by Dr. Kim Anderson
In spinal cord injury, or SCI, nerves that communicate between the brain and body are damaged. In addition to weakness and numbness, other functions, including the digestive track, are often impacted. For people living with SCI, bowel control and dysfunction are among their biggest perceived challenges. Constipation and incontinence (accidents) are still common despite numerous medications and time-consuming routines. More research and innovative tools are needed.
One such approach is genital nerve stimulation. Genital nerve stimulation involves electrodes (sticky pads) placed on the skin to stimulate the nerves in the pelvis. Other studies have shown that treatments with genital nerve stimulation can help calm and change the reflexes involved in urinating, resulting in fewer bladder accidents. Early data suggests that genital nerve stimulation can also improve bowel function by changing the reflexes used to defecate (pooh). By relaxing the colon, genital nerve stimulation may allow better storage of stool, which then can lead to fewer bowel accidents. An earlier study showed that genital nerve stimulation reduces bowel accidents in persons with unexplained fecal incontinence. So, it is reasonable to believe that genital nerve stimulation will help improve bowel control after SCI.
We recently received funding for a new study to help us understand this more. The goal of this study is to evaluate the short-term effect of genital nerve stimulation on the reflexes used to defecate and the practicality of using genital nerve stimulation daily at home to test the long-term effects.
This grant involves 2 separate studies. In the 1st study, which we are currently recruiting for, 52 persons with SCI from trauma (such as car crashes, falls, gunshot wounds, etc.) will be enrolled. During 1 or 2 study visits, each participant will be evaluated using physical exams, interviews, and a test called anorectal manometry. Anorectal manometry is a test that is kind of similar to the urodynamics cystoscopy test for the bladder. During anorectal manometry a catheter is placed a short distance into the rectum and measures the pressures, movements, reflexes, and sensations.
This is done first without any stimulation, then their response to low level (sham) and high level (treatment) genital nerve stimulation is tested. The results from this 1st study will help us understand how brief periods of surface stimulation of the genital nerve changes bowel reflex activity and it will help us predict who will be a responder versus a non-responder for the 2nd study.
In the 2nd study, 12 people who responded well to genital nerve stimulation in the 1st study will be enrolled. This study will not be open for recruitment until late 2024. All participants will maintain their usual bowel routine and nutritional habits while completing a daily diary of their bowel movements. Each participant will be re-evaluated using physical exams, interviews, and anorectal manometry evaluations, and will then be randomly assigned to the treatment stimulation group or the sham stimulation group. All participants will be trained to perform genital nerve stimulation at home, every day for 6-8 hours over four weeks. The sham group will have devices programmed to deliver ineffective stimulation, whereas the treatment group will receive effective stimulation. After four weeks, both groups will be reevaluated. Each person will not do any stimulation for another two weeks before being re-evaluated a final time. The results from the 2nd study will help us understand if genital nerve stimulation is a feasible option to improve bowel dysfunction, bowel incontinence, and quality of life in persons with SCI.
It is a high priority to individuals living with SCI to regain autonomic function such as bowel control. Bowel dysfunction has a significant impact on daily routines, social activities, and occupational activities, all of which impact quality of life. This trial will directly aid in our understanding and ability to treat bowel dysfunction related to spinal cord injuries. People living with SCI have expressed interest in external stimulation to improve fecal continence and overall bowel routine. This trial will help show if GNS is practical for people with SCI.
It is low risk (such as skin irritation or constipation, though this is unlikely) with high potential benefits (such as fewer bowel accidents and faster bowel routines). If successful, a larger future study will provide even stronger evidence for genital nerve stimulation to be included in normal clinical practice. Information learned should help us understand how the anorectal manometry evaluation looks in individuals with SCI and how it relates to fecal incontinence.
If you would like to know more information about this study, contact Ashley Callaway at acallaway@metrohealth.org or 216-957-3518. This study is funded by the Department of Defense.
