Constipation is one of the most common gastrointestinal disorders, affects 1.9%-27.2% of the population, with most estimates ranging from 12% to 19%. In adults it affects more women rather than men, while in children an equal incidence between sexes is experienced. The prevalence increases with age. This will include constipation characterized by infrequent passage of stool, hard stools, difficulty in passing, bloating, and abdominal pain, which may all amount to a precipitous fall in the quality of life. Functional constipation has been divided into four categories: normal transit with anorectal function, pelvic floor dysfunction or functional defecation disorders, slow transit constipation, and a mixture of slow-transit constipation with pelvic floor dysfunction.
Initial Treatment Approaches
The treatment for chronic constipation includes patient education and dietary changes with an emphasis on increasing dietary fiber intake. Laxatives and enemas are often prescribed, and biofeedback therapy is used to teach the patient to relax the pelvic floor muscles. In more resistant cases, retrograde or antegrade colonic irrigation may be necessary. The invasive surgical options, including subtotal colectomy with ileorectal anastomosis, are indicated only in patients with very severe symptoms or complications like rectal prolapse, but these surgeries are highly risky.
Neuromodulation Overview
Neuromodulation is a therapy that alters organ function via neural activity modification, usually accomplished by electrical stimulation. Nerves and muscle cells have the ability to be electrically excitable, with ion channels allowing flow of current, hence influencing gut motility. Electrical stimulation was utilized in the past to affect nerves, smooth muscles, or other cell types depending on the location of application, frequency, and intensity of the current.
Most electrical stimulation techniques used for constipation were primarily developed to treat urinary bladder dysfunction, notably urinary incontinence and urge incontinence. The techniques of TES and SNM demonstrated very significant improvements in bowel control and bowel frequency in patients with severe detrusor instability.
Sacral Neuromodulation (SNM)
The physiologic principle on which SNM is based is that activity in one neural pathway will modulate pre-existing activity in another through synaptic interaction. First applied to urology by Tanagho and Schmidt in the late 1980s for the treatment of neurogenic bladder diseases, SNM has been extended to the treatment of a variety of urological and gastrointestinal disorders, including fecal incontinence.
There are two phases to the procedure: percutaneous nerve evaluation, which is an initial diagnostic phase that only lasts three weeks, and then SNM. A needle is introduced under local or general anesthesia in the third sacral foramen, S3. Local anesthesia is preferred so as to have the patient's feedback during the procedure in order to lessen the need for hospital facilities. This is done to determine whether SNM will relieve symptoms of constipation, such as straining or infrequent bowel movements.
Strict selection criteria for the treatment of constipation with SNM are not established. Indeed, patients included in the current studies have mixed pathophysiologies, and positive results have been observed in both slow and normal transit constipation. PNE testing is indicated for patients suffering from constipation or irritable bowel syndrome with constipation who have not responded to conservative treatments.
Clinical Outcomes and Mechanisms of SNM
Comparability of these studies on SNM is limited because of variable selection criteria, heterogeneous patient groups, and small sample sizes. More than that, most studies included patients with both constipation and irritable bowel syndrome with constipation. Studies generally report increased bowel movements and reduced symptoms, indicating SNM's potential for treating constipation.
The mechanisms underlying SNM for constipation are yet unknown. It is, however, about fecal incontinence that part of the research was dedicated, and a common pathway might exist. Electrical stimulation of the pelvic floor by the pelvic plexus and the pudendal nerve seems to activate both the autonomic and somatic nervous systems, which would lead to therapeutic effects.
Transcutaneous Electrical Stimulation
Electrical stimulation via the skin, or TES, has been promising in constipation. The physical therapists treat bladder anomalies with TES by applying the stimulation via the rectum, vagina, abdomen, spine, and acupuncture points to strengthen the neck of the bladder and to treat incontinence and overactive bladder. The gastrointestinal applications have used TES in the treatment of intractable functional constipation, such as bloating and abdominal pain.
