In December 2015, the FDA issued a conditional safety provision for body MRI for Medtronic deep brain stimulation (DBS) devices. Conditional indicates certain conditions must be met to reduce the risk of unintended brain damage. Brain tissue damage can occur from excessive heat production during an MRI scan.
A Medtronic letter sent to patients in 2016 generalized body MRI safety information leaving my patients under the impression any MRI is safe. However, there are very specific guidelines that must be followed to avoid unintended brain damage. These guidelines were unknown to my patient’s internal medicine physician and/or surgeon in 2016. All four patients were seen coincidentally in our clinic for a routine DBS checkup prior to their MRI.
- Patient One – brain MRI was ordered requesting a protocol that is too intense and unsafe in any circumstance.
- Patient Two – body MRI was ordered and scheduled by a physician without following safety checklist.
- Patient Three – body MRI ordered and deemed safe for the patient by a non-clinical person involved in the person’s treatment. Patient has wire damage prohibiting any MRI.
- Patient Four– body MRI ordered without the knowledge of the checklist or that the person has an adapter.
All MRI scans were cancelled and a suitable alternative was ordered by the patient’s physician.
The MRI eligibility (safety) checklist will involve the DBS programmer, radiologist, MRI technician and Medtronic device registration.
Conditions that must be met for body MRI include:
- The DBS system must be unequivocally intact per the DBS programmer just prior to the scan. System integrity is determined by measuring impedance for all electrodes. Wire impedance irregularity (short, broken circuit) prohibits any MRI.
- The patient must have an approved device model as noted in the conditional approval per the FDA. The DBS programmer will check the device model. Any unapproved implanted device model does not meet the FDA conditional approval for body MRI.
- The presence of an adapter in the implanted system does not meet the FDA conditional approval.
- Incomplete implants are not approved for body MRI.
- Specific MRI strength and scanning protocols are indicated in the Medtronic MRI safety guidelines.
If any one criteria above is not met, a body and potentially brain MRI cannot be assumed to be safe in such that the risk of brain damage is minimized. Tips to consider include speaking with your DBS programmer if an MRI is being considered for your care, discuss with your physician if an alternative test is adequate, advocate for your safety by obtaining a copy of your eligibility check list and review the information. If the MRI is deemed to meet the FDA conditions, ask for a DBS system check after the MRI scan. Any change in symptoms after an MRI should be reported immediately to your neurologist.
As an additional precaution, stimulation setting changes may be required prior to the MRI. My clinic policy is that all my patients will be programmed to the highest possible safety setting prior to any MRI. For more specific information about your situation, talk with your DBS programmer, neurologist or neurosurgeon.