Improving Awakening Prognostication After Non Anoxic Coma Using PET-MRI in Intensive Care Unit

In last decades, several advances in the neuro-intensive management have lead to decrease mortality in Intensive Care Units. A significant morbidity remains as patients survive after a traumatic coma with uncertain quality of awakening and a high risk of functional disability. Predicting awareness recovery and functional disability of those who will awake constitutes a major challenge to inform patients' relatives, to give the best chances in terms of rehabilitation resources or to adapt intensive cares to a reasonable level. Tools currently available are not sufficient neither to predict bad awakening outcome nor to predict good functional outcome. In many countries, life's support cessation is a constant call for robust evaluation as soon as possible in ICU but it is mandatory to reach a positive predictive value of non-awaking close to 100%. Many clinical, electro-physiological, biological, radiological and functional parameters have been conducted with comatose patients assuming the purpose to predict outcome. Regarding unfavourable outcome, the gold standard is the abolition of the N20 component of somatosensory evoked potentials but the specificity is high enough only for patients with anoxic coma. Several neurophysiological markers such as MMN, P300 are correlated to a favourable outcome but the sensitivity and specificity remains low for patients who suffered a severe traumatic brain injury. New Diffusion Tensor imaging sequences provide complementary information to detect small structural lesions (diffuse axonal lesions). Recently, functional MRI analyzing Resting State has also been proposed as a prognostic marker during coma. PET using Fluoro-Desoxy-Glucose is able to assess the metabolism in key regions of the awakening network in either anaesthesia or sleep. Recent studies have reported interesting results at the chronic stage but to knowledge, these tools have only been used to address pathophysiology's issues and never to improve coma prognosis at the