Electrical and Magnetic Stimulation

Several electrical or magnetic stimulation methods have been proposed and tested for their ability to improve bowel function in individuals with upper motor neuron SCI. These techniques are varied, from the relatively inexpensive and non-invasive abdominal muscle stimulation belt (Korsten et al. 2004) and percutaneous peripheral nerve stimulation (Mentes et al. 2007), to more complex and invasive techniques including implantation of epineural electrodes (Davis et al. 2001) and epidural or anterior sacral root electrodes (Chia et al. 1996; Binnie et al. 1991; MacDonagh et al. 1990) for functional electrical stimulation. Magnetic stimulation techniques have also been used; a magnetic field is generated to induce an electric field, which then generates sufficient current to stimulate the peripheral nerves (Lin et al. 2002).

After upper motor neuron SCI, bowel reflex centres within the sacral spinal cord may be released from descending inhibition and may be influenced by somatic input (Frost et al. 1993). Several studies have shown that electrical or magnetic stimulation of the somatic nervous system can bring about an alteration in visceral function in humans. For example, Riedy et al. (2000) showed that short periods of electrical stimulation with perianal electrodes resulted in an increase in anal pressures.

Discussion

Bourbeau and colleagues (2020) investigated neurogenic bowel function management needs and found that people’s willingness to use neuromodulation interventions depended on their priorities and the device’s invasiveness. 61% of participants were willing to adopt an external device, but the largest concern regarding these methods were having to turn on and off the system while wearing wired electrodes. For implanted devices, the largest concern was requiring future surgery to correct complications or remove the implanted device. Fewer people (41%) were willing to adopt this method in comparison to external neuromodulation interventions. Overall, maintaining fecal incontinence, gaining bowel routine predictability, and reducing time of bowel management were some of the highest priorities identified (Bourbeau et al. 2020).

A systematic review reports that functional magnetic stimulation is a common, non-invasive treatment for neurogenic bowel (Parittotokkaporn et al. 2020). The use of functional magnetic stimulation decreased mean colonic transit time (Tsai et al. 2009; (62.6-50.4 hours); Lin et al. 2002; Lin et al. 2001; 105.2(6.66) to 89.4(6.94) hours), as did stimulation of the abdominal muscles (Hascakova-Bartova et al. 2009; Korsten et al. 2004). While preliminary results for posterior tibial nerve stimulation in individuals with SCI appear promising, it is important to note that the statistical significance of the improvements in clinical and physiological parameters were not reported and the study involved only two participants (Mentes et al. 2007).

Another systematic review found that majority of studies report electrical stimulation as a safe and effective treatment for people with neurogenic bowel (Deng et al. 2018). Subsequent studies using sacral anterior root stimulation or sacral neuromodulation yielded improvements in bowel function, including reduced constipation on the Wexner questionnaire (Chen & Liao 2015), better spontaneous evacuation (Lombardi et al. 2011; Sievert et al. 2010; Chia et al. 1996), reduced bowel program times (Kachourbos and Creasey 2000, Valles et al. 2009, Lombardi et al. 2009), elimination of autonomic dysreflexia related to bowel management (Kachourbos and Creasey 2000), elimination of manual help for defecation (Macdonagh et al. 1990). Both Holzer et al. (2007), and increased quality of life (Sievert et al. 2010; Lombardi et al. 2011; Lombardi et al. 2009; Holzer et al. 2007; Kachourbos and Creasey 2000).

Worsoe et al.’s (2013) review of nerve stimulation techniques in neurogenic bowel dysfunction viewed neurostimulation as a way of ‘re-establishing neurogenic control and alleviating symptoms. They reported that the sacral anterior root stimulator improves bowel function in some patients with complete SCI while sacral nerve stimulation can improve function in selected patients with a variety of incomplete neurologic lesions. They also suggest that peripheral stimulation using electrical stimulation or magnetic stimulation may offer non-invasive treatment alternatives for neurogenic bowels. However, they concluded that due to the lack of research evidence required to support informed choice, the latter techniques should be reserved for research at present.

There are currently investigations of epidural spinal cord stimulation for restoring volitional movement and autonomic responses related to bowel after SCI, which are outlined in Table 18 below.

Conclusions

There is one systematic review (Deng et al. 2018) that electrical stimulation for neurogenic bowel dysfunction treatment is a safe and effective intervention.

There is one systematic review (Parittotokkaporn et al. 2020) that reports non-invasive neuromodulation treatment is commonly used to affect colonic transit time and anorectal pressure, although results are not always definitive.

One systematic review (Worsoe et al. 2013) supports that sacral anterior root stimulation, sacral nerve stimulation, peripheral nerve stimulation, magnetic stimulation and nerve rerouting therapies may also improve bowel function for people with SCI and NBD.

There is level 1 evidence (from one RCT; Korsten et al. 2004) that electrical stimulation of the abdominal wall muscles can improve bowel management for individuals with tetraplegia.

There is level 2 evidence from one prospective controlled trial (Hascakova-Bartova et al. 2008) that neuromuscular electrical stimulation of the abdominal muscles has a positive effect on colonic transit activity in majority of the abdominal segments, but decreases lung capacity in people with SCI.

There is level 4 evidence (Worsoe et al. 2012) that acute dorsal genital nerve (DGN) stimulation reduces rectal cross-sectional area (CSA) and rectal pressure-CSA relation for people with complete supraconal SCI.

There is level 4 evidence (Chen & Liao, 2015) that found chronic sacral neuromodulation is a safe treatment that improves constipation, although it may not resolve all neurogenic bowel symptoms alone.

There is level 4 evidence (from eight pre-post studies; Rasmussen 2015, Valles et al. 2009; Gstaltner et al. 2008; Kachourbos and Creasey 2000; Holzer et al. 2007; Jarret et al. 2005; Lombardi et al. 2011; Chia et al. 1996) that supports the use of sacral anterior root stimulation to reduce constipation and incontinence and improve neurogenic bowel dysfunction in individuals with SCI. One study (Rasmussen 2015) concluded that the effect of stimulation does not seem to decrease with time.

There is level 4 evidence (from three pre-post studies; Tsai et al. 2009, Lin et al. 2001, 2002) that functional magnetic stimulation may reduce colonic transit time in individuals with SCI.

There is level 5 evidence (one survey; Bourbeau et al. 2020) that majority of people with SCI and NBD are willing to use neuromodulation interventions if they are safe, easy and non-invasive procedures, with fecal continence management as a priority.

There is level 3 evidence (Sievert et al. 2010) that early bilateral sacral nerve modulator implantation improves bowel movement control and may increase quality of life for people with complete SCI.

There is level 4 evidence (Lombardi et al. 2009) that sacral neuromodulation improves defecation time, constipation, fecal incontinence, and quality of life in people with incomplete SCI and neurogenic bowel symptoms.

There is level 4 evidence (MacDonagh et al. 1990) that people with complete supraconal spinal cord lesions can achieve defecation with shorter times and constipation improvements with the use of Brindley-Finetech intradural sacral anterior root stimulation.

There is level 4 evidence (from one pre-post study with two subjects: Mentes et al. 2007) that posterior tibial nerve stimulation improves bowel management for those with incomplete SCI.

There is level 4 evidence (from one pre-post study with two subjects: Johnston et al. 2005) that the Praxis FES system increases the frequency of defecation and decreases time required for bowel care in individuals with SCI.