Impact of long-term epidural electrical stimulation enabled task-specific training on secondary conditions of chronic paraplegia in two humans

Abstract

Introduction: Spinal cord injury (SCI) often results in chronic secondary health conditions related to autonomic and metabolic dysfunction. Epidural electrical stimulation (EES) combined with task-specific training has been shown to enable motor function in individuals with chronic paralysis. The reported effects of EES on secondary health conditions, such as bladder function and body composition, are limited. We report the impact of EES on SCI-related secondary health changes in bladder function and body composition.

Methods: Two participants with motor and sensory complete SCI performed 6 months of rehabilitation without EES followed by 12 months of task-specific training with EES after implantation of a 16-electrode array on the surface of the lumbosacral spinal cord. Participants performed three days of training per week in the laboratory, and additionally performed task-specific activities with EES at home during this time frame. Changes in bladder and body composition were recorded via clinically-available testing of neurogenic bladder functionality and dual-energy X-ray absorptiometry, respectively.

Results: In one participant, we observed an increase in episodes of urinary incontinence with worsening bladder compliance and pressures at the end of the study. Bone mineral density changes were insignificant in both participants; however, one participant showed a substantial increase in lean mass (+9.1 kg; 6 months of training) via redistribution of body fat through an android/gynoid ratio reduction (−0.15; 6 months of training).

Conclusion: EES optimized for standing and stepping may negatively impact neurogenic bladder functionality. Close monitoring of bladder health is imperative to prevent undesirable bladder compliance, which can lead to upper urinary tract deteriorations. Conversely, EES may serve as an adjunct tool with regular exercise modalities to improve body composition through activation of musculature innervated by spinal segments that are below the SCI.

Keywords:

• Neuromodulation
• Spinal cord injury
• Neurorehabilitation
• Epidural stimulation
• Chronic paraplegia

Acknowledgements

We thank Assistive and Restorative Technology Laboratory research support staff for their contributions to study design, data collection and general study support. All procedures were performed under the approval of the Mayo Clinic Institutional Review Board.

Disclaimer statements

Contributors None.

Conflicts of interest KL has previously served as a consultant to Medtronic’s Department of Technology Development focused on deep brain stimulation.

Additional information

Funding

Sources of funding for the work reported here include The Grainger Foundation, Regenerative Medicine Minnesota, Jack Jablonski Bel13ve in Miracles Foundation, Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic Center for Regenerative Medicine, Mayo Clinic Rehabilitation Medicine Research Center, Mayo Clinic Transform the Practice, Minnesota Office of Higher Education’s Spinal Cord Injury and Traumatic Brain Injury Research Grant, Craig H. Neilsen Foundation, Dana and Albert R. Broccoli Charitable Foundation, Christopher and Dana Reeve Foundation, Walkabout Foundation.