Researchers at the University of Michigan have found that the Apple iPad 2 can interfere with settings of magnetically programmable shunt devices, which are often used to treat children with hydrocephalus. The iPad 2 contains magnets that can change valve settings in the shunt if the tablet computer is held too close to the valve (within 2 inches). Such a change may result in shunt malfunction until the problem is recognized and the valve adjusted to the proper setting. Patients and their caregivers should monitor use of the tablet computer to ensure that no change is made to the valve settings. The results of this study can be found in the article "Programmable shunt valve affected by exposure to a tablet computer. Laboratory investigation," by Strahle and colleagues, published in the August 2012 issue of the Journal of Neurosurgery: Pediatrics and available online today.
The researchers first thought of performing this study because a tablet computer seemed to affect a programmable shunt in one of their patients, a 4-month-old girl with hydrocephalus. Three weeks after the baby had received the shunt, she was examined for shunt malfunction due to a changed setting in the magnetically programmable valve that regulates the flow of cerebrospinal fluid. The baby's mother stated that she had held an iPad 2 while holding the infant. Programmable shunt valve settings can be altered by exposure to magnetic fields. Indeed, specialized magnets are used by physicians to adjust the settings on these valves. Since in this case no other environmental factor could be identified that would have led to a shift in the valve settings, the authors decided to test whether the iPad 2 might be implicated because, unlike the initial iPad, the iPad 2 contains several magnets and is often used with an Apple Smart Cover, which contains additional magnets.
The researchers tested 10 programmable shunt valves with a variety of settings. They exposed the valves to an iPad 2 with and without the Smart Cover at different distances: less than 1 centimeter (cm), 1 to 2.5 cm, 2.5 to 5 cm, 5 to 10 cm, and greater than 10 cm. Each exposure lasted 10 seconds. Overall, the valves were tested 100 times for each of the five distances during exposures to the iPad 2 with the Smart Cover closed and 30 times for distances less than 1 cm for the tablet computer without the cover.