Assessing the severity of brain damage in people with little or no signs of consciousness is a daunting task for doctors,media reported. Now, a study from the University of Cambridge has found a possible new tool that could provide patients with clearer picture and improve their treatment plans.
A cheap “sniff test” suggests that it is possible to predict which patients will continue to regain consciousness for the rest of the year.
According to the scientists behind the new study, the current method of determining the state of consciousness in patients with severe brain injury has led to diagnostic errors in as many as 40 percent of cases. This may mean that the treatment plan is unwise and can hinder recovery. While we have seen some promising new alternatives, it is clear that new and better solutions are urgently needed.
Although the new study at the University of Cambridge is small, it raises an interesting possibility, at the heart of which is the human sense of smell and how the brain responds to certain stimuli. In other words, unpleasant stimuli cause the brain to breathe shorter and shallower, a reaction that manifests itself in a state of consciousness during wakefulness and sleep.
The team recruited 43 patients with severe brain damage. The researchers presented the different smells in the jar to the subjects and then monitored their breathing response through a small tube on their noses. These smells include a pleasant shampooy flavor, an unpleasantly rotting fishy smell, and a neutral smell that doesn’t smell. Each person was randomly shown 10 times, and the team then measured the amount of exhaled air the patient responded to.
The results showed that, although there was no significant difference in the response between pleasant and unpleasant smells, mildly conscious patients responded much less to the smell. The researchers also found that when they smelled neutral, their nasal air flow changed. The researchers said the neutral odor suggested they had feelings for the jar or had a “acquired expectation” of smell. Various reactions were observed in plant people, some showing changes in breathing and others did not.
Three-and-a-half years later, scientists continue to study how to use their olfactory test results to predict patients’ prognosis. 100% of the subjects who responded to the sniffer test regained consciousness, with 91% of the patients still alive and 63% of the non-reactive subjects having died.
Anat Arzi, a researcher in the Department of Psychology at the University of Cambridge and co-lead in the study, said: “The accuracy of the sniffing test is very high and I hope it will help treat patients with severe brain injury around the world. “
The team consistently observed that plant-human patients showed different reactions to sniffer tests, that plant ers may open their eyes or show signs of basic reflexes but no consciousness, and that those at the lowest levels of consciousness may have brief signs of consciousness. These subtle but important differences further increase the potential of sniffer testing as an accurate diagnostic tool that the team hopes will be used in clinical applications as soon as possible.