Abstract
Context:
Individuals with SCI typically live with neurogenic bowel dysfunction and impaired colonic motility that may significantly impact health and quality of life. Bowel management often includes digital rectal stimulation (DRS) to modulate the recto-colic reflex to promote bowel emptying. This procedure can be time-consuming, caregiver-intensive, and lead to rectal trauma. This study presents a description of using electrical rectal stimulation as an alternative to DRS to help manage bowel emptying in a person with SCI.
Methods:
We conducted an exploratory case study with a 65-year-old male with a T4 AIS B SCI who normally relies on DRS as the main component of his regular bowel management strategy. In randomly selected bowel emptying sessions during a 6-week period, the participant received burst-pattern electrical rectal stimulation (ERS) (50 mA, 20 pulses/s at 100 Hz), via a rectal probe electrode until bowel emptying was achieved. The primary outcome measure was number of cycles of stimulation required to complete the bowel routine.
Results:
17 sessions were performed using ERS. In 16 sessions, a bowel movement was produced after only 1 cycle of ERS. In 13 sessions, complete bowel emptying was achieved with 2 cycles of ERS.
Conclusions:
ERS was associated with effective bowel emptying. This work represents the first time ERS has been used to affect bowel emptying in someone with SCI. This approach could be investigated as a tool to evaluate bowel dysfunction, and it could be further refined as a tool for improving bowel emptying.
Key words: Colon, Functional electrical stimulation, Neurogenic bowel dysfunction, Neuromodulation
Introduction
Individuals living with SCI frequently struggle with Neurogenic Bowel Dysfunction (NBD) (1,2). NBD can cause major physical and psychological issues, and affect quality of life (3–5). Depending on the level of injury, there are two main types of NBD in SCI. Injuries that involve the conus medullaris and cauda equina result in a lower motor neuron injury with a flaccid bowel, while injuries above the conus medullaris result in an upper motor neuron lesion resulting in spastic bowel (6,7). Upper motor neuron injury is more common and retains reflexogenic activity of the recto-colic excitatory reflex. This reflex promotes stool evacuation via colon contractions that are produced by stimulation of mechanoreceptors in the internal anal sphincter. Digital rectal stimulation (DRS) is typically used to modulate this reflex in order to produce bowel movements (8). DRS is performed, often with assistance by a caregiver, by inserting gloved, lubricated fingers into the rectum and applying pressure in a circular pattern to distend the rectal wall. DRS is typically a component of the bowel care routine in individuals with SCI and recommended by clinical practice guidelines (7,9,10).
DRS can negatively impact quality of life as it can be associated with lost independence, lost time, lost dignity, and increased caregiver costs (5,11). Furthermore, DRS can be painful for individuals with preserved sensation and can be a trigger for autonomic dysreflexia (12). Though rare, digital rectal manipulation in general can lead to complications such as perforation, rectal bleeding and formation of anal fissures (13).
Individuals who use DRS as part of their regular bowel program still report a wide range of 5-310 min in the time required to complete their bowel routine (14). The International SCI Bowel Function Basic Data Set recognizes three categorical durations for average time required for defecation (within the last four weeks), including 0–30 min, 31–60 min, and more than 60 min (15). Thus, there is a need for safe, effective, and feasible alternatives to DRS to promote bowel emptying with shorter durations and greater independence.
The recto-colic reflex can be modulated using electrical stimulation to promote the movement of stools in the colon. In able-bodied individuals, intraluminal electrical stimulation has been shown to successfully treat chronic constipation refractory to biofeedback therapy (16). Our recent study in cats without spinal cord injury showed that electrical stimulation of the colon increased colonic activity and intraluminal pressure (17). Of note, stimulation of the proximal colon adjacent to the caecum only resulted in local activation of the colon, while stimulation of the distal colon adjacent to the rectum produced both proximal and distal responses, suggesting modulation of the recto-colic reflex.
The results from preclinical trials and from the constipation literature motivate testing a minimally invasive electrical stimulation approach for promoting bowel emptying in individuals with NBD. The purpose of this case study was to demonstrate a proof of concept for promoting bowel emptying using electrical rectal stimulation (ERS). We hypothesized that ERS would be associated with effective bowel emptying.
Methods
This experiment was conducted at the Syracuse VA Medical Center SCI Inpatient Unit with IRB approval. During a 6-week period, bowel emptying sessions were either unchanged (i.e. using DRS) or we administered ERS in place of DRS. DRS and ERS bowel emptying sessions were randomized. For DRS sessions, standard data for charting were collected, including confirmation of administration, size of bowel movement, and completeness of DRS. For ERS sessions, we also recorded the number of cycles to produce the first bowel movement and the total number of cycles of ERS administered. Per participant request, DRS was also administered once at the end of each ERS session to ensure complete bowel emptying. A bowel emptying session was considered complete when mucus and no stool were obtained following a cycle of rectal stimulation. Figure 1 shows the setup for the bowel routines.
