The use of all-terrain vehicles (ATVs) has increased in the United States and elsewhere over the last three decades, along with an increased frequency of incidents resulting in serious injuries, among which have been head injuries. ATVs are designed for motorized off-highway work and recreation, can weigh up to 600 lbs (272 kg), and may reach speeds as high as 75 mph (120 km/h). ATV crashes, in...