, et al
Programmable shunt valve affected by exposure to a tablet computer
J Neurosurg Pediatr.
; doi:

To determine the effect of magnetic field exposure from a tablet computer on programmable shunt valves used in treating children with hydrocephalus, investigators at the University of Michigan measured the magnetic field strength near the Apple iPad2 and iPad2 Smart Cover (Apple, Inc., Cupertino, CA) at distances between 0 cm and 100 cm. In an in vitro assessment, programmable valves were also exposed to the iPad2 device at distances of <1 cm, 1 cm to 2.5 cm, 2.5 cm to 5 cm, 5 cm to 10 cm, and >10 cm to determine how frequently shunt valve settings were changed as a result of the exposure.

The maximum recorded magnetic flux density of the iPad2 with Smart Cover was 17.0 mT and 7.6 mT for the iPad2 alone. In 100 exposures at distances between 0 cm and 1 cm, 58% of valves had different settings following exposure. In 100 exposures at distances >1 cm but <2.5 cm, 5% of valves had setting changes. Only a single setting change was noted in 100 exposures at distances >2.5 cm but <5 cm. No setting changes were noted at distances over 5 cm.

The investigators conclude that while exposure to the iPad2 may alter programmable shunt valve settings at very close ranges, no effects of the tablet computer device on the programmable valve over distances >5 cm were seen. The investigators suggest that patients and their caregivers should be warned of the potential for this interaction when the tablet is in very close proximity to the magnetically programmable shunt valve. The continued use of these devices in the general vicinity of patients with programmable shunt valves appears to be safe when proper precautions are observed to keep the tablet from close proximity to the valve.

Neurosurgical use of programmable valves began in the late 1980s. These devices improve the over-or-under drainage of cerebrospinal fluid in pediatric and adult patients and also allow the physician to change the valve pressure without an operation. Magnetically programmable shunt valves have been used with increasing frequency to treat children with hydrocephalus. The setting of these valves may be affected by magnetic fields.1-3  Intense magnetic fields from MRI will change the valve setting and require a nurse or physician to reprogram the valve after each MRI.

The authors do an excellent job answering a simple question that has important ramifications: does the magnet in the iPad and iPad2 cover affect the setting of a programmable valve? They demonstrate that the use of an iPad2 at normal working distances does not affect the pressure setting. Our patients can now be made aware that the iPad is safe at its normal working distance.

Another important study was published in 2009. Authors investigated 9 magnetic toys and...

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