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  4. Electronic Medical Devices, X-ray Imaging and Radiation Therapy: What to Know and How to Prevent Damage
  5. Preventing Damage to Neurostimulators During CT Scans
  1. Electronic Medical Devices, X-ray Imaging and Radiation Therapy: What to Know and How to Prevent Damage

Preventing Damage to Neurostimulators During CT Scans

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A healthcare provider assisting a patient in a CT machine and the title Preventing Damage to Neurostimulators During CT Scans

Neurostimulators and Radiation Procedures 

Neurostimulators are small devices that can be implanted in the body. They deliver mild electrical signals to stimulate nerves. 

If you have a neurostimulator or provide health care to people with these devices, this page can help you prevent damage to those devices from radiation therapy. 

The FDA has received a very small number of reports of problems thought to be associated with CT imaging for people with implantable neurostimulators (including vagus nerve, bladder, spinal cord, deep brain devices). The problems noted in these reports included:

  • involuntary movements (Dyskinesia)
  • pain
  • shocks
  • dizziness
  • shaking
  • loss of therapy (such as change in operating mode)
  • discomfort
  • overstimulation
  • tingling sensation
  • burning sensation
  • headache and
  • the neurostimulator spontaneously turning on or off during or immediately after CT scans

The FDA has received relatively few reports of issues with neurostimulators compared to the vast number of patients scanned without any complications. Advances in neurostimulator technology have led to a decrease in reported problems. Although the issues mentioned occurred during CT scans, there is minimal evidence to suggest that CT exposure was the direct cause of these problems.

Based on the available evidence1, the chance of device malfunction due to CT scan is extremely low. You can further reduce the risk of potential problems by following the recommendations below.

Recommendations for people with neurostimulators

If your doctor recommends a CT scan, it is for medical reasons. The probability of a problem occurring is extremely low. You can help reduce the risk by doing the following:

  • Tell your doctor who ordered the CT scan as well as the tech performing the scan that you have an implanted neurostimulator. This will help them plan imaging that minimizes the risks of problems.
  • If the neurostimulator can be safely turned off, turn it off before the CT scan and turn it back on after the CT scan.
  • Tell the radiology tech and your doctor right away if you experience symptoms such as pain, fainting, convulsions or shocks during or right after the CT scan.
  • Inform your doctor who is monitoring your device that you have had a CT scan at your next regularly scheduled appointment, so they can check the device for potential problems.

Recommendations for doctors ordering CT scan

If your patient has an implanted neurostimulator, it should NOT stop you from performing an appropriate, medically indicated CT scan. The chance of a problem being caused by exposing these devices to CT irradiation is extremely low and it is greatly outweighed by the clinical benefit of a medically indicated CT examination. 

Magnetic Resonance Imaging (MRI) may also be an option for MR Conditional neurostimulators. MR Conditional are conditions under which a medical device that is anticipated to enter the MR environment (e.g., implantable neurostimulator) can safely enter the MR Environment. An MR Unsafe device should not enter the MR environment.

  • Communicate with the radiologist and CT tech to help them plan imaging that will minimize the risk of adverse effects.
  • Communicate with the doctor who is monitoring the neurostimulator to ensure that they check the device at a convenient time after the CT exam.

Recommendations for radiologists and radiologic technologists

If your patient has an implanted neurostimulator, it should NOT stop you from performing an appropriate, medically indicated CT scan. The probability of an adverse event being caused by exposing these devices to CT irradiation is extremely low and it is greatly outweighed by the clinical benefit of a medically indicated CT examination. 

Magnetic Resonance Imaging (MRI) may also be an option for MR Conditional neurostimulators if the conditions of safe MR use can be met. An MR Unsafe device should not enter the MR environment and any device without explicit MR labeling should be considered MR Unsafe.

CT imaging facilities can use the following recommendations to develop protocols for planned and for urgently needed CT scans.

  • Use CT radiographs (for example: scouts or localizer views) while setting up the CT scan to verify if any implanted neurostimulator is present and if so, identify its location relative to the programmed scan range. Note: CT radiograph, scout or localizing scans have not been associated with X-ray interference with electronic medical devices.
  • If the neurostimulator can be safely turned off, instruct the patient to turn it off before the CT scan and remind them to turn it back on after the CT scan.
    • If possible, avoid including the implanted device inside the scanning range. It is important, however, to ensure that CT images of the prescribed anatomy are taken so that the necessary diagnostic information is obtained. Confirm the required anatomic range with the supervising radiologist.
    • For CT procedures in which the medical device is located within the programmed scan range, minimize direct X-ray exposure to the implanted electronic medical device by using: 
      • the lowest dose consistent with the needed level of diagnostic image quality and
      • a lower dose delivery rate, which can be accomplished by using a longer rotation time or lower pitch value, if appropriate for the ordered exam.
    • Imaging exams that would involve scanning directly over the electronics of the implanted device for more than several seconds require additional care unless the device can be safely turned off. Examples of such scans are CT perfusion exams or interventional procedures such as CT fluoroscopy. If turning the neurostimulator off is not possible and the scan is urgently needed, careful monitoring of the device during and after the procedure is required.
  • Be mindful that interference is possible and be ready to terminate the scan if the patient experiences adverse symptoms. Although adverse symptoms are rare, they could include pain, fainting, convulsions and shocks.

Recommendations for doctors who are monitoring the implanted device

The probability of an adverse event to implanted neurostimulators from CT exposure is extremely low. However, as a precaution, you should check the device after CT, during the patient’s next scheduled checkup. Although rare, the following adverse effects have been reported:

  • Battery depletion
  • Changes in device programming
  • Communication/interrogation issues
  • Error messages
  • Inoperable devices
  • Failure to deliver energy
  • High impedance

1In 2021, Cambridge University published in The Journal of Laryngology & Otology, documenting CT radiation interference with implantable neurostimulators. 

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