Sacral Neural Crest-Independent Origin of the Enteric Nervous System in Mouse

BACKGROUND & AIMS

The enteric nervous system (ENS), the gut's intrinsic nervous system critical for gastrointestinal function and gut-brain communication, is believed to mainly originate from vagal neural crest cells (vNCCs) and partially from sacral NCCs (sNCCs). Resolving the exact origins of the ENS is critical for understanding congenital ENS diseases but has been confounded by the inability to distinguish between both NCC populations in situ. Here, we aimed to resolve the exact origins of the mammalian ENS.

METHODS

We genetically engineered mouse embryos facilitating comparative lineage-tracing of either all (pan-) NCCs including vNCCs or caudal trunk and sNCCs (s/tNCCs) excluding vNCCs. This was combined with dual-lineage tracing and 3-dimensional reconstruction of pelvic plexus and hindgut to precisely pinpoint sNCC and vNCC contributions. We further used coculture assays to determine the specificity of cell migration from different neural tissues into the hindgut.

RESULTS

Both pan-NCCs and s/tNCCs contributed to established NCC derivatives but only pan-NCCs contributed to the ENS. Dual-lineage tracing combined with 3-dimensional reconstruction revealed that s/tNCCs settle in complex patterns in pelvic plexus and hindgut-surrounding tissues, explaining previous confusion regarding their contributions. Coculture experiments revealed unspecific cell migration from autonomic, sensory, and neural tube explants into the hindgut. Lineage tracing of ENS precursors lastly provided complimentary evidence for an exclusive vNCC origin of the murine ENS.

CONCLUSIONS

sNCCs do not contribute to the murine ENS, suggesting that the mammalian ENS exclusively originates from vNCCs. These results have immediate implications for comprehending (and devising treatments for) congenital ENS disorders, including Hirschsprung's disease.

Rectal biopsy: is it really necessary in anorectal malformations?

AIM OF THE STUDY

The coexistence of Hirschsprung's disease (HD) with anorectal malformation (ARM) is rare but many surgeons still ask pathologists to look for ganglia in the terminal rectum or fistula. In this study, we aimed to highlight the rarity of this association and question the necessity of histological evaluation.

METHODS

After obtaining board review approval, rectal specimens of ARM patients who underwent corrective surgery in the last 8 years were re-analyzed by two blinded pathologists for the presence and structure of ganglia. Clinical and radiological data of patients retrieved from center records and correlated with histopathologic findings.

MAIN RESULTS

67 patients with ARM were identified, distal rectal specimen was obtained in 47. The median age at the time of surgery was 11 months (2 days-59 months). A normal pattern of ganglia was present in 51.1% (24/47), 29.7% (14/47) had aganglionosis and 19.1% (9/47) were inconclusive due to insufficient material. None of the aganglionic specimens showed other histological findings of HD. Patients were followed up regularly in the outpatient colorectal clinic for a median of 87 months (42-117 m). Only 6 experienced severe constipation (3 ganglionic, 2 no biopsy, 1 aganglionic), all of whom responded to a bowel management program, and none developed other manifestations of HD (abdominal distension, failure to thrive or enterocolitis) or required additional surgery.

CONCLUSIONS

Our results strongly suggest that the association of ARM and HD is extremely rare and the practice of searching for ganglia in the distal rectum or fistula of ARM patients should be discouraged to avoid potential misdiagnosis and overtreatment.

Histopathological dimensions differ between aganglionic and ganglionic bowel wall in children with Hirschsprung's disease

BACKGROUND

In the validation of new imaging technology for children with Hirschsprung's disease (HSCR), basic anatomical parameters of the bowel wall must be established specifically for this patient group.

AIM

To explore differences in histoanatomical layers of bowel wall, comparing ganglionic and aganglionic bowel walls, and to examine if the bowel wall thickness is linked to patient weight.

METHODS

This was an observational study of bowel specimens from children weighing 0-10 kg, operated on consecutively during 2018-2020. Ganglionic and aganglionic bowel walls were measured in digitalized microscopy images from 10 sites per trans-sectional specimen and compared regarding the thickness of their histoanatomical layers.

RESULTS

Bowel walls were measured in 21 children. Full bowel wall thickness did not differ between aganglionic and ganglionic bowel (2.20 vs 2.04; p = 0.802) while weight at surgery correlated positively with both ganglionic and aganglionic bowel wall thickness (r = 0.688 and 0.849, respectively), and age at surgery with ganglionic bowel wall thickness (r = 0.517). In aganglionic segments, the muscularis externa layer was thicker compared to that in ganglionosis (0.45 vs 0.31 mm, p = 0.012) whereas the muscularis interna was thinner (0.45 vs 0.62 mm, p < 0.001). A diagnostic index was identified whereby a lower ratio of muscularis interna/externa thickness followed by a thinner muscularis interna differed between aganglionic and ganglionic bowel in all specimens.

CONCLUSION

Thicknesses of the bowel wall's muscle layers differ between aganglionic and ganglionic bowel walls in children with HSCR. These findings support a diagnostic index that could be validated for transfer to instant diagnostic imaging techniques.

LEVEL OF EVIDENCE

Diagnostic: 3.

Translational research in Hirschprung's disease at the National Children's Research Centre in Dublin

Hirschsprung's disease (HD) is a congenital condition characterised by aganglionosis in the distal bowel. Over the years, at the National Children's Research Centre (NCRC), HD has been one of the most prominent and successful research areas for Prof. Prem Puri's research team. Research fellows from around the world came to the NCRC to work on both animal and human studies of HD and, cumulatively, made important discoveries in this field, publishing a total of 144 HD articles in peer-reviewed journals. Through their published work, the NCRC has been recognised as the leading international centre for the investigation of HD and its allied disorders. In this review, I will summarise the main findings from this work.

Embryology and anatomy of Hirschsprung disease

Bowel has its own elegant nervous system - the enteric nervous system (ENS) which is a complex network of neurons and glial clones. Derived from neural crest cells (NCCs), this little brain controls muscle contraction, motility, and bowel activities in response to stimuli. Failure of developing enteric ganglia at the distal bowel results in intestinal obstruction and Hirschsprung disease (HSCR). This Review summarises the important embryological development of the ENS including proliferation, migration, and differentiation of NCCs. We address the signalling pathways which determine NCC cell fate and discuss how they are altered in the context of HSCR. Finally, we outline the anatomical defects and the mechanisms underlying gut motility in HSCR.

Hirschsprung disease in Down syndrome: An opportunity for improvement

BACKGROUND

Down syndrome (DS) is the most common abnormality associated with Hirschsprung disease (HD). It has been suggested patients with HD and DS have worse outcomes, however the literature is controversial.

METHODS

The Kids' Inpatient Database (KID) from 2003 to 2012 was used to identify newborns with HD. Demographics, hospital characteristics, and outcomes were compared among patients with and without DS using standard statistical tests.

RESULTS

There were 481 patients identified with HD, of which 45 (9%) had DS. Patients with DS were older at the time of first rectal biopsy (6 [3-11] days vs. 4 [3-6] days, p = 0.012). There were no differences in operative versus non-operative management in patients with and without DS (p = 0.706). Hospital length of stay was longer in the DS cohort (22 [13-33] days vs. 15 [10-24] days, p = 0.019), and patients with DS were more likely to have a concomitant diagnosis of wound infection (<12% vs. 3%, p = 0.002) and necrotizing enterocolitis (<14% vs. 5%, p = 0.018). The mortality rate for patients with DS was four times higher than those without DS (< 5% vs. < 0.8%, p = 0.018).

CONCLUSION

In this nationwide cohort of patients with Hirschsprung disease, those with Down syndrome experienced delays in diagnosis and worse outcomes.

LEVEL OF EVIDENCE

Level III.

TYPE OF STUDY

Treatment study, retrospective comparative study.

The science of Hirschsprung disease: What we know and where we are headed

The enteric nervous system (ENS) is a rich network of neurons and glial cells that comprise the gastrointestinal tract's intrinsic nervous system and are responsible for controlling numerous complex functions, including digestion, transit, secretion, barrier function, and maintenance of a healthy microbiome. Development of a functional ENS relies on the coordinated interaction between enteric neural crest-derived cells and their environment as the neural crest-derived cells migrate rostrocaudally along the embryonic gut mesenchyme. Congenital or acquired disruption of ENS development leads to various neurointestinal diseases. Hirschsprung disease is a congenital neurocristopathy, a disease of the neural crest. It is characterized by a variable length of distal colonic aganglionosis due to a failure in enteric neural crest-derived cell proliferation, migration, differentiation, and/or survival. In this review, we will review the science of Hirschsprung disease, targeting an audience of pediatric surgeons. We will discuss the basic biology of normal ENS development, as well as what goes awry in ENS development in Hirschsprung disease. We will review animal models that have been integral to studying this disease, as well as current hot topics and future research, including genetic risk profiling, stem cell therapy, non-invasive diagnostic techniques, single-cell sequencing techniques, and genotype-phenotype correlation.

