Programmable CSF Shunts and Magnetic Field Interference with Implanted Hearing Devices - Letter to Health Care Providers
Medical Specialties: Pediatricians, ear nose and throat physicians, neurosurgeons, neurologists, audiologists, urgent care physicians, emergency responders, nurses, and other health care providers present during shunt implant surgeries
July 16, 2019
Dear Health Care Provider,
The U.S. Food and Drug Administration (FDA) wants to increase awareness about potential complications in patients implanted with both programmable cerebrospinal fluid (CSF) shunt systems and some hearing implants that contain magnets, such as cochlear implants, bone conduction hearing devices, or middle ear hearing devices. Magnetic interactions between these devices may occur when implanted in close proximity to each other. These interactions may lead to unintended changes to the programmable CSF shunt valve settings.
If magnetic interactions inadvertently change the programmable CSF shunt valve settings, then over- or under-drainage of CSF may occur. Patients may experience symptoms such as altered mental status, headaches, lethargy, irritability, vomiting, changes in vision, and difficulty walking. If left untreated, symptoms could progress to include loss of consciousness, seizures, hemorrhage, or even death.
- Educate patients and caregivers about this potential risk and be sure they know when to have their programmable CSF shunt valve checked, what symptoms are associated with potential over- or under-drainage of CSF, and when to contact you.
- Check the programmable CSF shunt valve setting after placement or adjustment of other devices that contain magnets to ensure that the setting has not changed. Only a trained clinician, such as a neurosurgeon, should check the shunt valve setting and adjust the setting, if necessary.
- Consider the location of placement of the programmable CSF shunt valve if the patient has other implanted devices known to contain magnets in close proximity. For example:
- Consider placing the programmable CSF shunt valve on the contralateral side of a cochlear implant or implantable bone conduction hearing device, if the patient's anatomy and clinical picture permit such a strategy.
- For patients requiring bilateral hearing implants, which use magnets and a programmable CSF shunt, the implanting physician should position the CSF shunt valve and the ipsilateral hearing implant at a maximum distance from one another.
- Contact the applicable device manufacturer for further information.
Cerebrospinal Fluid (CSF) Shunt Systems are commonly used to treat hydrocephalus. Hydrocephalus can cause problems with physical and mental development. If untreated, it can be fatal. CSF shunt systems drain excess fluid from the brain to another part of the body where the fluid is absorbed.
Patients implanted with programmable CSF shunt systems may have a potential risk of experiencing an unintended change in their valve setting if exposed to strong magnetic fields. The FDA previously developed a website on the general topic of programmable CSF shunts which includes information about magnetic field interference with programmable CSF shunt valves and possible interactions with common magnetic sources (such as security screening systems, tablets, toys with magnets and cell phones).
REPORTING PROBLEMS TO THE FDA
Report all adverse events or suspected adverse events experienced with programmable CSF shunts and potential magnetic interference:
- Voluntary reports can be submitted through MedWatch, the FDA Safety Information and Adverse Event Reporting program.
- Device manufacturers and user facilities must comply with the applicable Medical Device Reporting (MDR) regulations.
- Health care personnel employed by facilities that are subject to the FDA's user facility reporting requirements should follow the reporting procedures established by their facilities.
- When possible, reports should include the following information:
- Details of the resetting event, specifically the suspected distance of programmable CSF shunt from the magnetic source
- Identify the suspected magnetic source(s)
- Severity of patient symptoms
- Change in valve setting value from intended setting
- Manufacturer and brand of the programmable CSF shunt and the brand of the hearing device
- Patient age, gender, underlying diagnosis for shunt (such as trauma, hydrocephalus)
- Other medical devices in region of shunt (for example cochlear implant)
- Device evaluation post-explant, if available
Prompt reporting of adverse events can help the FDA identify and better understand the risks associated with medical devices.
The FDA will continue to keep the public informed if new or additional information becomes available.
If you have questions about this communication, please contact the Division of Industry and Consumer Education (DICE) at DICE@FDA.HHS.GOV, 800-638-2041 or 301-796-7100.
William Maisel, MD, MPH
Director, Office of Product Evaluation and Quality
Center for Devices and Radiological Health
U.S. Food and Drug Administration