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Major Study Confirms Efficacy of Oxygen Therapy for Many Cluster Headaches


In the first major randomized double-blind placebo-controlled crossover trial comparing oxygen therapy versus placebo (forced air) for patients with cluster headache, 78 percent of those on the active treatment were pain-free after 15 minutes, compared with 20 percent of those on placebo, and there were no significant adverse events.

Breathing forced, high-flow oxygen can quickly reduce or eliminate many episodes of acute and episodic cluster headache, according to the results of the first major randomized double-blind placebo-controlled crossover trial.

Reported in the Dec. 9, 2009, issue of the Journal of the American Medical Association, the findings lend credence to an inexpensive form of therapy that many clinicians already recommend for patients, but a large number of insurers still regard with skepticism.

Jointly sponsored by the Headache Group at the University of California-San Francisco and the Institute of Neurology, National Hospital for Neurology and Neurosurgery-Queen Square, London, investigators compared oxygen therapy or placebo forced air in 109 adult patients during four headache bouts. Patients reported their responses in a diary that was returned to the researchers after their fourth treatment.

The trial was led by Peter J. Goadsby, MD, PhD, director of the Headache Center at the UCSF. Patients were asked to measure relief using a four-point pain relief scale, with zero being pain-free and four for the most severe pain. A reduction in in the pain scale was considered positive if the rating at each time was at least 1 category less than when the headache began.

After 15 minutes of therapy, patients taking oxygen reported good-to-excellent pain relief four times more often than did those given high-flow air placebo. Patients self-administered either 100 percent oxygen or air via facemask at a rate of 12 liters per minute, for 15 minutes, starting at headache onset. Complete or adequate pain relief after 15 minutes was the primary end point.

Seventy-eight percent of the patients were pain-free after 15 minutes with oxygen, compared with 20 percent those on placebo, and there were no significant adverse events.

“To our knowledge, this is the first adequately powered trial of high-flow oxygen compared with placebo, and it confirms clinical experience and current guidelines that inhaled oxygen can be used as an acute attack therapy for episodic and chronic cluster headache,” the researchers said.

A 2008 review of the medical literature on oxygen therapy for cluster headaches found only two studies. Published in the Cochrane Database of Systematic Reviews, the researchers found similar improvement in 65 patients after 15 minutes compared to those given sham therapy.


So called “suicide” and “alarm clock” headaches because of their intensity and the regularity of episodes, cluster headaches can last for 15 minutes or up to three hours. They occur frequently, sometimes daily, for weeks or months, and are then followed by months or years of remission before another attack. Chronic cluster headaches are more disabling because attacks are prolonged - some can last a year or more, with shorter periods of remission.

Many episodes begin during the first rapid-eye-movement sleep phase, and hypoxia can precipitate a headache; sleep apnea could be a factor. Because of this, some patients are afraid to sleep. Some patients have also reported seasonal patterns to their episodes, with greater frequency in spring and autumn.

The most common treatment is injection of sumatriptan (Imitrex), which was approved by the FDA in 1992. Subcutaneous sumatriptan injections(6 mg) are most effective in both acute and episodic cluster headaches because relief is more rapid, often within 15 minutes, but the drug can be administered only twice a day. Further, many patients with common health problems, including heart disease, hypertension, or stroke risk, are warned not to take the drug. The nasal spray (20 mg) can be effective after 30 minutes, but use is limited to three times per day. Another triptan, zolmitriptan (Zomig), is effective at 30 minutes when taken orally (10 mg), but only for episodic headache bouts, as is the nasal form (5 and 10 mg), which can be used only three times per day.


CLUSTER HEADACHES can last for 15 minutes or up to three hours. They occur frequently, sometimes daily, for weeks or months, and are then followed by months or years of remission before another attack. istockphoto


Although a number of medical societies, including the American Academy of Family Physicians, recommend oxygen therapy as the front-line treatment for cluster headaches, many insurers remain reluctant to pay for treatment, according to the National Headache Foundation.

“Sometimes this can be overcome by a letter from the treating physician. Since about 50 percent of patients respond to oxygen therapy, it is worth trying it before going to the expense and effort of having an oxygen tank installed in one's home,” the foundation advises.

Stephen D. Silberstein, MD, professor of neurology at Thomas Jefferson University in Philadelphia, PA, and director of the Jefferson Headache Center, said health insurers need to be made aware of the new findings.

“This study confirms what many physicians who regularly treat cluster headaches already know,” he told Neurology Today in a telephone interview.

“The problem with this is the insurers. Here we have a safe and effective treatment that is both inexpensive and effective, yet insurers still won't pay for it. ...This paper was done by a good group of researchers, with no personal interest in the results.”

Albert Einstein College of Medicine Neurology Professor Richard B. Lipton, MD, chief neurologist at the Montefiore Headache Unit at the Montefiore Medical Center in Bronx, NY, agreed that the new study could help convince reluctant carriers.

“Cluster headache has not been rigorously studied in double-blind, placebo-controlled studies, and it is too common to be an orphan illness and too rare for pharmaceutical companies to have much interest. Some pay for it, but many do not,” he explained, noting that subcutaneous and intranasal sumatriptan are effective in many patients, but expensive, and oral sumatriptan acts too slowly for patients with severe symptoms.

“The contributors to this study provide strong evidence ... and I'm hopeful that this study will encourage more third-party payers to cover treatment.”


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