What parents need to know about Hirschsprung disease

Hirschsprung's disease (HD) is a complex colorectal disorder that can be challenging to understand and overwhelming to many parents. Counseling parents is critical for ensuring they understand their child's condition, how it must be treated, pitfalls that can occur during treatment, and how they will do in the long term. This article breaks down this process into a series of informally worded questions and reviews evidence-based discussion points around the most common concerns parents will have: survival, pathophysiology, surgical correction and complications, etiology and genetic basis, associated issues, outcomes, and familial nature. Where evidence is unclear, expert opinion is included. Discussion is geared towards the parents of a newly diagnosed and otherwise healthy neonate, with a brief section on complex situations including associated syndromes and late diagnosis. Embarking on the longitudinal care of a child with HD is a complex undertaking and requires significant parental education to establish a proper parent-surgeon relationship, an essential factor for optimizing outcome and family satisfaction.

Skip segment Hirschsprung's disease: report of two rare cases and management

PURPOSE

Skip segment Hirschsprung's disease (SS-HSCR) is defined as the occurrence of a segment of ganglionated intestine surrounded proximally and distally by aganglionosis. The presence of the skip intestinal segment often leads to clinical misdiagnosis, missed diagnosis or inadequate resection of the lesions. The purpose was to describe two new cases of SS-HSCR with the aim of proposing questions regarding the diagnosis and treatment of this rare disease.

METHODS

We reported two cases of infants with SS-HSCR that were admitted to our institution within the last 3 years.

RESULTS

One patient had a skip segment of ganglionated intestine in the ascending colon. In the other patient, there were no ganglionic cells in the rectum and appendix, but ganglionic cells were visible in the proximal ascending colon. The entire colons in the both cases were finally resected, and a pull-through operation was performed.

CONCLUSION

Multipoint biopsy should be performed when the biopsy results are inconsistent with clinical manifestations. Intraoperative laparoscopic identification of the transition zone may be necessary when TCA is suspected. Multisegment biopsy is needed to as a preventative measure for SS-HSCR if TCA is indicated during surgery. Further study is required to determine the optimal length and method of retention of segments.

Management and outcomes for long-segment Hirschsprung disease: A systematic review from the APSA Outcomes and Evidence Based Practice Committee

OBJECTIVE

Long-Segment Hirschsprung Disease (LSHD) differs clinically from short-segment disease. This review article critically appraises current literature on the definition, management, outcomes, and novel therapies for patients with LSHD.

METHODS

Four questions regarding the definition, management, and outcomes of patients with LSHD were generated. English-language articles published between 1990 and 2018 were compiled by searching PubMed, Scopus, Cochrane Central Register of Controlled Trials, Web of Science, and Google Scholar. A qualitative synthesis was performed.

RESULTS

66 manuscripts were included in this systematic review. Standardized nomenclature and preoperative evaluation for LSHD are recommended. Insufficient evidence exists to recommend a single method for the surgical repair of LSHD. Patients with LSHD may have increased long-term gastrointestinal symptoms, including Hirschsprung-associated enterocolitis (HAEC), but have a quality of life similar to matched controls. There are few surgical technical innovations focused on this disorder.

CONCLUSIONS

A standardized definition of LSHD is recommended that emphasizes the precise anatomic location of aganglionosis. Prospective studies comparing operative options and long-term outcomes are needed. Translational approaches, such as stem cell therapy, may be promising in the future for the treatment of long-segment Hirschsprung disease.

Persistent bowel dysfunction after surgery for Hirschsprung’s disease: A neuropathological perspective

Hirschsprung’s disease (HD) is a congenital disorder, characterized by aganglionosis in the distal part of the gastrointestinal tract. Despite complete surgical resection of the aganglionic segment, both constipation and fecal incontinence persist in a considerable number of patients with limited treatment options. There is growing evidence for structural abnormalities in the ganglionic bowel proximal to the aganglionosis in both humans and animals with HD, which may play a role in persistent bowel dysfunction. These abnormalities include: (1) Histopathological abnormalities of enteric neural cells; (2) Imbalanced expression of neurotransmitters and neuroproteins; (3) Abnormal expression of enteric pacemaker cells; (4) Abnormalities of smooth muscle cells; and (5) Abnormalities within the extracellular matrix. Hence, a better understanding of these previously unrecognized neuropathological abnormalities may improve follow-up and treatment in patients with HD suffering from persistent bowel dysfunction following surgical correction. In the long term, further combination of clinical and neuropathological data will hopefully enable a translational step towards more individual treatment for HD.

Intrasphincteric botulinum toxin injections for post-operative obstructive defecation problems in Hirschsprung disease: A retrospective observational study

BACKGROUND

Patients with Hirschsprung disease may have obstructive symptoms after resection of the aganglionic segment. Botulinum toxin (BT) injections can help improve faecal passage by relaxing the internal anal sphincter. This study assess effect of BT injections and aims to identify factors associated with receiving BT injections and favourable response to the first BT injection.

METHODS

A retrospective study was performed in a cohort of consecutive patients treated for Hirschsprung disease in our centre between 2003 and 2017. The indication for BT injections was obstructive defecation problems that were non-responsive to high-dose laxatives or rectal irrigation, or an episode of Hirschsprung-associated enterocolitis (HAEC). Effectiveness of BT injections was measured in terms of clinical improvement. Relationships between factors associated with receiving BT injections and with response to the first BT injection were tested with group comparison and logistic regression.

RESULTS

Forty-one out of 131 patients received BT injections (31%) with a median of two injections (range 1-11). All patients had obstructive defecation problems non-responsive to high-dose laxatives or rectal irrigation, two patient also had an episode of HAEC. Twenty-five out of 41 patients (61%) had clinical improvement after first injection. In 29 of the 41 patients (71%) spontaneous defecation or treatment with laxatives only was achieved. Adverse effects were seen in 12 out of 41 patients (29%) after 14 injections (16%), and consisted of anal pain, temporary loss of stools and dermatitis. Patients who received BT injections more often had long segment disease, more often required laxatives or rectal irrigation and had longer length of hospital stay, both after corrective surgery and in follow-up. None of the tested factors was associated with clinical improvement after first BT injection.

CONCLUSION

Our findings show that BT injections effectively treat obstructive defecation problems in the majority of patients with Hirschsprung disease with mild adverse effects.

LEVEL OF EVIDENCE

Level III.

What is the appropriate aganglionic bowel length on contrast enema for attempting single stage transanal endorectal pull-through in Hirschsprung disease?

PURPOSE

To identify influence of different values of age and abnormal bowel length in HD patients selected for single stage TERPT which affects the technique of surgery.

METHODS

This observational study was carried out for over 2.5 years. All children younger than 14 years old with clinical suspicion for HD, typical transitional zone (TZ) on contrast enema (CE) distal to splenic flexure, preoperative diagnosis approved by full thickness biopsy, no previous surgical history and no urgency were included. The distance between the anus and TZ was considered as aganglionic length on CE. Biopsy was taken from distal to proximal of resected bowel to reach circumferentially normal innervated bowel. Paired sample Student's t-test, Pearson correlation test, receiver operating characteristic (ROC) analysis were performed.

RESULTS

Forty-eight patients were enrolled in this study. Measured mean for aganglionic bowel length on CE and pathology were 33.5 ± 17.1 cm and 56.8 ± 33.5 cm, respectively (p < 0.01). Correlation coefficient (R) and coefficient of determination (R2) were 0.632 and 40%, respectively (p < 0.01). The difference between radiologic and pathologic measurements in females was higher than males (mean: 29.3 vs 21.9 cm) but was not statistically significant (p = 0.75). There was statistically significant difference between CE and pathologic results in the infants younger than 10 months (p = .004). Abnormal bowel length equal to 52 cm predicted requirement of laparoscopy assistance/laparotomy with 75% sensitivity and 85% specificity.

CONCLUSION

Our investigation showed it is safe to attempt for single stage TERPT when aganglionic length on CE is less than 52 cm and the child with HD is older than 10 months. Chance of requiring additional laparotomy or laparoscopy assistance is low in these patients.

TYPE OF STUDY

Study of diagnostic test.

LEVEL OF EVIDENCE

Level II.

Hirschsprung disease and anorectal malformations - An uncommon association

BACKGROUND

The simultaneous occurrence of Hirschsprung disease (HD) and anorectal malformation (ARM) is extremely rare, with only a very limited amount of cases published in the literature. Constipation is a major problem in patients operated for ARM, and biopsies from the distal rectum in patients with ARM may not show ganglion cells owing to different reasons, leading to a false positive diagnosis of HD. A pull-through procedure for HD after previous anorectoplasty for ARM always leads to fecal incontinence. The aim of the present study was to assess the incidence of simultaneous diagnoses of ARM and HD in a single large cohort of ARM patients and to demonstrate that biopsies from the anal canal, which are negative for ganglion cells, may mislead to a diagnosis of HD.

