In this syndrome, one who is recovering from an initial concussion sustains a subsequent concussive injury, resulting in diffuse brain swelling and severe, permanent neurological dysfunction or death.

A rare condition described primarily in athletes who sustain a second head injury while still symptomic from an earlier one. Classically, the uthlete walks off the field under their own power after the second injury, only to deteriorate to coma within 1- 5 minutes and then, due to vascular engorgement, develops malignant cerebral edema that is refractory to all treatment and progresses to herniation.Mortality: 50-100%.