Usher's Stepson Kile Glover: What Happened?

'There is no one that has been declared brain dead that has survived to being functional,' said neurologist Dr. Bren Masel, who was not treating Glover.

More than a week after Usher's stepson, Kile Glover, was pronounced brain dead
 following a traumatic head injury suffered during a jet-ski accident
, the 11-year-old boy died
 of heart failure on Saturday.

Glover, the son of Usher's ex-wife, Tameka Foster, was reportedly taken off life support Saturday morning and died a short time later.

Given the seriousness of his injury, which resulted from blunt trauma to the head after Glover was hit by a jet-ski while floating in an inner tube on Atlanta's Lake Lanier, MTV News spoke to a neurologist about the prospects for victims of such major brain injuries.

"There is no one that has been declared brain dead that has survived to being functional," said neurologist Dr. Brent Masel, national director of the Brain Injury Association of America and medical director of the Transitional Learning Center of Galveston, Texas several days before Glover was pronounced dead. "They will not get better."

Masel, who was not treating Glover and had no first-hand knowledge of the case, explained that the prognosis in such cases is so grim because of the make-up of the brain. "When someone is declared brain dead, it's not that their brain is not functioning at all," he said. "There are two components to the brain, the cerebrum, which is the thinking part and the brain stem, which narrows and becomes the spinal cord."

The stem is the automatic part, which controls respiration and heart rate and someone can technically live without a functioning cerebrum, which is not unusual in such injuries. "The thinking part of the brain is no longer functioning and all the patient has functioning is the brain stem," he said. "Very often what happens when you're deciding if someone is brain dead, you take them off the respirator and they're not even breathing and the only thing going is their heart, which will stop functioning if you're not breathing."

Glover and a second victim, a 15-year-old girl, were struck by a Jet Ski while floating on an inner tube in Atlanta's Lake Lanier. Both children were airlifted to the Children's Healthcare of Atlanta at Egleston pediatric hospital. The girl is reported to have suffered from a cut on the head and a broken arm, while Glover took the brunt of the trauma to his head.

Asked how it's possible that Glover could have suffered such a terrible wound while the girl in the inner tube with him escaped with less serious injuries, Masel said it is part of the unpredictable nature of trauma medicine. Pointing to a jet-skiing accident he was involved in 10 years ago in which he nearly ran over a friend's son, as well as the shooting of Congresswoman Gabrielle Giffords (whose case he helped work on), Masel said "it's a matter of millimeters."

Just a few millimeters over and Glover may have come out with a very different wound, he said, noting that there are several very vulnerable spots on the brain that can result in such injuries.

"As physicians, especially with a child, it's the hardest thing in the world because very often the child sort of looks okay and there are miracles that could occur," he said.

"What I always try to do is ask, 'what would I do if this was my sister or brother?' If I were the doctor I would say, 'if this were my child this is what I would do.' Could you breathe for that patient forever? Yes, We know artificial respiration isn't adequate, [though] and it's not the same as breathing normally. You can have someone on a respirator for a long period of time and eventually the brain deteriorates. Even if they said they want[ed] to keep him on the respirator for six months, or a year and wait for a miracle, the brain [wouldn't] be the same."

The man driving the jet ski has been identified as 38-year-old Jeffrey S. Hubbard, a family friend. At this time the police have determined that no drugs were involved, and no charges have been filed.