitive impairments.

Methods and Findings

The trial population included 56 mTBI patients 1–5 years after injury with prolonged post-concussion syndrome (PCS). The HBOT effect was evaluated by means of prospective, randomized, crossover controlled trial: the patients were randomly assigned to treated or crossover groups. Patients in the treated group were evaluated at baseline and following 40 HBOT sessions; patients in the crossover group were evaluated three times: at baseline, following a 2-month control period of no treatment, and following subsequent 2-months of 40 HBOT sessions. The HBOT protocol included 40 treatment sessions (5 days/week), 60 minutes each, with 100% oxygen at 1.5 ATA. “Mindstreams” was used for cognitive evaluations, quality of life (QOL) was evaluated by the EQ-5D, and changes in brain activity were assessed by SPECT imaging. Significant improvements were demonstrated in cognitive function and QOL in both groups following HBOT but no significant improvement was observed following the control period. SPECT imaging revealed elevated brain activity in good agreement with the cognitive improvements.

Conclusions

HBOT can induce neuroplasticity leading to repair of chronically impaired brain functions and improved quality of life in mTBI patients with prolonged PCS at late chronic stage.

Trial Registration

ClinicalTrials.gov

NCT00715052

Effects of antioxidant treatment on blast-induced brain injury

Blast-induced traumatic brain injury has dramatically increased in combat troops in today’s military operations. We previously reported that antioxidant treatment can provide protection to the peripheral auditory end organ, the cochlea. In the present study, we examined biomarker expression in the brains of rats at different time points (3 hours to 21 days) after three successive 14 psi blast overpressure exposures to evaluate antioxidant treatment effects on blast-induced brain injury. Rats in the treatment groups received a combination of antioxidants (2,4-disulfonyl α-phenyl tertiary butyl nitrone and N-acetylcysteine) one hour after blast exposure and then twice a day for the following two days. The biomarkers examined included an oxidative stress marker (4-hydroxy-2-nonenal, 4-HNE), an immediate early gene (c-fos), a neural injury marker (glial fibrillary acidic protein, GFAP) and two axonal injury markers [amyloid beta (A4) precursor protein, APP, and 68 kDa neurofilament, NF-68]. The results demonstrate that blast exposure induced or up-regulated the following: 4-HNE production in the dorsal hippocampus commissure and the forceps major corpus callosum near the lateral ventricle; c-fos and GFAP expression in most regions of the brain, including the retrosplenial cortex, the hippocampus, the cochlear nucleus, and the inferior colliculus; and NF-68 and APP expression in the hippocampus, the auditory cortex, and the medial geniculate nucleus (MGN). Antioxidant treatment reduced the following: 4-HNE in the hippocampus and the forceps major corpus callosum, c-fos expression in the retrosplenial cortex, GFAP expression in the dorsal cochlear nucleus (DCN), and APP and NF-68 expression in the hippocampus, auditory cortex, and MGN. This preliminary study indicates that antioxidant treatment may provide therapeutic protection to the central auditory pathway (the DCN and MGN) and the non-auditory central nervous system (hippocampus and retrosplenial cortex), suggesting that these compounds have the potential to simultaneously treat blast-induced injuries in the brain and auditory system.

A prospective, randomized Phase II clinical trial to evaluate the effect of combined hyperbaric and normobaric hyperoxia on cerebral metabolism, intracranial pressure, oxygen toxicity, and clinical outcome in severe traumatic brain injury

OBJECT

Preclinical and clinical investigations indicate that the positive effect of hyperbaric oxygen (HBO2) for severe traumatic brain injury (TBI) occurs after rather than during treatment. The brain appears better able to use baseline O2 levels following HBO2 treatments. In this study, the authors evaluate the combination of HBO2 and normobaric hyperoxia (NBH) as a single treatment.