MATERIALS AND METHODS

A retrospective review of our database from 1980 to 2018 identified 164 patients with HD and 2397 patients with ARM. Four patients suffered from both HD and ARM.

RESULTS

The incidence of HD in ARM patients was 4/2397 = 0.17%, and the incidence of ARM in HD patients was 4/164 = 2.4%.

CONCLUSION

Our results strongly suggest that the association of ARM and HD is less common than previously reported.

TYPE OF STUDY

Therapeutic LEVEL OF EVIDENCE: IV.

Case report of a skip segment Hirschsprung's disease: A real phenomenon

INTRODUCTION AND IMPORTANCE

Hirschsprung's disease is a congenital anomaly that results from an incomplete craniocaudal migration and maturation of intestinal ganglion progenitor cells leading to distal intestinal aganglionosis. Skip segment Hirschsprung's disease is an extremely rare phenomenon. We report a case involving only the small bowel with confirmed colonic ganglionosis.

CASE PRESENTATION

A case report of a 14-month-old with a skipped segment involving the distal 50 cm of the small bowel associated with colonic ganglionosis is presented. A current review of the literature is discussed.

CLINICAL DISCUSSION

Our patient had persistent obstructive symptoms despite undergoing a technically good, ganglionic pull-through operation at an outside institution. A laparoscopic-assisted pull-through might have documented a small bowel wall diameter discrepancy.

CONCLUSION

Although rare, skip segment Hirschsprung's disease is a real phenomenon that paediatric surgeons should be aware of and could involve small and large bowels.

Questioning the failure of neural crest cell migration theory in Hirschsprung's disease: A case report and literature review

INTRODUCTION

Segmental aganglionosis (the absence of ganglions) is a rare presentation of Hirschsprung's disease, whereby only limited segment/segments of aganglionic bowel is interposed between segments of innervated bowel, or "skip'' area of normal innervations is present within an area of aganglionosis.

PRESENTATION OF CASE

We reported a case of a 3 day old male newborn who presented with failure to pass meconium along with progressive abdominal distension. There were skip lesions present in between. Mikulicz double barrel enterostomy was carried out, which was followed by an uneventful postoperative period. Four months later, the patient was admitted for levelling biopsies which revealed the absence of ganglions in the terminal ileum as well as in the rectosigmoid junction. But the ganglions were present in between and proximal to the terminal ileum where the previously dilated small bowel segment was resected. This presentation was contradicted the most accepted migration theory of Hirschsprung's disease.

DISCUSSION

As seen in our case, and in21 other cases published between 1954-2016, we highly recommend that leveling/mapping biopsies should definitely include the cecal pole and the small bowel segments proximal to the ileocecal valve as well as the multilevel colonic biopsies down till the rectum.

CONCLUSION

Reporting of these cases brings out interesting questions with respect to the pathogenesis and serves to highlight the existence of several variants within the spectrum of Hirschsprung's disease.

Mesenteric Neural Crest Cells Are the Embryological Basis of Skip Segment Hirschsprung's Disease

BACKGROUND & AIMS

Defective rostrocaudal colonization of the gut by vagal neural crest cells (vNCCs) results in Hirschsprung's disease (HSCR), which is characterized by aganglionosis in variable lengths of the distal bowel. Skip segment Hirschsprung's disease (SSHD), referring to a ganglionated segment within an otherwise aganglionic intestine, contradicts HSCR pathogenesis and underscores a significant gap in our understanding of the development of the enteric nervous system. Here, we aimed to identify the embryonic origin of the ganglionic segments in SSHD.

METHODS

Intestinal biopsy specimens from HSCR patients were prepared via the Swiss-roll technique to search for SSHD cases. NCC migration from the neural tube to the gut was spatiotemporally traced using targeted cell lineages and gene manipulation in mice.

RESULTS

After invading the mesentery surrounding the foregut, vNCCs separated into 2 populations: mesenteric NCCs (mNCCs) proceeded to migrate along the mesentery, whereas enteric NCCs invaded the foregut to migrate along the gut. mNCCs not only produced neurons and glia within the gut mesentery, but also continuously complemented the enteric NCC pool. Two new cases of SSHD were identified from 183 HSCR patients, and Ednrb-mutant mice, but not Ret^-/- mice, showed a high incidence rate of SSHD-like phenotypes.

CONCLUSIONS

mNCCs, a subset of vNCCs that migrate into the gut via the gut mesentery to give rise to enteric neurons, could provide an embryologic explanation for SSHD. These findings lead to novel insights into the development of the enteric nervous system and the etiology of HSCR.

A novel Lugol's iodine staining technique to visualize the upper margin of the surgical anal canal intraoperatively for Hirschsprung disease: a case series

Background

In cases of Hirschsprung disease, complete and reproducible resection of the aganglionic bowel is ideal to achieve good postoperative bowel function. Reliable identification of the upper margin of the surgical anal canal, which is the squamous-columnar junction, is necessary during transanal pull-through. Here, we describe a novel staining technique using Lugol’s iodine stain to visualize the upper margin of the surgical anal canal.

Methods

Lugol’s iodine staining was performed in five patients with Hirschsprung disease treated using a single-stage laparoscopic transanal pull-through modified Swenson procedure. In two of these patients, endocytoscopic observation with ultra-high magnification was performed using methylene blue and crystal violet to mark the border of the squamous epithelium at 1 week before surgery. The alignment between the incisional line, which was revealed using Lugol’s iodine staining and endocytoscopic marking, was evaluated. Complications, including postoperative bowel dysfunction, were evaluated.

Results

In all cases, Lugol’s iodine staining produced a well-demarcated line. The endocytoscopic marking of the upper margin of the surgical anal canal was aligned with the line revealed by Lugol’s iodine staining. There were no complications associated with the transanal pull-through procedure, including postoperative bowel dysfunction.

Conclusions

Lugol’s iodine staining could be a safe and practical method to visualize the upper margin of the surgical anal canal intraoperatively. This finding may be useful for surgeons to make a consistent removal of the aganglionic bowel during surgery for Hirschsprung disease.

RET overactivation leads to concurrent Hirschsprung disease and intestinal ganglioneuromas

Appropriately balanced RET signaling is of crucial importance during embryonic neural crest cell migration, proliferation and differentiation. RET deficiency, for example, leads to intestinal aganglionosis (Hirschsprung disease), whereas overactive RET can lead to multiple endocrine neoplasia (MEN) syndromes. Some RET mutations are associated with both intestinal aganglionosis and MEN-associated tumors. This seemingly paradoxical occurrence has led to speculation of a 'Janus mutation' in RET that causes overactivation or impairment of RET activity depending on the cellular context. Using an intestinal catenary culture system to test the effects of GDNF-mediated RET activation, we demonstrate the concurrent development of distal colonic aganglionosis and intestinal ganglioneuromas. Interestingly, the tumors induced by GDNF stimulation contain enteric neuronal progenitors capable of reconstituting an enteric nervous system when transplanted into a normal developmental environment. These results suggest that a Janus mutation may not be required to explain co-existing Hirschsprung disease and MEN-associated tumors, but rather that RET overstimulation alone is enough to cause both phenotypes. The results also suggest that reprogramming tumor cells toward non-pathological fates may represent a possible therapeutic avenue for MEN-associated neoplasms.

Advances and Pitfalls in the Diagnosis of Hirschsprung Disease

Surgical pathology for Hirschsprung disease (HSCR) occasionally is difficult, especially for those who encounter the disorder infrequently. This article reviews pathologic features of HSCR, considers various specimens the pathologist is required to evaluate, and discusses useful ancillary tests. Potential diagnostic pitfalls are highlighted, and helpful hints are provided to successfully navigate challenging situations. Finally, the article looks forward to new ancillary tests on the horizon and future topics for HSCR research.

Should the search for ganglia in the distal rectal fistula in patients with anorectal malformation be abandoned?

PURPOSE

Occurrence of Hirschsprung's disease in anorectal malformation (ARM) patients is rare, but many surgeons still ask to pathologists to search for ganglia in the terminal rectum/fistula; the histological procedure is time and money consuming and the results confounding. A consecutive series of ARM patients, in which the presence of ganglia in terminal rectum was revised, is herein presented.

MATERIALS AND METHODS

Rectal specimens of ARM patients who underwent corrective surgery in the last 6 years were retrieved. The histological protocol included H&E staining and calretinin immunohistochemistry. Each specimen is processed until all material is examined if no ganglia are retrieved after the first twelve sections.

RESULTS

Forty cases were examined. Eight patients were younger than 1 month of age at operation. The mean length of the specimen was 1.5cm (range: 1-3 cm). Upon clinical request, ganglia were searched in 15/40 cases (37.5%) and resulted absent in 10/15 (66.5%). All patients have been followed and none developed signs or symptoms suggestive for Hirschsprung.

CONCLUSIONS

The practice to search for ganglia in the terminal rectum/fistula in ARM patients should be abandoned, as incidence of associated colorectal diseases is rare. Moreover, the procedure is expensive both in terms of laboratory's reagents and working time of expert pathologists and technicians.

