 As part of the monitoring of the neurological disease, brain CT scans are frequently performed. At the same time, an acquisition sequence centered on the quadriceps will follow the brain sequences. Up to three brain CT scans coupled with a quadriceps imaging will be performed between the day of admission and on the tenth day of hospitalization. An ultrasound of the quadriceps will be performed concomitantly. The thickness of the quadriceps is measured by an independent operator on CT and ultrasound images. 