METHODS

Forty-two patients who sustained severe TBI (mean Glasgow Coma Scale [GCS] score 5.7) were prospectively randomized within 24 hours of injury to either: 1) combined HBO2/NBH (60 minutes of HBO2 at 1.5 atmospheres absolute [ATA] followed by NBH, 3 hours of 100% fraction of inspired oxygen [FiO2] at 1.0 ATA) or 2) control, standard care. Treatments occurred once every 24 hours for 3 consecutive days. Intracranial pressure, surrogate markers for cerebral metabolism, and O2 toxicity were monitored. Clinical outcome was assessed at 6 months using the sliding dichotomized Glasgow Outcome Scale (GOS) score. Mixed-effects linear modeling was used to statistically test differences between the treatment and control groups. Functional outcome and mortality rates were compared using chi-square tests.

RESULTS

There were no significant differences in demographic characteristics between the 2 groups. In comparison with values in the control group, brain tissue partial pressure of O2 (PO2) levels were significantly increased during and following combined HBO2/NBH treatments in both the noninjured and pericontusional brain (p < 0.0001). Microdialysate lactate/pyruvate ratios were significantly decreased in the noninjured brain in the combined HBO2/NBH group as compared with controls (p < 0.0078). The combined HBO2/NBH group's intracranial pressure values were significantly lower than those of the control group during treatment, and the improvement continued until the next treatment session (p < 0.0006). The combined HBO2/NBH group's levels of microdialysate glycerol were significantly lower than those of the control group in both noninjured and pericontusional brain (p < 0.001). The combined HBO2/NBH group's level of CSF F2-isoprostane was decreased at 6 hours after treatment as compared with that of controls, but the difference did not quite reach statistical significance (p = 0.0692). There was an absolute 26% reduction in mortality for the combined HBO2/NBH group (p = 0.048) and an absolute 36% improvement in favorable outcome using the sliding dichotomized GOS (p = 0.024) as compared with the control group.

CONCLUSIONS

In this Phase II clinical trial, in comparison with standard care (control treatment) combined HBO2/NBH treatments significantly improved markers of oxidative metabolism in relatively uninjured brain as well as pericontusional tissue, reduced intracranial hypertension, and demonstrated improvement in markers of cerebral toxicity. There was significant reduction in mortality and improved favorable outcome as measured by GOS. The combination of HBO2 and NBH therapy appears to have potential therapeutic efficacy as compared with the 2 treatments in isolation. CLINICAL TRIAL REGISTRATION NO.: NCT00170352 (ClinicalTrials.gov).

Hyperbaric oxygen induces late neuroplasticity in post stroke patients--randomized, prospective trial

Background

Recovery after stroke correlates with non-active (stunned) brain regions, which may persist for years. The current study aimed to evaluate whether increasing the level of dissolved oxygen by Hyperbaric Oxygen Therapy (HBOT) could activate neuroplasticity in patients with chronic neurologic deficiencies due to stroke.

Methods and Findings

A prospective, randomized, controlled trial including 74 patients (15 were excluded). All participants suffered a stroke 6–36 months prior to inclusion and had at least one motor dysfunction. After inclusion, patients were randomly assigned to "treated" or "cross" groups. Brain activity was assessed by SPECT imaging; neurologic functions were evaluated by NIHSS, ADL, and life quality. Patients in the treated group were evaluated twice: at baseline and after 40 HBOT sessions. Patients in the cross group were evaluated three times: at baseline, after a 2-month control period of no treatment, and after subsequent 2-months of 40 HBOT sessions. HBOT protocol: Two months of 40 sessions (5 days/week), 90 minutes each, 100% oxygen at 2 ATA. We found that the neurological functions and life quality of all patients in both groups were significantly improved following the HBOT sessions while no improvement was found during the control period of the patients in the cross group. Results of SPECT imaging were well correlated with clinical improvement. Elevated brain activity was detected mostly in regions of live cells (as confirmed by CT) with low activity (based on SPECT) – regions of noticeable discrepancy between anatomy and physiology.

Conclusions

The results indicate that HBOT can lead to significant neurological improvements in post stroke patients even at chronic late stages. The observed clinical improvements imply that neuroplasticity can still be activated long after damage onset in regions where there is a brain SPECT/CT (anatomy/physiology) mismatch.

