The results appear in the July issue of the Journal of Neurosurgery.
"Previously falls were considered relatively benign, because the head was assumed to move in a linear path at the terminus of a fall," said Susan S. Margulies, associate professor of bioengineering at Penn. "Linear motions are most frequently associated with skull fractures and focal brain injuries, but it is primarily rotational movements that produce more severe diffuse brain injuries. We found that when the head contacted a firm surface before the body, significant rotational motions were produced."
The Penn investigators found that rotational deceleration -- rapid changes in velocity as the head contacts a hard surface and then violently rebounds -- increased with higher falls and harder surfaces. The largest rotational decelerations, however, were measured when volunteers intentionally struck the doll's head against a hard surface. These inflicted impacts resulted in decelerations dramatically higher than those from even a five-foot fall onto concrete.
The findings by Margulies and her colleagues may help abuse investigators differentiate accidental falls from injuries caused by the striking of a child's head against a surface. Brain injuries -- accidental and inflicted -- hospitalize or kill an estimated 150,000 children annually in the U.S.
"Traumatic brain injury is the most common cause of death in childhood, and child abuse is believed to be responsible for at least half of infant brain injuries," Margulies
Contact: Steve Bradt
University of Pennsylvania