Study of Systemic Cooling in Acute Spinal Cord Injury

Abstract

This is an important subject because of the severity of cervical spinal cord injury, the paucity of methods for mitigating it, and the lack of information about the efficacy of hypothermia. During the early 1970s, localized cooling of the spinal cord during spinal surgery after traumatic cord injury was performed in several centers. However, the study designs, lack of controls, small numbers of patients, confounding factors and limited outcome measures did not allow conclusions to be drawn about any beneficial effect. Since then, techniques for systemic hypothermia have been refined and applied to patients with head injury, stroke and cardiac arrest. A recent Cochrane review1 concluded that it may be effective in reducing death and unfavorable outcomes in patients with head injury, but significant benefit was only found in low quality trials; it also concluded that hypothermia may increase the risk of pneumonia. This is the first report of a study of systemic cooling in acute spinal cord injury in humans. It focuses primarily on complications and concludes that while these were primarily respiratory they were no worse than in a group of historical controls, with the exception of pleural effusions and anemia. The retrospective analysis with historical controls treated in a prior period raises the possibility of change of practice between control and experimental groups. The controls were matched for age and for level and degree of SCI, but it is not clear whether they differed for other variables such as surgical intervention, steroids, maintenance of blood pressure or other injuries. The study does not show efficacy of hypothermia in improving neurological or functional outcomes. It is suggested in the Discussion that changes in the American Spinal Injury Association and International Medical Society of Paraplegia Impairment Scale seen in the experimental group appear greater than those in the literature, but this is not a valid comparison and they are not compared with those in the control group. A Position Statement and Evidence Based Recommendations issued in 2007 by the AANS/CNS Joint Section on Disorders of the Spine and the AANS/CNS Joint Section on Trauma concluded that there is not enough evidence available to recommend for or against the practice of either local or systemic therapeutic hypothermia as a treatment for acute spinal cord injury.2 While the current paper is of value in increasing confidence in the safety of modest controlled systemic hypothermia for acute spinal cord injury, it does not provide sufficient evidence to alter this conclusion. Hopefully, future randomized, controlled trials will demonstrate the clinical benefit of hypothermic treatment for acute spinal cord injury. Graham Creasey Gary K. Steinberg Stanford, California