Individuals implanted with programmable cerebrospinal fluid (CSF) shunts are at increased risk for unintended changes to valve settings through exposure to magnetic fields present in implantable medical devices, according to a letter from the US Food and Drug Administration (FDA) to clinicians.
In the letter, the FDA sought to increase awareness regarding potential complications in individuals with programmable shunts and devices such as cochlear implants, bone conduction hearing devices, and middle ear hearing devices. The FDA warned close proximity between such devices and programmable CSF shunts may lead to unintended changes in valve settings and, in turn, cause over- or under-drainage of CSF.
Symptoms Associated With Over- or Under-Drainage of CSF
- Altered mental status
- Vision changes
- Gait instability
Complications Associated With Untreated Over- or Under-Drainage of CSF
- Loss of consciousness
Recommendations to Prevent Complications
- Educate patients and caregivers regarding the potential risk of changes in programmable CSF valve shunt setting, symptoms associated with over- or under-drainage of CSF, and when to contact their health care provider.
- Trained clinicians should routinely check programmable CSF valve shunt settings, especially after placement or adjustment of devices with a magnetic field.
- For individuals with a unilateral device containing a magnetic field, the implanting physician should consider placing a programmable CSF shunt contralateral to the magnetic device.
- For individuals with a bilateral device containing a magnetic field (eg, hearing implant), the implanting physician should consider maximizing the distance between the programmable CSF shunt and the magnetic device.
The FDA recommended reporting confirmed or suspected adverse events associated with the interaction between programmable CSF shunts and devices with magnetic fields. Voluntary reports can be submitted through the FDA’s Safety Information and Adverse Event Reporting Program (MedWatch).
In a closing remark they indicated that, “[p]rompt reporting of adverse events can help the FDA identify and better understand the risks associated with medical devices.”
Programmable CSF Shunts and Magnetic Field Interference with Implanted Hearing Devices – Letter to Health Care Providers. US Food and Drug Administration. https://www.fda.gov/medical-devices/letters-health-care-providers/programmable-csf-shunts-and-magnetic-field-interference-implanted-hearing-devices-letter-health-care. Accessed July 16, 2019.