Repetitive long-term hyperbaric oxygen treatment (HBOT) administered after experimental traumatic brain injury in rats induces significant remyelination and a recovery of sensorimotor function

Hyperbaric oxygen treatment in delayed post-hypoxic encephalopathy following inhalation of liquefied petroleum gas: a case report

Delayed post-hypoxic encephalopathy can occur after an episode of anoxia or hypoxia. Symptoms include apathy, confusion, and neurological deficits. We describe a 47-year-old male patient who inhaled gas from a kitchen stove liquid petroleum gas cylinder. He was diagnosed with hypoxic ischaemic encephalopathy 12 hours after his emergency department admission. He received six sessions of hyperbaric oxygen treatment (HBOT) and was discharged in a healthy state after six days. Fifteen days later, he experienced weakness, loss of appetite, forgetfulness, depression, balance problems, and inability to perform self-care. One week later, he developed urinary and fecal incontinence and was diagnosed with post-hypoxic encephalopathy. After 45 days from the onset of symptoms, he was referred to the Underwater and Hyperbaric Medicine Department for HBOT. The patient exhibited poor self-care and slow speech rate, as well as ataxic gait and dysdiadochokinesia. Hyperbaric oxygen was administered for twenty-four sessions, which significantly improved the patient's neurological status with only hypoesthesia in the left hand remaining at the end of treatment. Hyperbaric oxygen has been reported as successful in treating some cases of delayed neurological sequelae following CO intoxication. It is possible that HBO therapy may also be effective in delayed post-hypoxic encephalopathy from other causes. This may be achieved through mechanisms such as transfer of functional mitochondria to the injury site, remyelination of damaged neurons, angiogenesis and neurogenesis, production of anti-inflammatory cytokines, and balancing of inflammatory and anti-inflammatory cytokines.

Treating Severe Traumatic Brain Injury: Combining Neurofeedback and Hyperbaric Oxygen Therapy in a Single Case Study

In 2014, a 26-year-old male was involved in a motor vehicle accident resulting in a severe traumatic brain injury (TBI). The patient sustained a closed-head left temporal injury with coup contrecoup impact to the frontal region. The patient underwent a left side craniotomy and was comatose for 26 days. After gaining consciousness, he was discharged to a brain injury treatment center that worked with physical, speech, and occupational issues. He was discharged after eight months with significant speech, ambulation, spasticity, and cognitive issues as well as the onset of posttraumatic epilepsy. His parents sought hyperbaric oxygen treatment (HBOT) from a doctor in Louisiana. After 165 dives, the HBOT doctor recommended an addition of neurofeedback (NFB) therapy. In March 2019 the patient started NFB therapy intermixed with HBOT. The combination of NFB and HBOT improved plasticity and functionality in the areas of injury and the correlated symptoms including short-term memory, personality, language, and executive function, as well as significantly reducing the incidence of seizures. Severe brain injuries often leave lasting deficits with little hope for major recovery and there is a need for further research into long-term, effective neurological treatments for severe brain injuries. These results suggest that HBOT combined with NFB may be a viable option in treating severe brain injuries and should be investigated.

Oxidative stress and mitochondrial dysfunction following traumatic brain injury: From mechanistic view to targeted therapeutic opportunities

Traumatic brain injury (TBI) is one of the most prevalent causes of permanent physical and cognitive disabilities. TBI pathology results from primary insults and a multi-mechanistic biochemical process, termed as secondary brain injury. Currently, there are no pharmacological agents for definitive treatment of patients with TBI. This article is presented with the purpose of reviewing molecular mechanisms of TBI pathology, as well as potential strategies and agents against pathological pathways. In this review article, materials were obtained by searching PubMed, Scopus, Elsevier, Web of Science, and Google Scholar. This search was considered without time limitation. Evidence indicates that oxidative stress and mitochondrial dysfunction are two key mediators of the secondary injury cascade in TBI pathology. TBI-induced oxidative damage results in the structural and functional impairments of cellular and subcellular components, such as mitochondria. Impairments of mitochondrial electron transfer chain and mitochondrial membrane potential result in a vicious cycle of free radical formation and cell apoptosis. The results of some preclinical and clinical studies, evaluating mitochondria-targeted therapies, such as mitochondria-targeted antioxidants and compounds with pleiotropic effects after TBI, are promising. As a proposed strategy in recent years, mitochondria-targeted multipotential therapy is a new hope, waiting to be confirmed. Moreover, based on the available findings, biologics, such as stem cell-based therapy and transplantation of mitochondria are novel potential strategies for the treatment of TBI; however, more studies are needed to clearly confirm the safety and efficacy of these strategies.

