Spinal cord stimulation (SCS) is a safe and effective treatment for refractory failed back surgery syndrome (FBSS). Two implantation procedures exist depending on the use of a surgical versus percutaneous lead. Percutaneous leads implantation is a less invasive procedure with low infection risks, but requires a higher X-ray exposure. In recent years, the assessment of radiation dose has become more important because of the understanding of the X-ray correlation with deterministic effects. The new MRI compatible percutaneous leads (Vectris®, Medtronic Neuromodulation, Minneapolis, MN, USA) appears stiffer because of its shielded structure and so seems to be easier to implant.The aim of this study is to compare the radiation exposure between percutaneous shielded Vectris® leads and former unshielded Octad® leads (Medtronic Neuromodulation, Minneapolis, MN, USA) in SCS implantation.
Material and Methods
We analyzed a series of 20 patients (Table 1) with FBSS who were implanted with a percutaneous lead. The first 10 patients were implanted with an Octad® lead and the 10 following with a shielded Vectris® lead (Figure 1). All patients were operated on by the same surgical team. Under local anesthesia, patients were positionned prone on an adjustable fluorosopy table. The surgical approach was made by the neurosurgeon, after which the epidural needle could be placed by the anesthesiologist. The neurosurgeon could then proceed to placing the SCS lead.In all cases, the same intra-operative X-ray device (Ziehm Vision 8000®, Ziehm Imaging Inc, Florida, USA) was used, with identical parameters aiming at a minimal X-ray exposure (pulse mode with 2 impulses/sec, and automatic mode for kVp and mAs). Fluoroscopic imaging was judiciously used, in that the fluoroscope was only activated when localizing adjusting or advancing a needle/lead. The low dose and automatic brightness control features were used with a 23 cm field view (FoV).Automatic kilovolt peak (kVp) and milliampere seconds (mAs) determines the best pictures on the screen with lower radiation doses.
Table 1 represents general patients data. The Male/Female ration was 1:1 for the Octad® lead group and 3:1 for the Vectris® lead one. There was no statistical difference between age group. Fluoroscopy time was significantly lower in patients implanted with the Vectris® lead (mean: 99 seconds) compared to the Octad® lead (mean 291 seconds) (p = 0,0035) (Figure 2). Subsenquently, the Dose Area Product in the Vectris® group (mean: 592 cGycm2) was significantly lower than in the Octad® group (mean: 1899 cGycm2) (p = 0,0005) (Figure 3).
The use of the new MRI compatible percutaneous Vectris® lead significantly reduces fluoroscopy time and hence X-ray exposure compared to the Octad® lead in SCS implantation. The use of these new shielded percutaneous leads, could therefore allow for patients to undergo a less invasive implantation procedure for SCS without such an increased X-ray exposure.