NEW YORK (Reuters Health) – Intravenous magnesium sulfate (MgSO4) does not benefit patients with acute aneurysmal subarachnoid hemorrhage, according to results of a phase III trial.
In the last decade, several studies have suggested that MgSO4 might reduce delayed cerebral ischemia and improve outcomes after this type of stroke. (For example, see Reuters Health reports of May 18, 2005 and Aug 7, 2007.)
To confirm these findings, Dr. Wai Sang Poon and associates analyzed 6-month outcomes for 327 patients enrolled within 48 hours of hemorrhage and randomly assigned to MgSO4 (n = 169) or normal saline (n = 158).
At 10 study centers, researchers administered MgSO4 in a loading dose of 20 mmol over 30 minutes followed by a continuous infusion of 80 mmol/day, adjusted to raise plasma magnesium to about twice the baseline concentration but less than 2.5 mmol/L.
Treatment lasted for 10 to 14 days. All patients also received nimodipine 60 mg every 4 hours if blood pressure remained stable. The investigators defined a favorable outcome as an Extended Glasgow Outcome Scale score of 5 to 8 at six months.
Dr. Poon, from The Chinese University of Hong Kong, and associates report that similar proportions of patients in each group had favorable outcomes: 64% in the MgSO4 group and 63% in the placebo group.
Outcomes did not differ by age, stroke severity, pre-stroke hypertension status, or presence or absence of intracerebral hematoma or intraventricular hemorrhage. Likewise, location and size of the aneurysm or the treatment type (clipping or coiling) did not affect results.
Furthermore, there was no difference between the groups in any secondary outcomes, including proportions of patients with clinical vasospasm and ability to independently carry out basic activities of daily living.
The researchers suggest that the negative findings could be due to low MgSO4 penetration of cerebrospinal fluid. Better outcomes might follow direct intracisternal infusion or earlier initiation of treatment, they say.
Nevertheless, they conclude,