Despite a huge potential, the level of evidence supporting TES in constipation is generally low, and more studies are needed to confirm its efficacy and establish optimal treatment protocols.
Conclusion
Electrotherapy neuromodulation is an emerging plausible new modality in the management of chronic, treatment-resistant constipation. Clinical trials document the effectiveness of SNM in the treatment of fecal incontinence, while emerging data support its use for intractable constipation, particularly in patients who have not responded to conservative treatments. PNE testing provides a predictive measure of treatment outcomes, making SNM a very promising option for selected patients. However, the evidence base remains limited, and further research is required to confirm these findings and further refine patient selection and treatment protocols.
Comprehensive Overview of Constipation Treatment Through Neuromodulation
Neuromodulation is used in the treatment of fecal incontinence and constipation. The gastrointestinal tract plays a crucial role in bowel movements. There exist a number of therapies, one of them being electrical stimulation, which affects the sphincters in such ways as to facilitate the control of bowel movements. Rectal stimulation is the kind of therapy applied in the case of constipation. Typical symptoms are infrequent bowel movements; abdominal pain; abnormal sensation in the anal area can be indicative of constipation problems. Stimulation at the anus could be helpful in the treatment of constipation, which typically leads to bowel obstruction and may be painful. The activity of the anal sphincter can be influenced to control constipation, and constipation's predominant symptom is difficulty passing stool. Interventions provided for constipation may also share similarities with the treatment administered for urinary incontinence, and anal stimulation techniques are also employed. Neuromodulation treatments are frequently targeted at enhancing the motility of the colon so as to augment bowel continence. Spinal cord involvement in neuromodulation significantly affects bowel function. Sacral nerve stimulation is one of the primary approaches used in the treatment of constipation, wherein the objective of treatment is to increase the frequency and facilitation of defecation. The pelvic floor muscles are strengthened, thus facilitating bowel emptying. Increased frequency of bowel movement is one of the primary objectives of treatment with regard to bowel movement. Gastroenterology is the study of gastrointestinal disorders, to which constipation is one of them. Constipation can be related to a serious disorder like rectal prolapse. Abnormal bowel habit and straining at stool are two major features of constipation, the symptoms of which the therapies relieve, with abdominal bloating being one such symptom. Some conditions show alternating constipation and diarrhea, many of which are due to disordered motility. Inability to pass out stools completely is a major symptom reflecting that the large intestine has an important function for passage of stool normally. Enemas are administered in the management of intractable constipation and colonoscopy identifies etiology. Enhancement of gastrointestinal motility is one of the goals of treatment where incontinence of stool is experienced. Sacral nerve stimulation and other modalities applied to urinary incontinence respond to constipation as well. The bowel movements involve a phase of muscular contraction and the modulation of colorectal function is central to the management of constipation. Hard stools and conditions like rectal prolapse common in chronic constipation are a significant concern. Neurological conditions such as multiple sclerosis can cause constipation, and ultrasound may be used at times in the evaluation. Patients may have to be referred to experts for the treatment of this condition, and constipation can also be managed by strengthening the sphincter muscle. The causes need to be understood for appropriate treatment; inability to pass stools can lead to severe discomfort and complications. Better bowel control is a major objective of treatment, with vaginal stimulation being indicated for linked disorders. Abdominal pain is an extremely common symptom in chronic constipation, which when very severe leads to fecal impaction. The development of chronic constipation may be contributed by neurologic disorders and, more importantly, dietary fiber plays a significant role in its management. Neuromodulation has a primary effect on reflex actions in the bowel, and the spinal cord likewise plays an important role in bowel function. Treatment approaches consider the whole digestive tract, with barium studies helping make a diagnosis of underlying issues.
This overview draws together the highlights of neuromodulation for the treatment of constipation in terms of gastrointestinal motility, the role of sacral and transcutaneous electrical stimulation, and the potential benefits for patients suffering from chronic and intractable constipation.
