One group watching the outcomes of these studies is the Undersea and Hyperbaric Medical Society, a non-profit group of doctors that investigates scientific claims linked to HBOT. Thus far the group has been skeptical of using HBOT to help neurological conditions such as autism or cerebral palsy.

"If we just had the evidence, we'd be happy to support it. But it just isn't there," Dr. Donald Chandler, executive director of the UHMS, has said in statements regarding the therapy.

As unproven as HBOT is for treating autism, it is widely accepted in other fields of medicine, where it has been used for decades. It is so well-documented to work in the treatment of slow-healing wounds, burns, carbon monoxide poisoning, intercranial abscesses, gangrene and the stubborn sores associated with diabetes that many insurance companies include HBOT in their list of reimbursable medical expenses.

One insurance reimbursement case, in Georgia, is pointed to most frequently by supporters of HBOT. The case involved Jimmy Freels, a child with such severe cerebral palsy, a neurological disorder that affects body movement and muscle coordination, that he was essentially a quadriplegic. With HBOT, the boy improved to such a degree that he could speak, swim, attend public school and play wheelchair football, according to court testimony. In court, brain scans — similar to those Markley shows of autism patients who have undergone HBOT — showed significant improvement in Jimmy's blood flow and metabolism in portions the brain.

A state judge ordered Georgia Medicaid to cover HBOT for Jimmy, saying the evidence had showed the therapy had helped.

The treatment is far from cheap. HBOT can range from about $180 to $800 per hour.

The therapy is not alleged by most of its critics to be dangerous. It carries, they say, a rare risk of prompting seizures, but most seem to believe it is simply a waste of time and money.

"My fear is that we're going to waste tax dollars and good time and money chasing quirky ideas," said Iyama, who heads an autism clinic in Madison. "The only effective treatment for autism is educational and behavioral treatment The rest is just wishful thinking."

Major medical groups have backed this sentiment. The American Academy of Pediatrics several years ago issued a statement dismissing most alternative-medicine treatments for autism.

Indeed, HBOT has a history of being oversold as something of a cure-all. The most notorious case came in the 1920s. A doctor in Cleveland built a compression chamber where long lines of patients went in hopes of curing everything from syphilis to cancer. When the treatment failed, the chamber was torn down and sold for scrap metal.

Iyama fears that parents deeply saddened and frustrated by their children's condition will make bad decisions about experimental therapies. She emphasized that the most accepted method for treating autistic children is the kind of intensive behavior therapy that requires at least 35 hours of work each week with an autistic child. She fears that some parents are drawn to treatments that promise faster results.

"I had one mother who told me her mom was willing to mortgage the family home in order to fund hyperbaric oxygen therapy for the child," Iyama said.

Wong, whose two children will begin HBOT in May, isn't putting her hopes on any one thing. She continues to immerse her children in behavioral therapies, to work with national autism educational experts and adhere to a rigorous gluten-free diet.

"The bottom line," Wong said, "is that when you are the parent of an autistic child, you learn to appreciate the treatments that yield even subtle changes."