LEVEL OF EVIDENCE

Level IV (Case Series with no Comparison Group).

Histopathological perspective of the pulled-through colon in Hirschsprung disease: Impact on clinical outcome

BACKGROUND

The outcome in HD has not been always satisfactory even after a technically sound operation.

PURPOSE

To define the characteristic histopathological features of the pulled-through colon in patients with HD, and it is impact on clinical outcome.

PATIENTS AND METHODS

The study included patients with HD who underwent surgical repair between 2010 through 2016. The proximal margin of resected bowel segments (which corresponds to the pulled through colon) was subjected to detailed histopathological examination by two experienced pathologists. Based on the frequency of postoperative attacks of HAEC (fever, vomiting, abdominal distention, fluid offensive stools), cases included in the study were divided into two groups: Group A, those with less frequent attacks of HAEC; and Group B, those with recurrent attacks of HAEC (more than 3).

RESULTS

The study included 35 patients (25 in group A; and 10 in group B). Their age ranged from 0.2 to 144 months (median 6 months). Comparing the histopathological findings in the two clinical groups, we have found that Group B (recurrent attacks of HAEC) had significantly more frequent focal disarray of nerve bundles and thicker nerve bundle diameter. Also, histopathological features of acute inflammation were more prevalent in examined specimens from group B.

CONCLUSION

Several histopathological features of the examined bowel specimens in HD, other than presence or absence of ganglion cells, are indicative of postoperative functional outcome. These include the thickness and maturity of nerve bundles, in addition to the presence of histopathological features of acute inflammation.

LEVEL OF EVIDENCE

This is a case control study (level III evidence).

Cholinergic innervation and ganglion cell distribution in Hirschsprung's disease

Background

The diagnostic gold standard of Hirschsprung’s disease (HD) is based on the histopathological assessment of colorectal biopsies. Although data on cholinergic innervation and ganglion cell (GC) distribution exist, only few studies have examined these two key features together. We assessed the pattern of cholinergic innervation and the amount of GCs in colorectal specimens of 14 HD patients.

Methods

We established a semi-quantitative score for cholinergic innervation using acetylcholinesterase (AChE) enzyme histochemistry and quantitatively analyzed the number of GCs via NADH tetrazolium reductase (NADH) enzyme histochemistry. We examined both the entire length of the resected specimens as well as defined areas of the transition zone of both pathological and healthy appearing segment.

Results

High AChE score values were associated with absence of GCs, and AChE scores were inversely correlated with the number of GCs. Nevertheless, we observed several cases in which one of the two features revealed a normal distribution pattern, whereas the other still displayed pathological features.

Conclusions

Our data support the need for transmural colon biopsies, to enable the best evaluation of both cholinergic innervation and GCs for a reliable assessment of HD.

Resection margin histology may predict intermediate-term outcomes in children with rectosigmoid Hirschsprung disease

INTRODUCTION

Recent studies suggest that some of the post-surgical morbidity in Hirschsprung disease (HSCR) is due to enteric nervous system structural defects in the proximal, ganglionated bowel that remains after surgery. We hypothesized that resection margin histology would predict intermediate-term outcomes in HSCR patients.

METHODS

Following IRB approval, HSCR patients with rectosigmoid disease born between 2009 and 2016 were reviewed and tissue blocks were obtained for new analyses. Proximal resection margins were analyzed for ganglion size, Hu + neurons/ganglion, and % nitric oxide synthase (NOS) neurons/ganglion as compared to control (non-HSCR) patient samples. Chart reviews were performed for 1- and 2-year outcomes. Patients were contacted for survey to determine Rintala bowel function score.

RESULTS

45 patients had recto-sigmoid disease and were further analyzed. HSCR patients had significantly smaller individual ganglion size (4533 μm², range 1744-16,287 vs. 6492 μm², range 1932-30,838, p = 0.0192) and fewer HuC/D + neurons per ganglion (15, range 5.2-34 vs. 21, range 5.2-6.7, p = 0.0214). HSCR patients demonstrated a markedly increased percentage of NOS (relaxation neurotransmitter) neurons (50, range 22-85 vs. 37, range 16-80, p = 0.0266). None of the histology measures correlated with presence/absence of constipation at 1-2 year follow-up (p = NS). However, smaller ganglion size and higher percentage of NOS neurons correlated with decreased patient-reported quality of life (r = 0.3838, r =  - 0.1809).

CONCLUSION

1-2 year follow-up may be insufficient to determine if resection margin histology correlates with outcomes. Patient-reported quality of life surveys, although limited in number, suggest that neurotransmitter imbalance at the resection margin may predict poor outcomes in HSCR patients. This study supports the concept that the ganglionated portion of the remaining colon post-surgery may not sustain normal bowel function.

A study on genetic polymorphism of RET proto-oncogene in Hirschsprung's disease in children

BACKGROUND

Hirschsprung's disease (HD) is a genetic disorder with a complex pattern of inheritance. Some single-nucleotide polymorphisms (SNPs) are identified to be associated with the risk of Hirschsprung's Disease (HSCR).

AIMS AND OBJECTIVES

The aim of this study is to know the association between the rearranged during transfection (RET) proto-oncogene polymorphism and HD and to characterize the SNPs of RET proto-oncogene affecting HD.

MATERIALS AND METHODS

The study was conducted in the Department of Pathology in association with the Department of Pediatric Surgery. Blood samples were collected from the patients diagnosed with confirmed HD and from age- and sex-matched controls. This case-control study consisted of 53 HSCR cases and 50 controls. Genotypes of rs1800860 and rs1800861 were analysed in by polymerase chain reaction amplification and sanger sequencing. Associations with the risk of HSCR were estimated by odds ratio (OR) and their 95% confidence intervals (95% CI) using.

RESULTS

We observed that in the case of rs1800860A > G genotype AG was not associated with the increasing risk of disease (OR with 95% CI = 0.568 [0.238-1.356]) while genotype GG was associated with increasing the risk of the disease (OR with 95% CI = 2.278 [0.967-5.366]). In the case of rs1800861G > T genotype GT was associated with lowering the risk of the disease (OR with 95% CI = 0.230 [0.0981-0.539]) while genotype TT was associated with increasing the risk of the disease (OR with 95% CI = 9.647 [3.830-24.302]). The difference in the genotypic distribution of GT and TT at rs1800861G > T between Short segment disease (SSD) cases and Long Segment Disease (LSD) and total colonic aganglionosis was made by Fisher's exact test and it was statistically significant (P = 0.0476 and 0.0054).

CONCLUSION

The results of this study support the hypothesis that variations in RET pathway might play an important role in the development of HSCR.

Decreased expression of TRAAK channels in Hirschsprung's disease: a possible cause of postoperative dysmotility

AIM OF THE STUDY

Potassium (K⁺) channels with a two-pore domain (K2P) are a large family of hyperpolarising ion channels which play a key role in cell excitability. This family comprises three members: TREK-1, TREK-2 and TRAAK. TRAAK channels have previously been reported to be expressed in murine enteric ganglia. To date, no data exist regarding TRAAK channel expression in the human colon. Thus, we designed this study to investigate TRAAK gene expression in the normal human colon and in Hirschsprung's disease (HSCR).

METHODS

HSCR tissue specimens (n = 6) were collected at the time of pull-through surgery, while control samples were obtained at the time of colostomy closure in patients with imperforate anus (n = 6). qRT-PCR analysis was undertaken to quantify TRAAK gene expression, and immunolabelling of TRAAK proteins was visualized using confocal microscopy.

MAIN RESULTS

Confocal microscopy revealed TRAAK protein expression within both neurons and interstitial cells of Cajal in the myenteric plexus, with a reduction in both ganglionic HSCR colon and aganglionic HSCR colon, compared to controls. qRT-PCR analysis revealed a significant downregulation of the TRAAK gene in both aganglionic and ganglionic HSCR specimens compared to controls (p < 0.05).

CONCLUSIONS

TRAAK gene expression is significantly downregulated in HSCR colon, suggesting a role for these ion channels in colonic neurotransmission. TRAAK downregulation within ganglionic specimens highlights the dysfunctional nature of ganglia in this region.

The Extent of the Transition Zone in Hirschsprung Disease

BACKGROUND

Retained transition zone is a leading cause of obstructive symptoms after pull-through operation in Hirschsprung's disease.

OBJECTIVE

We aimed to evaluate the extent of the histological transition zone in patients with Hirschsprung's disease.

DESIGN

We performed an observational study. DAB+ immunohistochemistry for Protein Gene Product 9.5 was used to evaluate the neuronal networks in serial sections of pull-through specimens obtained from children with Hirschsprung's disease (n = 12). Reference ranges for ganglion size/density and nerve trunk diameter were statistically determined using healthy controls obtained from colostomy specimens from children with anorectal malformations (n = 8). The transition zone was defined as ganglionic bowel exhibiting ganglion hypoplasia, hypertrophic nerve trunks, or partial circumference aganglionosis.

