Reaction to the odors predicted output from a vegetative state

Unlike patients in a vegetative state, people with weak minds of the average react to odors: in response to the bright flavors they reduce the flow of air through the nose. For individual diagnosis level of consciousness this method is bad, as it gives a high level of false negative and false positive results. But it has predictive potential: the majority of patients in a vegetative state, if they react to the smells got better and lived for several years after the study. Article published in the journal Nature.

When brain damage can be difficult to determineif the person is in a vegetative state or had remained weak consciousness. In 40 percent of cases, doctors erroneously determine the level of consciousness of patients, and depends on a number of aspects of treatment: do I need painkillers and what is the point of euthanasia.

The olfactory system is involved in the basic reactions of activation of the nervous system. Smells like auto start smelling reactions (for example, if the smell is unpleasant, the flow of air in your nose is reduced), and cognitive, which require understanding of the situation, so the behavioral response to different smells could be a marker of the level of consciousness of patients with brain damage.

Scientists from Britain and Israel, under the leadership of Yaron Sacher (Yaron Sacher) from tel Aviv University and Noam Sobel (Noam Sobel) from the Weizmann Institute investigated the response to odors in 43 patients with impaired consciousness. 24 of them were in a vegetative state and 31 were apallic syndrome in which there is a weak manifestation of consciousness (between sessions some patients have varied level of consciousness, so that groups overlap). Patients were taken to the nose pleasant smells (the scent of the shampoo) or unpleasant (rotten fish) and recorded the volume of the first three nasal breaths.

On average, patients in a vegetative state has not changed the flow of air through the nose in response to bright smells, and people with apallic syndrome the nasal volume of the first two breaths after the presentation of both odors were significantly decreased (p < 0.0001). Between the response to pleasant and unpleasant odors were not statistically significant differences.

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