From the Guidelines
Patients with spinal nerve stimulators should not undergo MRI procedures unless absolutely necessary and under controlled conditions, as the risks of device malfunction, displacement, overheating, or damage are significant, as highlighted in the 2019 guidelines from the Association of Anaesthetists and the Neuro Anaesthesia and Critical Care Society of Great Britain and Ireland 1. When considering an MRI for a patient with a spinal nerve stimulator, it is crucial to weigh the potential benefits against the risks, which include thermal injury during scanning due to the interaction between the device and the MRI's magnetic fields and radiofrequency energy.
- The device may need to be checked after an MR scan, and it is essential to liaise with the supervising pain or neurosurgical team when these patients are booked for an MR scan, as most major neurostimulator manufacturers require this step.
- Newer spinal cord stimulators that are "MR Conditional" can undergo MRI under specific conditions outlined by the device manufacturer, which typically include using particular MRI machines, specific body parts that can be scanned, and certain scanner settings.
- Before any MRI is considered, the exact model of the device must be identified, and the manufacturer's guidelines must be consulted to ensure safe scanning conditions.
- Alternative imaging modalities such as CT scans or ultrasound should be considered when possible to avoid the risks associated with MRI in patients with spinal nerve stimulators.
- If an MRI is deemed necessary, the stimulator may need to be turned off or reprogrammed before and after the procedure by a qualified specialist, as indicated in the guidelines 1.
From the Research
Spinal Nerve Stimulators and MRI Compatibility
- The compatibility of spinal nerve stimulators (SNS) with Magnetic Resonance Imaging (MRI) is a concern due to potential interactions between the device and the magnetic field 2, 3, 4, 5, 6.
- Some studies suggest that MRI can be safe for patients with SNS under certain conditions, such as using specific scanning protocols and ensuring the device is intact and functioning properly 3, 4, 5, 6.
- However, other studies highlight the potential risks of MRI for patients with SNS, including heating of the device, functional disturbances, and artifacts 2, 4, 5.
Precautions for MRI in Patients with SNS
- Before undergoing MRI, it is essential to ascertain that the SNS system is intact and functioning properly, without any lead breaks or low impedances 5.
- The use of bipolar cautery instead of monopolar cautery is recommended when necessary, and modern electrocautery units should be used with caution 2, 5.
- Patients with SNS should be monitored continuously during and after the MRI procedure, and their devices should be re-programmed to their previous setup after the procedure 6.
Specific Studies on SNS and MRI
- A study published in 2019 found that MRI is feasible, safe, and diagnostically useful in patients with high-frequency spinal cord stimulators (HF-SCS) under certain conditions 3.
- Another study published in 2020 evaluated the MRI safety issues for a new wirelessly powered spinal cord stimulation lead with receiver and found no substantial concerns under specific conditions 4.
- A study published in 2006 found that MRI at 1.5Tesla is safe in patients with implanted sacral nerve stimulators when the area to be imaged is outside the pelvis and other precautions are taken 6.