Medical Devices

Information for Patients and Caregivers about Magnetic Field Interference

If you have a CSF shunt or you care for someone who has one, the following strategies may help prevent unintended changes to your CSF shunt valve:

Know your Shunt

  • Make sure you know what type of CSF shunt you have (or that the person you are caring for has). Knowing the shunt type can help you get appropriate treatment if a shunt-related problem occurs. This is particularly important if you need medical attention in an emergency, where the doctors may not be familiar with all of your medical history or have access to your medical records.
  • The only sure way to know if an adjustable shunt valve setting has changed is to have the pressure setting checked by a physician with an X-ray or specialized magnetic tool known as a shunt checker. Only a qualified physician should check your shunt valve setting. It is preferable to have the shunt checked by a clinician (e.g. neurosurgeon) who can also adjust the setting if necessary. Shunt checkers are specific to each shunt device manufacturer. It is important that the shunt checker be compatible with the shunt.

Know your Risk of Harm is Low

  • The FDA believes that serious adverse events due to unintended changes in magnetic externally adjustable CSF shunt valve settings are rare compared to other CSF shunt malfunctions such as blockage or infection. Early detection of unintended changes can be maximized through maintaining routine physician visits, checking and resetting valves following MRIs, and understanding the symptoms of over or underdrainage.
  • Unintended changes in shunt valve setting are usually not life-threatening. Headache is often the first symptom when a shunt is not draining properly. For most patients, problems with drainage are addressed before health conditions worsen. However, young children with shunts may not be able to communicate that they are experiencing headache and may progress to additional symptoms before they receive medical care. The degree of symptoms depends on how much the setting changed, for how long the setting was changed, and how sensitive the patient is to changes in pressure. In some cases, the patient could experience symptoms of hydrocephalus. In other cases, the patient could experience no symptoms at all.
  • Additional data is needed to understand the possible relationship between magnetic externally adjustable CSF shunt valves and magnets found in the environment. However, it is reasonable to assume that a shunt valve that is manipulated by a hand-held magnetic tool may also be vulnerable to other external magnetic sources. This is why FDA recommends keeping magnets some distance away from shunts with magnetic externally adjustable valves.

Prevention Tips for Children with CSF Shunt Systems

Some children may be more prone to force trauma (blows to the head) due to their developmental stage and physical ability. Additionally, children may be exposed to different types of magnetic sources than adults, for example in toys or in sources closer to the ground. Children may also need assistance caring for their device or with their activities of daily living, which can expose them to multiple caregivers. Some ways you can help keep your child safe include:

  • Be aware of strong magnetic sources and keep them away from your child, particularly at the site of their device. Inform children how to interact safely with known magnetic sources that they may encounter at home, school, or at other activities. For example, encourage your child to use a cell phone on the opposite side of the head from the shunt.
  • Be aware that strong forces can cause physical damage to implanted CSF shunts. For example, some amusement park rides, contact sports, or playground injuries can damage a shunt. If in doubt about whether or not a certain activity may damage your child’s shunt, contact your physician.
  • Read label information and talk to the child’s health care professional when considering which CSF shunt to use. Important factors to consider include the child’s age and size, other medical conditions, as well as the child’s ability to tolerate the device for the time it will be used. In addition, not all pediatric patients are alike. Devices might need to be changed or replaced as children grow.
  • Be alert for signs of device problems because some children may not be able to communicate discomfort or distress.
  • Watch for signs of infection around the device location, such as redness, swelling, discharge, heat, or pain.
  • Make sure that the people with whom your child is in regular contact, such as family members, teachers, babysitters, coaches, etc., know about your child’s shunt, what exposures and activities might place the child at risk for device damage, what health symptoms to look for that might indicate a problem, and what to do in case of a shunt-related problem.

Report Problems

Parents and other caregivers can report problems with medical devices through MedWatch: The FDA Safety Information and Adverse Event Reporting program. Make sure to include the patient's age and as much information about the event and device as possible to facilitate identifying pediatric device problems.

Page Last Updated: 01/05/2018
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