When a person suffers a brain injury serious enough to make them unresponsive, doctors face a difficult challenge in administering treatment. They may have trouble determining whether a patient is in a permanent unresponsive state, or if they have a good chance of regaining consciousness. In fact, according to research, there is an error rate of up to 40% in determining the state of consciousness in patients with brain injuries.

However, this same study, published in Nature in April 2020, suggests an unconscious person’s olfactory response to odors can reliably predict whether or not they will survive and recover.

This test, called the “sniff test,” could help medical professionals and families of patients with traumatic brain injuries make more accurate and easier decisions regarding their care.

How the sniff test works

For the study, researchers tested the responses of 43 unconscious patients at a rehabilitation hospital when presented with pleasant and unpleasant odors (shampoo and rotten fish, respectively). They did this by attaching a small device to the nose to measure how much air they inhaled when exposed to the odors, as compared to how much air they inhaled when exposed to no odors.

Typically, we all sniff or inhale deeply when we smell something pleasant, but tend to sniff sharply and quickly when we detect something unpleasant. So, researchers theorized that patients who still had enough brain activity to regain consciousness might reflexively respond to the sniff test.

The results

Researchers tested the patients repeatedly, as a brain injury patient’s consciousness can vary. Every patient who showed a response to the sniff test eventually regained consciousness, and all patients who remained unconscious did not respond to the test.

“If an unresponsive patient with a brain injury has a sniff response, chances are very high that the person will recover consciousness and will have high survival chances for years,” says lead study author Anat Arzi. Arzi also points out that it’s unclear whether or not the test shows current consciousness or predicts that a patient will regain consciousness. It also cannot predict a patient’s future quality of life.

However, when used in conjunction with other diagnostic tools, the sniff test may be valuable for early intervention and treatment for patients. “When the sniff response is functioning normally it shows that the patient might still have some level of consciousness even when all other signs are absent,” said Dr. Tristan Bekinschtein from the University of Cambridge’s Department of Psychology, who was involved in the study. “This new and simple method to assess the likelihood of recovery should be immediately incorporated in the diagnostic tools for patients with disorders of consciousness.”

The Alabama brain injury attorneys at Mezrano Law Firm protect the rights of injury victims across Alabama. If you or a loved one were injured in accident that wasn’t your fault, we can help. To set up a free consultation, give us a call today at 205-206-6300, or leave us a message through our contact form. We offer our services to residents of Mobile, Birmingham, Tuscaloosa, Florence, Montgomery, and Gadsden.