Brain wound or injury is a serious health problem where an insult or trauma to the brain is caused by external mechanical forces. Significant levels of cognitive, behavioral and communicative disabilities are the possible impacts of brain injury. Because of the complexity of brain injury, daily clinical practice has not offered any effective treatment/intervention till recent past. At present, introduction of hyperbaric oxygen therapy (HBOT) has proved to be beneficial as a safe clinical adjunctive therapy.
Improvement for patients with brain injury undergoing HBOT has been claimed since 1960. Therapeutic effect of HBOT in brain trauma was first carried out by Fasano et al in 1964. This first clinical observation reported that HBO improved the outcome after brain trauma. Following this, many successful uses of intensive HBO2 as a therapeutic modality in various brain injury cases and studies were revealed. Some of the positive effects were:
- In acute cerebral damage, HBOT has been shown to change Intra Cranial Pressure (ICP) and reduce Cerebrospinal Fluid (CSF) pressure.
- Computerized tomography scan in closed head injury showed improved grey matter metabolic activity.
- Improved glucose metabolism after brain injury.
- HBOT decreased mortality and improved functional outcome in severe brain injury.
- Improved CBF, amelioration of neuropsychological disorders in chronic brain injury
- Enhanced neuropsychological and electrophysiological improvements.
- Improved quality of life in patients with post-concussion syndrome or mild brain trauma at late chronic stage.
Hyperbaric oxygen therapy (HBOT) is defined as the inhalation of 100% oxygen under the pressure greater than 1 atmosphere absolute (ATA). HBOT has been reported to dramatically and permanently improve symptoms of chronic brain injury over several months or even many years after the original head injury. Yet, HBO2 treatment has been limited to symptom management and rehabilitative services as it is established within the medical system that post-concussion symptoms persisting beyond 6 months post head injury cannot be repaired. However, currently, HBOT has been proved as a safe, effective adjuvant therapy in the field of neurological diseases due to diverse mechanisms leading to neuro protection. Following mechanisms work parallel or in coordination to induce neuro protection in the brain:
- Improves tissue oxygenation – The basis for increased tissue oxygen tensions with HBO treatment is on Henry’s law which states that the amount of gas dissolved in a liquid or tissue is proportional to the partial pressure of that gas in contact with the liquid or tissue. The physiological condition of oxygen carried in the blood by haemoglobin as well as oxygen carried in solution is increased with the pressure in HBOT. Increased arterial oxygen tensions and tissue oxygen tensions markedly increase oxygen tension gradient from the blood to metabolizing cells. This mechanism of arterial blood hyper-oxygenation can improve effective cellular oxygenation even at low rates of tissue blood flow. Increased oxygen in solution can even reach physically obstructed areas of the brain where red blood cells cannot pass.
- Diminishes inflammation – Secondary brain damage after traumatic brain injury happens by acute inflammatory responses such as cytokine release, neutrophil activation and microvascular adherence. For effective treatment of brain injury, it is essential to reduce inflammation. Exposure to hyperbaric oxygen has the ability to temporarily inhibit circulating neutrophils to adhere to target tissues that reduce inflammation. Decreased brain oedema, blood-brain barrier leakage, cell apoptosis and improved neurological disorders after brain injury are associated with the positive inhibitory effect of HBOT on inflammation.
- Reduces apoptosis – Neuronal apoptosis or nerve cells death occurs in brain tissues after a trauma. Apoptosis of nerve cells in the regions of brain after an injury can significantly affect the growth and progression of the lesion. One of the therapeutic strategies to preserve brain tissues and promote functional recovery is to inhibit brain cell apoptosis. On investigating the neuro protective, anti-apoptotic effects of HBOT in the development of secondary brain damage after brain injury, HBOT has proved to improve neurological deficits by preventing neuron apoptosis. Further research has revealed that reduced apoptosis is a partial mediator for neuro protective effects of HBO.
- Reduces Intracranial Pressure (ICP) – The leading cause of morbidity and mortality in patients suffering from brain wound is critical levels of intracranial pressure. Definite positive effect of HBOT was reported with ameliorated outcome and reduced ICP through decreased endothelin, improved blood velocity of middle cerebral artery and decreased cerebral vascular resistance in severe brain injuries. Sustained improvement in tissue metabolism of the traumatized brain subsequent to HBOT is attributed to the mechanism of HBO2 reducing ICP.
- Promotes neurogenesis and angiogenesis – Neurological deficits and cognitive impairments at the acute and at late chronic stages few months to years after brain injury could be improved by multiple levels of HBOT. Activation of angiogenesis, triggering of neuroplasticityand induced proliferation and differentiation of neuronal stem cells offer multifaceted repair as long-term therapeutic effects of HBOT. Repeated exposure of HBO2 is understood to intensify neuroplastic responses by promoting axonal regeneration and synapse remodelling, which contributes to the recovery of locomotor performances in traumatic brain wounds.
Adequate blood flow in the brain is vital for mental health. Investigations reveal that low blood flow is associated with disorders such as depression, anxiety, panic attacks, stress disorders, bipolar disorder, psychosis, schizophrenia, ADHD, suicide and substance abuse after a brain trauma. The foremost predictor for Alzheimer’s disease is low blood flow. Overall studies of HBOT on people show the result of remarkable improvement in blood flow to the brain. According to research, treating the underlying brain injury with concentrated oxygen can promote healing.
A brain imaging study involving 16 soldiers suffering from Post-Traumatic Stress Disorder (PTSD) following a brain injury subjected them to HBOT. Brain imaging and neuropsychological testing before and after 40 sessions of HBOT were compared. The results after treatment, demonstrated significant improvement in impulsivity, mood, anxiety, quality of life scores and more positive effects as compared to before HBOT. Remarkable overall improvement in blood flow was shown in the scan images after the HBOT sessions as compared to earlier images. HBOT has also shown improved brain metabolism leading to better memory and concentration, decreased disorientation, less frustration and no anxiety in post-traumatic Alzheimer’s disease. These findings suggest that HBOT would be a potential adjuvant therapy for brain wounds or brain injuries.
