Correspondence

Magnetic Resonance Imaging and Cerebrospinal Fluid Shunt Valves

N Engl J Med 2005; 353:1413-1414September 29, 2005

Article

To the Editor:

In about 80 percent of all cases of hydrocephalus, the accumulation of cerebrospinal fluid is treated with shunt valves.1 Over the past 30 years, magnetically adjustable valves have become widely accepted and routinely implanted devices. In central and northern Europe, adjustable valves are routinely implanted for about 40 percent of all shunts (in Sweden, 37 percent of those used are made by Codman-Medos, 3 percent by Sophysa).2 Despite the widespread use of these valves, only a few studies regarding possible interactions with clinical magnetic resonance imaging (MRI) have been published. As high-field MRI is increasingly available and used, information is needed about MRI in patients with hydrocephalus who have implanted adjustable cerebrospinal fluid valves.

Two externally adjustable pressure valves, the Codman-Medos adjustable valve (Medos) and the Sophy SU8 valve (Sophysa), were exposed to magnetic fields in a 3.0-T MRI scanner (Magnetom Trio, Siemens).3 The valves that were investigated (12 Codman-Medos devices and 4 Sophy SU8 devices) were adjustable,4,5 and to simulate highly realistic conditions, predominantly explanted valves were investigated. After the valves had been inspected and damage or failure had been ruled out, the valves were fixed to the external surface of a spherical phantom and positioned in the scanner to simulate conditions during a standard clinical MRI scan. In order to simulate variations in examination duration and the potential need for repeated MRI examinations in patients with an adjustable valve, each valve was subjected to magnetic fields in the MRI scanner for 15 minutes and 1, 6, and 12 hours and subjected to measurements after each time point.

Six of the 12 Codman-Medos valves (50 percent) showed permanent failure of adjustability after exposure to the magnetic fields for most of the tested time periods, especially in high-pressure settings (Table 1Table 1Adjustability of 12 Explanted Codman-Medos Valves to the Indicated Opening Pressures after Exposure to 3.0-T MRI for the Indicated Time Periods.). Our data indicate the need for more extensive studies and the need to emphasize the clinical problems that may be encountered in this setting.

Michael Akbar, M.D.
Christoph Stippich, M.D., Ph.D.
Alfred Aschoff, M.D., Ph.D.
University of Heidelberg, 69118 Heidelberg, Germany
michael.akbar@ok.uni-heidelberg.de

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Citing Articles (6)

Citing Articles

1. 1

   Uwe Max Mauer, Ulrich Kunz. (2011) More malfunctioning Medos Hakim programmable valves: cause for concern?. Journal of Neurosurgery 115:5, 1047-1052
   CrossRef

2. 2

   Maria Blatow, Julia Reinhardt, Katharina Riffel, Ernst Nennig, Martina Wengenroth, Christoph Stippich. (2011) Clinical functional MRI of sensorimotor cortex using passive motor and sensory stimulation at 3 tesla. Journal of Magnetic Resonance Imaging 34:2, 429-437
   CrossRef

3. 3

   Uwe Max Mauer, Jens Schuler, Ulrich Kunz. (2007) The Hakim programmable valve: reasons for reprogramming failures. Journal of Neurosurgery 107:4, 788-791
   CrossRef

4. 4

   S. Paczynski, K.P. Braun, W. Müller-Forell, C. Werner. (2007) Fallgruben in der Magnetresonanztomographie. Der Anaesthesist 56:8, 797-804
   CrossRef

5. 5

   Gary L Gallia, Daniele Rigamonti, Michael A Williams. (2006) The diagnosis and treatment of idiopathic normal pressure hydrocephalus. Nature Clinical Practice Neurology 2:7, 375-381
   CrossRef

6. 6

   (2006) Magnetic Resonance Imaging and Cerebrospinal Fluid Valves. New England Journal of Medicine 354:5, 531-532
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