Impact of Hyperbaric Oxygen Therapy on Cognitive Functions: a Systematic Review

Hyperbaric oxygen therapy (HBOT) is a modality of treatment in which patients inhale 100% oxygen inside a hyperbaric chamber pressurised to greater than 1 atmosphere. The aim of this review is to discuss neuropsychological findings in various neurological disorders treated with HBOT and to open new perspectives for therapeutic improvement. A literature search was conducted in the MEDLINE (via PubMed) database from the inception up 10 May 2020. Eligibility criteria included original articles published in English. Case studies were excluded. Full-text articles were obtained from the selected studies and were reviewed on the following inclusion criteria (1) performed cognitive processes assessment (2) performed HBOT with described protocol. Two neuropsychologists independently reviewed titles, abstracts, full texts and extracted data. The initial search retrieved 1024 articles, and a total of 42 studies were finally included after applying inclusion and exclusion criteria. The search yielded controversial results with regard to the efficiency of HBOT in various neurological conditions with cognitive disturbance outcome. To the best of our knowledge this is the first state-of-the art, systematic review in the field. More objective and precise neuropsychological assessment methods are needed to exact evaluation of the efficacy of HBOT for neuropsychological deficits. Future studies should widen the assessment of HBOT effects on different cognitive domains because most of the existing studies have focussed on a single process. Finally, there is a need for further longitudinal studies.

Hyperbaric oxygen therapy for cognitive impairments in patients with traumatic brain injury: A systematic review

Cognitive deficits are the most common impairments after traumatic brain injury (TBI). It can be linked with poor physical function. Hyperbaric oxygen therapy (HBOT) increases blood flow and oxygen supply to the brain. This review aimed to summarize and evaluate the available literature on the influences of HBOT on cognitive deficits in patients with TBI. PubMed, SCOPUS, PEDro, REHABDATA, MIDLINE, CHINAL, EMBASE, and Web of Science were searched from inception until June 2021. The methodological quality was measured using the physiotherapy evidence database (PEDro) scale. Ten studies met the eligibility criteria. Six studies were randomized controlled trials, and four were pilot studies. The scores on the PEDro scale ranged from two to nine, with a median score of seven. The included studies showed heterogeneity results for the beneficial effects of HBOT on improving cognitive functions in patients with TBI. The evidence for the beneficial effects of HBOT on cognitive functions post-TBI was limited. Further randomized controlled trials with large sample sizes are strongly needed to understand the effects of HBOT on cognitive functions in patients with TBI.

Real-world effectiveness of hyperbaric oxygen therapy for delayed neuropsychiatric sequelae after carbon monoxide poisoning

To assess real-world effectiveness of hyperbaric oxygen therapy (HBOT) on delayed neuropsychiatric sequelae (DNS) after carbon monoxide (CO) poisoning we conducted a retrospective review of patients with CO poisoning admitted to Linkou Chang-Gung Memorial Hospital, Taiwan's largest medical center, during 2009-2015. We included patients developing DNS after CO poisoning and compared improvements in neuropsychiatric function, with and without HBOT, after 12 months post-DNS to understand differences in recovery rates. DNS improvement-associated factors were also evaluated. We used receiver operating characteristic (ROC) curve analysis to assess the role of time elapsed between DNS diagnosis and HBOT initiation in predicting DNS improvement. A total of 62 patients developed DNS, of whom 11 recovered while the rest did not. Possible factors predicting DNS improvement included receiving HBOT post-DNS (72.7% vs 25.5%; P = 0.006), and treatment with more than three HBOT sessions during acute stage CO poisoning (81.8% vs 27.5%; P = 0.003). The relevant area under the ROC curve was 0.789 (95% CI 0.603-0.974), and the best cut-off point was 3 days post-DNS diagnosis, with 87.5% sensitivity and 61.5% specificity. Early HBOT in patients who developed DNS after CO poisoning significantly improved their DNS symptoms, with treatment effects sustained for 1 year after DNS diagnosis.

