When riding in cars, children older than four years are safer in belt-positioning booster seats. In a cross-sectional study published in JAMA, researchers collected data on injuries to children four to seven years of age from insurance claims records and telephone surveys in 15 states (probability sample of 3,616 crashes involving 4,243 children). Injuries occurred in 1.81 percent of all four- to seven-year-old children, including 1.95 percent of those in seat belts and 0.77 percent of those in belt-positioning booster seats. The risk of injury was 59 percent lower in the children who were in belt-positioning booster seats. In these children, there also were no reports of injuries to the abdomen, neck, spine, back, or lower extremities. Belt-positioning booster seats function by raising a child up so that the seated height is more like that of an adult, allowing the car's seat belt to fit properly.

A medical mystery solved? A study published in Conservation Biology suggests that an appetite for flying fox bats may be the reason for a high incidence of a neurologic disease in Guam's indigenous Chamorro people. Historically, up to one third of persons in every village developed a complex neurologic syndrome with clinical features of amyotrophic lateral sclerosis, parkinsonism, and dementia. Researchers believe that eating the bat could be dangerous because the animal eats cycad seeds, which contain a neurotoxin. The Chamorro people put all parts of the bat, including the wings, fur, and brains, in a stew that is popular at weddings, parties, and religious events.

Are glare-reducing products worn by athletes anything more than psychologic warfare? A study published in the Archives of Ophthalmology showed that eye black grease, a form of face paint smeared on the cheekbones, does reduce glare and improve contrast sensitivity. Using a Pelli-Robson contrast chart, researchers tested 46 student volunteers from Yale University for contrast sensitivity changes as they faced into the sun for three hours. The students first were tested without a glare-reducing product and then randomized to application of eye black grease, antiglare stickers, or petroleum jelly (control) at the infraorbital rim. They showed a significant difference between eye black grease and antiglare stickers or petroleum jelly.

Carotid artery dissection is a possibility in patients who present with pulsatile tinnitus. In a case report published in The Lancet, a 40-year-old man presented to the emergency department with right-sided tinnitus. He first noticed the tinnitus after riding a bicycle for four hours in mountainous terrain. Magnetic resonance angiography showed right-sided carotid artery dissection with segmental loss of flow signal and a hematoma in the ventral vessel wall. Aspirin was prescribed to reduce the risk of embolization, and the tinnitus resolved within one week. The authors of the case report noted that the cyclist's hyperextended neck plus the rough terrain probably contributed to the arterial dissection.

Myth or fact: stress causes acne. It's a fact, according to the results of a prospective cohort study published in the Archives of Dermatology. Twenty-two college students with acne were evaluated one month before any scholastic examination and again three days before to seven days after a test period. During both visits, the students' perceived stress was measured. Researchers found that increased stress correlated strongly with a progressive increase in the severity of acne. Stress may provoke increased release of hormones associated with acne.