By : Laura LECRAC and Marine MORILLON
In the city of Lyon (France), researchers from the Institute of Cognitive Sciences at the Pierre Wertheimer neurological hospital have succeeded in making a man lying in a vegetative state for 15 years to a “minimal state of consciousness”.
In order to understand the context of this medical feat, some aspects should be clarified. First, who is the patient ? Fifteen years ago, the patient, now aged thirty-five years old, was the victim of a road accident that led him in a coma. Now, his state never improved and for fifteen years, he is in a vegetative state. A vegetative state means that the consciousness is impaired (Giacino, Fins, Laureys & Schiff, 2014). This impairment is caused by brain lesions.
The purpose of this study is to improve the state of consciousness of a patient lying in a vegetative state. To do this, researchers have implanted an electrode in the neck to stimulate the left vagus nerve. Although invasive, this technique is now widely understood, it has been used for twenty years in the treatment of drug-resistant epilepsy and depressions (Shi, Flanagan, & Samadani, 2013).
According to the protocol, the stimulation of the vagus nerve was repeated and progressive by increasing the electrical intensity.
But why stimulate the vagus nerve? For this, it is necessary to understand its action. Benjamin Rohaut, neurologist resuscitator and researchers at Columbia University (New York), explains: “It is this nerve that ensures the functions called vegetative such as breathing heart rate or digestion.” (Le Figaro, 2017). This nerve thus seems important in the management of vital functions. In fact, it seems that stimulation of the vagus nerve increases the metabolism of the anterior brain, thalamus and reticular formation; the latter being particularly involved in awareness.
One month after implantation, findings indicate an improvement of general arousal, attention, visual pursuitand body mobility. The Coma Recovery Scale-Revised (CRS-R) scale reveals a transition from the vegetative state to a minimal state of consciousness.
To conclude, during the six months of application of this protocol, the results seem to demonstrate the benefits of vagus nerve stimulation in this patient lying in a vegetative state. This stimulation has improved both the behavioural reactivity of the patient and the connections within the brain.
Thus, this study seems to be a source of hope. However, this research raises ethical issues. The patient, in a vegetative state, is not able to give his consent to participation. Indeed, even if his family agreed, what would have been the wish of the patient ? Besides, the patient has not woken up for many years, negative emotions (e.g. fear) could be felt, especially when researchers report the observation of reactions to threatening stimuli. Thus, this situation may have generated anxiety.
Moreover, since the protocol was stopped, no further analysis was carried out. This raises the question of the long-term beneficial effects of this stimulation because this technique implied a permanent stimulation of the vagus nerve.
This study for this patient was stopped. After this convincing result, researchers are applying this protocol to three other patients who are also in a state of altered consciousness.
Reference
Corazzol, M., Lio, G., Lefevre, A., Deiana, G., Tell, L., André-Obadia, N., Bourdillon, P., Guenot, M., Desmurget, M., Luauté, J., & Sirigu, A. (2017). Restoring consciousness with vagus nerve stimulation. Current biology, 27, 994-996. doi: http://dx.doi.org/10.1016/j.cub.2017.07.060
Giacino, J. T., Fins, J. J., Laureys, S., & Schiff, N. D. (2014). Disorders of consciousness after acquired brain injury: the state of the science. Nature Reviews Neurology, 10(2), 99– 114. https://doi.org/10.1038/nrneurol.2013.279
Shi, C., Flanagan, S. R., & Samadani, U. (2013). Vagus nerve stimulation to augment recovery from severe traumatic brain injury impeding consciousness: a prospective pilot clinical trial. Neurological Research, 35(3), 263–276. https://doi.org/10.1179/1743132813Y.0000000167
Tristan Vey. (2017, 26/09). Après 15 ans d’état végétatif, un patient recouvre une forme de «conscience». Le Figaro. http://sante.lefigaro.fr/article/apres-15-ans-d-etat-vegetatif-un-patient-recouvre-une-forme-de-conscience-/