A review on the neuroprotective effects of hyperbaric oxygen therapy

Hyperbaric oxygen therapy, intermittent breathing of 100% oxygen at a pressure upper than sea level, has been shown to be some of the neuroprotective effects and used therapeutically in a wide range of neurological disorders. This review summarizes current knowledge about the neuroprotective effects of hyperbaric oxygen therapy with their molecular mechanisms in different models of neurological disorders.

Effects of repetitive hyperbaric oxygen therapy on neuroprotection in middle cerebral artery occlusion rats

Hyperbaric oxygen (HBO) has been suggested as a possible therapy for brain injury. However, the effects of HBO after transient brain ischemia are inconsistent and the underlying mechanisms are not fully known. The present study aimed to investigate the effects of repetitive HBO intervention in a transient middle cerebral artery occlusion (MCAO) animal model. Seventy-two Sprague-Dawley rats received MCAO and were randomly assigned to normal air control or HBO intervention groups. Each group was divided into 3 subgroups according to the intervention time period (7, 14, and 21 days). HBO was started 24 h post-MCAO for 1 h/day at 3.0 ATA with no-air breaks. After the final intervention, half of the rats in each subgroup were sacrificed and the right motor cortex was removed to examine levels of Akt phosphorylation and glutathione (GSH), as well as glutathione peroxidase (GPx) and reductase (GR) activity. The other half of the rats were used to examine infarct volume. At 24 h post-MCAO and the end of the final intervention, rats underwent tests to examine motor performance. We noted that 14- and 21-day HBO interventions significantly reduced infarct volume and increased Akt phosphorylation and GSH levels and GPx and GR activity. Motor performance was also significantly improved after 14- and 21-day interventions. No significant differences were observed between the controls and 7-day intervention groups. Repetitive HBO intervention starting 24 h post-MCAO and applied for at least 14 days, provided neuroprotective effects through modulating the cell survival pathway and antioxidative defense system.

Molecular and Therapeutic Aspects of Hyperbaric Oxygen Therapy in Neurological Conditions

In hyperbaric oxygen therapy (HBOT), the subject is placed in a chamber containing 100% oxygen gas at a pressure of more than one atmosphere absolute. This treatment is used to hasten tissue recovery and improve its physiological aspects, by providing an increased supply of oxygen to the damaged tissue. In this review, we discuss the consequences of hypoxia, as well as the molecular and physiological processes that occur in subjects exposed to HBOT. We discuss the efficacy of HBOT in treating neurological conditions and neurodevelopmental disorders in both humans and animal models. We summarize by discussing the challenges in this field, and explore future directions that will allow the scientific community to better understand the molecular aspects and applications of HBOT for a wide variety of neurological conditions.

Oligodendrocyte dysfunction and regeneration failure: A novel hypothesis of delayed encephalopathy after carbon monoxide poisoning

Carbon monoxide (CO) poisoning usually causes brain lesions and delayed encephalopathy, also known as delayed neurological sequelae (DNS). Demyelination of white matter (WM) is one of the most common sites of abnormalities in patients with DNS, but its mechanisms remain unclear. Oligodendrocytes (OLs) are myelinated cells that ensure the rapid conduction of neuronal axon signals and provide the nutritional factors necessary for maintaining nerve integrity in the central nervous system (CNS). OLs readily regenerate and replace damaged myelin membranes around axons in the adult mammalian CNS following demyelination. The ability to regenerate OLs depends on the availability of precursor cells (OPCs) in the CNS of adults. Multiple injury-related signals can induce OPC expansion followed by OL differentiation, axonal contact and myelin regeneration (remyelination). Therefore, OL dysfunction and regeneration failure in the deep WM of the brain are the key pathophysiological mechanisms leading to delayed brain injury after CO poisoning. CO-induced toxicity may interfere with OL function and render OPCs unable to regenerate OLs through some unclear mechanisms, leading to progressive demyelinating damage and resulting in DNS. In the future, combination therapies to reduce OL damage and promote OPC differentiation and remyelination may be important for the prevention and treatmentof DNS after CO poisoning.