Figure 1.
Administration of bowel stimulation. The bowel routine is typically performed with the individual lying on their left side (top). For DRS, a gloved finger is inserted through the anus and the rectum is mechanically distended (bottom left). For ERS, we inserted a rectal probe electrode, which was connected to a stimulator unit, to electrically modulate the recto-colic reflex (bottom right).
Inclusion criteria included the presence of SCI with neurogenic bowel dysfunction, the use of DRS as part of the bowel care regimen, neurologically stable with at least 6 months since SCI, skeletally mature, and at least 18 years old. Exclusion criteria included active sepsis, open wounds in direct contact with the rectum, history of significant colon trauma, impaired mental status or memory impairment and presence of colostomy.
The study participant was a 65-year-old male with a T4 AIS B spinal cord injury due to a fall 28 years prior, and was admitted to the SCI unit with sacral osteomyelitis. His home bowel routine included a suppository and DRS, and was performed every other day and takes more than 60 min. He took 100 mg of docusate/sennosides twice per day and 1 packet (17 g) of polyethylene glycol 3350 mixed with a glass of water in the morning. Since he had a history of internal hemorrhoids prone to bleeding, he also took a daily serving 2.4 g of sugar-free psyllium fiber. He reported episodes of fecal and flatus incontinence. There was no GI or anal sphincter dysfunction unrelated to SCI; no surgical procedures previously performed on the GI tract; no reported uneasiness, headache, or perspiration during defecation; no need to wear a pad; and no abdominal pain and discomfort.
ERS was administered via a rectal probe electrode (TensCare, Epsom, UK), which was 110 mm in length and 19.6 mm in maximum width. The electrode was connected to a stimulator (DS7, Digitimer, Letchworth Garden City, UK) that was in turn connected to a function generator (DS345, Stanford Research Systems, Sunnyvale, CA). The stimulator administered square pulses of 50 mA amplitude and 0.2 ms pulse width. The stimulation amplitude was determined based on our experiences with similar neuromodulation approaches and on participant comfort (18). The function generator triggered the stimulator to deliver these pulses in a burst pattern of 20 pulses at 100 Hz delivered once per second. This stimulation pattern was chosen based on previous preclinical experiments by our group (17). ERS was administered using the same pattern as DRS, including application for 30 s, once every 20 min. The number of cycles of ERS was based on the average number of cycles of DRS, which was 4. However, the participant and nurse were allowed to reduce the number of ERS cycles if they believed the bowel was emptied, following the same determination strategy as for DRS.
Results
ERS was randomly chosen to replace DRS in 17 bowel emptying sessions recorded during the 6-week testing period. Table 1 summarizes the results of the bowel emptying sessions using ERS. In 13 of 17 ERS sessions, 2 cycles of stimulation were administered to achieve complete bowel emptying. In 4 ERS sessions, 3 cycles of stimulation were administered. The study participant reported that his average bowel routine when using DRS typically required a total of 4–5 cycles of DRS to achieve complete bowel emptying. In 16 out of 17 ERS sessions, a bowel movement was produced following the first cycle of electrical rectal stimulation. In 13 sessions, 2 cycles of ERS were administered to achieve complete bowel emptying, and in 4 sessions 3 cycles of ERS were administered. In addition, only one session did not produce a bowel movement with ERS alone. In that session, a bowel movement was produced after administration of a suppository. Eleven ERS sessions produced a large bowel movement after one ERS cycle. Two ERS sessions produced an extra-large bowel movement and three sessions produced a small bowel movement. There was no clinically significant difference in the sizes of bowel movements between DRS and ERS treatments.
Table 1.
Electrical rectal stimulation session data.
| Session # | # ERS cycles to BM | Total # ERS cycles | Size of BM | Outcome from DRS at end of ERS session |
|---|---|---|---|---|
| 1 | 1 | 3 | large | mucus |
| 2 | 1 | 2 | small | mucus |
| 3 | 1 | 2 | extra large | mucus |
| 4 | 1 | 3 | small | mucus |
| 5 | 1 | 3 | extra large | mucus |
| 6 | 1 | 2 | large | mucus |
| 7 | 1 | 2 | large | mucus |
| 8 | 1 | 2 | small | mucus |
| 9 | 1 | 2 | large | mucus |
| 10 | 1 | 2 | large | mucus |
| 11 | 1 | 2 | large | mucus |
| 12 | 1 | 3 | large | mucus |
| 13 | 1 | 2 | large | mucus |
| 14 | 1 | 2 | large | mucus |
| 15 | 1 | 2 | large | mucus |
| 16 | 1 | 2 | large | mucus |
| 17 | no BM with ERS | 2 | no BM | BM after suppository |
No complications were reported during ERS sessions. There were no episodes of autonomic dysreflexia, bleeding, or discomfort. In one ERS session, a brief episode of lower limbs spasms during stimulation was noted. Once the study was completed, the participant returned to his regular bowel care routine. The study participant was satisfied with the session and reported that ERS “seems to get it all in one go”.
