Brain response to thermal stimulation predicts outcome of patients with chronic disorders of consciousness

Objective: To study the role of brain responses to thermal stimulation in outcome prediction of patients in either vegetative or minimally conscious states. Methods: We performed a prospective study with 22 patients and used functional magnetic resonance imaging (fMRI) and EEG reactivity (EEG-R) tests in conjunction with thermal stimulation. We conducted thermal stimulation on patients by stimulating either their feet (fMRI) or hands (EEEG-R) with warm water (42 +/- 2 degrees C). Each patient received a 1-year follow-up. Results: Among the 22 patients, 1 was lost to follow-up, 10 had improved outcomes, and the remaining 11 patients showed no improvement. Thermal stimulation induced three different fMRI brain activation patterns: (1) high-order activation in 4 patients, (2) primary activation in 6 patients, and (3) no activation in 11 patients. Eight of the 10 patients with either high-order or primary activation had an improved outcome. Contrastingly, only 2 of the 11 patients with no activation pattern showed improvement. EEG-R was elicited in 11 patients and 9 of them showed improved outcomes. However, among the 10 patients with no EEG-R, 9 patients did not improve. Conclusions: Using fMRI and EEG to measure brain responses to thermal stimulation is capable of predicting patient outcomes with a high degree of predictive accuracy. Significance: Thermal stimulation can be used as an objective and quantifiable somatosensory stimulation mode for clinical EEG-R and fMRI tests. (c) 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.