Hyperbaric oxygen produces a nitric oxide synthase-regulated anti-allodynic effect in rats with paclitaxel-induced neuropathic pain

Research has demonstrated that hyperbaric oxygen (HBO₂) treatment produced relief of both acute and chronic pain in patients and animal models. However, the mechanism of HBO₂ antinociceptive effect is still elusive. Based on our earlier findings that implicate NO in the acute antinociceptive effect of HBO₂, the purpose of this study was to ascertain whether HBO₂-induced antinociception in a chronic neuropathic pain model is likewise dependent on NO. Neuropathic pain was induced in male Sprague Dawley rats by four injections of paclitaxel (1.0 mg/kg, i.p.). Twenty-four hours after the last paclitaxel injection, rats were treated for one day or four consecutive days with 60-min HBO₂ at 3.5 atmospheres absolute (ATA). Two days before HBO₂ treatment, some groups of rats were implanted with Alzet® osmotic minipumps that continuously infused a selective inhibitor of neuronal NO synthase (nNOS) into the lateral cerebral ventricle for 7 days. Mechanical and cold allodynia were assessed every other day, using electronic von Frey and acetone assays, respectively. Rats in the paclitaxel control group exhibited a mechanical or cold allodynia that was significantly reversed by one HBO₂ treatment for mechanical allodynia and four HBO₂ treatments for cold allodynic. In rats treated with the nNOS inhibitor, the effects of HBO₂ were nullified in the mechanical allodynia test but unaffected in the cold allodynia test. In summary, these results demonstrate that the antiallodynic effect of HBO₂ in two different pain tests is dependent on NO in the CNS.

The Effect of Hyperbaric Oxygen Therapy on Functional Impairments Caused by Ischemic Stroke

Background

While research suggests a benefit of hyperbaric oxygen therapy (HBOT) for neurologic injury, controlled clinical trials have not been able to clearly define the benefits.

Objective

To investigate the effects of HBOT on physical and cognitive impairments resulting from an ischemic stroke.

Methods

Using a within-subject design a baseline for current functional abilities was established over a 3-month period for all subjects (n=7). Each subject then received two 4-week periods of HBOT for a total of 40 90-minute treatments over a 12-week period. Subjects completed a battery of assessments and had blood drawn six times over the 9-month total duration of the study.

Results

We found improvements in cognition and executive function as well as physical abilities, specifically, improved gait. Participants reported improved sleep and quality of life following HBOT treatment. We also saw changes in serum levels of biomarkers for inflammation and neural recovery. In the functional domains where improvement was observed following HBOT treatment, the improvements were maintained up to 3 months following the last treatment. However, the physiological biomarkers showed a pattern of more transient changes following HBOT treatment.

Conclusions

Findings from this study support the idea of HBOT as a potential intervention following stroke.

Hyperbaric Oxygen Therapy in the Treatment of Acute Severe Traumatic Brain Injury: A Systematic Review

There has been no major advancement in a quarter of a century for the treatment of acute severe traumatic brain injury (TBI). This review summarizes 40 years of clinical and pre-clinical research on the treatment of acute TBI with hyperbaric oxygen therapy (HBO₂) in the context of an impending National Institute of Neurologic Disorders and Stroke-funded, multi-center, randomized, adaptive Phase II clinical trial -the Hyperbaric Oxygen Brain Injury Treatment (HOBIT) trial. Thirty studies (eight clinical and 22 pre-clinical) that administered HBO₂ within 30 days of a TBI were identified from PubMed searches. The pre-clinical studies consistently reported positive treatment effects across a variety of outcome measures with almost no safety concerns, thus providing strong proof-of-concept evidence for treating severe TBI in the acute setting. Of the eight clinical studies reviewed, four were based on the senior author's (GR) investigation of HBO₂ as a treatment for acute severe TBI. These studies provided evidence that HBO₂ significantly improves physiologic measures without causing cerebral or pulmonary toxicity and can potentially improve clinical outcome. These results were consistent across the other four reviewed clinical studies, thus providing preliminary clinical data supporting the HOBIT trial. This comprehensive review demonstrates that HBO₂ has the potential to be the first significant treatment in the acute phase of severe TBI.

