WEDNESDAY, Oct. 26, 2016 (HealthDay News) -- A new tool may help doctors determine a patient's chances of survival after a gunshot wound or other penetrating injury to the brain, researchers report.

Based on their work, the researchers say two factors strongly predict survival: how well a patient's pupils respond to light and how well a patient can move in response to stimuli, such as withdrawing from pain or obeying commands.

"Gunshot wounds are the number one cause of penetrating traumatic brain injuries," said study author Dr. Susanne Muehlschlegel, of the University of Massachusetts Medical School.

"Much of our knowledge about surviving such injuries comes from the battlefield, not from shootings among civilians. Being better able to determine the average person's chance of survival could help doctors and families make important decisions about medical treatment," she explained.

The researchers created the tool by analyzing the medical records of more than 400 people, average age 33, who suffered a penetrating wound -- mostly gunshots -- to the brain.

Overall, the Surviving Penetrating Injury to the Brain (SPIN) Score was 96 percent accurate in predicting survival, according to the study.

The results were published online Oct. 26 in the journal Neurology.

The researchers found that the risk of death was 80 percent higher if a gunshot wound to the brain was self-inflicted. Also, for unknown reasons, women had a 76 percent higher chance of survival than men.

"More research is needed to validate the SPIN-Score, so for now, it remains a preliminary prediction tool," Muehlschlegel said in a journal news release. "Still, developing this tool is an important step toward improving overall outcomes."

More information

The American Association of Neurological Surgeons has more on gunshot wounds to the head.