Outcomes of implementation of sacral nerve stimulation on urination, defecation, and sexual function in patients with spinal cord injury

Sacral neuromodulation and sexual function: a systematic review and meta-analysis of the literature

INTRODUCTION AND HYPOTHESIS

Sexual function is being increasingly recognized as an important patient-reported outcome. Sacral neuromodulation (SNM) is a treatment with an expanding list of indications. The effect of sacral neuromodulation on sexual function has been examined in a number of studies with variable results. In this review, we aim to systematically review the literature and pool the data if appropriate.

METHODS

The literature search was conducted primarily on the Healthcare Databases Advanced Search (HDAS) platform using the Medline, EMBASE and CINHAL search engines. Of 196 initial citations, 17 articles met our predefined inclusion criteria. Thirteen studies reported enough information to be included in our meta-analysis. RevMan5 software was used for analysis.

RESULTS

Eight of 17 studies reported a positive effect of SNM on sexual function. Pooled analysis of data from 11 studies involving 573 patients before SNM and 438 patients after SNM showed significant improvement in sexual function (SMD = -0.39; 95% CI: -0.58 to -0.19; p = 0.0001). The results remained significant in most subgroup analyses except in patients suffering from fecal incontinence.

CONCLUSIONS

SNM in women with pelvic floor disorders, especially bladder dysfunction, seems to have a positive effect on sexual function. This needs to be verified in adequately powered primary research using sexual function as the primary outcome.

A systematic review of clinical studies on electrical stimulation therapy for patients with neurogenic bowel dysfunction after spinal cord injury

BACKGROUND

This study aimed to perform a systematic literature review of the clinical trial evidence on electrical stimulation for the treatment of neurogenic bowel dysfunction (NBD) after spinal cord injury (SCI).

METHODS

Systematic electronic searches were carried out in the PubMed/Medline, EMBASE, Cochrane Central Register of Controlled Trials, and China National Knowledge Infrastructure databases, along with the reference lists in the include studies. Studies were eligible for inclusion if they adopted a controlled clinical design based on human population, the patients suffered from spinal cord injury, the main outcomes were the disorders of bowel function and the intervention was electrical stimulation. Also, the language was limited to English and Chinese.

RESULTS

Eleven studies were included in this systematic review, comprising transcutaneous electrical stimulation, transrectal bowel stimulation, sacral nerve stimulation, intravesical electrical stimulation, etc. Of the 11 studies, 3 were randomized controlled trials, 8 were controlled before-and-after trials. The quality of the included studies was moderate bias risk. Most studies revealed that the electrical stimulation was beneficial for the patient with NBD after SCI.

CONCLUSIONS

Only 11 small clinical studies with 298 participants have evaluated the efficacy of electrical stimulation for NBD after SCI. Although some studies showed electrical stimulation was benefit for the patient with NBD after SCI, there was currently not enough evidence to support the use of electrical stimulation could improve the clinical symptoms of those patients. Thus, well-designed randomized controlled trials with larger patient population are warranted to establish its benefit in clinical practice in the future.

Electrical Stimulation and Motor Recovery

In recent years, several investigators have successfully regenerated axons in animal spinal cords without locomotor recovery. One explanation is that the animals were not trained to use the regenerated connections. Intensive locomotor training improves walking recovery after spinal cord injury (SCI) in people, and >90% of people with incomplete SCI recover walking with training. Although the optimal timing, duration, intensity, and type of locomotor training are still controversial, many investigators have reported beneficial effects of training on locomotor function. The mechanisms by which training improves recovery are not clear, but an attractive theory is available. In 1949, Donald Hebb proposed a famous rule that has been paraphrased as “neurons that fire together, wire together.” This rule provided a theoretical basis for a widely accepted theory that homosynaptic and heterosynaptic activity facilitate synaptic formation and consolidation. In addition, the lumbar spinal cord has a locomotor center, called the central pattern generator (CPG), which can be activated nonspecifically with electrical stimulation or neurotransmitters to produce walking. The CPG is an obvious target to reconnect after SCI. Stimulating motor cortex, spinal cord, or peripheral nerves can modulate lumbar spinal cord excitability. Motor cortex stimulation causes long-term changes in spinal reflexes and synapses, increases sprouting of the corticospinal tract, and restores skilled forelimb function in rats. Long used to treat chronic pain, motor cortex stimuli modify lumbar spinal network excitability and improve lower extremity motor scores in humans. Similarly, epidural spinal cord stimulation has long been used to treat pain and spasticity. Subthreshold epidural stimulation reduces the threshold for locomotor activity. In 2011, Harkema et al. reported lumbosacral epidural stimulation restores motor control in chronic motor complete patients. Peripheral nerve or functional electrical stimulation (FES) has long been used to activate sacral nerves to treat bladder and pelvic dysfunction and to augment motor function. In theory, FES should facilitate synaptic formation and motor recovery after regenerative therapies. Upcoming clinical trials provide unique opportunities to test the theory.