By JANE E. BRODY
Published: March 9, 2009
Hyperbaric oxygen therapy was long called a treatment in search of diseases. But in recent years, laboratory and clinical studies have found more than a dozen serious diseases for which it is considered a valuable — and sometimes life-saving — treatment.
Although the administration of pure oxygen in a high-pressure chamber has been around as a therapy for more than 300 years, it is only now beginning to reach its potential, according to a report in the November issue of the journal Emergency Medicine.
At the same time, hyperbaric oxygen therapy has joined the ranks of unproven remedies for many conditions, especially incurable ones like cerebral palsy and autism. The use of the therapy in these situations often borders on quackery that exploits desperate patients and parents. One family I know spent $40,000 in a futile attempt to reverse their child’s cerebral palsy; another spent more than that and even bought a home hyperbaric unit to treat their child’s autism.
The Credibility Factor
The Undersea and Hyperbaric Medical Society, the professional organization in this field, recognizes 13 conditions for which it is legitimate to place patients in high-pressure chambers that force pure oxygen into their blood and tissues. Eleven of those conditions have been approved by Medicare for reimbursement, indicating that solid evidence supports these uses of hyperbaric oxygen.
The list includes decompression sickness (“the bends”), necrotizing fasciitis (flesh-eating disease), carbon monoxide poisoning, gas gangrene, the bone infection osteomyelitis, nonhealing wounds and delayed radiation injury to bone and soft tissue.
But nowhere in the list are cerebral palsy, autism, multiple sclerosis, stroke, macular degeneration, spinal cord injury, sports injuries, heart attack, postpolio syndrome, Lyme disease, migraine, cirrhosis, myasthenia gravis, fibromyalgia or chronic fatigue syndrome — among the dozens of conditions that independent clinics claim to treat with hyperbaric oxygen. Not to mention the claims of celebrities like Michael Jackson, who used it in the hope that it will keep him alive to 150, and Keanu Reeves, who used it for insomnia.
“Credibility is a huge problem,” said Richard E. Clarke, director of the Baromedical Research Foundation, which sponsors scientifically sound research. “We are all tarred by the same brush.”
“Although hyperbaric oxygen therapy has been suggested as beneficial in several other conditions, unfortunately, clinically valid evidence is virtually nonexistent,” he said. “This is relatively expensive and time-consuming therapy, and it makes sense to ask whether it is cost-effective and whether the benefits are long-lasting.”
Even for conditions approved by Medicare, supporting evidence is often contradictory. “A persistent criticism of hyperbaric medicine regards the lack of large-scale, multicenter, randomized studies for several of the primary indications,” noted Dr. Chris Maples and Dr. Moss Mendelson of Eastern Virginia Medical School in Norfolk, in the Emergency Medicine report. “Data are conflicting, particularly on carbon monoxide poisoning, crush injuries and some soft tissue infections. Some trials demonstrate benefit while others show no difference.”
Problems and Risks
One problem in conducting good studies is the difficulty of randomly assigning patients into treatment and control groups in a way that “blinds” them to the group they are in, Dr. Charles S. Graffeo, a specialist in hyperbaric medicine at the Eastern Virginia Medical School, said in an interview. Another problem is finding enough patients with the same condition, which is crucial in gathering statistically significant data.
Dr. Graffeo said there was “a good theoretical basis and some promising evidence that hyperbaric oxygen therapy could help treat clots on the retina, acute frostbite, recluse spider bites and thermal burns.”
“But there are just not enough scientific studies,” he said. “Conducting controlled clinical trials of hyperbaric oxygen is a bit more challenging than testing drugs.”
He cautioned patients to steer clear of independent hyperbaric centers owned by a single doctor or small medical group that is not affiliated with a major hospital or medical school. Commenting on claims commonly made by such clinics, he said: “No legitimate organization would condone treating cerebral palsy with hyperbaric oxygen therapy. I haven’t seen anything that is even potentially promising to support such a use. If I had a C.P. child, I wouldn’t even consider it.”
Furthermore, the therapy is not without risks, though most are mild and usually short-lived and there has been no documented fatality in more than 75 years of use in North America. The risks include ear and sinus pain, low blood sugar, nearsightedness that can last for weeks, and anxiety attacks resulting from confinement in the chamber. Also, the therapy is clearly dangerous for some patients, including those with a collapsed lung and those receiving chemotherapy with cisplatinum or adriamycin. The therapy may also be hazardous for pregnant women and people with poorly controlled asthma or active cancer, among others.
