Slow transit colon constipation is not related to the number of interstitial cells of Cajal

Ca2+ dynamics in interstitial cells: foundational mechanisms for the motor patterns in the gastrointestinal tract

The gastrointestinal (GI) tract displays multiple motor patterns that move nutrients and wastes through the body. Smooth muscle cells (SMCs) provide the forces necessary for GI motility, but interstitial cells, electrically coupled to SMCs, tune SMC excitability, transduce inputs from enteric motor neurons, and generate pacemaker activity that underlies major motor patterns, such as peristalsis and segmentation. The interstitial cells regulating SMCs are interstitial cells of Cajal (ICC) and PDGF receptor (PDGFR)α+ cells. Together these cells form the SIP syncytium. ICC and PDGFRα+ cells express signature Ca2+-dependent conductances: ICC express Ca2+-activated Cl- channels, encoded by Ano1, that generate inward current, and PDGFRα+ cells express Ca2+-activated K+ channels, encoded by Kcnn3, that generate outward current. The open probabilities of interstitial cell conductances are controlled by Ca2+ release from the endoplasmic reticulum. The resulting Ca2+ transients occur spontaneously in a stochastic manner. Ca2+ transients in ICC induce spontaneous transient inward currents and spontaneous transient depolarizations (STDs). Neurotransmission increases or decreases Ca2+ transients, and the resulting depolarizing or hyperpolarizing responses conduct to other cells in the SIP syncytium. In pacemaker ICC, STDs activate voltage-dependent Ca2+ influx, which initiates a cluster of Ca2+ transients and sustains activation of ANO1 channels and depolarization during slow waves. Regulation of GI motility has traditionally been described as neurogenic and myogenic. Recent advances in understanding Ca2+ handling mechanisms in interstitial cells and how these mechanisms influence motor patterns of the GI tract suggest that the term "myogenic" should be replaced by the term "SIPgenic," as this review discusses.

Searching for a definition for pharmacologically refractory constipation: A systematic review

BACKGROUND AND AIM

Surgery and other non-pharmacological treatments such as sacral nerve stimulation are used for the treatment of difficult-to-treat chronic constipation. Novel pharmacological therapeutic agents are also being introduced. To evaluate the efficacy of these treatments, it is imperative to have a consistent definition of pharmacologically refractory constipation. A systematic review of studies on refractory, difficult-to-treat or surgically treated constipation was carried out to determine the criteria that various authors used to define this group of patients.

METHODS

A systematic review was performed for literature published from June 2005 to June 2015 using PubMed, Cochrane, and Scopus databases, as well as manual searches. Studies on patients with refractory or intractable constipation were extracted. Criteria used for defining refractory constipation, as well as pharmacological agents tried including dosage, frequency, and duration, were reviewed.

RESULTS

Sixty-one studies were included in this review. Forty-eight involved surgical treatment of constipation, while 13 examined non-surgical therapies for refractory constipation. There is no generally accepted definition of refractory constipation. Authors consider constipation to be refractory when response to management is suboptimal, but there is no consensus on the choice of drug, order of usage, and dosage or treatment duration. Prior medical therapy was not mentioned at all in five studies.

CONCLUSIONS

There is need for a detailed definition of pharmacologically refractory constipation before submitting patients to invasive treatments and to evaluate new pharmacological agents.

Evaluation of interstitial cells of Cajal in patients with severe colonic inertia requiring surgery: a clinical-pathological study

AIM

Subtotal colectomy is the treatment of last resort in patients with severe colonic inertia (SCI) refractory to laxatives. Some studies have reported hypoplasia of the interstitial cells of Cajal (ICC) using a semi-quantitative analysis. The aims of this study were first to investigate if semi-quantitative analysis or morphometry is better at the quantification of colonic ICC and second to determine whether there is a relationship between the number of ICC and the severity of constipation.

