In this case study, we report the longitudinal and multimodal follow-up of a catastrophic initial presentation of cerebral fat embolism syndrome. We show that despite the initial severity, the cognitive outcome was ultimately very good but with a highly nonlinear time-course and prolonged loss of consciousness (more than 2 months). Repeated clinical assessments and brain-imaging techniques (electroencephalography, event-related potential, 18-Fluoro-Deoxy-Glucose-PET and magnetic resonance imaging) allowed us to monitor and anticipate this dynamic, providing relevant information to guide decision making in front of withdrawal of life-sustaining therapy discussions. This case illustrates the value of multimodal functional imaging in devastating brain injuries.