Established Benefits
Hyperbaric oxygen can be life-saving for patients with the bends, like divers who have surfaced too quickly. For those suffering from severe carbon monoxide poisoning, the most rigorous study so far found that three hyperbaric treatments decreased cognitive damage later. Traumas like crush injuries and thermal burns that deprive tissues of adequate oxygen also benefit from high-oxygen therapy, as do life-threatening infections called necrotizing fasciitis, if the condition is treated in its early stages, the experts in Virginia reported. The therapy may also be useful for sepsis, a potentially life-threatening bacterial infection in the blood and tissues.
Dr. Graffeo said the therapy was useful in treating diabetic foot ulcers and bone infections. It is beneficial for patients whose tissues were damaged by radiation therapy — cancer patients, for example, who can develop oxygen-deficient wounds that do not heal well. Hyperbaric oxygen promotes the release of growth hormone and helps to form blood vessels in irradiated tissue, he said.
A study published last September in the International Journal of Radiation Oncology, Biology, Physics found hyperbaric oxygen helpful for patients with radiation proctitis, which can cause bleeding, rectal ulcers and loss of bowel control. Though the costly treatment can involve as many as 40 two-hour sessions, “the net effect is reversal of the problem in the majority of patients, which in the end is cost-saving and greatly improves quality of life,” said Mr. Clarke, whose foundation sponsored the study.
Oxygen therapy is being tested in patients with new diagnoses of head or neck cancer to increase the tumor’s sensitivity to radiation treatments, Mr. Clarke said. Future studies will test benefits to patients with cancers of the larynx, skin and gynecological organs.
“The most important question to answer, in addition to cost-effectiveness,” he said, “is whether the therapeutic benefit lasts and clearly improves patients’ quality of life.”
Showing posts with label MS. Show all posts
Showing posts with label MS. Show all posts
12 March 2009
08 February 2009
MRI scans can predict effects of multiple sclerosis 'flare-ups' on optic nerve
One of the most pernicious aspects of multiple sclerosis (MS) - its sheer unpredictability - may finally be starting to yield to advanced medical imaging techniques.
Researchers from Washington University School of Medicine in St. Louis report online in the journal Neurology that an approach known as magnetic resonance diffusion tensor imaging (DTI) allowed them to estimate three months in advance the chronic effects of inflammation of the optic nerve. The condition occurs most often as a result of MS, a neurodegenerative disorder that can present with an extremely broad variety of symptoms that range from vision loss and other sensory damage to muscle weakness, spasticity or paralysis to depression, sleep loss or incontinence. MS affects an estimated 500,000 Americans.
"We see this as part of a battery of tests we hope to give patients within the next decade to help our clinical assessment and tailor it to an optimal treatment," says lead author Robert T. Naismith, M.D., assistant professor of neurology and a staff physician at Barnes-Jewish Hospital. "It may also help further refine our basic understanding of MS in terms of expanding our insights into where and how damage occurs and why it can affect patients differently."
Scientists believe MS results from misdirected immune system attacks against the nervous system. Symptoms occur in bouts that vary unpredictably in nature, severity, duration and frequency. Symptoms of optic nerve inflammation, known as optic neuritis, include loss of vision, blurring or fogginess and pain in the affected eye.
Regular MRI scans can detect optic neuritis but offer no information on its severity and potential lasting consequences for a patient's vision.
Currently in use clinically to detect and follow up on strokes, DTI uses a rapid series of MRI scans to track water diffusion in tissue. Noting that inflammation and the cell damage it causes would likely alter water diffusion in the affected tissues, Naismith and his colleagues hypothesized that this information might allow them to assess the severity and potential for lasting damage of MS flare-ups. Over the past five years, the new paper's senior authors, Sheng-Kwei Song, Ph.D., associate professor of radiology, and Anne Cross, M.D., professor of radiology, did much of the quantitative work in animal models of MS. The new data, based upon this successful collaborative history, are the first to show that DTI can produce potentially useful predictive information in humans.
For the study, researchers used DTI to image the optic nerves of 12 healthy volunteers, 12 patients who had begun to suffer from optic neuritis within the past month and 28 patients with a history of earlier outbreaks. They gave participants with optic neuritis or a history of it detailed assessments of their visual health, including tests of visual acuity and the thickness and conductivity of their optic nerves.
In the healthy subjects, DTI scans showed that the water diffusion along the length of the subjects' optic nerves, a characteristic known as axial diffusivity, averaged about 1.66 micrometers squared per millisecond. In three patients with acute optic neuritis, those levels went down as much as 0.45 micrometers squared per millisecond.