Differences in Cognitive Function of Rats with Traumatic Brain Injuries Following Hyperbaric Oxygen Therapy

Background

Hyperbaric oxygen (HBO) is a historical therapeutic option in the treatment of various types of brain damage. At present, clinical treatment of hypoxic-ischemic injury is giving priority to cognitive training. The effects of HBO on cognitive dysfunction were observed in a controlled cortical impact (CCI) rat model.

Material/Methods

Seventy male SD rats were randomly divided into control (n=10) and intervention (n=60) groups. All rats underwent baseline water maze testing 1 day before modeling, and were retested 8 weeks after modeling. The percentage of residence time during escape latency in the target quadrant and the total time were recorded. Data were analyzed by SPSS 16.0 software. P<0.05 was considered statistically significant.

Results

After 8 weeks, no statistical difference (P>0.05) existed in spatial learning ability in the 3-day and 5-day groups when compared with baseline. The other groups were statistically different by auto-comparison (P<0.05). No statistical difference (P>0.05) in spatial memory existed in the 5-day and 1-week groups when compared with baseline, while a significant difference was noted in the other groups by self-comparison (P<0.05). No statistical difference (P>0.05) was noted in the level of expression of growth-associated protein-43 (GAP-43) and synaptophysin (Syn) in the 1-day group compared with the control group. The remaining groups and the control group were statistically different (P<0.05), while the level of expression of GAP-43 and Syn in the 5-day, 1-week, and 2-week groups was significantly different compared with that in the control group (P<0.01).

Conclusions

If HBO therapy was provided 5–7 days after craniocerebral trauma, there was apparent improvement in cognitive function and neuroplasticity.

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.

Hyperbaric Oxygen Therapy Alleviates Carbon Monoxide Poisoning-Induced Delayed Memory Impairment by Preserving Brain-Derived Neurotrophic Factor-Dependent Hippocampal Neurogenesis

OBJECTIVE

To test the hypothesis that hyperbaric oxygen therapy ameliorates delayed cognitive impairment after acute carbon monoxide poisoning by promoting neurogenesis through upregulating the brain-derived neurotrophic factor in the hippocampus.

DESIGN

Laboratory animal experiments.

SETTING

University/Medical center research laboratory.

SUBJECTS

Adult, male Sprague-Dawley rats.

INTERVENTIONS

Rats were divided into five groups: (1) non-carbon monoxide-treated control, (2) acute carbon monoxide poisoning, (3) acute carbon monoxide poisoning followed by 7-day hyperbaric oxygen treatment, (4) carbon monoxide + hyperbaric oxygen with additional intracerebroventricular infusion of Fc fragment of tyrosine kinase receptor B protein (TrkB-Fc) chimera, and (5) acute carbon monoxide poisoning followed by intracerebroventricular infusion of brain-derived neurotrophic factor. Acute carbon monoxide poisoning was achieved by exposing the rats to carbon monoxide at 2,500 ppm for 40 minutes, followed by 3,000 ppm for 20 minutes. Hyperbaric oxygen therapy (at 2.5 atmospheres absolute with 100% oxygen for 60 min) was conducted during the first 7 days after carbon monoxide poisoning. Recombinant human TrkB-Fc chimera or brain-derived neurotrophic factor was infused into the lateral ventricle via the implanted osmotic minipump. For labeling of mitotic cells in the hippocampus, bromodeoxyuridine was injected into the peritoneal cavity. Distribution of bromodeoxyuridine and two additional adult neurogenesis markers, Ki-67 and doublecortin, in the hippocampus was evaluated by immunohistochemistry or immunofluorescence staining. Tissue level of brain-derived neurotrophic factor was assessed by enzyme-linked immunosorbent assay. Cognitive behavior was evaluated by the use of eight-arm radial maze.

