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Magnesium infusions provide no benefit after bleeding stroke

May 25, 2012|By Thomas H. Maugh II
  • A new study finds that magnesium sulfate infusions do not benefit victims of hemorrhagic strokes.
A new study finds that magnesium sulfate infusions do not benefit victims… (National Library of Medicine…)

The common practice of infusing magnesium sulfate into patients who have suffered a hemorrhagic (bleeding) stroke provides no discernible benefit, Dutch researchers reported Friday. The study could lead to a change in treatment for victims of such strokes, which account for about 13% of the estimated 795,000 strokes that afflict Americans each year -- and about 30% of the 133,000 stroke deaths. The rest of the strokes are caused by blood clots that impede circulation in the brain. Many survivors of hemorrhagic strokes, which occur when a blood vessel in the brain leaks blood into the organ, causing acute pressure, are left permanently impaired.

The only treatments for such strokes that have proved modestly effective are calcium-channel antagonists such as nimodipine. Magnesium has been proposed as a treatment because it also acts as a calcium antagonist and because it has neuroprotective effects. Small clinical trials, however, have produced mixed results.

Dr. Sanne Dorhaut Mees of the Utrecht Stroke Center in the Netherlands and her colleagues had previously performed a phase 2 trial of magnesium infusions with 283 patients in the Netherlands, half of whom received infusions of the drug and half who got infusions of saline solution as a placebo. They found that the magnesium provided a 23% reduction in poor outcomes, prompting them to begin a larger phase 3 trial.

For the larger study, they enrolled 1,203 patients at four centers in the Netherlands and one center each in Scotland and Chile. Half were given a placebo and half were given magnesium infusions for 20 days or until discharge from the hospital, whichever came first. Poor outcome was defined as severe disability or death at three months after the first stroke.

The team reported Friday in The Lancet that there was no difference between the two groups: 158 of the 606 patients (26.2%) given magnesium had a bad outcome, compared to 151 of the 597 patients (25.3%) given placebo. Similar results were obtained when they broke the patients into various subgroups. No group showed a benefit. There were four unexpected adverse events during the trial, all in the magnesium group; one involved unusually low calcium levels, while three were characterized by unusually high magnesium levels.

The team then performed a meta-analysis, combining their new results with those obtained in other clinical trials, giving a total of 2,047 patients. Again, they found no benefit from magnesium. They concluded that "routine administration of magnesium cannot be recommended."

In an editorial in the same journal, neurologists Dr. Jose Suarez and Dr. Chethan Venkatasubba of the Baylor College of Medicine in Houston echoed that conclusion, noting that the results were "disappointing. ... We agree with the researchers, and previous findings, that routine intravenous magnesium sulfate infusionĀ  cannot be recommended for patients with aneurysmal subarachnoid hemorrhage."


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