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  1. Cerebral Spinal Fluid (CSF) Shunt Systems

Information for Clinicians about Magnetic Field Interference

July 16, 2019: To increase awareness about programmable CSF shunt valves and magnetic field interference from hearing devices that use magnets, the FDA issued a Letter to Health Care Providers with suggestions for mitigating the risk of unintended valve setting changes.

The following strategies may help prevent unintended changes to magnetic externally programmable CSF shunt valves:

Ensure Patients and Caregivers Understand the Risks

  • Provide patient education about precautions, including environmental sources of magnetic fields.
  • Inform patients of signs and symptoms that may be associated with valve setting changes.

Check Valve Settings Routinely

  • Verify that settings are correct. 
  • Examine patients to ensure that they are not experiencing over- or underdrainage of CSF.

Report Problems

As the primary users of CSF Shunts, clinicians play a critical role in conducting safety checks, assessing the performance of these devices, and reporting issues that impact their performance. Prompt reporting of adverse events can help the FDA identify and better understand the risks associated with medical devices.

Additional data are needed to understand fully the possible relationship between magnetic externally programmable 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.

  • Report all details surrounding unintended valve-setting change events including, but not limited to:
    • Details of the resetting event, including the suspected distance of the 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 magnetically programmable shunt
    • Patient age, gender, underlying diagnosis for shunt (such as trauma, hydrocephalus)
    • Other medical devices in region of shunt (for example, cranial plate, cochlear implant
    • Device evaluation post-explant, if available
  • Be aware that adverse event reports can still be submitted to the FDA under the Health Insurance Portability and Accountability Act (HIPAA) Privacy Rule.