Trial Registration

ClinicalTrials.gov NCT00715897

Concussion in athletics: ongoing clinical and brain imaging research controversies

Concussion, the most common form of traumatic brain injury, proves to be increasingly complex and not mild in nature as its synonymous term mild traumatic brain injury (mTBI) would imply. Despite the increasing occurrence and prevalence of mTBI there is no universally accepted definition and conventional brain imaging techniques lack the sensitivity to detect subtle changes it causes. Moreover, clinical management of sports induced mild traumatic brain injury has not changed much over the past decade. Advances in neuroimaging that include electroencephalography (EEG), functional magnetic resonance imaging (fMRI), resting-state functional connectivity, diffusion tensor imaging (DTI) and magnetic resonance spectroscopy (MRS) offer promise in aiding research into understanding the complexities and nuances of mTBI which may ultimately influence clinical management of the condition. In this paper the authors review the major findings from these advanced neuroimaging methods along with current controversy within this field of research. As mTBI is frequently associated with youth and sports injury this review focuses on sports-related mTBI in the younger population.

The effect of hyperbaric oxygen on symptoms after mild traumatic brain injury

In this single-center, double-blind, randomized, sham-controlled, prospective trial at the U.S. Air Force School of Aerospace Medicine, the effects of 2.4 atmospheres absolute (ATA) hyperbaric oxygen (HBO₂) on post-concussion symptoms in 50 military service members with at least one combat-related, mild traumatic brain injury were examined. Each subject received 30 sessions of either a sham compression (room air at 1.3 ATA) or HBO₂ treatments at 2.4 ATA over an 8-week period. Individual and total symptoms scores on Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT®) and composite scores on Post-traumatic Disorder Check List-Military Version (PCL-M) were measured just prior to intervention and 6 weeks after completion of intervention. Difference testing of post-intervention means between the sham-control and HBO₂ group revealed no significant differences on the PCL-M composite score (t=-0.205, p=0.84) or on the ImPACT total score (t=-0.943, p=0.35), demonstrating no significant effect for HBO₂ at 2.4 ATA. PCL-M composite scores and ImPACT total scores for sham-control and HBO(2) groups revealed significant improvement over the course of the study for both the sham-control group (t=3.76, p=0.001) and the HBO₂ group (t=3.90, p=0.001), demonstrating no significant HBO₂ effect. Paired t-test results revealed 10 ImPACT scale scores in the sham-control group improved from pre- to post-testing, whereas two scale scores significantly improved in the HBO₂ group. One PCL-M measure improved from pre- to post-testing in both groups. This study showed that HBO₂ at 2.4 ATA pressure had no effect on post-concussive symptoms after mild TBI.

Association of sleep and co-occurring psychological conditions at 1 year after traumatic brain injury

OBJECTIVES

To compare individuals' sleep 1 year after traumatic brain injury (TBI) with that of a healthy comparison group, and examine the relationship between sleep, co-occurring conditions, and functional status in those with TBI.

DESIGN

Longitudinal assessment of a prospectively studied sample of individuals with moderate to severe TBI. Assessment of sleep occurred at 1 year after TBI.

SETTING

Inpatient acute rehabilitation for TBI and community follow-up at 1 year postinjury.

PARTICIPANTS

Individuals with TBI (N=174) were recruited from consecutive admissions to an inpatient rehabilitation unit and enrolled into the TBI Model Systems study. Participant mean age was 38, and mean Glasgow Coma Scale score on admission was 9.3. Seventy-eight percent of the sample were men.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Sleep was assessed with the Pittsburgh Sleep Quality Index (PSQI). Depression, anxiety, and pain were measured with the Patient Health Questionnaire-9, the Generalized Anxiety Disorder-7 Scale, and an analog pain rating scale, respectively.

RESULTS

Participants with TBI reported significantly greater sleep difficulties than the healthy comparison group. Forty-four percent of participants with TBI reported significant sleep problems (PSQI>5). Participants with 1 or more co-occurring conditions (depression, pain, or anxiety) had significantly worse sleep than those without such a condition. The highest level of sleep problems was reported by participants with multiple co-occurring conditions. Sleep problems were also associated with poor functional status.

CONCLUSIONS

Sleep difficulties are a frequent problem at 1 year after TBI, and often co-occur with depression, anxiety, and pain. Assessment and treatment of sleep difficulties should be included in clinical practice. Future research on the potential causal relationship among co-occurring conditions may assist in additional intervention planning.