RESULTS

The mean submucosal nerve trunk diameter in controls was 19.56 μm +/- 3.87 μm. The median age at pull-through for Hirschsprung's disease was 5 months (3-14 months). The median length of the transition zone across the population was 8 cm (4-22 cm). Median transition zone extent was significantly longer in patients with long-segment aganglionosis (n = 6) compared to rectosigmoid aganglionosis (n = 6, 13 cm vs 6 cm, p = 0.041). Due to the age of the patients enrolled, long-term follow-up of bowel function is not yet available.

CONCLUSION

Our data suggest that, in children with rectosigmoid Hirschsprung's disease, the transition zone can extend for up to 13 cm. In children with long-segment disease, a longer transition zone is possible. Extended resection at a minimum 5 cm beyond the most distal ganglionic intra-operative biopsy and intra-operative histological examination of the proximal resection margin are required to minimize transition zone pull-through.

LEVEL OF EVIDENCE

2.

Guidelines for synoptic reporting of surgery and pathology in Hirschsprung disease

BACKGROUND/PURPOSE

Synoptic, or standardized, reporting of surgery and pathology reports has been widely adopted in surgical oncology. Patients with Hirschsprung disease may experience morbidity related to surgical factors or underlying pathology and often undergo multiple operations. Our aim is to improve the postoperative outcome and care of patients with Hirschsprung disease by proposing a standardized set of data that should be included in every surgery and pathology report.

METHODS

Members of the American Pediatric Surgical Association Hirschsprung Disease Interest Group and experts in pediatric pathology of Hirschsprung disease participated in group discussions, performed literature review and arrived at expert consensus guidelines for surgery and pathology reporting.

RESULTS

The importance of accurate operative and pathologic reports and the implications of inadequate documentation in patients with Hirschsprung disease are discussed and guidelines for standardizing these reports are provided.

CONCLUSIONS

Adherence to the principles of reporting for operations and surgical pathology may improve outcomes for Hirschsprung disease patients and will facilitate identification of correlations among morphology, function, genetics and outcomes, which are required to improve the overall management of these patients.

LEVEL OF EVIDENCE

V.

Distal rectal skip segment Hirschsprung disease: Case report and review of literature

Background: Lack of ganglion cells on adequate suction rectal biopsy is the gold standard for diagnosis of neonatal Hirschsprung disease (HD), and the presence of ganglion cells precludes such a diagnosis. Case report: A 10-day old male neonate presented with clinical symptoms concerning for HD. However, suction rectal biopsies demonstrated submucosal ganglion cells on the distal suction rectal biopsies (2 cm from anal verge) and not on the proximal (3 cm from anal verge), with similar findings on repeat biopsies. Clinical suspicion remained high, and diagnostic laparoscopy with intraoperative biopsies confirmed aganglionosis with a sigmoid transition. A pull through resection confirmed the diagnosis of distal rectal skip segment HD (SSHD) with a ∼6 cm length of circumferential aganglionosis extending into the proximal sigmoid. Conclusions: Discordant results on suction rectal biopsies should raise the possibility of SSHD. Awareness of the entity can facilitate timely definitive management in neonatal period.

Altered ryanodine receptor gene expression in Hirschsprung's disease

AIM OF THE STUDY

Ryanodine receptors are the largest of all ion channels, named after their exogenous ligand, ryanodine. The ryanodine receptor calcium release channel is central to cytoplasmic Ca²⁺ signalling in skeletal muscle, the heart, and many other tissues, playing a vital role in muscular contraction. Three ryanodine receptors exist, Ryr1, Ryr2 and Ryr3. The ryanodine receptor, Ryr3, is encoded by the Ryr3 gene, which has been reported to be highly specific to colonic smooth muscle cells in mice. We designed this study to investigate Ryr1, Ryr2 and Ryr3 gene expression in the normal human colon and in Hirschsprung's disease (HSCR).

METHODS

HSCR tissue specimens (n = 6) were collected at the time of pull-through surgery, while control samples were obtained at the time of colostomy closure in patients with imperforate anus (n = 6). qRT-PCR analysis was undertaken to quantify Ryr1, Ryr2 and Ryr3 gene expression, and immunolabelling of Ryr1, Ryr2 and Ryr3 proteins was visualised using confocal microscopy.

MAIN RESULTS

qRT-PCR analysis revealed a significant downregulation of the Ryr1 and Ryr3 genes in both aganglionic and ganglionic HSCR specimens compared to controls (p < 0.05). Confocal microscopy revealed Ryr1, Ryr2 and Ryr3 protein expressions within the smooth muscle, with a reduction in aganglionic and ganglionic HSCR colon compared to controls.

CONCLUSIONS

Ryr1 and Ryr3 gene expression is significantly downregulated in HSCR colon, suggesting a role for these genes in colonic smooth-muscle motility. Ryr1 and Ryr3 downregulations within ganglionic specimens highlight the physiologically abnormal nature of this segment which may explain the occurrence of persistent bowel symptoms in some HSCR patients following a properly performed pull-through operation.

Delayed appearance of mature ganglia in an infant with an atypical presentation of total colonic and small bowel aganglionosis: a case report

Background

Total colonic and small bowel aganglionosis (TCSA) occurs in less than 1% of all Hirschsprung’s disease patients. Currently, the mainstay of treatment is surgery. However, in patients with TCSA, functional outcomes are often poor. A characteristic transition zone in TCSA can be difficult to identify which may complicate surgery and may often require multiple operations.

Case presentation

We present the case of a male infant who was diagnosed with biopsy-proven total colonic aganglionosis with extensive small bowel involvement as a neonate. The patient was diverted at one month of age based on leveling biopsies at 10 cm from the Ligament of Treitz. At 7 months of age, during stoma revision for a prolapsed stoma, intra-operative peristalsis was observed in nearly the entire length of the previously aganglionic bowel, and subsequent biopsies demonstrated the appearance of mature ganglion cells in a previously aganglionic segment.

Conclusions

TCSA remains a major challenge for pediatric surgeons. Our case introduces new controversy to our understanding of aganglionosis. Our observations warrant further research into the possibility of post-natal ganglion maturation and encourage surgeons to consider a more conservative surgical approach.

Controlled outcome of Hirschsprung's disease beyond adolescence: a single center experience

PURPOSE

The aim of this study was to assess the function and quality of life of Hirschsprung's Disease (HD) beyond adolescence and relate it to matched controls.

METHODS

All 203 patients diagnosed with HD at our department from 1961 to 1995 were identified. 21 had died, 43 had unclear diagnosis and 16 could not be traced. The remaining 123 patients were sent bowel function and SF-36 quality of life questionnaires. 69 patients (mean age 37.8, range 22-58, 13 female) responded and were matched with 138 age and sex-matched controls.

RESULTS

Function: HD-patients had significantly higher number of bowel movements per week, higher incidence of soiling, urgency, permanent stomas, use of laxatives, enemas and loperamide. HD-patients also scored significantly lower in their satisfaction with their bowel function. There was, however, no significant difference in Miller Incontinence score. QOL: HD-patients reported a significantly higher incidence of negative impact by their bowel function on daily life, social interaction and ability to go on vacation. There were no significant differences in SF-36-scores.

CONCLUSIONS

Bowel function has a lifelong negative impact on the lives of patients with HD. This strongly indicates a need for structured follow-up beyond adolescence.

Gfra1 Underexpression Causes Hirschsprung's Disease and Associated Enterocolitis in Mice

BACKGROUND & AIMS

RET, the receptor for the glial cell line-derived neurotrophic factor (GDNF) family ligands, is the most frequently mutated gene in congenital aganglionic megacolon or Hirschsprung's disease (HSCR). The leading cause of mortality in HSCR is HSCR-associated enterocolitis (HAEC), which is characterized by altered mucin composition, mucin retention, bacterial adhesion to enterocytes, and epithelial damage, although the order of these events is obscure. In mice, loss of GDNF signaling leads to a severely underdeveloped enteric nervous system and neonatally fatal kidney agenesis, thereby precluding the use of these mice for modeling postnatal HSCR and HAEC. Our aim was to generate a postnatally viable mouse model for HSCR/HAEC and analyze HAEC etiology.

METHODS

GDNF family receptor alpha-1 (GFRa1) hypomorphic mice were generated by placing a selectable marker gene in the sixth intron of the Gfra1 locus using gene targeting in mouse embryonic stem cells.

RESULTS

We report that 70%-80% reduction in GDNF co-receptor GFRa1 expression levels in mice results in HSCR and HAEC, leading to death within the first 25 postnatal days. These mice mirror the disease progression and histopathologic findings in children with untreated HSCR/HAEC.

CONCLUSIONS

In GFRa1 hypomorphic mice, HAEC proceeds from goblet cell dysplasia, with abnormal mucin production and retention, to epithelial damage. Microbial enterocyte adherence and tissue invasion are late events and therefore unlikely to be the primary cause of HAEC. These results suggest that goblet cells may be a potential target for preventative treatment and that reduced expression of GFRa1 may contribute to HSCR susceptibility.

