UPDATED July 6, 11:13 a.m.: TMZ reports that Kyle Glover, Usher's stepson, may be removed from life support by next month because his insurance coverage will end.

TMZ explained:

According to our sources, Tameka can only keep Kyle on life-support as long as her insurance company agrees to pay ... otherwise she doesn't have the funds to cover the enormous hospital bills.

For more, click over to TMZ.

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Kyle Glover, the 11-year-old stepson of Usher, was declared brain dead after being struck by a jet ski on Sunday, according to news reports.

Glover was riding in an inner tube in Atlanta's Lake Lanier, when a jet ski struck him, MTV reported. He was immediately taken by air to Children's Healthcare of Atlanta.

TMZ reported that Glover, who is the son of Tameka Foster, Usher's estranged wife, did not have any brain activity when he arrived at the hospital, and is still on life support.

Brain death occurs when all brain activity has stopped permanently, the person is in a coma, and the person is no longer breathing, USA Today reported. However, this state is different from, say, a vegetative state, because there has never been a case where someone has been able to wake up from a brain-dead state. It's also different from a coma, because people are able to wake up from comas, unlike brain death.

The U.S. Department of Health & Human Services reported that brain death occurs when oxygen from blood is no longer delivered to the brain, which results in brain cell death. Common causes of brain death include stroke, a ruptured brain aneurysm, trauma to the head, drowning or a gunshot wound.

According to the most recent definition published in the journal Pediatrics, brain death in children "is a clinical diagnosis based on the absence of neurologic function with a known diagnosis that has resulted in irreversible coma."

The guidelines note that in order to have an official diagnosis of brain death, there must be coma and apnea (which means to cease breathing) at the same time.

Wired reported that even if a person is brain dead, he or she can still have a heart beat with or without the help of a ventilator.

Wired explains:

Harvard Medical School officials conceived the term "brain dead" in a 1968 paper. Officials there hoped to resolve a novel phenomenon: With new technology patients who were dead could still have a heartbeat -- and give the false impression that they were very much alive while kept on a ventilator.