Up to one in four patients who are unresponsive after suffering serious brain injuries might actually still be conscious – indicating more patients may be aware of their surroundings than previously realized, new research suggests.

This state of 'hidden consciousness' is now officially known as cognitive motor dissociation (CMD), where cognitive (or thinking) abilities aren't connected to motor (or movement) abilities. Researchers have been looking into CMD for several years.

However, 62 percent of an additional 112 patients who were visibly responding to instructions at the bedside didn't exhibit the expected brain signals showing responsiveness – so the researchers suggest their methods still don't detect everyone with cognitive function.