Intermittent bouts of extremely low blood pressure may cause debilitating chronic fatigue, say Johns Hopkins researchers.
In this week’s issue of Lancet, they report that seven teenagers with constant malaise had “neurally mediated hypotension,” a blood pressure abnormality brought on by a nervous system reflex.
“When their condition was treated, chronic fatigue also disappeared in four of the seven adolescents,” said Peter Rowe, M.D., associate professor and general pediatrician at the Johns Hopkins Children’s Center. During routine examinations of weary teenagers, the researchers noted that chronic fatigue symptoms mimicked those of neurally mediated hypotension, minus the fainting spells.
According to Rowe, patients with neurally mediated hypotension (also known as neurocardiogenic syncope or vasodepressor syncope) have a tendency to faint while upright for an extended period, such as standing in a line, especially in warm environments. This type of hypotension is often detected using a tilt table test. Patients lie flat on a special table and then are tilted upright to a 70-degree angle. After several minutes, lightheadedness, nausea and fainting occur in those with the condition.
In the Hopkins study, all of the teens, aged 12 to 16, became lightheaded or fainted during the tilt table test. Their average blood pressure dropped from 105/64 to roughly 65140, which established the diagnosis of neurally mediated hypotension. None had a previous history of fainting.
“It is unlikely that such consistent responses in seven consecutive patients are due to chance,” says Hugh Calkins, M.D., director of electrophysiology in Hopkins’ division of cardiology and co-author of the study.
After treatment directed at this condition, including increased salt uptake, four of the teens’ chronic fatigue and related symptoms disappeared within one week. The other three reported no change in their condition. “Neurally mediated hypotension occurs when the nervous system’s communications are out of kilter,” explains Rowe.
In normal individuals, blood pools in the legs when standing and blood flow to the heart is diminished. To compensate, the body discharges a surge of adrenaline that makes the heart pump faster and more vigorously so an adequate amount of blood can reach the brain and other organs, says lean Kan, M.D.), professor and director of the division of pediatric cardiology.
In-patients with neurally mediated hypotension, there is a “miscommunication” between the heart and the brain, she says. Just when it needs to beat more rapidly, the heart slows down and even more blood collects in the arms and legs. Lightheadedness and fainting can result.
Researchers do not yet know the extent to which genetic influences, infections, or other factors trigger neurally mediated hypotension, but they know that increasing dietary salt can help treat it.
“We normally encourage patients with this kind of hypotension to shake more salt on their food, eat saltier foods (like pickles, olives, and tunafish), take salt tablets, and increase their intake of fluid to help salt do its job,” says Issam Bou-Holaigah, M.D., a fellow in Hopkins’ division of pediatric cardiology and a co-author. Drugs that allow the kidneys to retain sodium otherwise lost in urine are effective, as are drugs that block the response to adrenaline.
Although the physicians point out that the research is preliminary, they say it is possible that neurally mediated hypotension is linked to chronic fatigue syndrome, a disease that is hallmarked by bouts of malaise lasting six months or more. Some patients in this study have classic chronic fatigue syndrome. Others had many similar symptoms of the syndrome.
Future studies will help determine the prevalence of neurally mediated hypotension in patients with chronic fatigue syndrome and will attempt to discover treatments that will improve their daily lives.
©1995 by Roger Burns. Reprinted with permission from CFS-NEWS Electronic Newsletter, a chronic fatigues syndrome electronic newsletter published and edited by Roger Burns, Washington, D.C.
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