"As the inflammation breaks down the structure of the axons or branches of the optic nerves, the normal water diffusion in this direction is impeded," Naismith explains. "After several months, though, the debris is cleared away, and this value and another characteristic known as radial diffusivity then start to increase."
In acute patients, the initial decrease in axial diffusivity brought on by optic neuritis correlated with decreased sensitivity to visual contrast one month and three months later. In patients with a history of optic neuritis, the increase in radial diffusivity was a good predictor of lower scores on several tests of visual health. Scientists plan to assess the acute patients again one year after the onset of symptoms to see if the scan results continue to be predictive.
Researchers are currently working to expand the approach to assess MS attacks in the brain and spinal cord.
"The optic nerve was our proof of concept, because it's structurally a very simple tract with all the nerves going one way, like a one-way street," he says. "The next step is taking the technique into the brain and spinal cord, where there are many different streets crossing. Measuring damage and correlating it to dysfunction will be more complex as a result."
http://www.medicine.wustl.edu/
Researchers from Washington University School of Medicine in St. Louis report online in the journal Neurology that an approach known as magnetic resonance diffusion tensor imaging (DTI) allowed them to estimate three months in advance the chronic effects of inflammation of the optic nerve. The condition occurs most often as a result of MS, a neurodegenerative disorder that can present with an extremely broad variety of symptoms that range from vision loss and other sensory damage to muscle weakness, spasticity or paralysis to depression, sleep loss or incontinence. MS affects an estimated 500,000 Americans.
"We see this as part of a battery of tests we hope to give patients within the next decade to help our clinical assessment and tailor it to an optimal treatment," says lead author Robert T. Naismith, M.D., assistant professor of neurology and a staff physician at Barnes-Jewish Hospital. "It may also help further refine our basic understanding of MS in terms of expanding our insights into where and how damage occurs and why it can affect patients differently."
Scientists believe MS results from misdirected immune system attacks against the nervous system. Symptoms occur in bouts that vary unpredictably in nature, severity, duration and frequency. Symptoms of optic nerve inflammation, known as optic neuritis, include loss of vision, blurring or fogginess and pain in the affected eye.
Regular MRI scans can detect optic neuritis but offer no information on its severity and potential lasting consequences for a patient's vision.
Currently in use clinically to detect and follow up on strokes, DTI uses a rapid series of MRI scans to track water diffusion in tissue. Noting that inflammation and the cell damage it causes would likely alter water diffusion in the affected tissues, Naismith and his colleagues hypothesized that this information might allow them to assess the severity and potential for lasting damage of MS flare-ups. Over the past five years, the new paper's senior authors, Sheng-Kwei Song, Ph.D., associate professor of radiology, and Anne Cross, M.D., professor of radiology, did much of the quantitative work in animal models of MS. The new data, based upon this successful collaborative history, are the first to show that DTI can produce potentially useful predictive information in humans.
For the study, researchers used DTI to image the optic nerves of 12 healthy volunteers, 12 patients who had begun to suffer from optic neuritis within the past month and 28 patients with a history of earlier outbreaks. They gave participants with optic neuritis or a history of it detailed assessments of their visual health, including tests of visual acuity and the thickness and conductivity of their optic nerves.
In the healthy subjects, DTI scans showed that the water diffusion along the length of the subjects' optic nerves, a characteristic known as axial diffusivity, averaged about 1.66 micrometers squared per millisecond. In three patients with acute optic neuritis, those levels went down as much as 0.45 micrometers squared per millisecond.
"As the inflammation breaks down the structure of the axons or branches of the optic nerves, the normal water diffusion in this direction is impeded," Naismith explains. "After several months, though, the debris is cleared away, and this value and another characteristic known as radial diffusivity then start to increase."
In acute patients, the initial decrease in axial diffusivity brought on by optic neuritis correlated with decreased sensitivity to visual contrast one month and three months later. In patients with a history of optic neuritis, the increase in radial diffusivity was a good predictor of lower scores on several tests of visual health. Scientists plan to assess the acute patients again one year after the onset of symptoms to see if the scan results continue to be predictive.
Researchers are currently working to expand the approach to assess MS attacks in the brain and spinal cord.
"The optic nerve was our proof of concept, because it's structurally a very simple tract with all the nerves going one way, like a one-way street," he says. "The next step is taking the technique into the brain and spinal cord, where there are many different streets crossing. Measuring damage and correlating it to dysfunction will be more complex as a result."
http://www.medicine.wustl.edu/
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