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Imagine being trapped inside your body, unable to move speak or even communicate by blinking, yet you remain very much aware of everything that goes on around you.

Terrifyingly, many people find themselves in this nightmare, and now scientists are hoping they can identify these trapped souls.

Some individuals with brain injuries could seem to be in a coma, but they are not. Though they are unable to physically react, they are able to absorb what is going on around them.

According to Sudhin Shah, a neuroscientist at Weill Cornell Medicine in New York City, if a patient doesn’t physically respond, a doctor may infer that they haven’t understood, but, “Unfortunately, it might be that you were thinking about it, understanding it, and wanting to communicate to me. You simply cannot”.

This break between understanding and responding is called cognitive motor dissociation (CMD), a disorder of consciousness following brain injury. Most patients do not receive this diagnosis, since it requires both sophisticated tools and specialised training, but it’s believed that about 15% of patients who are thought to be unresponsive are expected to be suffering from CMD.

Researchers have now identified brain lesion patterns exclusive to CMD patients using structural magnetic resonance imaging (MRI), a method that is currently utilised in everyday clinical care.

These MRI scans could be used as a screening tool to find individuals who are likely to have CMD, increasing the likelihood that they won’t be taken off life support too soon and will be able to recover.

Today, if a patient arrives at an emergency room with a brain injury, the medical staff will frequently use structural MRI or CT scans, which produce images of the patient’s brain, to find any problems that require immediate attention, such as swelling, fluid leaks, or haemorrhaging.

Patients will receive medication, perhaps to stop seizures, based on the results of those tests, and may even be put on life support.

“Right now, diagnosis for CMD requires access to a handful of labs around the world,” said Shah, who was not involved in the study. To diagnose CMD, there are two main options: functional EEG, a far more advanced approach than traditional EEG, and functional magnetic resonance imaging (fMRI), which measures changes in blood flow throughout the brain.

Over the course of about 30 minutes, the patients are then asked to respond to questions or commands — for instance, “Open and close your hand,” and “Imagine opening and closing your hand.” Scientists and physicians however need extensive training to analyse and interpret the patients’ brain activity data collected during questioning.

The team have, however, worked to make CMD diagnosis simpler by incorporating equipment already available in most hospitals. They were able to recognise two patterns of brain lesions that were unique to CMD patients after comparing EEG and MRI data.

These lesion patterns were in areas of the brain important for motor output, but not in regions important for command comprehension or arousal, indicating that patients with CMD would be able to process information but be unable to physically respond.

Knowing which lesion patterns are more likely in patients with CMD could ultimately be used as a screening tool when someone enters a hospital with a brain injury.

Knowing if a loved one has CMD will also allow families to make better decisions about care, or even worse, decide when to cease treatment.

“For CMD patients, we want to be aggressive and continue with care.”

Researchers are now working on methods to ‘reach’ these people, and eventually get them out of their comas. “There are people potentially locked in for decades,” Shah said, “with none of their family members and the rest of the world knowing what’s going on.”