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By Nitin K. Sethi, MD
Assistant Professor of Neurology, Weill Cornell Medical College
Dr. Sethi reports no financial disclosures relevant to this field of study.
Synopsis: This well-designed, randomized, controlled trial, which included a sham arm, showed no evidence for the efficacy of hyperbaric oxygen therapy to treat the symptomatic, cognitive, and behavioral sequelae of postconcussion syndrome in soldiers after combat-related mild traumatic brain injury.
Source: Cifu DX, et al. Hyperbaric oxygen for blast-related postconcussion syndrome: Three-month outcomes. Ann Neurol 2014;75:277-286.
Blast-related mild traumatic brain injury (tbi) has been recognized as the "signature injury" of America’s global war on terrorism in Iraq and Afghanistan. The Military Acute Concussion Evaluation test is increasingly identifying mild TBI and postconcussion symptoms (PCS), such as headaches, dizziness, balance problems, problems with concentration and memory, and behavioral and personality changes, in soldiers post exposure to a blast from an improvised explosive device. There is increasing concern about the long-term health consequences in these soldiers and concussion management algorithms have been developed for use both on the battlefield and in the garrison setting. Hyperbaric oxygen therapy (HBO2T), which refers to the therapeutic administration of 100%
oxygen at environmental pressures > 1 atmosphere absolute (ATA), has been used as a treatment for mild TBI and PCS, but its efficacy has never been proven in appropriate clinical trials.
In this study, Cifu et al investigated the use of HBO2T to treat mild TBI and PCS in 61 male Marines. Forty once-daily, 60-minute hyperbaric chamber compressions at 2.0 ATA were given at one of three randomly preassigned oxygen fractions, resulting in the Marines being randomly assigned to one of the three groups with an oxygen-breathing exposure equivalent: 1) surface air (sham group), 2) 100% oxygen at 1.5 ATA, or 3) 100% oxygen at 2.0 ATA. The Rivermead Post-Concussion Questionnaire-16 (RPQ-16) was applied before treatment and 2 months after treatment to assess outcome of HBO2T. Unfortunately, the trial showed no significant differences between the groups, and no evidence of efficacy at 3 months post compression in treating the symptomatic, behavioral, or cognitive sequelae of PCS after mild TBI.
Mild TBI and PCS are being increasingly recognized, both in the military and civilian (sports) setting. Patients usually present with a constellation of symptoms following mild closed TBI. Concussion identification algorithms aid timely identification and management of mild TBI and concussions, both on the battlefield and in the civilian arena. Treatment at present is conservative and includes removal from the battle or the sport field, reduction of environmental stimuli, pharmacological management of headache, and a mandatory recovery period until total symptom resolution. The ongoing international conflicts have resulted in an increasing number of soldiers returning from the battlefield with mild TBI and PCS, creating a public health issue, and there is an acute need for more effective interventions. HBO2T (at pressures between 1-3 ATA) has been proposed to aid recovery in TBI patients by reducing intracranial pressure, improving tissue oxygenation and cellular metabolism, anti-apoptotic effects, immune modulation, reactivation of damaged but functional neuronal circuits, neurotransmitter modulation, and stem cell mobilization.1,2 A Cochrane review in 2004 concluded that while the adjunctive use of HBO2T in TBI patients may reduce the risk of death and improve the final Glasgow Come Scale, survivors failed to achieve a good outcome and many were left with severe disability.3 A concern for pulmonary impairment was further raised in the HBO2T treated patients. At the present time, evidence for effectiveness is conflicting and the routine application of HBO2T in these patients is not justified. Further studies in animal models of TBI and humans, including dose-ranging and safety studies, are needed.