Each year, thousands of Americans suffer a traumatic brain injury. In 2013, about 2.8 million TBI-related emergency department visits, hospitalizations and deaths occurred in the United States, according to the Centers for Disease Control and Prevention. Most of these are what are called mild traumatic brain injuries, or mTBIs — head injuries that don’t cause a coma. People with an mTBI typically get better within a few weeks, but for as many as 20 percent, problems can linger for months or years.

Many of these patients find themselves stuck with depression, cognitive problems, headaches, fatigue and other symptoms. Known as post-concussion syndrome, this phenomenon is often difficult to treat. Antidepressants can lift moods, painkillers can ease headaches and physical therapy may ease dizziness, but most researchers agree that these remedies don’t heal the injury within the brain.

Could oxygen do the trick? A growing group of scientists and physicians say that hyperbaric treatment, which exposes patients to pure oxygen at higher-than-normal air pressure, may work.

“These patients don’t have enough oxygen to heal the injured parts of their brains,” said Shai Efrati, a researcher and physician at Tel Aviv University in Israel and a leading hyperbaric scientist. “Hyperbaric treatment massively increases the amount of oxygen available to the brain.”

The nature of the human brain makes it particularly susceptible to chronic injury. The organ requires large amounts of energy under normal circumstances, and even more to heal when injured. And often, the initial trauma damages blood vessels that supply the brain with oxygen. So, just as the brain needs extra resources, it faces an energy crisis. Often, Efrati and others say, injured brain cells don’t die, but may persist for years or decades, alive but hobbled. Hyperbaric therapy, he said, can return them to full function, even years after the injury.