Spinal cord epidural stimulation for motor and autonomic function recovery after chronic spinal cord injury: A case series and technical note

Abstract

Background: Traumatic spinal cord injury (tSCI) is a debilitating condition, leading to chronic morbidity and mortality. In recent peer-reviewed studies, spinal cord epidural stimulation (scES) enabled voluntary movement and return of over-ground walking in a small number of patients with motor complete SCI. Using the most extensive case series (n = 25) for chronic SCI, the present report describes our motor and cardiovascular and functional outcomes, surgical and training complication rates, quality of life (QOL) improvements, and patient satisfaction results after scES.

Methods: This prospective study occurred at the University of Louisville from 2009 to 2020. scES interventions began 2-3 weeks after surgical implantation of the scES device. Perioperative complications were recorded as well as long-term complications during training and device related events. QOL outcomes and patient satisfaction were evaluated using the impairment domains model and a global patient satisfaction scale, respectively.

Results: Twenty-five patients (80% male, mean age of 30.9 ± 9.4 years) with chronic motor complete tSCI underwent scES using an epidural paddle electrode and internal pulse generator. The interval from SCI to scES implantation was 5.9 ± 3.4 years. Two participants (8%) developed infections, and three additional patients required washouts (12%). All participants achieved voluntary movement after implantation. A total of 17 research participants (85%) reported that the procedure either met (n = 9) or exceeded (n = 8) their expectations, and 100% would undergo the operation again.

Conclusion: scES in this series was safe and achieved numerous benefits on motor and cardiovascular regulation and improved patient-reported QOL in multiple domains, with a high degree of patient satisfaction. The multiple previously unreported benefits beyond improvements in motor function render scES a promising option for improving QOL after motor complete SCI. Further studies may quantify these other benefits and clarify scES's role in SCI patients.

Keywords: Epidural stimulation; Functional recovery; Neuromodulation; Rehabilitation; Spinal cord injury; Spinal cord stimulation; Spinal surgery; Technical note.

Figure 1:

Training protocols for spinal cord epidural stimulation (scES) studies. Cohort 1 (n = 8) was implanted to evaluate motor and functional outcomes, including standing, stepping, and voluntary movement. Cohort 2 n = 5) was implanted to assess cardiovascular function. This cohort also trained for voluntary movement and standing. Individuals in Cohort 3 (n = 12) were implanted as part of a prospective randomized control trial evaluating the effect of scES on cardiovascular function and voluntary movement.

Figure 2:

Surgical techniques. Illustration of surgical technique. A laminotomy is performed L1-2 (or adjacent level depending on the level of the conus) to allow passage of the paddle electrode into the epidural space (ribs not depicted). Intraoperative fluoroscopic image showing final midline positioning of the electrode between T11 and L1 vertebrae. Epidural stimulator sleeves shown exiting the epidural space. White silicon anchors secure the leads. A strain relief loop was left between the anchors and the exit point of the epidural space when possible. 2-0 silk sutures anchored the leads to the fascia, where a strain relief loop was typically placed. Leads were tunneled to a posterior flank site for the internal pulse generator Image showing postoperative incisions in midline and posterior flank.

Figure 3:

Intraoperative electrophysiology testing. Initial testing of Rostral and Caudal electrode configurations to assess activation sequence of lower extremity muscles. Fluoroscopy shows initial placement of the electrode paddle. Re-testing of rostral and caudal electrode configurations following movement of electrode paddle to optimize activation of rostral muscles. Fluoroscopy shows final placement of electrode paddle. Muscles: IL: Iliopsoas, RF: Rectus femoris, VL: Vastus lateralis, MH: Medial hamstrings, TA: Tibialis anterior, MG: Medial gastrocnemius, SOL: Soleus, STIM: Stimulation pulse.

Figure 4:

Intraoperative electrophysiology testing assessing rostral and caudal ends of paddle stimulator. Key muscle groups are tested from stimulation parameters. (a and b) panels juxtapose differing outcomes based on positioning.

Figure 5:

Final lateral and posterior-anterior X-rays demonstrating positing of epidural stimulator and pulse generator.