MEASUREMENTS AND MAIN RESULTS

Acute carbon monoxide poisoning significantly suppressed adult hippocampal neurogenesis evident by the reduction in number of bromodeoxyuridine-positive, Ki-67⁺, and doublecortin⁺ cells in the subgranular zone of the dentate gyrus. This suppression of adult neurogenesis by the carbon monoxide poisoning was appreciably alleviated by early treatment of hyperbaric oxygen. The hyperbaric oxygen treatment also promoted a sustained increase in hippocampal brain-derived neurotrophic factor level. Blockade of hippocampal brain-derived neurotrophic factor signaling with intracerebroventricular infusion of recombinant human TrkB-Fc chimera significantly blunted the protection by the hyperbaric oxygen on hippocampal neurogenesis; whereas intracerebroventricular infusion of brain-derived neurotrophic factor mimicked the action of hyperbaric oxygen and preserved hippocampal neurogenesis after acute carbon monoxide poisoning. Furthermore, acute carbon monoxide poisoning resulted in a delayed impairment of cognitive function. The hyperbaric oxygen treatment notably restored the cognitive impairment in a brain-derived neurotrophic factor-dependent manner.

CONCLUSIONS

The early hyperbaric oxygen treatment may alleviate delayed memory impairment after acute carbon monoxide poisoning by preserving adult neurogenesis via an increase in hippocampal brain-derived neurotrophic factor content.

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.

Repetitive hyperbaric oxygenation attenuates reactive astrogliosis and suppresses expression of inflammatory mediators in the rat model of brain injury

The exact mechanisms by which treatment with hyperbaric oxygen (HBOT) exerts its beneficial effects on recovery after brain injury are still unrevealed. Therefore, in this study we investigated the influence of repetitive HBOT on the reactive astrogliosis and expression of mediators of inflammation after cortical stab injury (CSI). CSI was performed on male Wistar rats, divided into control, sham, and lesioned groups with appropriate HBO. The HBOT protocol was as follows: 10 minutes of slow compression, 2.5 atmospheres absolute (ATA) for 60 minutes, and 10 minutes of slow decompression, once a day for 10 consecutive days. Data obtained using real-time polymerase chain reaction, Western blot, and immunohistochemical and immunofluorescence analyses revealed that repetitive HBOT applied after the CSI attenuates reactive astrogliosis and glial scarring, and reduces expression of GFAP (glial fibrillary acidic protein), vimentin, and ICAM-1 (intercellular adhesion molecule-1) both at gene and tissue levels. In addition, HBOT prevents expression of CD40 and its ligand CD40L on microglia, neutrophils, cortical neurons, and reactive astrocytes. Accordingly, repetitive HBOT, by prevention of glial scarring and limiting of expression of inflammatory mediators, supports formation of more permissive environment for repair and regeneration.

Hyperbaric oxygen therapy applied research in traumatic brain injury: from mechanisms to clinical investigation

Traumatic brain injury (TBI) is the leading cause of mortality and morbidity for millions of young people and military personnel around the world every year. Regardless of severity, neurological dysfunction is a sequela of TBI. Although many preclinical and clinical trials have been carried out to explore its underlying pathophysiology, few effective treatment options have been used to ameliorate the prognosis of TBI, particularly with regard to the recovery of neurological deficits. Translational medicine has increasingly emphasized secondary brain injury, as distinguished from the mechanical damage occurring at the moment of traumatic impact; this includes cerebral ischemia, vasospasm, metabolic dysfunction, oxygenation absence and edema. Hyperbaric oxygen therapy (HBOT) is defined as the inhalation of pure oxygen in a hyperbaric chamber that is pressurized to greater than 1 atm. High concentrations of oxygen in the blood could affect brain tissue hypoxia readily thereby avoiding neuronal cell death through increased cerebral oxygen metabolism. Therefore, HBOT has been suggested as a scientific and effective treatment for TBI. The effectiveness and feasibility of HBOT has been confirmed by several studies. Following the widespread application of HBOT in cerebrovascular diseases and TBI, non-standard therapies frequently occur in primary care institutions, causing great controversy. The systematic analysis of the progress of both animal and clinical studies in this article provides the basis for further study of HBOT.