I found this brief interesting discussion about epidural ( and subdural) hematomas in a discussion about Natasha Richardson's death.
"Talk and Die Syndrome
Symptoms don't always emerge right away after an injury like Richardson's—sometimes called "Talk and Die Syndrome"—making it difficult to determine the right response. "'Talk and Die Syndrome' refers to a lucid interval before a person begins to lose consciousness after a brain injury," says Douglas I. Katz, M.D., associate professor of neurology at Boston University School of Medicine and medical director of the brain injury programs at Braintree Rehabilitation Hospital in Braintree, MA. "The person may appear fine initially because the mass of blood in the head is expanding and there isn't too much pressure on the brain yet," he says.
If the bleeding continues, the amount of blood may become large enough to put pressure on the brain, according to Rolland S. Parker, Ph.D., a neuropsychologist in private practice in New York, NY, and adjunct professor of clinical neurology at New York University School of Medicine. "Eventually the blood clot may be large enough to interfere with oxygen entering the brain, pressing upon areas that create heartbeats and breathing," Dr. Parker explains."
We still don't know when and how the impact occurred in Mr. Sagert's case, but this Talk and Die Syndrome interval does make sense to how he was found, perhaps 12 hours after the accident. And he either didn't think it was serious enough to call for help, or was rapidly obtunded from the increased intracranial pressure.