title: Effect of amusement park rides on programmable shunt valve settings.
abstract: BACKGROUND
  Magnetically programmable shunt valves are susceptible to environmental factors including magnetic fields and accelerative forces. It is unknown if rollercoasters with or without magnetic brakes or linear induction motors (LIMs) are capable of altering the setting of a programmable shunt valve.
  
  
  METHODS
  Two different valve types (type A, n = 10; type B, n = 9) were tested at varying resistance settings in 2 trials on 6 different amusement park rides including 2 rides with LIMs, 2 rides with magnetic brakes, and 2 rides without magnetic technology.
  
  
  RESULTS
  The performance level of valve type A and the setting of valve type B changed on rollercoasters with magnets (A = 2.5% [2/80]; B = 5.6% [4/72]) and without magnets (A = 7.5% [3/40]; B = 2.8% [1/36]). Neither valve setting changed when exposed to a Ferris wheel or during ambulation throughout the park.
  
  
  CONCLUSIONS
  Magnetically programmable valves are susceptible to changes in pressure settings when exposed to amusement park rides with elevated vertical gravitational forces, irrespective of the presence of LIMs or magnetic brakes.
authors.affiliation: Department of Neurosurgery, University of Michigan, Ann Arbor, Mich., USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Strahle
authors.forename: Kelly
authors.initials: K
authors.lastname: Collins
authors.forename: William R
authors.initials: WR
authors.lastname: Stetler
authors.forename: Brandon W
authors.initials: BW
authors.lastname: Smith
authors.forename: Thomas
authors.initials: T
authors.lastname: Garton
authors.forename: Catherine
authors.initials: C
authors.lastname: Garton
authors.forename: Hugh J L
authors.initials: HJ
authors.lastname: Garton
authors.forename: Cormac O
authors.initials: CO
authors.lastname: Maher
mesh_terms: D000054:Acceleration / Q000009:adverse effects*; D002557:Cerebrospinal Fluid Shunts / Q000009:adverse effects*; D002648:Child; D004867:Equipment Design; D006112:Gravitation; D006801:Humans; D006849:Hydrocephalus / Q000601:surgery*; D007899:Leisure Activities; D060526:Magnetic Fields / Q000009:adverse effects*; D018570:Risk Assessment