METHOD

Clinical and pathological data from patients with subtotal colectomy for SCI were collected. Quantification of ICC using CD117 immunohistochemistry and morphometric methods was performed at three different colonic sites in patients and controls.

RESULTS

Twenty patients had a colectomy for SCI. All were considered to have failed maximal medical treatment and 45% were hospitalized at least once for colonic obstruction due to faecaloma. Using a semi-quantitative methodology, 30% of patients displayed ICC hypoplasia (< 7 per high power field) and all controls had normal ICC. Using morphometry, the percentage of colonic ICC was significantly less in patients compared with controls with no significant differences between the ascending, transverse and descending colonic segments. Overall 60% of patients had ICC hypoplasia (< 1% vs 20% of controls, P = 0.009). The severity of constipation was not related to the quantity of ICC.

CONCLUSION

In patients with SCI, morphometric analysis is more sensitive than semi-quantitative analysis in the detection of ICC hypoplasia. The severity of constipation was not related to the quantity of ICC.

Functional Disorders: Slow-Transit Constipation

Constipation is a very common complaint, with slow-transit constipation (STC) accounting for a significant proportion of cases. Old age, female gender, psychiatric illness, and history of sexual abuse are all associated with STC. The exact cause of STC remains elusive; however, multiple immune and cellular changes have been demonstrated. Diagnosis requires evidence of slowed colonic transit which may be achieved via numerous modalities. While a variety of medical therapies exist, these are often met with limited success and a minority of patients ultimately require operative intervention. When evaluating a patient with STC, it is important to determine the presence of concomitant obstructed defecation or other forms of enteric dysmotility, as this may affect treatment decisions. Although a variety of surgical procedures have been reported, subtotal colectomy with ileorectal anastomosis is the most commonly performed and well-studied procedure, with the best track record of success.

Histological Findings in Resected Bowel of Motility-disordered Patients

Gastrointestinal (GI) motility disorders are prevalent conditions associated with pain and bowel dysfunction. Some motility-disordered patients with intractable symptoms have undergone bowel resection aimed at palliating their symptoms. Our objective was to describe a population of motility-disordered patients with histopathological abnormalities identified in full-thickness surgical biopsies. A retrospective cohort study using prospectively collected clinical data and pathology reports was conducted. All adult patients referred to a tertiary motility clinic from 1996 to 2011 who had bowel resection for motility disorder were consecutively sampled. Fisher's exact test was used. Ninety-seven patients were referred for motility disorder during this time and pathology reports were available for 62 patients (63.9%). Hypertrophy or hyperplasia of the myenteric plexus was reported in 13 patients (21.0%). These patients were predominantly females with constipation-dominant symptoms. They were more likely to have objective evidence of colonic inertia ( P = 0.01) than patients without myenteric plexus hypertrophy/hyperplasia. Consistent histopathologic abnormalities of myenteric plexus hypertrophy/hyperplasia were described in 21 per cent of patients with refractory GI motility disorders referred for surgical management. Our findings contrast with the hypoganglionosis reported in the slow transit constipation literature. Future studies are needed to systematically investigate these novel histologic findings through a follow-up immunohistochemical study of stored bowel specimens.

The role of hand-assisted laparoscopic surgery in total colectomy for colonic inertia: a retrospective study

Purpose

To compare and assess the efficacy, safety and utility of hand-assisted laparoscopic surgery (HALS) with open surgery (OS) in total colectomy with ileorectal for colonic inertia.

Methods

From January 2001 to February 2012, 56 patients diagnosed with colonic inertia who failed to respond to medical treatments underwent hand-assisted laparoscopic total colectomy with ileorectal anastomosis. Another 68 patients underwent laparotomy. Main parameters such as clinical manifestations, conversion to open procedure, operative time, incision length, pain score, intraoperative blood loss, time to first flatus and hospitalization, early postoperative complications and hospitalization cost were retrospectively analyzed. Postoperative defecating frequencies were followed up in both groups.

