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Research Journal Feature: Hypothermia

When a person is suspected to have a spinal cord injury (SCI), medical staff follow a relatively standardized protocol: stabilize the patient, stabilize the spinal column to prevent further mechanical injury, and perform a surgical decompression procedure if required. However, these measures are supportive rather than protective or reparative, and there is little that can be done for the spinal cord itself. When the spinal cord is injured, a cascade of additional (secondary) damage begins due to bleeding, swelling, and the body’s natural inflammatory responses to trauma. Neuroprotective strategies, aimed at minimizing that secondary neural injury and maximizing the chances for recovery, have been a major goal for neuroscientists and clinicians for the management of acute SCI.

Hypothermia, cooling the body temperature, is one neuroprotective strategy that holds much promise for acute SCI.

Hypothermia, cooling the body temperature, is one neuroprotective strategy that holds much promise for acute SCI. Numerous animal studies using various models of mechanical SCI in diverse species have  demonstrated the protective effects of hypothermia. Positive outcomes have been demonstrated in rat, ferret, cat, dog, and monkey models, which is important in showing that the effects are robust and can be replicated across species, injury models, and laboratories. Researchers at The Miami Project / University of Miami have demonstrated that hypothermia can decrease the degree of bleeding at the site of primary injury, decrease cell loss, reduce axon swelling, and have a positive impact on behavioral recovery.

Over the past 9 years, scientists at The Miami Project have also been gathering data from acutely injured patients who receive modest hypothermia treatment as part of their medical care at the University of Miami/Jackson Memorial Hospital. Results from this study were published on thirty-five patients in 2013 and the data have shown that modest hypothermia treatment is safe, can be started early after injury (within 8 hours), and may have beneficial effects on neurological recovery as 31% of participants converted from “complete” to “incomplete” status and 43% of all injured patients improved one AIS grade or more at 1 year post-treatment. While the results so far have been positive, further studies are needed from a larger sample of participants and with a comparison to individuals who have not received hypothermia treatment. Currently 50 patients have been cooled since the start of the study in 2007.

Systemic hypothermia in acute cervical spinal cord injury: a case-controlled study. Dididze M, Green BA, Dietrich WD, Vanni S, Wang MY, Levi AD. Spinal Cord. 2013 May;51(5):395-400.

Recently, Dr. Allan Levi, Professor and Chairman of the Department of Neurological Surgery has received funding from the Department of Defense to conduct a prospective multi-center trial to investigate the effects of hypothermia treatment in acute cervical SCI. The partnering sites will be Emory University School of Medicine/Grady Memorial Hospital in Atlanta, Thomas Jefferson University in Philadelphia, and Indiana University School of Medicine in Indianapolis. Over a 4 year time period, 120 newly-injured patients (C1 to C8), ASIA Impairment Scale (AIS) Grade A, B, or C will be recruited to participate in the study and randomized to either a control (normothermia/standard of care) or treatment (hypothermia) group. Intravascular hypothermia will be induced in the treatment group via a catheter inserted into the femoral vein and the body temperature will be cooled from 37°C (normal) to 33°C at about 2°C per hour. This “hypothermic” body temperature will be maintained for 48 hours, after which rewarming will occur very slowly at 0.1°C per hour. Evaluations of neurological and functional outcomes will be performed at 6 weeks, 6 months, and 1 year post-treatment. Results from the hypothermic group will be compared to the control group. The results from this large, multicenter, prospective trial should provide data to determine whether systemic modest hypothermia should be implemented as part of the new standard of care treatment for cervical SCI.