Programmable shunt valve affected by exposure to a tablet computer

Laboratory investigation

Restricted access

Object

The authors investigated the effect of a tablet computer on performance-level settings of a programmable shunt valve.

Methods

Magnetic field strength near the tablet computer with and without a cover was recorded at distances between 0 and 100 mm. Programmable valves were exposed to the tablet device at distances of less than 1 cm, 1–2.5 cm, 2.5–5 cm, 5–10 cm, and greater than 10 cm. For each distance tested, the valves were exposed 100 times to the tablet with the cover, resulting in 500 total valve exposures. The tablet alone, without the cover, was also tested at distances of less than 1 cm for 30 valve exposures. Changes in valve performance-level settings were recorded.

Results

The maximum recorded magnetic flux density of a tablet with a cover was 17.0 mT, and the maximum recorded magnetic flux density of the tablet alone was 7.6 mT. In 100 exposures at distances between 0 and 1 cm, 58% of valves had different settings following exposure. At distances greater than 1 cm but less than 2.5 cm, 5% of valves in 100 exposures had setting changes. Only a single setting change was noted in 100 exposures at distances greater than 2.5 cm but less than 5 cm. No setting changes were noted at distances greater than 5 cm, including 100 exposures between 5 and 10 cm, and 100 exposures of more than 10 cm. For the 30 valve exposures to the tablet without a cover, 20 valve performance-level changes (67%) were noted.

Conclusions

Based on these results, exposure to tablet devices may alter programmable shunt valve settings.

Article Information

* Drs. Strahle and Selzer contributed equally to this work.

Address correspondence to: Cormac O. Maher, M.D., Department of Neurosurgery, University of Michigan, 1500 East Medical Center Drive, Room 3552 Taubman Center, Ann Arbor, Michigan 48109-5338. email: cmaher@med.umich.edu.

Please include this information when citing this paper: published online June 26, 2012; DOI: 10.3171/2012.3.PEDS1211.

© AANS, except where prohibited by US copyright law.

Headings

Figures

  • View in gallery

    Photograph showing areas (circles) on the iPad 2 where the highest magnetic field was recorded for each of 3 tested devices. There was a slightly higher magnetic field at the location marked by the asterisk; therefore this location was used for testing.

  • View in gallery

    Line graph depicting magnetic field strength according to distance from the tablet device with cover, and the tablet alone, for distances ranging between 0 mm (contact) and 100 mm.

  • View in gallery

    Bar graph illustrating percent (in decimals) of valves with a change in performance level following exposure to the iPad 2 at increasingly greater distances.

References

1

Anderson RCWalker MLViner JMKestle JR: Adjustment and malfunction of a programmable valve after exposure to toy magnets. Case report. J Neurosurg 101:2 Suppl2222252004

2

Miwa KKondo HSakai N: Pressure changes observed in Codman-Medos programmable valves following magnetic exposure and filliping. Childs Nerv Syst 17:1501532001

3

Schneider TKnauff UNitsch JFirsching R: Electromagnetic field hazards involving adjustable shunt valves in hydrocephalus. J Neurosurg 96:3313342002

4

Sprung CSchlosser HGLemcke JMeier UMessing-Jünger MTrost HA: The adjustable proGAV shunt: a prospective safety and reliability multicenter study. Neurosurgery 66:4654742010

5

Taking the tablets: the iPad's dominance of the market for tablet computers may prove short-lived. Economist March22011. (http://www.economist.com/blogs/dailychart/2011/03/tablet_computers) [Accessed April 9 2012]

6

Utsuki SShimizu SOka HSuzuki SFujii K: Alteration of the pressure setting of a Codman-Hakim programmable valve by a television. Neurol Med Chir (Tokyo) 46:4054072006

7

Zuzak TJBalmer BSchmidig DBoltshauser EGrotzer MA: Magnetic toys: forbidden for pediatric patients with certain programmable shunt valves?. Childs Nerv Syst 25:1611642009

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