Results

All patients received successful operation, no surgical mortality happened and none of the patients required conversion to an exploratory laparotomy in HALS group. The clinical features, the estimated blood loss, incision length, pain score, first passing flatus time, and postoperative hospitalization time were superior in HALS group (P < 0.05). The early postoperative complications and frequency of defecation were similar. However, the mean operative time was longer and hospitalization cost was higher in HALS group than those in OS group (P < 0.05).

Conclusion

HALS total colectomy can be a safe and efficient technique in the treatment of colonic inertia. HALS can result in a better cosmetic result and a quicker postoperative recovery, but requires higher direct cost.

Cellular and molecular basis of chronic constipation: Taking the functional/idiopathic label out

In recent years, the improvement of technology and the increase in knowledge have shifted several strongly held paradigms. This is particularly true in gastroenterology, and specifically in the field of the so-called “functional” or “idiopathic” disease, where conditions thought for decades to be based mainly on alterations of visceral perception or aberrant psychosomatic mechanisms have, in fact, be reconducted to an organic basis (or, at the very least, have shown one or more demonstrable abnormalities). This is particularly true, for instance, for irritable bowel syndrome, the prototype entity of “functional” gastrointestinal disorders, where low-grade inflammation of both mucosa and myenteric plexus has been repeatedly demonstrated. Thus, researchers have also investigated other functional/idiopathic gastrointestinal disorders, and found that some organic ground is present, such as abnormal neurotransmission and myenteric plexitis in esophageal achalasia and mucosal immune activation and mild eosinophilia in functional dyspepsia. Here we show evidence, based on our own and other authors’ work, that chronic constipation has several abnormalities reconductable to alterations in the enteric nervous system, abnormalities mainly characterized by a constant decrease of enteric glial cells and interstitial cells of Cajal (and, sometimes, of enteric neurons). Thus, we feel that (at least some forms of) chronic constipation should no more be considered as a functional/idiopathic gastrointestinal disorder, but instead as a true enteric neuropathic abnormality.

Gastrointestinal neuromuscular pathology in chronic constipation

Some patients with chronic constipation may undergo colectomy yielding tissue appropriate to diagnosis of underlying neuromuscular pathology. The analysis of such tissue has, over the past 40 years, fueled research that has explored the presence of neuropathy, myopathy and more recently changes in interstitial cells of Cajal (ICC). In this chapter, the data from these studies have been critically reviewed in the context of the significant methodological and interpretative issues that beset the field of gastrointestinal neuromuscular pathology. On this basis, reductions in ICC appear to a consistent finding but one whose role as a primary cause of slow-transit constipation requires further evaluation. Findings indicative of significant neuropathy or myopathy are variable and in many studies subject to considerable methodological bias. Methods with practical diagnostic utility in the individual patient have rarely been employed and require further validation in respect of normative data.

Can "functional" constipation be considered as a form of enteric neuro-gliopathy?

Constipation has been traditionally viewed and classified as a functional or idiopathic disorder. However, evidence has been accumulating that suggests how constipation might be considered as due to abnormalities of the enteric nervous system, since alterations of this system, not evident in conventional histological examination, may be present in these patients. These abnormalities often consist in decrease or loss of the enteric glial cells, a pathological finding present in most types of constipation so far investigated. In this article we will discuss these evidences, and will try to consider constipation no more as a simple functional or idiopathic disorder but as a form of enteric neuro-gliopathy.

Constipation and obstructed defecation

Difficulties with bowel function are common and may be due to several causes including slow colonic transit and obstructed defecation. The anatomical and pathophysiological changes associated with these conditions are varying, often incompletely understood, and in many cases have limited treatment outcomes. Patients present with variable complaints and have previously tried a plethora of over-the-counter medications in an effort to relieve their symptoms. Physicians need an organized approach to manage these patients optimally. Improvements over the past few years in our understanding of the complex process of defecation, along with the increasing use of radiological and anorectal physiology studies, have led to improved treatment results.