Single-stage laparoscopic transanal pull-through modified Swenson procedure without leaving a muscular cuff for short- and long-type Hirschsprung disease: a comparative study

PURPOSE

The Soave procedure (SO) is performed most commonly for Hirschsprung disease. SO reduces the risk of injury to the pelvic structures; however, a residual aganglionic muscle cuff could interfere with bowel movement and lead to obstructive enterocolitis. The Swenson procedure is considered ideal in terms of peristalsis. Currently, laparoscopic surgery provides better visualization and facilitates precise dissection, possibly leading to feasible performance of the laparoscopic modified Swenson procedure (SW). We present our operative technique and the efficacy of the SW compared with that of SO.

METHODS

We retrospectively reviewed the records of 16 and 27 patients who underwent SW and SO, respectively, between 2012 and 2017.

RESULTS

Operative time, blood loss, length of stay, and frequency of bowel movements showed no significant difference between the two groups. In the SW group, temporary dysuria occurred in one patient, postoperative enterocolitis in two, wound infection in one, and severe perianal excoriation in four, whereas in the SO group, obstructive symptoms occurred in three patients, small-bowel obstruction in one, and severe perianal excoriation in three. The complications and outcomes were comparable between both groups.

CONCLUSION

Laparoscopic SW was safe and feasible for the short-term follow-up outcomes.

Full-thickness rectal biopsy in children suspicious for Hirschsprung's disease is safe and yields a low number of insufficient biopsies

INTRODUCTION

The diagnosis of Hirschsprung's disease (HD) relies on the histological demonstration of aganglionosis in the bowel wall. Biopsies may be obtained by rectal suction biopsy (RSB) or by transanal full-thickness excision biopsy (FTB). The objective of the present study was to evaluate the frequency of complications and inconclusive biopsies after FTB in children referred with suspicion of HD. The secondary objective was to calculate the frequency of proven aganglionosis.

METHODS

A retrospective chart review was performed of all patients under the age of 16years who underwent transanal FTB during the time period of 2008-2014.

RESULTS

A total of 555 patients were included in the review. Inconclusive biopsies were found at the primary biopsy in 35 patients (5.9%). Aganglionosis was found in 12% of the cases. The complication rate was 6.6% (39 patients), 85% of which were classified as a Clavien-Dindo I-II and 15% were classified as Clavien-Dindo III.

CONCLUSIONS

In this retrospective evaluation of FTB for the diagnosis of HD, the frequency of inconclusive biopsies at primary attempt was low and the complication rate was relatively high. However, most were minor complications.

LEVEL OF EVIDENCE

III.

Are all patients with short segment Hirschsprung's disease equal? A retrospective multicenter study

BACKGROUND/PURPOSE

Short segment Hirschsprung's disease (HSCR) carries a better prognosis than long segment disease, but the definition of short is controversial. The objective of this study is to determine anatomically the extent of disease involvement that would be associated with a better functional outcome.

METHODS

This is a retrospective multicenter (n = 3) study with patients (≥ 3 years) who had transanal pullthrough operation done for aganglionosis limited to the recto-sigmoid colon were reviewed. The extent of disease involvement and bowel resection was retrieved by reviewing the operative records as well as histopathological reports of the resected specimens. Clinical assessment was performed according to the criteria of a seven-itemed bowel function score (BFS) (maximum score = 20). Manometric assessment was performed with anorectal manometry.

RESULTS

The study period started from 2003 to 45 patients were studied with median age at assessment = 52.0 months and operation = 3.0 months. The disease involvement was categorized into upper sigmoid-descending colon (DC) (n = 8), sigmoid colon (SC) (n = 12), upper rectum (UR) (n = 14) and lower rectum (LR) (n = 11) according to the level of normal biopsy result. There was no significant difference in the age of assessment between the four groups. The median BFSs in the DC, SC, UR and LR were 13, 15, 17 and 17, respectively (p = 0.01). Nine patients from the DC and SC groups reported soiling for more than twice per week. Sub-group analysis comparing patients with and without the entire sigmoid colon resected revealed worse functional outcomes in terms of the incidence of soiling (40.7 vs 22.2%, p = 0.05) and the BFS (14 vs 18, p = 0.04) in the former group. Anorectal manometry did not reveal any significant difference between the four groups, but a higher proportion of patients in the UR and LR groups appeared to have a normal sphincter resting pressure (DC vs SC vs UR vs LR = 62.5 vs 75.0 vs 85.7 vs 80.0%, p = 0.10).

CONCLUSION

Patients with short segment HSCR are not equal at all. HSCR patients with aganglionosis limited to the rectum without the need of removing the entire sigmoid colon have a better bowel control and overall functional score. Less bowel loss and colonic dissection maybe the underlying reasons. Although future studies with a larger sample size and a longer follow-up period are required to validate the results of this study, it has provided a new insight to the current understanding of short segment disease in HSCR.

Pathologically assessed grade of Hirschsprung-associated enterocolitis in resected colon in children with Hirschsprung's disease predicts postoperative bowel function

PURPOSE

The aim of this study was to investigate the relationship between the grade of enterocolitis on pathological assessment of resected colon and postoperative bowel function in children with Hirschsprung's disease (HD).

METHODS

Children with HD who were seen at a large tertiary center from January 2012 to December 2013 were enrolled into this study. Resected colon was assessed using the histopathologic grade scoring system for Hirschsprung-associated enterocolitis (HAEC), and the relationship of these scores to postoperative bowel function was assessed. Time of recovery to normal defecation was the primary outcome measure. The t-test, analysis of variance, and Kaplan-Meier, univariate, and multiple regression analyses were performed.

RESULTS

Eighty children with HD (median age at repair 7.9months; range 1.3months to 9years) were included in the study. Nineteen children dropped out of the study and were considered as providing censored data, giving a follow-up rate of 76.3%. A total of 21 children (34.4%) were admitted to hospital with at least one episode of enterocolitis. Multivariate Cox proportional hazards models showed that compared with patients with a normal proximal colon, those with an inflamed proximal segment had a 1.5-fold higher risk of a poor recovery. Logistic regression analyses suggested that postoperative HAEC admissions increased by 57% with each HAEC pathological grade of the transitional segment and by 50% with each grade of the overall segment. Compared with normal bowel in the transitional segment, the detection of grade ≥3 HAEC in the transitional area increased the incidence of postoperative HAEC by 4.75-fold.

CONCLUSIONS

Children whose resected proximal colon showed inflammation on pathological assessment were at risk of poor recovery after surgery. A higher pathological HAEC score for the sum of the overall three segments suggested an increased risk for the subsequent development of enterocolitis. Among three segments, the severity of enterocolitis in the transitional segment was the most significant factor in predicting postoperative HAEC.

TYPE OF STUDY

Clinical study.

LEVEL OF EVIDENCE

Moderate.

Hirschsprung's disease in twins: a systematic review and meta-analysis

AIM OF THE STUDY

Hirschsprung's disease (HSCR) is known to occur in families. The reported overall incidence of familial cases is 7.6%, with a higher incidence of 15-21% in total colonic aganglionosis and 50% in the rare total intestinal aganglionosis. HSCR is extremely rare in twins. The aim of this study was to systematically analyse the patterns of HSCR in twins published in the literature.

METHODS

Electronic databases Pubmed and Medline were screened for relevant articles using the keywords "Hirschsprung's disease", "aganglionosis", "twins", "monozygotic", and "dizygotic". Examining reference lists identified further relevant papers.

MAIN RESULTS

Twelve studies with a total of 18 twin pairs were included in this analysis. 67% twins were discordant. HSCR was found in 24 out of 36 twin subjects (67%), of which 83% affected were male. Rectosigmoid type was reported in 71% of patients, long-segment disease in 21, and 8% presented with a total aganglionosis. Three twin pairs had at least one family member affected with HSCR.

CONCLUSION

HSCR was found in two-thirds of twin subjects with a male predominance. Rectosigmoid aganglionosis was the most common variant. Disease discordance was identified, where environmental insults were postulated to be predisposing factors to disease expression. Future studies investigating the disease-associated mutations in the already identified HSCR genes should provide insights into the genetic basis of HSCR in twins.

Guidelines for the management of postoperative obstructive symptoms in children with Hirschsprung disease

Although most children with Hirschsprung disease ultimately do well, many experience a variety of ongoing problems after pull-through surgery. The most common include obstructive symptoms, soiling, enterocolitis and failure to thrive. The purpose of this guideline is to present a rational approach to the management of postoperative obstructive symptoms in children with Hirschsprung disease. The American Pediatric Surgical Association Board of Governors established a Hirschsprung Disease Interest Group. Group discussions, literature review and expert consensus were then used to summarize the current state of knowledge regarding causes, methods of diagnosis, and treatment approaches to children with obstructive symptoms following pull-through for Hirschsprung disease. Causes of obstructive symptoms post-pull-through include mechanical obstruction; persistent or acquired aganglionosis, hypoganglionosis, or transition zone pull-through; internal sphincter achalasia; disordered motility in the proximal intestine that contains ganglion cells; or functional megacolon caused by stool-holding behavior. An algorithm for the diagnosis and management of obstructive symptoms after a pull-through for Hirschsprung disease is presented. A stepwise, logical approach to the diagnosis and management of patients experiencing obstructive symptoms following pull-through for Hirschsprung disease can facilitate treatment. Level of evidence V.

