Electrical stimulation of the urethra evokes bladder contractions and emptying in spinal cord injury men: Case studies

Abstract

Objective

Electrical stimulation of the urethra can evoke bladder contractions in persons with spinal cord injury (SCI). The objective of this study was to determine whether electrical stimulation of the urethra could evoke bladder contractions that empty the bladder.

Methods

The first patient was a 45-year-old man with a T6 ASIA A SCI secondary to a gunshot wound 15 years prior. The second patient was a 51-year-old man with a T2 ASIA A SCI secondary to a fall from scaffolding 2 years prior. Both patients demonstrated neurogenic detrusor overactivity on urodynamics and managed their bladder with clean intermittent catheterization and oxybutynin medication. Following informed consent, each patient discontinued oxybutynin 2 days prior to urodynamic testing. Urodynamics were performed with a custom 12 French balloon catheter mounted with ring-shaped electrodes (3 mm) positioned in the prostatic urethra. After filling the bladder to approximately three-fourth of capacity at a rate of 25 ml/minute, the urethra was stimulated with a range of parameters to determine whether electrical stimulation could evoke a bladder contraction and empty the bladder.

Results

Electrical stimulation of the prostatic urethra evoked bladder contractions (peak detrusor pressures of 60–80 cm H₂O) that emptied the bladder in both subjects. In the first subject, stimulation (9–12 mA, 20 Hz) emptied 64–75%, leaving post-void residual volumes (PVRs) of 41–20 ml. In the second subject, stimulation (20 mA, 20 Hz) emptied 68–77%, leaving PVRs of 56–45 ml.

Conclusion

Urethral stimulation evoked bladder emptying in persons with SCI.

Keywords:

• Spinal cord injury
• Electrical stimulation
• Neurogenic bladder
• Oxybutynin

Acknowledgements

The authors would like to thank Kimberly Arena, PA-C, Nell Shaffer, RN, and Robbin Clark Scott, RN for their technical assistance. This investigation was conducted with extramural financial support from the National Institute of Neurological Disorders and Stroke (R43NS055393) and the pelvic health business of NDI Medical, LLC, which is now Medtronic Urinary Solutions.

All authors (1) contributed substantially to the conception and design, (2) participated in the drafting and revising of the intellectual content of the article, and (3) provided final approval of the version to be published.

Conflicts of interest statement

The authors' conflicts of interest include: (Code: 2) four of the authors (M.E.B., W.M.G., J.H.G., and J.W.B.) are named inventors on patents controlled by Medtronic; (Code: 3) four of the authors (M.E.B., W.M.G., J.H.G., and J.W.B.) are directors or employees of NDI Medical; (Code: 4) two of the authors (W.M.G. and J.W.B.) may receive royalties related to the patents; (Code: 5) four of the authors (M.E.B., W.M.G., J.H.G., and J.W.B.) have equity interest in NDI Medical; (Code: 6) one author (M.J.K.) received a research grant from NDI Medical.

Institution

The work was performed at Carolinas Rehabilitation, Urology Department, in Charlotte, NC after approval by the IRB.