Cyclooxygenase-dependent alterations in substance P-mediated contractility and tachykinin NK1 receptor expression in the colonic circular muscle of patients with slow transit constipation

Tachykinins are important neurotransmitters regulating intestinal motility. Slow transit constipation (STC) represents an extreme colonic dysmotility with unknown etiology that predominantly affects women. We examined whether the tachykinin system is involved in the pathogenesis of STC. Isolated sigmoid colon circular muscle from female STC and control patients was studied using functional and quantitative reverse transcriptase-polymerase chain reaction methods. A possible alteration of neurotransmission was investigated by electrical field stimulation (EFS) and ganglionic stimulation by dimethylphenylpiperazinium (DMPP). Substance P (SP)-mediated contractions in circular muscle strips were significantly diminished in STC compared with age-matched control (P < 0.001). In contrast, contractile responses to neurokinin A, the selective tachykinin NK(2) receptor agonist, [Lys(5),MeLeu(9),Nle(10)]NKA(4-10), and acetylcholine were unaltered in STC. The reduced responses to SP in STC were fully restored by indomethacin, partially reversed by tetrodotoxin (TTX), but unaffected by atropine or hexamethonium. The restoration by indomethacin was blocked by the NK(1) receptor antagonist CP99994 [(2S,3S)-3-(2-methoxybenzylamino)-2-phenylpiperidine] and TTX. In STC colonic muscle, there was a significant increase of NK(1) receptor mRNA expression, but no difference in NK(2) mRNA level. DMPP generated biphasic responses, relaxation at lower and contraction at higher concentrations. Although the responses to DMPP were similar in STC and control, an altered contractile pattern in response to EFS was observed in STC circular muscle. In conclusion, we postulate that the diminished contractile response to SP in STC is due to an increased release of inhibitory prostaglandins through activation of up-regulated NK(1) receptors. Our results also indicate some malfunction of the enteric nervous system in STC.

Hand-assisted laparoscopic total colectomy for slow transit constipation

PURPOSE

Current medical treatments for slow transit constipation (STC) are often ineffective, and total colectomy with ileorectal anastomosis has been the procedure of choice for selected patients with refractory STC. Today, minimally invasive approaches are being utilized in a greater number of procedures as surgeons become more familiar with the techniques involved. The aim of this study was to assess the safety and utility of hand-assisted laparoscopic total colectomy for STC.

METHOD

From January 2002 to December 2005, 44 women presented with complaints of intractable constipation and failed to respond to medical treatment. Slow transit constipation was diagnosed after a series of examinations, including a colonic transit test, anal manometry, balloon expulsion test, and barium enema. All eligible patients underwent a hand-assisted laparoscopic total colectomy with ileorectal anastomosis. Main outcome measures included the operative time, conversion to open procedure, blood loss, time to return of flatus, length of postoperative hospital stay, and complications.

RESULT

The mean operative time was 197 min (range, 125-295 min). The mean estimated blood loss was 113 ml (range, 100-300 ml). The mean day of first time to flatus was 2 days, and the mean hospital stay was 7.6 days. There was no conversion to an open procedure and no surgical mortality. In the following period, two patients developed intestinal obstruction, which underwent exploratory laparotomy. However, some 39 patients (88.6%) expressed excellent or good in satisfaction.

CONCLUSION

Hand-assisted laparoscopic total colectomy could be a safe and efficient technique in the treatment of STC.

Slow transit constipation: A functional disorder becomes an enteric neuropathy

Slow transit constipation has been traditionally considered and classified as a functional disorder. However, clinical and manometric evidence has been accumulating that suggests how most of the motility alterations in STC might be considered of neuropathic type.In addition, further investigations showed that subtle alterations of the enteric nervous system, not evident to conventional histological examination, may be present in these patients. In the present article we will discuss these evidences, and will try to put them in relation with the abnormal motor function of the large bowel documented in this pathological condition.