Long-term results of the Duhamel technique are superior to those of the transanal pullthrough: A study of fecal continence and quality of life

BACKGROUND/PURPOSE

The Duhamel and transanal pull-through (TAPT) techniques have been commonly used for the treatment of children with Hirschsprung disease (HD). However, despite adequate treatment, some patients present with fecal incontinence that severely affects the quality of life (QoL) and lead to psychiatric disorders. The objectives of the present study were to evaluate, through previously adapted questionnaires, the incidence of fecal incontinence and the quality of life (QoL) of children with HD who underwent Duhamel or TAPT techniques. In addition, we compared the incidence of fecal incontinence and QoL indices in these patients with those in healthy children.

MATERIALS/METHODS

The Fecal Continence Index (FCI) questionnaire and the questionnaire for the Assessment of Quality of Life in Children and Adolescents with Fecal Incontinence (AQLCAFI) were used in this study. A series of 41 patients with HD were divided into 2 groups according to the utilized surgical technique: the Duhamel group (20 patients) and the TAPT group (21 patients). The patients were compared with a control group of 59 healthy children.

RESULTS

In the control group, 25 (42.4%) children had good continence and 34 (57.6%) had normal continence. In contrast, among patients with HD, 4 (9.8%) had poor fecal continence, 11 (26.8%) had fair continence, 18 (43.9%) had good continence, and 8 (19.5%) had normal continence. The QoL of children with HD was globally impaired in all domains of the AQLCAFI as well as in the FCI, when compared with the QoL of healthy children (P=0.001). The comparison between children who underwent surgery with the Duhamel technique and those who underwent surgery with TAPT technique showed similar outcomes according to the FCI. However, the results were inferior in patients who underwent TAPT technique according to the AQLCAFI questionnaire (P=0.003), lifestyle (P=0.006), behavior (P=0.01), depression (P=0.01), and embarrassment (P=0.003).

CONCLUSION

The QoL and the FCI were impaired in patients who underwent surgery for correction of HD compared with healthy children; however, the impairment in QoL was greater in patients who underwent TAPT technique.

LEVEL OF EVIDENCE

2B.

Expression of connexin 26 and connexin 43 is reduced in Hirschsprung's disease

BACKGROUND

Despite having an optimal pull-through operation, some children with Hirschsprung's disease (HSCR) continue to experience persistent bowel symptoms. Coordinated colonic electrical activity depends on intercellular communication between the enteric nerves, interstitial cells of Cajal (ICCs), smooth muscle cells, and fibroblast-like (platelet-derived growth factor receptor-alpha-positive) cells. Gap junctions are low-resistance channels composed of connexin (Cx) proteins which couple cells electrically and chemically. We aimed to evaluate the expression patterns of Cx26, Cx36, and Cx43 in the colon of children with HSCR and in healthy control colon.

MATERIALS AND METHODS

Entire resected colonic specimens were collected from children undergoing pull-through surgery for HSCR (n = 10). Colonic controls were collected at colostomy closure in children with imperforate anus (n = 8). Distribution of Cx26, Cx36, and Cx43 was assessed using double-labeled immunofluorescence and confocal microscopy. Protein expression was quantified using Western blot analysis.

RESULTS

Sparse punctate Cx36 expression was seen in the myenteric plexus in nerve trunks and some platelet-derived growth factor receptor-alpha-positive cell and ICC fibers. Cx26 was similarly distributed, although it was not coexpressed in ICCs. Cx43 was only coexpressed with ICCs in the myenteric plexus. Expression of Cx26 and Cx43 was markedly reduced in the aganglionic colon in HSCR compared to controls, while Cx26 expression was also moderately reduced in the ganglionic bowel in HSCR.

CONCLUSIONS

Reduced expression of Cx26 and Cx43 is implicated in the pathophysiology of colonic dysmotility in the aganglionic bowel as well as, in the case of Cx26, the ganglionic bowel in HSCR.

Submucosal nerve diameter of greater than 40 μm is not a valid diagnostic index of transition zone pull-through

BACKGROUND

Submucosal nerve hypertrophy is a feature of the transition zone in Hirschsprung disease and has been used as a primary diagnostic feature of transition zone pull-through for patients with persistent obstructive symptoms after their initial surgery. Most published criteria for identification of hypertrophy rely on a nerve diameter of greater than 40μm, based primarily on data from a relatively small number of infants with Hirschsprung disease and controls. The validity of these objective measures has not been validated in appropriate controls for post-pull-through patients.

SCIENTIFIC APPROACH

The primary pull-through specimens and post pull-through biopsies +/- redo pull-through resections from a series of 9 patients with Hirschsprung disease were reviewed to assess the prevalence of submucosal nerves >40μm in diameter and 400× microscopic fields containing two or more such nerves. Similar data from multiple colonic locations were collected from a series of 40 non-Hirschsprung autopsy and surgical controls.

RESULTS

The overwhelming majority of Hirschsprung patients harbored submucosal nerves >40μm in their post-pull-through specimens independent of other features of transition zone pathology, and despite normal innervation at the proximal margins of their initial resections. Measurement of submucosal nerve diameters in autopsy and surgical non-Hirschsprung control samples indicated that nerves >40μm are normal in the distal rectum after 1year of age and are found in more proximal colon at older ages.

CONCLUSIONS

These results suggest that diagnostic criteria currently used to recognize submucosal nerve hypertrophy in the neorectum after a pull-through for Hirschsprung disease are not justified and should not be regarded as definitive evidence for transition zone pull-through.

Long-term results of transanal pull-through for Hirschsprung's disease: a meta-analysis

INTRODUCTION

Several operative techniques have been developed for the treatment of Hirschsprung's disease (HD) in the past decades. Since one-stage transanal pull-through (TAPT) was first performed in 1998, multiple studies have shown favourable short-and midterm results compared to other techniques with shorter operation length, shorter hospital stay and lower complication rates. The aim of this meta-analysis was to determine the longterm results following TAPT for HD.

METHODS

A systematic literature search for relevant articles was performed in four databases using the following terms "Hirschsprung/Hirschsprung's disease", "aganglionosis", "transanal", "pullthrough/pull-through", "longterm/long-term" "results", "follow-up" and "outcome". A meta-analysis was conducted for relevant articles for one-stage transanal pull-through for HD with a minimal follow-up of median 36 months regarding constipation, incontinence/soiling, enterocolitis and secondary operations. Odds ratio (OR) with 95 % confidence intervals (CI) were calculated.

RESULTS

Six studies with 316 patients matched the set criteria and were included in this analysis. Overall 45 (14.2 %) patients had disturbances of bowel function (OR 0.05, 95 % CI 0.03-0.07, p < 0.00001). Of these, 24 (53.3 %) patients experienced constipation, 8 (17.8 %) incontinence/soiling and 13 (28.9 %) enterocolitis. 10 (3.2 %) patients developed complications requiring secondary surgery. Most patients had a daily defecation frequency of 1-3 bowel movements 3 years postoperatively, resembling the stooling patterns of healthy controls.

CONCLUSION

Nearly 15 % of all patients operated with TAPT for HD continue to experience persistent bowel symptoms with constipation as the main problem. Further studies on the long-term outcome of children operated with this technique for HD are necessary to evaluate stooling patterns, urinary and sexual function as well as general quality of life during adolescence and adulthood.

Genetics of enteric neuropathies

Abnormal development or disturbed functioning of the enteric nervous system (ENS), the intrinsic innervation of the gastrointestinal tract, is associated with the development of neuropathic gastrointestinal motility disorders. Here, we review the underlying molecular basis of these disorders and hypothesize that many of them have a common defective biological mechanism. Genetic burden and environmental components affecting this common mechanism are ultimately responsible for disease severity and symptom heterogeneity. We believe that they act together as the fulcrum in a seesaw balanced with harmful and protective factors, and are responsible for a continuum of symptoms ranging from neuronal hyperplasia to absence of neurons.

Deficiency of platelet-derived growth factor receptor-α-positive cells in Hirschsprung's disease colon

AIM: To investigate whether the expression of platelet-derived growth factor receptor-α-positive (PDGFRα⁺)-cells is altered in Hirschsprung’s disease (HD).

METHODS: HD tissue specimens (n = 10) were collected at the time of pull-through surgery, while colonic control samples were obtained at the time of colostomy closure in patients with imperforate anus (n = 10). Immunolabelling of PDGFRα⁺-cells was visualized using confocal microscopy to assess the distribution of these cells, while Western blot analysis was undertaken to quantify PDGFRα protein expression.

