Researchers may have a way to recognize consciousness disorders in comatose and vegetative patients just days after a brain injury ̵
A research team in New York has recorded this electrical activity in the brain of unresponsive patients while giving simple spoken commands such as "open and close the right hand" or "move the toes". Of 104 nonresponsive patients tested, 16 (15%) showed some activity. Of these 16 patients, eight (50%) were able to follow spoken orders when they left the hospital. One year later, seven of them (44%) were able to function independently for at least eight hours.
In contrast, only 14% of those who showed no early electrical activity achieved this level of recovery after one year. The findings were published this week in the New England Journal of Medicine.
The study was small and the authors warn that the results "need to be validated in larger, multi-center studies to detect differences in long-term outcomes. However, if the results are correct, the study could offer physicians an opportunity to assess which patients may possibly emerge from a coma or vegetative state.
The Study Is Not the First Find out that some otherwise unresponsive patients show brain activity on spoken commands that do not seem to be translated into behavior, that is, they actually wiggle their toes. Researchers refer to such separation as "cognitive-motor dissociation," and a meta-analysis of dozens of studies in 2016 found that it occurs in approximately 14% of chronically unresponsive patients. This roughly matches the prevalence found by the New York team.
The electrical activity seems to be an answer to the spoken commands. Maybe it's the brain that recognizes the commands and tries to actually execute them. However, as the New York researchers note, "it is uncertain whether the detected signal is the recognition or understanding of commands." The researchers are also unsure whether the activity detected has any impact on patient outcomes.
The New Trial Tries to Answer this question by monitoring patients for over a year. All work was performed on a single intensive care unit with patients admitted between 2014 and 2017. Unresponsive patients were examined and tested in the hospital during the first few days. Researchers recorded patients who were in a coma, in a vegetative state, or in a state of "minimal awareness – minus" and where certain low-level behaviors were preserved. This includes tracking moving objects visually and responding to pain or discomfort.
The cause of these conditions was different in the 104 enrolled unresponsive patients. Some patients had suffered cardiac arrest, others had suffered traumatic brain injury or bleeding.
Eye Opening Collisions
To assess brain activity, the researchers used a common, relatively easy-to-use test: an electroencephalogram. It is also referred to as EEG and detects electrical impulses using scalp-mounted electrodes (in this case, a standard 21-electrode assembly was used). EEGs are commonly used to diagnose epilepsy, assess post-stroke brain activity or sleep disorders.
The researchers performed the tests in 25-minute voice commands and tested the 104 nonresponsive patients along with 10 healthy individuals as a control group. 16 of the unresponsive patients showed electrical activity, 88 did not. The following year, six died of EEG activity and 50 of those without EEG, some of whom were deprived of life support (four and 24, respectively). However, of the 16 originally with EEG activity, seven went up and achieved a recovery level scoring a 4 or higher on the Extended Glasgow Outcome Scale. This is a clinical scale that classifies the results of brain injuries from 1 (dead) to 8 ("upper good"), which generally means a resumption of normal life. A score of 4 is considered an "upper severe disability". Patients with this score rely on daily support, but can stay home alone for eight or more hours. While 44% (seven patients) with EEG activity reached 4 or more within one year after injury, only 14% (12 of the 88 patients) without EEG had a score of 4 or more. The study was not large enough to link such findings to causes of brain injury.
NEJM, 2019. DOI: 10.1056 / NEJMoa1812757 (About DOIs).