Researchers are calling for space headache to be established as a new secondary disorder after carrying out a study of 17 astronauts, published in the June issue of Cephalalgia .
Their study jettisons the theory that astronauts' headaches are normally caused by space motion sickness, after showing that more than three-quarters of those studied had no connection.
"Our research shows that space flights may trigger headaches without other space motion sickness symptoms in otherwise super healthy subjects" says lead researcher Dr Alla Vein from Professor Michel Ferrari's Headache Research team at the Department of Neurology, Leiden University Medical Center, The Netherlands.
"We propose to classify space headache as a separate entity among the secondary headaches attributed to disorders of homeostasis, which is the maintenance of a constant internal environment within the body."
The research team asked one female and 16 male astronauts, ranging from 28 to 58 years of age, to provide anonymous feedback on headaches experienced during four specific time frames - launch, the stay at the space station, activities outside the space station and landing.
All the astronauts had undergone rigorous medical examinations before they went into space. Nine has taken part in short-duration missions averaging just under 11 days and eight had taken part in long-duration missions averaging just under 202 days.
Key findings included:
"Although headaches in space are not generally considered to be a major issue, our study demonstrated that disabling headaches frequently occur during space missions in astronauts who do not normally suffer from headaches on earth" says Dr Vein.
"Previous research has shown that astronauts can be reluctant to reveal all the physical complaints they experience in space, so the actual incidence could be even higher than our study suggests."
The authors state that there are a number of reasons why space travel could cause headaches including the physical effects of microgravity.
"Our research shows that space headache is a common and often isolated disabling complaint during space flight" concludes Dr Vein.
"As such we feel that it should be classified as a new secondary headache."
Notes to editors
Space headache: a new secondary headache. Vein et al. Cephalalgia . 29, 683-686. (June 2009).
Cephalalgia is published by Wiley-Blackwell on behalf of the International Headache Society. It contains original research papers, review articles and short communications on all aspects of headache. www.blackwell-synergy.com/loi/CHA
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