Discussion
Due to the incidence of NBD, its impact on quality of life and potential complications in individuals with SCI, and the limitations of DRS, a search for potential alternatives is needed. We report a proof-of-concept of an individual with SCI and neurogenic bowel dysfunction using ERS as an adjunct in their bowel routine to successfully produce a bowel movement and achieve complete bowel emptying. These data represent the first evidence in a person with SCI that ERS has the potential to promoting bowel emptying as part of the bowel routine.
Potential effectiveness of ERS
DRS is usually a component of upper motor neuron NBD management (10), but DRS has some limitations. Published data show that several cycles of DRS may be needed to evoke a bowel movement (8). In a study of the effects of DRS on colonic motility in 6 study participants, an oatmeal barium paste was used as a proxy for stool. This paste was expulsed by the third DRS cycle in 1 participant, by the fourth in 3 participants and 2 participants required five DRS cycles (9). These results are similar to our experience with DRS and discussions with other SCI providers. This study participant reported that his average bowel routine when using DRS typically required a total of 4–5 cycles of DRS to achieve complete bowel emptying. In comparison, we observed that most ERS sessions produced a bowel movement with a single cycle of ERS in contrast to DRS.
Performing DRS can be a difficult task for individuals with SCI, especially in those with lesions that may impair core stability as well as hand function. DRS may affect self-esteem and for some it can be unpleasant both to have someone assist with DRS or to perform DRS on oneself. By having the use of a device instead of using a gloved finger, we expect that some of these issues may be mitigated. ERS may require the same or less amount of time to perform DRS for bowel care. Furthermore, we expect less discomfort and improved compliance with ERS.
We observed no complications during the study and the study participant reported overall satisfaction with ERS. The nursing staff also reported that the application of ERS was easier compared to DRS. Multiple nurses reported that they were pleased with being able to apply the ERS and step away from the patient’s rectal area to face the patient, giving time to speak with the patient and interact better than with typical bowel care – and even being able to perform medical documentation while the ERS was being applied. Nurses reported improved interaction with the participant while performing bowel care.
These data suggest that ERS may be as effective as DRS, but without the drawbacks of DRS. Overall, we envision a system using ERS that could potentially reduce bowel management time, reduce caregiver assistance needed, and increase dignity, which could improve quality of life for individuals with SCI.
Study limitations
This experiment was conducted over a short period in a single individual with SCI. Because (1) the study participant uses DRS and (2) both DRS and ERS should be modulating the same recto-colic reflex (17), we hypothesized that ERS would be associated with effective bowel emptying and could be used to produce complete bowel emptying. Given the drawbacks of DRS, an approach that performs as well as DRS, but without those limitations, may be desirable. In this single participant, we observed that ERS was associated with productive bowel movements and has the potential to be more efficient at achieving bowel emptying than DRS, but more data are needed to provide evidence for this approach.
It is possible that movement of stools was associated with insertion of the rectal probe electrode itself. We believe that it is unlikely that insertion of the rectal probe electrode would modulate the recto-colic reflex because (1) it is not large enough to distend the rectum and (2) we waited for 60–90 s after insertion before turning the stimulator on. If insertion of the rectal probe electrode contributed to bowel emptying, then we would expect that bowel emptying would occur sooner or with a similar pattern to DRS.
A direct comparison with parallel DRS data would have been ideal, but we were not able to collect those DRS data beyond what the study participant reported to us as their typical bowel routine. The purpose of this experiment was to perform a first-in-human test of ERS and evaluate the feasibility of administering this stimulation. Because we found that ERS was feasible and was associated with bowel emptying, we are motivated to pursue further study of ERS and include this direct comparison with DRS.
Conclusion
This work represents the first time electrical rectal stimulation has been used to affect bowel emptying in someone with SCI. ERS was associated with effective bowel emptying that appeared to be equivalent to DRS for this study participant. This approach could be investigated as a tool to evaluate bowel dysfunction, and it could be further refined as a tool for improving bowel emptying.
Acknowledgements
The authors would like to acknowledge Dr. Kevin Suarez for his contributions to study coordination and data management.
Funding Statement
This work was supported by the U.S. Department of Veterans Affairs Rehabilitation Research and Development Service RX001962. The contents do not represent the views of the U.S. Department of Veterans Affairs or the United States Government.
Disclaimer statements
COI statement The authors have no conflicts of interest to report.
Conflicts of interest No potential conflict of interest was reported by the authors.
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