Every year, more than 32,000 Americans die from gunshot wounds. A significant proportion of these deaths involve head wounds. Despite this massive public health burden, researchers know little about the variables that determine whether a victim of these injuries will live or die.
Now, for the first time ever, researchers at the University of Maryland School of Medicine (UM SOM) have developed a system to help answer this question. The system has created a way to better understand the variables involved in survival from these wounds. The paper appears in the latest issue of the journal Neurology.
"This kind of analysis has never been done before," said one of the study's principal authors, Thomas M. Scalea, MD, FACS, MCCM, the Honorable Francis X. Kelly Distinguished Professor of Trauma Surgery, Director, Program in Trauma, and Physician-in-Chief, R Adams Cowley Shock Trauma Center. "Using this knowledge, we can improve treatments and focus our care to maximize survival chances."
The study was a partnership between scientists at UM SOM and researchers at the University of Massachusetts Medical School, Massachusetts General Hospital and Brigham & Women's Hospital, Harvard Medical School and Yale University. Besides Dr. Scalea, the other UM SOM researcher was Deborah M. Stein, MD, MPH, FACS, FCCM, R Adams Cowley Professor in Shock & Trauma, University of Maryland School of Medicine, Chief of Trauma and Director of Neurotrauma Critical Care.
The researchers looked at 413 patients, most whom were treated at the Shock Trauma Center. All of the patients had penetrating brain injuries, 93 percent of them from gunshot wounds. Of the overall group, 42 percent, 175 in total, survived. The researchers looked at a range of variables to see which seemed to correlate with survival.
One key variable appears to be the level of consciousness upon arrival. The researchers used a measure known as the Glasgow Coma Scale (GCS), which tracks patient awareness after injury. The higher the score, the more aware the person is. The study found that patients with a lower GCS score were significantly less likely to survive. This was particularly true for movement -- patients who were not moving after injury had a higher risk of death.
Another key measure appears to be pupillary reactivity, the ability of the eye's pupils to change diameter in response to light. This is a measure of the nervous system's basic functioning. In patients with low or absent pupillary reactivity, survival rates were significantly lower. Also crucial was Injury Severity Score (ISS), a measure of overall bodily trauma. The higher the ISS, the lower the survival rate.
The study also found that having only a single penetrating brain injury, rather than multiple penetrating brain injuries, was associated with 87 percent higher odds for survival.
Interestingly, female patients had 76 percent higher odds for survival than men. The reason for this is not clear. The researchers note that progesterone, a hormone that tends to be higher in women than in men, may have a protective effect in these injuries. The overwhelming majority of the subjects in the study, however, were men: women made up only 13 percent of the subjects in the study.
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