Magnesium Tested in Rats for Treatment of Spinal Cord Injury

Spinal cord injury (SCI) is a traumatic condition affecting an estimated 200,000 people in the United States, with approximately 10,000 new cases each year. The total annual cost of caring for patients with SCI in the United States is estimated to be $9.73 billion. Improving outcome following SCI would not only improve a patient's quality of life, but also lessen the social and economic impact of this condition. A new study, "Magnesium Efficacy in a Rat Spinal Cord Injury Model," that discusses the use of magnesium in treatment of spinal cord injury, will be presented during the 71st Annual Meeting of the American Association of Neurological Surgeons (AANS) in San Diego.

The study will be presented by Diana B.Wiseman, MD; David Lundin, MD; Jiegang Zhou, MD; Adam Lipson, MD; Alexis Falcov, MD and Christopher I. Shaffrey, MD, on Monday, April 28, from 2:45 to 3 p.m. Presently, pharmacological treatment is often administered within an eight-hour window following SCI and is used primarily to decrease the severity of the injury and reduce the likelihood of permanent paralysis. To date, there is only one pharmacological therapy, high dose methylprednisolone (an anti-inflammatory agent), which has gained widespread acceptance for the treatment of SCI.

"We wanted to determine whether alternative pharmacologic agents such as magnesium may show benefit in outcome, and ultimately either supplement methylpredisolone therapy, or replace it," said Diana B. Wiseman, MD, co-author of the study and an AANS member.

The authors of the study evaluated the effect of magnesium on a rat SCI model when administered within 10 minutes after the injury. They also evaluated how magnesium affects recovery outcome in comparison to methylprednisolone and also when used in combination with methylprednisolone. For the study, 75 female rats weighting 250-300 g were used. The study design included four animal groups: a control group (which received normal saline); a magnesium group; a methylprednisolone group; and a magnesium plus methylprednisolone group.

To begin, the rats were anesthetized and the spinal cord was surgically exposed. The animals then underwent a 10 g weight dropped 25 cm to produce a moderate SCI. After the SCI each test group then received (by random selection) normal saline or magnesium, methylprednisolone or magnesium plus methlprednisolone. All injections occurred within 10 minutes post injury.

After care was taken to assure adequate pain control and weight maintenance, the researchers conducted an evaluation for signs of infection or autophagia.

The researchers started animals that lost up to 10 percent of body weight on an aggressive twice-daily high calorie oral supplement. Despite aggressive attempts to maintain animal weights, the majority of animals who demonstrated signs of significant autophagia, urinary tract infections or weight loss greater than 20 percent of body weight within the first two weeks, were required to be euthanized per University of Washington animal care protocol.

Unfortunately the majority of the methylprednisolone group, as well as the methylprednisolone plus magnesium group, suffered weight loss greater than 20 percent of initial body weight. Methylprednisolone use was therefore complicated by severe weight loss and mortality, thus limiting its evaluation.

"Given these findings, methylprednisolone use in rats appears to be detrimental to their overall health," said Dr. Wiseman. "Further study would be necessary to evaluate if methylprednisolone causes significant weight loss in humans controlling for other causes of weight loss in the trauma patient."

The magnesium, administered immediately after spinal cord injury, has shown promising longer-term neurological as well as histologic (tissue structure) outcomes, compared to controls. Further direction for this study could include evaluation to determine whether magnesium is effective when administered at different time intervals, up to 24 hours after the injury.

With current pharmacologic therapy for spinal cord injury being limited now to an eight -hour window, further research could provide a valuable medical treatment option for those patients who arrive at the hospital beyond the eight-hour window for methylprednisolone use. The researchers are hopeful that magnesium may ultimately prove to be an overall more effective pharmacologic treatment option for patients suffering from spinal cord injury.

Founded in 1931 as the Harvey Cushing Society, the American Association of Neurological Surgeons (AANS) is a scientific and educational association with more than 6,500 members worldwide. The AANS is dedicated to advancing the specialty of neurological surgery in order to provide the highest quality of neurosurgical care to the public. All active members of the AANS are certified by the American Board of Neurological Surgery, the Royal College of Physicians and Surgeons (Neurosurgery) of Canada or the Mexican Council of Neurological Surgery, AC. Neurological surgery is the medical specialty concerned with the prevention, diagnosis, treatment and rehabilitation of disorders that affect the entire nervous system including the spinal column, spinal cord, brain and peripheral nerves.