Mark S. Dias, MD, comments on the "Lucid Interval":
"First, 60% of children, and 80% of infants with EDH have no LOC at the moment of injury, and 7% have no alteration in level of conciousness at any time after the trauma (a scary statistic for those of us who see minor head injured children!). Second, a 'lucid interval' with EDH, despite the well known dictum, is NOT as common occurrence as you might think - I seem to recall that only about 30% of such individuals have a lucid interval, the remainder having no lucid interval. From the first statement above, however, one might calculate that as many as 53% of children, and 73% of infants, might have no LOC, only to deteriorate later in time. My own clinical experience is that this occurs much less frequently. The quality of that lucid interval is variable. Some children are completely asymptomatic, while others aren't 'right' during the lucid interval, complaining about headaches, not acting appropriately, etc.
As for the length of a lucid interval, I don't think you can say definitively whether the injury was minutes or hours before he was found, although the brisk arterial bleeding from the middle meningeal artery ar surgery would certainly make me think that it must have been a short time (minutes rather than hours) since arterial bleeding doesn't usually remain asymptomatic for long, as opposed to the venous oozing that we see with fractures, etc. The literature also describes children with asymptomatic epidurals who deteriorated (rarely) after periods of observation - you would want to check the literature on non-operative, or conservative, management of epidural hematomas (the first paper was by Dachling Pang in the late 80s I believe, and there have been many published subsequently). These series followed many children non-operatively, and demonstrate how long a child could remain asymptomatic or minimally symptomatic as well. However, you have to remember that these are the venous oozing variety, that I spoke of above, rather than the middle meningeal artery 'pumper' types.
Obviously, a normal 10 year old should be able to fully describe any trauma to the head severe enough to cause him an EDH."
Mark S. Dias, MD, FAAP
Associate Professor, State University of New York at Buffalo
Chief, Division of Pediatric Neurosurgery
Children's Hospital of Buffalo
219 Bryant Street
Buffalo, NY 14222
Phone: (716) 878-7386
Fax: (716) 888-3843