CHARLOTTESVILLE, VA (JULY 7, 2015). Researchers at Brown University examined three magnetically programmable shunt valves to see if the magnetic field emissions of headphones can cause unintentional changes in shunt valve settings. Based on their findings, the researchers state that it is highly unlikely that commercially available headphones will interfere with programmable shunt valve settings. Full details of this study can be found in "Programmable shunts and headphones: Are they safe together?" by Heather S. Spader, MD, and colleagues, published today online, ahead of print, in the Journal of Neurosurgery: Pediatrics.
A variety of everyday objects emit electromagnetic fields that can potentially affect magnetically programmable shunt valve settings if brought too close to the valve. Examples include the iPad 2 and household magnets such as those found in refrigerator doors. Patients need to keep a safe distance between their heads and these objects. As far as the authors know, there has been no study to determine whether headphones affect magnetically programmable shunt valve settings. Given that the wearing of headphones has become ubiquitous and headphones are placed quite near the location of most shunt valves, Dr. Spader and colleagues decided to test whether potential problems may exist.
The researchers used three programmable shunt valves that are widely used to treat hydrocephalus (the Codman® Hakim® programmable valve, Medtronic Strata® II valve, and Aesculap proGAV™) to test the effects of three popular headphones (Apple earbuds, Beats by Dr. Dre, and Bose QuietComfort® Acoustic Noise Cancelling headphones). Electromagnetic field emissions from the headphones were examined using a direct-current gaussmeter. The researchers measured electromagnetic field emissions at distances ranging from 0 to 50 mm away from the headphones. All measurements were taken three times, and the mean emissions detected at the various distances were recorded. The gaussmeter detected high magnetic field emissions at 0 mm, but the emission levels dropped down quickly as the gaussmeter was moved away from the headphones.
To determine what effect headphones would have on programmable valve settings, the researchers set up each valve 0, 5, 10, 15, 20, and 50 mm away from each headphone. When there was direct contact between the headphone and valve (0 mm), the magnetic field strength of all earphones was sufficient to change the settings of the Codman® Hakim® and Medtronic Strata® II valves. At distances of 5 mm or greater, however, no changes in valve settings occurred. Settings on the Aesculap proGAV™ valve were unaffected by all headphones at all distances tested.
Based on their findings, the researchers state: "Neurosurgeons should be aware that the potential for shunt reprogramming in patients using headphones is remote unless a headphone is in direct contact with a programmable shunt valve or there is tangential movement of a headphone around a valve. . . . Shunts are more likely to fail from obstruction, infection, or valve failure than from reprogramming from magnets."
When asked whether the authors were surprised about the results of their study, Dr. Spader said, "Given the published risk of iPads and programmable shunts, we were worried that headphones could have a similar effect. We were surprised to find that headphones are unlikely to reprogram shunts." Despite the strong findings, Dr. Spader adds, "Given the limitations of our study, we think that the public should be aware that there are magnets in headphones and there could still be some adverse interaction."
Spader HS, Ratanaprasatporn L, Morrison JF, Grossberg JA, Cosgrove GR. Programmable shunts and headphones: Are they safe together? Journal of Neurosurgery: Pediatrics, published online, ahead of print, July 7, 2015; DOI: 10.3171/2015.1.PEDS14400.
Disclosure: The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.
The Journal of Neurosurgery: Pediatrics is a monthly peer-reviewed journal focused on diseases and disorders of the central nervous system and spine in children. This journal contains a variety of articles, including descriptions of preclinical and clinical research as well as case reports and technical notes. The Journal of Neurosurgery: Pediatrics is one of four monthly journals published by the JNS Publishing Group, the scholarly journal division of the American Association of Neurological Surgeons. Other peer-reviewed journals published by the JNS Publishing Group each month include the Journal of Neurosurgery, Neurosurgical Focus, and the Journal of Neurosurgery: Spine. All four journals can be accessed at http://www.
Founded in 1931 as the Harvey Cushing Society, the American Association of Neurological Surgeons (AANS) is a scientific and educational association with more than 8,300 members worldwide. The AANS is dedicated to advancing the specialty of neurological surgery in order to provide the highest quality of neurosurgical care to the public. All active members of the AANS are certified by the American Board of Neurological Surgery, the Royal College of Physicians and Surgeons (Neurosurgery) of Canada or the Mexican Council of Neurological Surgery, AC. Neurological surgery is the medical specialty concerned with the prevention, diagnosis, treatment and rehabilitation of disorders that affect the entire nervous system including the brain, spinal column, spinal cord, and peripheral nerves. For more information, visit http://www.