Hyperbaric oxygen treatment in autism spectrum disorders

Traditionally, hyperbaric oxygen treatment (HBOT) is indicated in several clinical disorders include decompression sickness, healing of problem wounds and arterial gas embolism. However, some investigators have used HBOT to treat individuals with autism spectrum disorders (ASD). A number of individuals with ASD possess certain physiological abnormalities that HBOT might ameliorate, including cerebral hypoperfusion, inflammation, mitochondrial dysfunction and oxidative stress. Studies of children with ASD have found positive changes in physiology and/or behavior from HBOT. For example, several studies have reported that HBOT improved cerebral perfusion, decreased markers of inflammation and did not worsen oxidative stress markers in children with ASD. Most studies of HBOT in children with ASD examined changes in behaviors and reported improvements in several behavioral domains although many of these studies were not controlled. Although the two trials employing a control group reported conflicting results, a recent systematic review noted several important distinctions between these trials. In the reviewed studies, HBOT had minimal adverse effects and was well tolerated. Studies which used a higher frequency of HBOT sessions (e.g., 10 sessions per week as opposed to 5 sessions per week) generally reported more significant improvements. Many of the studies had limitations which may have contributed to inconsistent findings across studies, including the use of many different standardized and non-standardized instruments, making it difficult to directly compare the results of studies or to know if there are specific areas of behavior in which HBOT is most effective. The variability in results between studies could also have been due to certain subgroups of children with ASD responding differently to HBOT. Most of the reviewed studies relied on changes in behavioral measurements, which may lag behind physiological changes. Additional studies enrolling children with ASD who have certain physiological abnormalities (such as inflammation, cerebral hypoperfusion, and mitochondrial dysfunction) and which measure changes in these physiological parameters would be helpful in further defining the effects of HBOT in ASD.

Hyperbaric oxygen treatment for inflammatory bowel disease: a systematic review and analysis

Background

Traditionally, hyperbaric oxygen treatment (HBOT) has been used to treat a limited repertoire of disease, including decompression sickness and healing of problem wounds. However, some investigators have used HBOT to treat inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis.

Methods

Comprehensive searches were conducted in 8 scientific databases through 2011 to identify publications using HBOT in IBD. Human studies and animal models were collated separately.

Results

Thirteen studies of HBOT in Crohn's disease and 6 studies in ulcerative colitis were identified. In all studies, participants had severe disease refractory to standard medical treatments, including corticosteroids, immunomodulators and anti-inflammatory medications. In patients with Crohn's disease, 31/40 (78%) had clinical improvements with HBOT, while all 39 patients with ulcerative colitis improved. One study in Crohn's disease reported a significant decrease in proinflammatory cytokines (IL-1, IL-6 and TNF-alpha) and one study in ulcerative colitis reported a decrease in IL-6 with HBOT. Adverse events were minimal. Twelve publications reported using HBOT in animal models of experimentally-induced IBD, including several studies reporting decreased markers of inflammation or immune dysregulation, including TNF-alpha (3 studies), IL-1beta (2 studies), neopterin (1 study) and myeloperoxidase activity (5 studies). HBOT also decreased oxidative stress markers including malondialdehyde (3 studies) and plasma carbonyl content (2 studies), except for one study that reported increased plasma carbonyl content. Several studies reported HBOT lowered nitric oxide (3 studies) and nitric oxide synthase (3 studies) and one study reported a decrease in prostaglandin E₂ levels. Four animal studies reported decreased edema or colonic tissue weight with HBOT, and 8 studies reported microscopic improvements on histopathological examination. Although most publications reported improvements with HBOT, some studies suffered from limitations, including possible publication and referral biases, the lack of a control group, the retrospective nature and a small number of participants.

Conclusions

HBOT lowered markers of inflammation and oxidative stress and ameliorated IBD in both human and animal studies. Most treated patients were refractory to standard medical treatments. Additional studies are warranted to investigate the effects of HBOT on biomarkers of oxidative stress and inflammation as well as clinical outcomes in individuals with IBD.