Brain scans may help to predict when people will wake from a coma.
According to MediLexicon, coma is "a state of profound unconsciousness from which one cannot be roused; maybe due to the action of an ingested toxic substance or of one formed in the body, to trauma, or to disease."
It can also result from a traumatic injury, such as a blow to the head sustained in a road traffic accident or a sports injury.
A coma can sometimes be artificially induced to enable healing in a person who would otherwise be in great pain.
A person who is in a coma is unconscious and has minimal brain activity. They are alive but cannot be woken up.
Signs and assessment of coma
Common signs and symptoms of coma include closed eyes, depressed brainstem reflexes, such as pupils not responding to light, no responses of limbs, except for reflex movements, no response to painful stimuli, except for reflex movements, and irregular breathing.
The severity of a coma is assessed using the Glasgow Coma Scale (GCS), which gives a score based on eye opening, verbal response to a command and voluntary movements in response to a command.
A coma may last for days, weeks or even longer, if it leads to a vegetative state. Except in the case of induced coma, doctors cannot normally predict when a patient will regain consciousness.
However, a recent study into connections between areas of the brain that play a role in regulating consciousness has indicated that brain scans may be able to predict when the person is likely to come round.
Brain scans predict who will regain consciousness
Functional magnetic resonance imaging (fMRI) scans were taken of the brains of 27 people in a coma with severe brain injuries and 14 healthy controls.
Scans on coma patients were conducted after any sedative drugs had left their systems. Three months after their injuries, four of the people with coma had recovered consciousness. The others remained in a minimally conscious or vegetative state at 3 months.
All of the people in a coma had significant disruption in the connections between brain areas and the posterior cingulate cortex. These changes were the same whether the brain injury was due to trauma or to lack of oxygen, such as from cardiac arrest.
However, the coordination of activity between the posterior cingulate cortex and the medial prefrontal cortex was significantly different between those who went on to recover from the coma and those who remained in a minimally conscious state or a vegetative state.
The coordination between the two brain areas was the same for the healthy participants and those who regained consciousness.
Study author Dr. Stein Silva, PhD, of the French National Research Institute INSERM U825 in Toulouse, says that more research is needed before these results can be used to guide decisions about people in comas.
Dr. Silva says:
"We need to do more studies with larger numbers of patients to substantiate these results, but the findings are promising. We could be able to predict better who is more likely to recover from a coma and eventually develop innovative networks-based personalized treatments for people with brain injuries."
Earlier this year, Medical News Today reported that coma patients may recover more quickly if they hear the voices of their family and loved ones.