Specify 5 6 5 lead

During the scES implantation procedure, a midline bilateral laminotomy was performed typically at the L1-L2 disk space. An electrode array with 16 contacts (Medtronic Specify 5–6-5 lead, size: 10 mm × 64.2 mm; contact size: 1.5 mm × 4.0 mm; edge-to-edge contact spacing: 4.5 mm–column–and 1.0 mm–row) was placed into the epidural space at midline. Electrophysiological mapping was performed after initial placement to optimize the location of the paddle electrode based on evoked responses recorded from bilateral surface EMG electrodes (Motion Lab Systems, Baton Rouge, LA) placed over representative lower limb muscles. After the final placement of the electrode array, the electrode lead was tunneled subcutaneously and connected to the neurostimulator (Medtronics, Intellis in participants B24, A100, B07, and A105; RestoreADVANCED in participant A45). The neurostimulator delivered monophasic, rectangular pulses.

During the scES implantation procedure, a midline bilateral laminotomy was performed typically at the L1-L2 disc space. The electrode array with 16 contacts (Medtronic Specify 5-6-5 lead) was placed into the epidural space at midline. Electrophysiological mapping was performed after initial placement to optimize the positioning of the paddle electrode based on the evoked responses recorded by surface EMG electrodes from representative lower limb muscles. After the final placement of the electrode array, the electrode lead was tunneled subcutaneously and connected to the neurostimulator.

After the scES implantation surgery, anterior–posterior and lateral X-ray images of the spinal cord at the location of the scES paddle electrode implant were obtained prior to participant discharge. The anterior–posterior image was used to identify the T12 vertebra based on the location of the last floating rib, while the lateral image was used to identify the exact locations of the rostral and caudal ends of the paddle electrode with respect to the vertebral body. After identifying the exact location of the paddle electrode with respect to the vertebrae using X-ray images, the location of the paddle was estimated with respect to the spinal cord by integrating the lateral X-ray with the sagittal and axial MRI scans. Based on the length of the paddle electrode (46.5 mm for Medtronic Specify® 5-6-5 lead), 15 MRI axial slices (total of 15 × 3 mm = 45 mm in length) that best describe this location were identified. The paddle electrode was placed on the 3D model based on the location of the identified 15 axial slices (Fig. 1D). Percentage of volumetric coverage of lumbosacral spinal cord by scES paddle electrode was calculated for each participant using the methodology explained in Supplementary Fig. 2.