RESULTS: Confocal microscopy revealed PDGFRα⁺-cells within the mucosa, myenteric plexus and smooth muscle in normal controls, with a marked reduction in PDGFRα⁺-cells in the HD specimens. Western blotting revealed high levels of PDGFRα protein expression in normal controls, while there was a striking decrease in PDGFRα protein expression in the HD colon.

CONCLUSION: These findings suggest that the altered distribution of PDGFRα⁺-cells in both the aganglionic and ganglionic HD bowel may contribute to the motility dysfunction in HD.

Aganglionosis with the absence of hypertrophied nerve fibres predicts disease proximal to rectosigmoid colon

PURPOSE

The gold standard for the diagnosis of Hirschsprung's disease (HSCR) is the pathologic evaluation of a rectal biopsy that demonstrates the absence of ganglion cells and nerve fibre hypertrophy. However, it has been frequently reported that hypertrophic nerves may not be present in some variants like long-segment HSCR, total colonic aganglionosis, premature and very young infants. The aim of this study was to determine this association.

METHODS

We performed a retrospective review of the HSCR database at our tertiary care children's hospital from 2000 to 2013. In order to analyse the relationship between the diameter of the nerve fibres and the level of aganglionosis, we classified the patient sample into two groups-fibres ≤40 and >40 μm. The groups were statistically compared with P < 0.05 being significant.

RESULTS

Rectal biopsies of 92 patients confirmed as HSCR with definitive operation performed at the same institution were reviewed. The mean nerve diameter was 50.1 μm (range 20-87.5 μm). Nerve fibre diameter ≤40 μm was predictive of transition zone above the sigmoid colon. A specificity of 77.3 % and a likelihood ratio of 2.03 supported this perception. No correlation was noted between nerve fibre diameter and gestational age at birth, birth weight or age at biopsy.

CONCLUSION

The absence of nerve fibre hypertrophy in the presence of aganglionosis on rectal biopsy specimens is predictive of long-segment HSCR.

Use of anoctamin 1 (ANO1) to evaluate interstitial cells of Cajal in Hirschsprung's disease

PURPOSE

Interstitial cells of Cajal (ICCs) are pacemaker cells involved in facilitating neurotransmission and the generation of slow electrical waves necessary for colonic peristalsis. Their distribution has been found to be abnormal in the aganglionic and ganglionic colon in Hirschsprung's disease (HSCR) using c-kit-labelling. Anoctamin-1 (ANO1) is a Ca(2+)-activated Cl(-) channel thought to be specifically expressed on ICCs. Unlike c-kit, it plays a key role in ICC pacemaker activity. We aimed to investigate the utility of ANO1 in evaluating the colonic ICC network in HSCR.

MATERIALS AND METHODS

We collected full-length pull-through specimens from children with HSCR (n = 10). Control colon specimens were collected at colostomy closure in children with anorectal malformation (n = 6). The distribution of ANO1 and c-kit expression was evaluated using immunofluorescence and confocal microscopy. ANO1 expression was quantified using Western blot analysis.

RESULTS

ANO1 was not expressed on 23 % of c-kit immuno-positive cells in the circular muscle; however, 100 % of ANO1-positive ICCs were c-kit positive. The distribution of ANO1-positive ICCs was sparse in aganglionic colon, with a modest reduction in ICCs seen in the ganglionic colon in HSCR compared to controls (p = 0.044). ANO1 protein expression was reduced in aganglionic colon but similar in ganglionic colon relative to controls.

CONCLUSIONS

ANO1 is preferential to c-kit in evaluating the ICC network in HSCR due to its specificity and functional importance. Abnormal distribution of ANO1-positive ICCs in the ganglionic colon in HSCR may contribute to persistent bowel symptoms in some patients after pull-through surgery.

Altered fecal short chain fatty acid composition in children with a history of Hirschsprung-associated enterocolitis

PURPOSE

Children with Hirschsprung disease (HD) who have a history of enterocolitis (HAEC) have a shift in colonic microbiota, many of which are necessary for short chain fatty acid (SCFA) production. As SCFAs play a critical role in colonic mucosal preservation, we hypothesized that fecal SCFA composition is altered in children with HAEC.

METHODS

A multicenter study enrolled 18 HD children, abstracting for history of feeding, antibiotic/probiotic use, and enterocolitis symptoms. HAEC status was determined per Pastor et al. criteria (12). Fresh feces were collected for microbial community analysis via 16S sequencing as well as SCFA analysis by gas chromatography-mass spectrometry.

RESULTS

Nine patients had a history of HAEC, and nine had never had HAEC. Fecal samples from HAEC children showed a 4-fold decline in total SCFA concentration vs. non-HAEC HD patients. We then compared the relative composition of individual SCFAs and found reduced acetate and increased butyrate in HAEC children. Finally, we measured relative abundance of SCFA-producing fecal microbiota. Interestingly, 10 of 12 butyrate-producing genera as well as 3 of 4 acetate-producing genera demonstrated multi-fold expansion.

CONCLUSION

Children with HAEC history have reduced fecal SCFAs and altered SCFA profile. These findings suggest a complex interplay between the colonic metabolome and changes in microbiota, which may influence the pathogenesis of HAEC.

Rho-kinase expression in Hirschsprung's disease

BACKGROUND

Rho-kinase (ROCK) is the primary effector protein in the RhoA pathway, which regulates Ca(2+)-independent smooth muscle contraction in the human bowel. This pathway has been reported to be hyper-activated in the aganglionic bowel of EDNRB-null (-/-) rats compared to the ganglionic bowel from EDNRB (+/+) rats. We hypothesised that ROCK expression is up-regulated in human aganglionic bowel and designed this study to investigate ROCK 1 and ROCK 2 expression in Hirschsprung's disease (HSCR) and controls.

MATERIALS AND METHODS

Full-length specimens were collected following pull-through surgery for HSCR (n = 9). Colonic controls (n = 6) were obtained during colostomy closure from patients with anorectal malformations. Distribution of ROCK 1/2 expression was evaluated using double-labelled immunofluorescence and confocal microscopy. ROCK1/2 protein expression was assessed in mucosa and tunica muscularis using western blot analysis.

RESULTS

There was strong expression of both ROCK 1 and ROCK 2 in interstitial cells of Cajal (ICCs) and ganglia. ROCK 1 expression was reduced in aganglionic bowel compared to HSCR ganglionic bowel and controls in both mucosa and tunica muscularis. ROCK 2 expression was similar in the colon of children with HSCR and controls.

CONCLUSIONS

This is the first report of strong ROCK expression in colonic ICCs. Although the rat model of aganglionic bowel suggests that Ca(2+)-independent smooth muscle contraction involving ROCK is hyper-activated, our data indicate ROCK 1 expression is decreased in aganglionic bowel and ROCK 2 expression is unaltered in children with HSCR.

Enteric Neural Cells From Hirschsprung Disease Patients Form Ganglia in Autologous Aneuronal Colon

BACKGROUND & AIMS

Hirschsprung disease (HSCR) is caused by failure of cells derived from the neural crest (NC) to colonize the distal bowel in early embryogenesis, resulting in absence of the enteric nervous system (ENS) and failure of intestinal transit postnatally. Treatment is by distal bowel resection, but neural cell replacement may be an alternative. We tested whether aneuronal (aganglionic) colon tissue from patients may be colonized by autologous ENS-derived cells.

METHODS

Cells were obtained and cryopreserved from 31 HSCR patients from the proximal resection margin of colon, and ENS cells were isolated using flow cytometry for the NC marker p75 (nine patients). Aneuronal colon tissue was obtained from the distal resection margin (23 patients). ENS cells were assessed for NC markers immunohistologically and by quantitative reverse-transcription polymerase chain reaction, and mitosis was detected by ethynyl-2'-deoxyuridine labeling. The ability of human HSCR postnatal ENS-derived cells to colonize the embryonic intestine was demonstrated by organ coculture with avian embryo gut, and the ability of human postnatal HSCR aneuronal colon muscle to support ENS formation was tested by organ coculture with embryonic mouse ENS cells. Finally, the ability of HSCR patient ENS cells to colonize autologous aneuronal colon muscle tissue was assessed.

RESULTS

ENS-derived p75-sorted cells from patients expressed multiple NC progenitor and differentiation markers and proliferated in culture under conditions simulating Wnt signaling. In organ culture, patient ENS cells migrated appropriately in aneural quail embryo gut, and mouse embryo ENS cells rapidly spread, differentiated, and extended axons in patient aneuronal colon muscle tissue. Postnatal ENS cells derived from HSCR patients colonized autologous aneuronal colon tissue in cocultures, proliferating and differentiating as neurons and glia.

CONCLUSIONS

NC-lineage cells can be obtained from HSCR patient colon and can form ENS-like structures in aneuronal colonic muscle from the same patient.